Category Archives: Technology

In The Dyno Cell

“Trust but verify.”

Mercury Racing trusts technology and believes in the accuracy of all the cutting-edge computer-driven design tools at its disposal. The computer predicts the power potential of a new engine or an updated design. But that digital prediction is verified in the real world using a dynamometer, one of the most important tools in the Mercury Racing shop.

A dynamometer, or dyno, is a tool used to simultaneously measure torque against rotation and rotational speed (rpm), which is then used to calculate horsepower. The dyno can be used to generate a map of horsepower and torque curves, either through a transient sweep through the rpm range or through discrete steady-state points. For power development, Mercury Racing relies on steady-state, point-by-point power curves where the engine is held at wide-open throttle to saturate oil, air, and water temperatures. 

The Mercury Racing engineering department has six dyno cells. Two Schenck eddy-current dynamometers are dedicated to outboard engines.

Dynos at Mercury Racing are almost always in use. Mercury Racing technicians will often build the engine, instrument it, rig it on the dyno, run the dyno, and calibrate or develop the engine. The dyno is a primary development tool for Mercury Racing engine programs.

“Performance predictions, analysis in GT-Power, and computer simulations are qualified and refined by dyno data so that future predictions are more accurate,” said Mercury Racing Development Engineering Manager Chris Jenks. “A moderately instrumented engine for calibration will have about 40 thermocouples in air, exhaust, and water, and 20 pressure transducers reading everything from air-intake pressure at multiple points to exhaust back pressure to water pressures in the block and cylinder heads. Air, fuel, water, and blow-by flow rates are all measured. There are eight in-cylinder combustion pressure transducers that can be used for real-time monitoring of cylinder pressure in .10-degree increments, a useful tool for balancing cylinders and working to the edge of normal combustion. Typically, there are more than 400 raw or calculated channels of data are being recorded, reviewed, or monitored as shutdown limits as we work through development or are optimizing the calibration for an engine. The dyno allows us to run the engine consistently, week after week, at every operating point at which a customer can run the engine, and at some they can’t.”

Jenks explains that calibrating an engine is a circular process that is similar to painting a car, in which each layer of paint is followed by wet sanding and buffing to make the entire surface smoother. It’s a complex, time-consuming process. For example, there are 916 maps or required control inputs that build the calibration in the ECU (engine control unit) that operates the Mercury Racing 450R outboard. Sixty-three of those are considered base maps, whose foundation is relied on for the rest of the calibration. Those base maps contain 18,207 cells that represent roughly 7,000 discrete running conditions (rpm, load, engine temperature, ambient conditions), which are run on the dyno to rough map, check, and re-check for errors and interactions. Final calibration checks before production will go through each of those 18,000 cells point by point. 

In addition to engine development, the dynos are sometimes used for outboard exhaust emissions or power audits before they leave for customers. Warranty returns, although rare, are run on the dyno to re-create the complaint and diagnose the root cause. All sterndrive engines are run on the dynos for break-in and a power-verification run before shipping. 

Dyno development allows Mercury Racing to run an engine in a laboratory setting that captures all the extremes our customers are likely to dole out on the water. The result is a high-performance marine engine product that is powerful, reliable and refined.  

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Refined Performance

The new R-Series Outboards catalog features detailed information on our 250R, 300R and 400R outboards, propellers and accessories.

The Mercury Racing R-Series line of consumer performance outboards is simply amazing. From bass boats to flats boats, to bay boats and multi-species hulls, to performance catamarans and vee-bottoms, to center consoles and even pontoons the R-Series offers a wide array of models to fit virtually any high-performance application.

 No Replacement for Displacement

The proprietary V8 architecture is enhanced by our Quad Cam Four Valve (QC4) design with double over-head camshafts and aluminum cylinder heads that maximize airflow and power.

Every ounce of our naturally aspirated V8 4.6L FourStroke engines is devoted to wide-open exhilaration. And while 4.6 Liters is a massive amount of displacement, power density is a key to high performance, and no marine engine delivers more punch in a lighter package than our 250R and 300R FourStrokes.

Mercury Transient Spark Technology applies pre-programmed timing advance to optimize torque output for stronger hole-shot performance.

The proprietary V8 architecture is enhanced by our Quad Cam Four Valve (QC4) design with double over-head camshafts and aluminum cylinder heads that maximize airflow and power. Mercury Transient Spark Technology applies pre-programmed timing advance to optimize torque output for stronger hole-shot performance.

 Low Cost of Ownership

To squeeze more power from less fuel, the V8 FourStrokes feature Advanced Range Optimization (ARO), a closed-loop fuel-control system that utilizes electronic sensors to precisely adjust the fuel mixture for the best-possible efficiency at all speeds.

Our naturally aspirated V8 outboards run on 87-octane pump fuel. This provides a lower operating cost and the peace of mind that comes from knowing you will be able to find fuel anywhere you go. To squeeze more power from less fuel, the V8 FourStrokes feature Advanced Range Optimization (ARO), a closed-loop fuel-control system that utilizes electronic sensors to precisely adjust the fuel mixture for the best-possible efficiency at all speeds. The Quad Cam Four Valve (QC4) valve train is maintenance-free for the life of the engine.

Supercharged Superstar

The inherently balanced inline six-cylinder arrangement offers smooth operation and a slim profile on the transom, so it’s perfect for multi engine installations.

The 400R shook up the high-performance outboard world when it was introduced in 2015 and the legend has been growing ever since. This brilliant Verado design launched an outboard performance revolution, and it has become by far the most popular outboard Mercury Racing has ever produced.

The inherently balanced inline six-cylinder arrangement offers smooth operation and a slim profile on the transom, so it’s perfect for multi engine installations. Supercharged induction delivers immediate response and astonishing power, yet it’s thoroughly refined for rock-solid reliability and effortless efficiency.

Don’t Knock It

The 400R requires 91-octane fuel for peak power, but a sophisticated knock sensor system permits the use of 89-octane fuel with only a slight reduction in performance. So you can still boat in areas where 91-octane fuel is unavailable or is unreliable – without giving up any meaningful amount of power, and without damage to your engine.

Race-Inspired Design

All R-Series Outboards feature stiff mounts which function akin to a sports car suspension – enhancing high-speed handling and drivability.

High-performance midsections and gearcases differentiate R-Series outboards from the typical consumer engine. All models feature stiff mounts which function akin to a sports car suspension – enhancing high-speed handling and drivability.

Gearcase Options

All R-Series outboards are available with Mercury Racing’s exclusive Sport Master gearcase.

The Sport Master gearcase comes standard on the 250R outboard and is available on selected 300R and 400R models as well.

The surface-piercing gearcase – designed for boats capable of speeds well over 85 mph – features low-water pickups to ensure a steady flow of cooling water, and a crescent leading edge to maximize efficiency and speed. The available cambered skeg counteracts prop torque on single-engine installations for improved performance and handling.

The Torque Master gearcase, available on the 300R, is designed to run partially surfaced to carry heavier tournament bass and multi-species fishing boats with maximum speed and control.

The 5.44-inch HD gearcase, available on select 300R and 400R models, comes equipped with a robust gear set for ultimate durability when pushing heavy bay boats and multi-engine performance center console boats that require a more submerged gearcase.

Mercury Racing Propellers

The CNC Outboard Cleaver propeller is popular for selected 300R and 400R Sport Master applications.

Simply stated, Mercury Racing Propellers are the gold standard in high-performance props, and they’re the perfect match for R-Series outboards.

Cast from proprietary stainless-steel alloys, then hand finished and zero balanced by artisan technicians in our prop shop, Mercury Racing Propellers offer the ultimate in performance and durability.

Choose the precision-tuned performance of a Mercury Racing Pro Finish model or the race-spec perfection of a Mercury Racing Lab Finish® propeller to ensure that every bit of that R-Series power gets to the water.

Unprecedented Warranty

Mercury Racing R-Series consumer performance outboards are tested, tested and tested again – in the lab and on the water – in a never-ending quest to exceed the highest expectations of even the most demanding and discerning boater. Run wide open with confidence backed by a three-year limited factory warranty.

Extend that coverage for up to five more years with a Mercury Product Protection (MPP) factory-backed extended service plan, and you’ll still be leaving others in your wake – and still covered – long after many other so-called high-performance engines have gone to the scrapyard.

Visit our website to learn more about our R-Series consumer performance outboards.






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Hi-Performance Boat Operation – Part 2: Rigging Fit & Function

The 4.6L V8 300R FourStroke is very popular for single and multiple engine applications.

Spring is a great time for newbie and veteran performance boaters alike to get familiar with their craft. For starters, you should review your owners manuals — really, you should — and review the key components of your new boat.

The 300Rs on this MTI 340X catamaran feature the 20-inch Heavy Duty Midsection with rear tie-bar and side steer. The rear tie-bar and optional hydraulic steering cylinders provide enhanced engine stability for high speed applications. Surface piercing Sport Master gearcases are designed for use on boats capable of speeds in excess of 85 mph.

Performance boats vary widely in propulsion and size. Outboards come in 20, 25 and 30-inch drive shaft lengths to accommodate a variety of applications. Mercury (and other brand) outboards are fitted with a standard gearcase for most applications. Hulls that can take advantage of the high power-to-weight ratio of a 300R may benefit from its wide range of gearcase options. Similarly, Mercury Racing offers a variety of sterndrives for differing power capacities and hull types.

Mechanical control:  performance outboards such as the 60 EFI Formula Race, 250R and selected 300R models are rigged with a shift cable, throttle cable and fuel line.  Sterndrives, such as our 600 SCi throttle and shift is accomplished with cables, but steering is hydraulic.

Digital Zero Effort Controls.

Digital control: Selected 300R models and the 400R are Digital Throttle & Shift (DTS) Compatible.  We also have a full suite of DTS compatible sterndrives; 520, 540, 565, 860, 1100,  Dual Calibration 1350/1100, 1350, Dual Calibration 1550/1350, Class 1 Competition, 1100 Competition1650 Competition and 1750 Competition.  Here – mechanical throttle and shift cables are replaced with a single electronic cable.

Application Specific: Selected 300R models feature a heavy-duty swivel/clamp bracket and trim cylinder to endure the rigors of extended use in rough seas. The trim cylinder is actuated via a remotely mounted pump. A majority of today’s outboards feature trim systems mounted within the swivel clamp bracket assembly. Verado outboards come equipped with integral power trim and steering.  250R and 300R outboards come standard with mechanical steering.

Rear tie-bar 300R models feature the heavy duty midsection with a factory installed tie-bar mounting plate.

Two steering system types are available: Full Feedback and No Feedback. With Full Feedback, steering loads from an outboard or sterndrive are continually transmitted to the steering wheel. This is the preferred system used by tunnel boat drivers for “feel” of their craft while driving at the limit. One disadvantage: steering forces increase as engine or drive height or trim is increased. The steering wheel must be secured at all times to maintain control.

Mercury Racing sterndrive packages are equipped with power steering. The system requires actuation of external hydraulic steering cylinders.  Our Integrated Transom System (ITS) provides external power steering for Bravo One XR, Bravo One XR Sport Master and Bravo Three XR drive engine packages.  Power trim and steering cylinders are integrated in the M-series transom plate that comes standard with all engine packages featuring  M6 and M8 sterndrives.

A close up view of a 300R cat ready model featuring factory installed rear tie-bar mounting bracket and optional side steering cylinders. The tie-bar and side steering kit work together to enhance engine stability.

Performance boats with two or more outboards or sterndrives are rigged with both external power steering cylinders and tie bars. These components work together to minimize steering backlash and enhance drive stability.

The units tied together (outboards or sterndrives) should be adjusted parallel to each other, at rest, where play in the steering can be adjusted to zero. Always be sure to have a qualified professional check to ensure your outboards or sterndrives and all related components are mounted securely.























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Prop School – Part 6: Slip

Response to my Prop School series has been gratifying. It has generated a lot of good discussion (online and off) regarding propeller design, function and application. One of the most common questions is about prop slip. It is the most misunderstood of all propeller terms.

A wing moving through air produces a pressure differential: low pressure above the wing, with high pressure below it, creates lift.

Propeller blades work like wings on an airplane. Wings carry the weight of the plane by providing lift; marine propeller blades provide thrust as they rotate through water. If an airplane wing were symmetrical (air moves across the top and bottom of the wing equally), the pressure from above and below the wing would be equal, resulting in zero lift.   The curvature of a wing reduces static pressure above the wing — the Bernoulli effect — so that the pressure below the wing is greater. The net of these two forces pushes the wing upward. With a positive angle of attack, even higher pressure below the wing creates still more lift.

Marine propeller blades need to move through water with an angle of attack to create thrust.

Similarly, marine propeller blades operating at a zero angle of attack produce nearly equal positive and negative pressures, resulting in zero thrust. Blades operating with an angle of attack create a negative (lower or pulling) pressure on one side and a positive (higher or pushing) pressure on the opposite side.  The pressure difference, like the airplane wing, causes lift at right angles to the blade surface. Lift can be divided into a thrust component in the direction of travel and a torque component in the opposite direction of prop rotation.

Prop Slip 

Slip is the difference between actual and theoretical travel through the water. For example, if a 10-inch pitch prop actually advances 8-1/2 inches per revolution through water, it is said to have 15-percent slip (8-1/2 inches is 85% of 10-inches). Similar to the airplane wing, some angle of attack is needed for a propeller blade to create thrust. Our objective to achieve the most efficient angle of attack.  We do this by matching the propeller diameter and blade area to the engine horsepower and propeller shaft RPM. Too much diameter and or blade area will reduce slip, but at a consequence of lower overall efficiency and performance.

Calculating Rotational Speed, Blade Tip Speed and Slip

Our propeller engineers study props at the 7/10 radius (70% of the distance from the center of the prop hub to the blade tip). The 7/10 radius rotational speed in MPH can be calculated as follows:

And can be shown by a vector arrow.

Rotational speed.

Blade tip speed can be calculated using the following equation:

Forward speed is shown by an arrow in the direction of travel. The length of the arrows reflect speed in MPH for both the measured speed and the theoretical (no slip) forward speed.

Forward speed.


The original Quicksilver prop slip slide rule calculator.

Prop Slip Calculator 

Back in the day when the Everything You Need to Know About Propellers book was published, the Internet didn’t exist and you had to actually use these cumbersome formulas or rely on the Quicksilver Propeller Slip Calculator.

We Have an App for That

Today, you can get all of your prop information with our Prop Slip Calculator App. Download it for free from Google Play Store or Apple iTunes.

The Mercury Racing Prop Slip Calculator App is available for free download from Google Play Store or Apple iTunes.

Click here to see some real world examples on how I use the app.

I hope you have found my Prop School blog series both educational and useful. I’ve enjoyed sharing with you.


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Project 1080: Smooth Operator


Stu runs Project 1080 Wide Open at the FPC Winter Poker Run in the Florida Keys.

Florida Powerboat Club founder Stu Jones is ecstatic with the results of Project 1080 – the restoration and re-power of an epic Cigarette 38 Top Gun powered by twin Mercury Racing 540 sterndrive engine packages. 

The classic hull is updated from helm to stern with modern hardware. Mechanical throttle and shift cables were replaced with Digital Throttle and Shift (DTS). The digital cables transmit real-time data from the engines to the helm and is then displayed on the Mercury VesselView 703 touchscreen monitor. The Mercury Racing Digital Zero Effort Control transmits data back to the 540 sterndrives – signaling driver intent with effortless shifting and instant throttle response. 

Project 1080 is the official pace boat of the Florida Powerboat Club.

Stu is now focused on dialing in props. He is starting with a selection of Mercury Racing Bravo I props. He will follow up with our performance propeller specialists, Scott Reichow and Nick Petersen, to ensure he gets maximum performance for the boat’s primary application as FPC’s official pace boat. Stu loads the boat with performance-boating enthusiasts who get to enjoy a first-hand experience of the best poker runs on the water.

Look for follow-up Project 1080 posts regarding props as well as the fit and function of K-Plane trim tabs

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Prop School – Part 5: Blade Efficiency

For this, the fifth installment of my Prop School series I will review the various propeller blade designs and how they – along with rotation – affect propeller efficiency and overall boat performance.

Rotation. Propellers come in both right and left-hand rotation. Standard rotation for both outboards and sterndrives is right-hand: the prop spins clockwise when in forward gear.  Left-hand props spin counter clockwise.  Left-hand props are typically used with multi-engine applications. The counter-rotation prop works to balance (or reduce) the torque effects from the right-hand prop. Most twin engine applications are setup with the props “turning in”; the port engine spinning right-hand and the starboard engine spinning counter clockwise.

Hull types and designs respond differently to prop rotations. Some need additional stern lift to reach maximum efficiency and performance. To obtain this, the rotation of both propellers is set up, so they rotate away from each other. We call this turning the props out.  The left-hand rotation prop is on the port side and the right-hand rotation is on the starboard side.

For example, a high-speed catamaran loaded with gear and passengers often runs best with 5-blade cleaver props with 15-degree rake. Turning the props in pulls the stern down, enabling the boat to float over chop. With lighter loads and ideal conditions, the same cat can gain 6 to 8 mph when using 18-degree rake, 5 blade cleavers “turned-out.”

Performance combo pack. Racing’s 4-blade Bravo I FS and Pro Max propellers.

Number of Blades

In theory, two blade props are most efficient since they have the least amount of surface dragging through the water.  Two blade props are commonly used on lower horsepower outboards and trolling motors. Three -blade and four-blade props are the most common designs used today. The added blades reduce vibration while maintaining most of the efficiency of a two-blade design at a convenient size and reasonable cost.

The Pro Finish 5-Blade CNC Sterndrive Cleaver propeller.

Racers and performance boaters raise sterndrive mounting heights (x-dimensions) on ventilated, stepped hulls. The steps create air bubbles, raising the hull off the water on a drag-reducing cushion. This, combined with reduced drag from the higher drive heights, improves hull efficiency. This trend has spawned an evolution of prop designs featuring four, five and even six blades.  The additional blade surface helps offset slip induced by air bubbles flowing from the ventilation steps toward the props.

Cross section showing the thickness of a common prop blade.

Blade Thickness

For efficiency, blades should be as thin as possible to reliably handle a particular power range. A cross section of a typical constant pitch prop blade reveals a flat section on the positive (pressure) side and an arc surface on the negative (suction side) of the blade. Edges are usually 0.06″ to 0.08″ (1.5 mm to 2.0 mm) thick for aluminum props, thinner for stainless steel.

The cross section of a cleaver style prop blade is shaped like a wedge.

The blade cross section on surfacing props such as our T.E. Cleaver  and Pro Finish CNC Cleavers is wedge shaped. The thick trailing edge adds strength. Surface air ventilates a low-pressure cavitation pockets behind the trailing edge, enhancing efficiency.  The contour or shape of most propeller blade tips (other than cleaver) are round.

I will discuss propeller slip more thoroughly in Prop School – Part 6.



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Hi-Performance Boat Operation – Part 1: Introduction

It’s boat show season – the perfect time of year to check out the latest performance boats and Mercury Racing propulsion. For those of you who are about to purchase your first performance hull, congratulations!

With Winter in full swing, now is the time to review the basics of high-performance boat operation to ensure you and your passengers have safe experiences out on the water.  We include a Guide to Hi-Performance Boat Operation with every engine we ship. We encourage new and current owners to review the book and then take in-boat driving lessons from your local high-performance dealer or boat builder.

Our operation guide is packed with general performance boating information, including  propellers, hull types and overall boat performance. Let’s first review the various performance-boat hull configurations.


Project 1080, Florida Powerboat Club’s official pace boat is a year 2000 Cigarette 38 Top Gun with a traditional vee bottom hull.

The traditional vee-bottom is the most common hull design. It offers good speed and a softer ride, especially in rough water. The softness of the ride depends on the angle of the “V” (called deadrise), radius of the keel line and the use of strakes.

If your boating is mostly in larger bodies of water such as the Great Lakes or open seas, you may want to consider a boat with this hull type.

This Outerlimits race boat features the stepped vee-bottom hull design.

The most recent change in this design over the past decade has been the incorporation of strategically placed notches or steps in the hull. The steps create air bubbles, raising the hull off the water on a drag-reducing cushion.

Some high performance hulls such as Allison feature a vee-bottom with a pad at the rear of the hull. The boat is designed to run up on the pad, minimizing drag for maximized speed and performance.

Some vee-bottom hulls feature a small flat area toward the rear of the keel called a pad. Similar to steps, the pad reduces the wetted surface area the hull runs on, increasing top speed with minimal effect on the ride quality. Mercury Racing offers a full array of outboard and sterndrive propulsion options for the vee-bottom boater.


Outboard tunnel boats are the fastest-turning race vehicles on earth. The sharp, 90-degree transfer where the tunnel sides meet the bottom of the sponsons helps the boat settle in the water as it enters a turn.

F1H20 competitor Thani Al Qemzi slams his DAC tunnel boat through a turn at the 2018 Grand Prix of Sharjah race event.

The submerged sponsons make the boat turn as if it were on rails. It is common for drivers to experience 4.5 to 5Gs as they enter a turn at 120 mph and come out at 90+ mph. Obviously, only experienced racers should consider this type of hull.


I like to refer to catamarans (or cats as they are often called) as tunnel boats on steroids. The design principal is similar. The boat rides on two sponsons or hulls separated by a tunnel. Air entering the tunnel generates lift as speed increases. The wetted surfaces and hull drag are reduced, for enhanced speed and ride quality. This design is not for the novice operator.

Catamaran boats ride on two sponsons or hulls separated by a tunnel. Air entering the tunnel generates lift as speed increases. The wetted surfaces and hull drag are reduced, for enhanced speed and ride quality.

The air entrapment hull is sensitive to engine trim, wind, and water conditions. In general, they produce a smoother and faster ride over a vee-bottom in calm to mild chop. The vee bottom is king in rough water.

The fastest recreational cats on the water today are powered by the venerable dual calibration 1550 sterndrive. The V8 4.6L 300R FourStroke is a popular choice for those who choose outboard power for entry into the cat experience.

In Hi-Performance Boat Operation – Part 2: Rigging Fit & Function, I will review the important things to consider when preparing your new Mercury Racing outboard – or sterndrive-powered boat for the upcoming season.



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Project 1080: Start Me Up

Stu Jones and Pat Sullivan catch some air as they sea trial Project 1080 for the first time. The Resto Mod Cigarette 38 Top Gun is the result of a nine month restoration of the legacy hull.

Florida Powerboat Club founder Stu Jones and Pat Sullivan – owner of the Mercury Racing dealership Performance Marine Trading tested FPC’s official pace boat for the first time on Wednesday. The freshly restored Cigarette 38 Top Gun features modern Mercury Racing hardware including 540 sterndrive engine packages with Integrated Transom Systems, Bravo One XR drives, Mercury Racing Bravo I Propellers and K-Plane trim tabs.  Digital Zero Effort Controls transfer driver intent to the twin 540 powerhouses.

One of the many custom upgrade made to the Cigarette is the addition of non skid SeaDek material to the deck.

The sea trial was the culmination of a project that involved stripping the 2000 model year boat to an empty shell, and updating all aspects of the legendary hull from bow to stern in form, fit and function.

Stu was anxious to share his first-time experience in the Resto Mod Cigarette with us.

“It was an amazing experience, given how the project evolved from a a simple repower to a complete restoration. It is amazing how it turned out. I honestly felt like I was driving an entirely new boat,” said Stu.

Installation of the 540 sterndrives and all rigging was handled by  Pat Sullivan and his crew at Performance Marine Trading.

The epic vee-bottom handled the ocean swells with ease. The durable 280S K-Plane trim tabs worked like a charm.

Stu handed over the helm to Pat, a former offshore racer for the initial shake down cruise. Pat eased the Zero Effort controls forward as the 540s quickly brought the Cigarette on plane. The epic vee-bottom handled the ocean swells with ease.

Race-proven Bravo I XR sterndrives transfer the 540 power to the water.

Pat said, “Stu you really have a great package here. The switch from mechanical to digital controls is like night and day. There is no comparison. And beauty of the new power is you don’t really have to worry about anything. These engines are so reliable, you just push the throttles and go.”

The Project 1080 Cigarette will make it’s pace boat debut this weekend at FPC’s Winter Poker Run to the Florida Keys, the first run for the 2019 season.The durable 280S K-Plane trim tabs worked like a charm. Both Pat and Stu grew an appreciation for the intuitive design of the VesselView 703 touch screen monitor as well. The replication of vital engine data on the larger Garmin display was easy on the eyes, providing a constant view of vital functions throughout their 20-minute journey.

Pat and Stu will return to dial-in props to take full advantage of the 540s’ 4800-5400 operating rpm range.

The Project 1080 Cigarette will make it’s pace boat debut this weekend at FPC’s Winter Poker Run to the Florida Keys, the first run for the 2019 season.

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Prop School – Part 4: Blade Cup

Continuing from Prop School…Part 3. Here I will explain everything you need to know about Blade Cup.

An illustration of cup added to the trailing edge of a typical through hub exhaust prop.

Cup is a curl formed or cast into the trailing edge of a propeller blade.  When done correctly, the face of a cupped prop blade is completely concave.

The first three-blade aluminum props for MerCruiser powered boats featured flat blades, with 15-degree rake. The heavy, deep-vee hull ran best with the drive trimmed up (raising the bow, reducing the wetted surface, and increasing hull efficiency). We got our first experience with cupped, 3-blade aluminum props in the mid ’70s. We immediately realized greater top-end speeds. We also noticed the engine didn’t work as hard. The cupped props were more efficient. Our measurement? The paint was still on the blades at the end the season. Cavitation burns, mostly from abusive teenage kids over trimming dad’s boat, would burn away the paint. The cupped prop definitely made  a difference.

Location. Location. Location.

Originally, cupping was done to gain similar benefits as you get from progressive pitch or higher blade rake. In fact, cupping reduces full-throttle engine speed 150-300 RPM below the same pitch prop with no cup. The location of cup on the blade determines the affect it has on performance. When the cupped area intersects pitch lines, pitch increases. Cupping in this area will reduce engine RPM.  Cupping can also prevent prop cavitation or blow out.   Blade rake can be increased when the cup intersects the rake lines. Slip is a measurement of propeller efficiency as it turns through the water, the normal range is 10-15%. Most racing and performance boats slip can be as low as 5-7% where as performance vee and step vee bottom boats with high X dimension (outboard engines or sterndrives mounted high) can see slip as high as 20-22% at WOT

Cleaver Cup.

All Mercury Racing propellers spend time on the grinding wheel.

Adjusting cup on cleaver-style propellers is more difficult. The trailing edge is very thick and runs straight out on the rake line. Pitch can be altered some by grinding away some of the cup. Rake may also be altered slightly.  The rake can be reduced by decreasing the cup near the tip of the blade. Rake can be increased by reducing the cup near the prop hub. Remember that any change in cup affects engine RPM. The Bravo I propeller family is a good example of how cup changes RPM and the attitude of the boat I will discuss blade configurations and factors that effect propeller efficiency in Prop School – Part 5.


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300R vs 300XS: And the Winner Is?

The business end of 112 mph!

I recently wrote a feature post on Liberator Boats of Florida and their initial experience with our new 4.6L V8 300R FourStroke outboard. I elected to feature Liberator as company owner Randy Corson had just received his first 300R in June. Randy has extensive experience with our V6 300XS two-stroke. I was anxious to get his feedback regarding our new engine and how it compared  with the 300XS it replaced.

Randy provided some initial performance numbers and then compared them with his archival 300XS data:

The 300R Sport Master gearcase features a 5.44 inch diameter torpedo for enhanced durability. The larger case is needed to handle 40% increase in bottom-end torque produced by the 4.6L V8 FourStroke engine.

Both engines featured the Sport Master gearcase. The 300XS had a 1.62:1 gear ratio. The 300R had a 1.75:1 gear ratio.  Due to the gear ratio difference, the 300XS ran a 32-inch pitch propeller. The 300R ran a 34-inch pitch prop. The bare hull weight of the 300XS hull is 940 pounds. Randy said it is the fastest 300XS powered 21-foot Liberator he has ever had.  The bare hull weight of the 300R boat was 1063 pounds.

The CNC outboard cleaver propeller.

“We saw  1.5 to 2 mph faster top-end speeds with the 300R compared to the 300XS with comparable props. At the time, the 300R topped out at 106 mph; that’s 5-6 mph faster than the 300XS when running a 15-1/4-inch diameter – 34-inch pitch Mercury Racing 5-blade CNC outboard cleaver.

Randy ran the CNC cleaver again on Christmas Day and was blown away by the performance – a top speed of 112 mph!

While the top-speed difference is impressive, acceleration is where the 300R really shines. The 300XS accelerates from 40-100 mph in 25 seconds. The 300R boat catapults from 40-100 in 18 seconds! The big difference can be attributed to a 44% advantage in displacement (4.6L vs 3.2L) the 300R has over the 300XS. That results in a 40% increase in bottom-end torque.

While the top-speed difference is impressive, acceleration is where the 300R really shines. The 300XS accelerates from 40-100 mph in 25 seconds. The 300R boat catapults from 40-100 in 18 seconds! The big difference can be attributed to a 44% advantage in displacement (4.6L vs 3.2L) the 300R has over the 300XS. That results in a 40% increase in bottom-end torque.

Hole shot acceleration is exhilarating as well. From 0-20 mph, the 300R is 25% quicker than the 300XS. Mercury’s proprietary transient spark calibration boosts torque by as much as 7% by optimizing spark timing and fueling to assist in superior hole shot performance.

We are excited to see the performance gains people are experiencing with our new 300R in both single and multi-engine applications.



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300R with Integrated Rear Tie-Bar & Side Steer

Select 300R models featuring the heavy-duty midsection and Sport Master gearcase come with our exclusive factory installed integrated rear tie-bar bracket. The bracket enables the installation of a tie bar (an optional aftermarket part) for multi-engine performance cat and vee-bottom applications.

We’ve recently released the 4.6L V8 300R FourStroke outboards featuring our Racing exclusive heavy-duty midsection fitted with a factory installed rear tie-bar mounting bracket.

Rear tie-bar 300R models feature the heavy-duty midsection with a factory installed tie-bar mounting bracket.

The heavy-duty midsection comes with solid mounts and robust, forged transom brackets with single ram power trim and a remote trim pump designed to endure the harsh offshore environment. These models are available with the Sport Master gearcase.

The optional factory installed integrated rear tie-bar bracket enables the installation of a tie bar (an optional aftermarket part) for multi-engine performance cat and vee-bottom applications.

The optional rear side steer kit greatly enhances steering robustness. The tie bar and rear side steering kit work together to enhance engine stability on high speed multiple engine applications.

Select rear tie-bar models are available with side steering kits. Hydraulic steering cylinders mounted off the rear tie bar bracket – connect to the steering tube integrated within the transom clamp bracket assembly.

The optional rear side steer kits greatly enhance steering robustness. The tie-bar and rear side steering kit work together to enhance engine stability on high speed multiple engine applications.

Check out our Application Dependent to learn more about the various 300R midsection and gearcase options.

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Future Techs

I’ve led many tours of Mercury Racing over the past 30 years. People are constantly amazed to see our skilled labor handcrafting outboards, sterndrives, propellers and accessories. Some of the more common questions asked are, “where does your labor comes from and how do they learn their skills?”

Mercury Racing technicians handcraft products with passion and perfection.

Our employees come with a strong skill set and work ethic in place. The only training needed are for things that may be specific to the job at hand. I attribute their strong  work ethic to the Midwest culture. In Fond du Lac, it most likely also stems from the rich German ethnic mix and heavy farming influence. I truly believe farming brings with it an inherent mechanical aptitude that has been ingrained within Mercury since the late Carl Kiekhaefer founded the company in 1939.

The education and interests of today’s generation has changed. Millennials grow up using technology – aspiring to play video games and becoming “device” experts from an early age. They are used to instant gratification.

I recently came across an article in Forbes magazine entitled, “Why We Desperately Need To Bring Back Vocational Training in Schools.”  The timing of the article couldn’t have been better.

Mercury Racing employees come with a strong skill set and work ethic in place.

Industries such as ours are beginning to feel the pinch in finding skilled labor with a strong work ethic and passion to build and service the products we manufacture. Many say Millennials don’t want to get their hands dirty or have the desire to actually learn skills to build or repair products. I personally believe they are as interested and as capable as ever. We just need to provide them the education and tools they need to succeed.

Millennial Diamond

Marine Service School Senior Michael Signorelli shadowed with Stock Outboard competitors Talbot at the 2015 Super Boat International Offshore World Championships. The twin Mercury 2.5 EFIs were prepped by his uncles Marty and Joe Signorelli (Diamond Marine).

Marty Signorelli – owner of Diamond Marine – a Mercury Racing dealer located in Ft. Lauderdale – made me aware of one school that is making a difference when it comes to filling the void in skilled labor. His nephew Michael attends Coral Shores High School in Key Largo, Florida. The school has a dedicated marine vocational program. Students who attend the 4-year program learn skills to service marine engines.  Several current and former students work in marine  work in marine shops or related businesses on the water.  I spoke with instructor Chris Catlett regarding the program. Chris has been teaching  for 13 years. He is a 20-year Coast Guard Veteran with over 30 years of marine experience.  Eighty students are currently attending the program.

Marine Service School Instructor Chris Catlett (L) with former student Blye Hofstetter and Michael Signorelli.

“Mercury Marine helped launch the Marine Service School program. We have 60 Mercury outboards made up of a mix of 2-stroke and 4-stroke models. The kids learn  everything; from  rebuilding powerheads and gearcases to diagnosing and repairing hydraulic and electrical systems. We are one of five marine mechanic trade schools in the nation which provide students an alternative to a formal four year college education,” said Chris.

For the past several years, Chris has taken the students to Key West for the annual Super Boat International Offshore World Championships. Twelve students got to work with race teams this year.

“The kids see the boats go past the school on their way down to Key West for the races. I feel it is important for them to see the engines in use – be it the recreational outboards they work on day in and day out or the exotic – high powered race motors they see competing in the extreme race environment. They get to see cutting edge technology in their own backyard, ” Chris said.

We encourage poker run and race promoters and participants to invite tech school students to their events. Get them involved. It lights a fire in the students for sure.

2-Stroke DNA

Michael Signorelli has mechanical aptitude built into his DNA. His uncle Marty and Joe are legendary in their ability to maximize the performance of  our legacy 2.5 EFI 2-stroke competition outboards. His father Frank is a private boat captain. Michael started the Marine Service School program in 2015. His first project was rebuilding a 2-stroke 9.9 h.p. Mercury. His current project is a tear down and rebuild of a 75 h.p. OptiMax.

We are thankful for instructors such as Chris Catlett and the various vocational programs around the country. I am confident program graduates will  provide tech support for Mercury and Mercury Racing products well into the future.





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Prop School – Part 3: Blade Rake

Ventilation occurs when blades break and re-enter the water’s surface.

Continuing from Prop School….Part 2 .   Here, I will explain the science behind blade rake.

Rake is the angle of a propeller blade face relative to its hub. If the blade face is perpendicular to the hub, the prop has zero-degree rake. As a blade face slants back toward the rear of the prop, blade rake increases. Rake is either flat (straight) or curved (progressive). Most lower horsepower (“lower” by Mercury Racing’s reckoning)  propellers, like Black Max aluminum and Vengeance, have 15-degree rake and are designed to operate fully submerged to push a boat across the water. Typically, higher horsepower outboard and sterndrive propellers have a higher flat or progressive rake.

Rake is the angle of a propeller blade face relative to its hub. If the blade face is perpendicular to the hub, the prop has zero-degree rake. As a blade face slants back toward the rear of the prop, blade rake increases.

A greater rake angle generally improves the ability of the propeller to operate in a ventilating situation. Ventilation occurs when blades break and re-enter the water’s surface — such as occurs with 1) a Bravo sterndrive (XR, XR Sport Master or XR Sport) installed with a high “X” dimension, 2) a surfacing drive (M6 or M8) or 3) an outboard installed or jacked high on a transom. In surfacing operation, higher rake can hold the water better as it’s being thrown into the air — deflecting it aft and creating more thrust.

In surfacing operation, higher rake can hold the water better as it’s being thrown into the air — deflecting it aft and creating more thrust.

On lighter, faster boats with a high prop shaft, increased rake often will improve performance by holding the bow higher. This results in higher speeds due to less hydrodynamic hull drag. However, on some very light boats, more rake can cause too much bow lift. That will often make a boat less stable. Then, a lower rake propeller (or a cleaver style for outboard) is a better choice.

Looking at examples:

  • A runabout with Alpha sterndrive usually performs best with a lower rake Black Max or Vengeance pushing the boat. The aim is broad capability and utility for many recreational activities.
  • A lighter weight runabout with Alpha drive may increase performance with higher rake Enertia propellers lifting the bow offering less wet running surface (lower drag).
  • Bass boats can vary widely because of the design differences among hulls in the market. Mercury offers high rake propellers such as the Tempest Plus and Fury for these applications. Mercury Racing specialty props for the bass market include the Lightning E.T., Bravo I FS, Bravo I XS and Pro Max.
  • The Bravo XR drive, used with higher horsepower multi-length and weight applications, typically use props with high rake and large blade area — such as the Bravo I and Maximus.

Our Pro Finish 5-blade CNC Cleaver prop is available with 15, 18, or 21-degree rake.

The Pro Finish 5-blade CNC cleaver propeller shown on the M8 surface sterndrive.

Performance applications using Mercury Racing’s CNC Pro Finished Cleavers with  M6 or M8 drives have three rake choices: 15, 18 or 21 degree. Most “V” and step “V” bottom boats utilize a 15 degree rake — unless the center of gravity is forward of the helm; then, 18 degree rake works best. The higher rake helps lift the bow — positioning the boat to ride appropriately on the steps. Air entrapment hulls (catamarans and tunnel hulls) pack air and lift during forward motion; they typically use props with 15 to 18 degree rake — since air pressure does most of the lifting.

The Pro Finish 5-blade CNC cleaver propeller.

The 15-degree and 18-degree rake Pro Finish CNC Outboard Cleaver is being used in a variety of applications including bass boats, performance center consoles and catamarans.

Your head probably hurts by now, so I will discuss blade cup in Prop School – Part 4.

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Prop School – Part 2: Terminology

Continuing from Prop School….Part 1 .   Here, I will explain basic propeller terminology and fitment.


On right-hand rotation propellers, the blades slant from lower left to upper right when looking at the blade face. A left-hand propeller, however, has the opposite slant; from lower right to upper left.

Propellers are available in both right-hand and left-hand rotation. Most single engine outboard and sterndrive powered boats use right-hand rotation propellers. A right-hand rotation propeller will spin clockwise when pushing the boat forward, while a left-hand propeller will spin counter-clockwise.

Number of Blades

Four blade props are popular for suppressing vibrations even further while improving acceleration by putting more blades in the water.

The most popular propellers used for recreational boating have three or four blades. Three-blade props are efficient and do a good job of minimizing vibration. Four blade props are popular for suppressing vibrations even further while improving acceleration by putting more blades in the water.


In “prop speak,” diameter is the distance across a circle made by the blade tips as a propeller rotates. The proper diameter is determined by the power that is delivered to it and the resulting propeller rpm.

The more a propeller is surfacing above the water, the larger the diameter needs to be.

Type of application is also a factor. The amount of propeller in the water (partially surfaced vs fully submerged) plays a role in determining diameter. The more a propeller is surfacing above the water, the larger the diameter needs to be (so what’s left under water can still push). On rare occasions, diameter may be physically limited by drive type or in close, staggered engine installations where tips can touch.

Within a specific propeller style, diameter is usually larger on slower boats and smaller on faster boats. Similarly, for engines with a lower maximum engine speed (or with more gear reduction), diameter will tend to be larger. Also, diameter typically decreases as propeller blade surface areas increase (for the same engine power and rpm). A four bladed prop replacing a three blade of the same pitch will typically be smaller in diameter.

Physical limits

The Mercury Racing M8 sterndrive fitted with our 18-inch diameter 5-blade CNC propeller.

Mercury Racing engines fitted with the Bravo One XR or Bravo Three XR drives are designed for props up to 16-inches in diameter. Bravo One XR drives fitted with the short Sport Master gearcase accepts props up to 15-1/4 inch in diameter. Sterndrive engines with surface piercing M6 or M8 sterndrives run cleaver props up to 18-inches in diameter. Our 4.6L V-8 250R and 300R FourStroke outboards as well as the 400R Verado accept props up to 16-inches in diameter.





In this example, the propeller moves forward 21-inches in one revolution.

Pitch is the distance a propeller would move in one revolution if it were moving through a soft solid, like a screw in wood. When we list an outboard four-blade Pro Max prop as a 14-1/2 X 32, we are saying it is 14-1/2 inches in diameter with 32-inches of pitch.

Pitch is measured across the face of a propeller blade. Actual pitch can vary from the pitch number stamped on the prop. Modifications made by propeller shops may alter the pitch. Undetected damage from a submerged object may result with a bent blade, altering the pitch as well.

 There are two common types of pitch; constant and progressive. Constant pitch means the blade pitch is the same – from the leading edge to trailing edge. Progressive pitch, referred to as blade camber, starts low at the leading edge and progressively increases toward the trailing edge. The pitch number, “32” in the Pro Max example, is the average pitch over the entire blade.

Pitch is like another set of gears. Since an engine needs to run within its recommended maximum rpm range, proper pitch selection achieves that rpm. The lower the pitch, the higher the engine rpm. Mercury Racing propellers are designed so that a one-inch change in pitch results in a 150 rpm change in engine speed.

A lower pitch propeller may provide greater acceleration for water sports activities, but your top speed and fuel efficiency may suffer. If you run at full throttle with a prop selected for acceleration and not top-end speed, your engine rpm may be too high, placing an undesirable stress on the engine. If you select too high of a pitch, your engine may lug at a lower rpm – which can also cause damage.  Acceleration will be slower as well. It will be reduced further with a full load of fuel and maximum capacity of people on board.

Proper pitch selection allows the engine to operate near the top of its recommended rpm range at light load (1/2 fuel tank and two people). Using this pitch selection method, the engine usually operates near the low end of the recommended engine operating range when the boat is fully loaded (full fuel tank, boating gear, full live wells, and maximum capacity). Full load engine speed is usually reduced 200 to 300 rpm. The power output of naturally aspirated engines can be affected by high heat and humidity which is another factor that can reduce engine speed by 200 to 300 rpm.

The Mercury Racing Prop Slip Calculator App is very helpful in determining the proper pitch for your application.

Smart, pressure charged engines like the supercharged 400R outboard and our turbocharged QC4 sterndrives will auto-regulate power output for heat and humidity. Adaptive Speed Control, a standard feature on our 250R and 300R outboards, is another factor to consider when dialing in your boat for maximum power and top-end speed.

In my next Prop School post, I will discuss blade rake.


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Optimizing Your Ride: Adaptive Speed Control Explained

Mercury Racing’s new 4.6L V-8 250R and 300R FourStroke outboards are equipped with Adaptive Speed Control (ASC). This Mercury-exclusive feature allows boaters to maintain engine speed (rpm) regardless of load or condition changes – such as rough water, tight turns, tow sports and lower speeds on plane – without having to frequently adjust throttle position, a first for the outboard industry.

You may be wondering how this technology works and how to “dial in” your boat to take full advantage of the improved throttle response and “sportier” feel it provides.

While the system is designed to be intuitive to operate, understanding boat setup and operation with and without ASC will help maximize performance when changing the setup or when running the engine to its limits.

Mercury Racing’s new 4.6L V-8 250R and 300R FourStroke outboards are equipped with Adaptive Speed Control (ASC). This Mercury-exclusive feature allows boaters to maintain engine speed (rpm) regardless of load or condition changes – such as rough water, tight turns, tow sports and lower speeds on plane – without having to frequently adjust throttle position, a first for the outboard industry.

Boating Without Adaptive Speed Control 

To get a boat up on plane without Adaptive Speed Control, push the throttle full forward, pulling back once on plane. Trim the engine to lift the hull, reduce drag, and increase engine rpm even with constant throttle. Heavy boats require more throttle to reach the same rpm as a lightly loaded boat.

We’ve  become accustomed to trimming the engine to lift the hull, reduce drag, and increase rpm even with constant throttle.

Prop selection for this scenario is relatively straightforward. Too little pitch will result in engine revving past its recommended rpm operating range. Too much pitch will limit the engine from reaching its peak rpm for maximum speed.

Prop selection is relatively straightforward in this scenario. Too little pitch will result in engine revving past its recommended rpm operating range. Too much pitch will limit the engine from reaching its peak rpm for maximum speed.

250R & 300R  FourStrokes 

With Mercury Racing’s new V-8 FourStroke outboards, Adaptive Speed Control constantly adjusts the engine throttle and available airflow to achieve or maintain a given rpm. When the boat’s load curve is within expected limits, getting on plane no longer requires a throttle overshoot or pull-back to maintain speed.

Adaptive Speed Control constantly adjusts the engine throttle and available airflow to achieve or maintain a given rpm. When the boat’s load curve is within expected limits, getting on plane no longer requires a throttle overshoot or pull-back to maintain speed.

Adjusting trim will still lift the hull and allow higher efficiency, however, engine rpm will be maintained unless helm throttle demand is increased or already at 100%.

The greatest advantage of Adaptive Speed Control is experienced when maintaining RPM operating in heavy seas or turns.

Propping for Maximum Performance
The largest difference when propping for Adaptive Speed Control is experienced when running the engine at the top of the recommended operating rpm. For example, running a 300R with an under-pitched propeller, on a lighter than normal boat load, or over-trimmed will result with the engine reaching its maximum 6400 rpm operating range without using maximum power. In the past, the engine would continue to climb in rpm until the rev limit was reached.

Adaptive Speed Control has limited authority to reduce power at 100% demand. If the engine is grossly under-propped or the prop leaves the water for an instant, the rev-limiter will activate to prevent engine damage.

With Adaptive Speed Control, the 300R Engine Control Unit (ECU) will automatically pull power to maintain the 6400 rpm limit without any indication to the driver. The only way to verify 100% power output at 6400 rpm is to have your dealer run an engine diagnostics test via the Mercury G3 tool.  Any rpm less than 6400 (or max rated rpm) with the helm throttle control at full forward or 100% will result with full power output of the engine.

Working from higher pitch props down will reduce the guesswork and the time to find the ideal prop.

To ensure maximum power and performance with a 300R, we recommend working down from larger pitch propellers until you reach (6350 rpm) at 100% throttle. If the engine is under-propped or the prop leaves the water for an instant, the rev-limiter will activate to prevent engine damage.

Adaptive Speed Control is not a version of traction control and thus will not reduce power or helm demand during acceleration.

Prop Slip and Cavitation

Common in high-performance applications, prop hub vent holes, aerators, or over-the-hub exhaust are used to allow the propeller to cavitate. Cavitation increases engine rpm, which in turn assists in getting the hull on plane. Adaptive Speed Control is not a version of traction control and thus will not reduce power or helm demand during acceleration. Under hole shot conditions, stabbing the throttle will demand 100% power from the engine and continue until the maximum 6400 rpm propping limit is reached.

Where the operator used to pull back on power to prevent engine rpm from going too high, Adaptive Speed Control will reduce power to maintain the set rpm demanded by the operator. This can be experienced by entering a medium-speed turn while leaving the throttle untouched, then slowly tightening the turn until the boat slows and the propeller cavitates.

Propeller cavitation during a partial helm throttle demand, i.e., while getting a up on plane, in turns or because of over-trimming is controlled differently. Where the operator used to pull back on power to prevent engine rpm from going too high, Adaptive Speed Control will reduce power to maintain the set rpm demanded by the operator. This can be experienced by entering a medium-speed turn while leaving the throttle untouched, then slowly tightening the turn until the boat slows and the propeller cavitates. Initially, Adaptive Speed Control will increase power to maintain engine rpm. When cavitation occurs, it will reduce power to maintain the same rpm.

We hope this information is helpful to you in optimizing your Mercury Racing V-8 FourStroke outboard for maximum performance.



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Prop School – Part 1: Introduction

Working in performance boating is exciting: It’s fast-paced. Propulsion systems and hull designs are in continual evolution. Our customers are generally astute, technically oriented and often quite colorful characters. We’re all performance freaks! We’re all continually learning. That’s what makes my job so much fun!

The fifth edition of the iconic propeller guidebook which was first published in the 1980s.

If you are like me, your first boating experiences were in lower horsepower boats used primarily for family recreation, fishing, skiing, wakeboarding, or general cruising. And like me, your boating experiences and knowledge have evolved over time.

When working with high-end performance boats and experienced customers, one tends to assume people have basic product knowledge. However, a propeller is complicated. Because our backgrounds vary widely, our levels of understanding vary widely, too. So, we’ll revisit the basics and then dive deeper on propeller form, fit and function. Read more

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No Sweat with Digital Zero Effort Controls

Our Digital Zero Effort Controls provide an intuitive experience for performance  boaters and competitors alike.

Digital Zero Effort Controls provide an intuitive experience for performance boaters and competitors alike.

Mercury’s exclusive Digital Throttle & Shift (DTS) technology takes the sweat out of boating by replacing the lag and hesitation of traditional throttle and shift cables with digital precision, resulting in smooth shifting and instant throttle response. Digital Zero Effort Controls are enabled to provide automatic throttle synchronization and shadow mode for up to four engines (where two levers operate four engines) and go hand-in-hand with engines equipped with Mercury’s exclusive Joystick Piloting technology.

Form Follows Function 

Short throw levers, made of stainless steel, provide effortless shifting and ultra-fast throttle response.

The high styled  controls are tough as nails – and ergonomically friendly as well. We build them utilizing stainless steel for lever, mechanism and hardware strength. The housing material is corrosion-resistant, marine-grade aluminum specially coated for enhanced protection in the extreme saltwater environment. Short throw levers, made of stainless steel,  provide effortless shifting and ultra-fast throttle response. Shift and throttle handles are made of an anodized aluminum for enhanced corrosion resistance.

Optional silver handles compliment virtually any helm.

An integrated throttle handle trim switch enables trim adjustment while maintaining hands-on throttle control. Black and red shift/throttle handles comply with American Boat and Yacht Council (ABYC) standards. Optional silver handles compliment virtually any helm.

The all-new 300R FourStroke accepts both mechanical and Digital Throttle and Shift (DTS) controls. Mercury Controls & Rigging offers a variety of DTS controls for single engine bass boats and sport boats where a digital panel mount control or foot throttle are a more feasible solution.

Digital Zero Effort controls are backed by a one-year factory warranty and supported by a Mercury Marine’s global dealer network.

Key Features

  • A variety of shift and throttle lever configurations available
  • Ergonomic design features short throw levers for effortless shifting and ultra-fast throttle response.
  • Robust stainless steel levers for unmatched durability in the offshore environment.
  • Variable friction adjustment provides custom tactile feel and resists throttle creep.
  • Integrated throttle trim switch for hands-on trim control.
  • Automatic throttle synchronization and shadow mode for up to four engines (where two levers operate four engines).
  • Handle color options include silver, red and black.

Mercury Controls & Rigging offers a variety of DTS controls for single engine bass boats and sport boats where a digital panel mount control or foot throttle are a more feasible solution.

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Application Dependent: Which Racing V-8 is Right for You?

I thought it would be helpful to share with you  details regarding the two midsection and three gearcase options available for our new  V-8 Four-Stroke outboards.

The Tri-ram midsection features triple trim rams and a trim pump integrated within the die-cast clamp bracket assembly.

The Tri-ram midsection is featured on the 250R and selected 300R models.  Triple power trim rams along with the power trim pump are integrated within the die-cast clamp bracket assembly. A stiffer, high-durometer elastomer upper mount and solid lower mounts are used for enhanced handling at higher speeds. The 250R comes with the Sport Master gearcase. Sport Master and Torque Master gearcases are both options for selected 300R Tri-ram models. The Tri-ram midsection is designed for use on lighter weight hulls on protected waters.

The Heavy duty midsection with ultra robust, forged clamp brackets and a large, single ram trim cylinder.

Heavy duty midsection 300Rs come with solid mounts and robust, forged transom brackets with single ram power trim and a remote trim pump designed to endure the harsh offshore environment. These models are available with the Sport Master and 5.44″ HD gearcases.

Rear tie-bar 300R models feature the heavy duty midsection with a factory installed tie-bar mounting plate.

Rear tie-bar models feature a factory installed tie-bar mount plate. The tie-bar, not included but available from after market suppliers,  provides enhanced engine stability for high speed catamarans and vee bottoms.


The Sport Master gearcase features a crescent leading edge and low water pickups.

Gearcase Options 

The surface piercing Sport Master, designed for boats capable of speeds in excess of 85 mph, features low-water pick-ups and a crescent leading-edge for maximized efficiency and speed.

The Torque Master gearcase features dual water pickups.

The Torque Master, designed to run partially surfaced, carries the load of heavier tournament bass boats and multi-species hulls while maximizing top speed and drivability.

The 5.44″ HD gearcase, featuring dual water pickups, is designed for applications which require a more submerged gearcase.

The 5.44” HD is designed for use on bay boats and multi engine performance center consoles where the application requires a more submerged gearcase.






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Runway 9-27 : The Road to SEMA

The 1650 Ultima GTR at rest on runway 9-27. Photo Credit: John Erlien - Mercury Marine.
The 1650 Ultima GTR at rest on runway 9-27. Photo Credit: Jon Erlien – Mercury Marine.

We’re back in Las Vegas for the 2014 Specialty Equipment Market Association (SEMA) show. It’s hard to believe a year has passed since we unveiled our QC4v automotive crate engine here.  Since then – we’ve received a lot of interest in the product and its capabilities. Various applications have been suggested – off road racing, drag racing and high performance street rods to name a few.   Read more

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Hush the Magic 520!

The 520 sterndrive comes with cast iron manifolds with stainless steel exhaust elbows.
The 520 sterndrive comes with cast iron manifolds with stainless steel exhaust elbows.

Mercury Racing 520s with Axius Joystick Piloting technology is a popular option for their 400FX Sport Cruiser.
The 520 with Axius Joystick Piloting technology is a popular option for Formula’s 400FX Sport Cruiser.

Our new 520 sterndrive has been a resounding success since it was introduced one year ago at  the LOTO (Lake of the Ozarks) Shootout. It’s become even more popular since the release of a  Joystick Piloting for Sterndrives – Axius option for selected models fitted with the Bravo Three XR sterndrive. Formula boats have been early adopters of the engine package. They are also the first OEM boat builder to install the potent engines with joystick control. A Formula 400FX used to demonstrate joystick 520 maneuvers at the Miami Boat Show had standard through transom exhaust fitted with aftermarket mufflers. For our traditional sport boat crowd – they had a nice exhaust note. For those looking for enhanced performance without all the rumble – it might have been a bit much.

Alpha maleness without all the barking!
Alpha maleness without all the barking!

This CAD drawing shows the the port and starboard exhaust connected by a custom y-pipe.
This CAD drawing shows a 520 engine fitted with the starboard X-haust Noise Reducer System – Stage 1.

We took note, no pun intended, and went to work to create an X-haust Noise Reduction system designed specifically for the 520.  The system will appease our friends at Formula and a variety of our OEM boat builder partners, dealers and consumers looking to take advantage of the 520’s performance value.  It will also be adopted in European Union countries where the engine is certified in meeting the stringent RCD (Recreational Craft Directive) exhaust emissions standards. Read more

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Got Wheels?

An electronic file of the SEMA brochure.
An electronic file of the SEMA brochure.

The QC4v crate engine shares attributes of its marine cousins.
The QC4v crate engine shares attributes of its marine cousins.

We are excited to unveil our concept QC4v crate engine this week at the 50th annual SEMA show. The A multitude of configurations are possible, fom basic long block form to ready to run engines.  The project has to be one of our best kept secrets ever.

QC4v in the tightly confined engine bay a mid-engine two-seater.
QC4v in the tightly confined engine bay a mid-engine two-seater.

This is our first  SEMA show and there is a lot to see. We brought  an exotic supercar fitted with a turbocharged QC4v 1650 crate engine. The car is complimented with an equally exotic DCB M41-Wide Body catamaran sport boat powered by twin 1350 sterndrives.

The brilliant  QC4v crate engine cutaway.
The brilliant QC4v crate engine cutaway.

An  immaculate cutaway crate engine display shows the brilliantly engineered inner workings of the QC4v engine design. That is flanked by a complete QC4v 1350 and 8.2 Liter 520 sterndrive engine displays. A complete QC4v crate engine is featured in SEMA’s New Products Showcase. Read more

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This is the 5th in a series on design features of Mercury Racing’s  Quad Cam, four valve sterndrive engine.

The heart of our turbo compressor: hot gas expands through turbine blades, while at the other end of the shaft, compressor blades pack air into the inlet plenum.

Imagine the pulse rate in this triple 1350 powered Cigarette Marauder!

As I mentioned in The Valve Train That Could, valves exist to get air in and exhaust out. Well, the exhaust isn’t finished just because it’s past the intake valves. It’s got work to do: It’s time to “Peg the fun-o-meter” for some lucky boater! Exhaust heat remains from combustion. All turbocharged engines use that “waste” energy to spin a turbine, compressing incoming air to higher density. QC4v does that – and more.

It’s less commonly known (except by header designers and a few other social deviants), the exhaust flow also has pressure waves racing down and back up the exhaust system. When an exhaust valve opens to expel spent combustion gases, the rapid pressure rise sends a pulse down the pipe at the speed of sound. Read more

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Erik’s Reality

The all-new 1650 RACE features closed cooled turbochagers.
The all-new 1650 RACE features closed cooled turbochagers.

The 1350 is no longer the fastest or strongest in Racing's H.P. stable.
The 1350 is no longer the fastest or strongest in Racing’s H.P. stable.

It’s hard to believe a year has passed and the 2013 Miami Boat Show is underway. We’ve experienced some major events since our last visit to South Beach. Fred Kiekhaefer has moved on after 22 years of service. With Fred’s departure, Erik Christiansen has been named General Manager. Fred will continue to represent Mercury Racing over the next two years. In fact, he’s at the show. If your there, be sure to stop by the Mercury booth and say hello. Erik and our staff of sales, service and engineering personnel are there to support the brand as well.

I decided to forgo the show this year to be with my son. I’ll miss seeing everyone and the exciting new products being unveiled. Jay Nichols has ensured me he will keep me abreast of the action via his acclaimed photography.

Rumor Mill

The 1650 RACE features reversed colors from the std. 1350 offering.
The 1650 RACE features reversed colors from the std. 1350 offering.

Some of you may be aware of the rumor mill started a while back when Powerboat Nation posted a story speculating we were going to release a 1700 h.p. engine. The story featured a dated 1350 model shot. Erik squashed all rumors when he unveiled the all-new 1650 RACE sterndrive. Based on our exclusive quad cam, four valve 1350, this monster features new pistons, larger turbos and requires 112 AKI race fuel.

So there, PB Nation. You were correct in that – yes – we did release a higher power engine based on our exclusive quad cam, four valve engine platform. You were off on the power and color, however. And no, this is not your father’s poker run engine. It is a race engine that is sold, without warranty, to qualified powerboat racing professionals. I’ll make sure you get a press kit:) Read more

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Key West Poker Run Recap

The QC4v 1350 sterndrive always draws a crowd.

Mercury Racing was recognized for our title sponsorship at the Friday Night sponsor party.

Whew! I’m just getting back to a “normal” schedule after last week’s Key West Poker Run. It was a great event. We had people at the Mercury Racing truck from the moment we unloaded our 1350 and 565 display engines through the 10:00 p.m. closing time. It was non-stop action Thursday through Saturday. It’s always fun to meet and greet folks who enjoy our products. It is equally enjoyable to establish new relationships with future customers.

This year was the 20th anniversary of the event. Stu Jones and the Florida Powerboat Club staff didn’t disappoint. This has to be the largest gathering of performance boats on earth. It is also the largest gathering of performance boat builders and dealers. Industry movers and shakers included Reggie Fountain, Randy Scism (MTI), Peter Hledin (Skater), Chad Braver (Cigarette), Todd Warner (Statement), Nils Johnson and Trond Schou (Nor-Tech), Paul Loguidice (Hustler), David Woods and Scott Shogren (Pier 57). Read more

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565: How’d We Do That – Part 2?

Mercury Racing’s dynos enable precise calibration by our exceptionally talented engineering techs, like Johnny Bauer. They also validate that every production 565 meets its targets.

Mercury Racing’s 565 – with digital throttle and shift (DTS), better fuel economy and more grunt – prompted questions. Part 1 answered “How’d you do that?” by reviewing the 565’s torque and power. Part 2 continues to answer: We’ll discuss 565 fuel and DTS.

In this early development engine, one can see the two computer modules stacked behind the second throttle body. Also visible is the digitally controlled shift actuator – mounted on the transom for this test mule.

Fuel Economy. Miserly fuel consumption is a hidden benefit of digital instrumentation. Not just in the boat, but in our laboratory. Since we designed the 525EFI and 600SCi, we have substantially upgraded our dynamometers and engineering analysis tools. In large part, this was done for exhaust emissions, both design feasibility studies and product development, so that we could remain compliant with regulations. As a side benefit: we gained a capability to look at each individual cylinder’s behavior in much finer detail than ever before. Plus, our incredible technicians have the talent to do so.

Read more

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565: How’d We Do That – Part 1?

Mercury Racing’s 565 – with digital throttle and shift (DTS), better fuel economy and more grunt – prompted more than a few questions. Mostly variations of: “How’d you do that?” We agreed to blog and provide some answers. In Part 1, I’ll discuss about torque and power. Part 2, fuel and DTS.

Torque. How big are the bombs and where do they push?

The 565’s all new cylinder head flows about as much as is possible with a 2-valve.

As I said in discussing our QC4v 1350, “The Valve Train That Could,” bigger bombs make more power.  We pack more air because we designed the heads and inlet valves to flow better. Admittedly, they’re still two valve heads and not as free flowing as our four valve engines, but they’re better than our previous two valve designs. With more air, more fuel is added for combustion and makes a bigger bomb. Yet, fuel economy is better! How? Improved and more precise fuel delivery to each combustion event makes less wasted (unburned) fuel. Easy to say; hard to do – but we did it. (More about that in Part 2.) Read more

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Virtual Tour – Part 7: Cleaver Revolution

CNC machines produce our perfectly matched 5-blade or 6-blade cleaver propellers.

Skilled craftsmen hand-finish each CNC prop.

Continuing from Virtual Tour –  Part 6: Propellers…we’ll review the evolution of surface piercing propellers, culminating with our amazing CNC Sterndrive Cleavers.

I first reviewed my classic literature collection for information regarding the evolution of surface piercing propellers. Copy from the propeller section of  a 1972 Hi-Performance Mercury/MerCruiser Accessories catalog references our change from bronze to stainless steel that year. I sent Dick Snyder an e-mail to get his input regarding racing propeller history.

Dick Snyder

Three-blade “elephant ear” props on a quad 1250BP rig ready for testing at Lake X.

A 2-blade stainless prop on a merCruiser III drive. This drive was packaged with a 475 h.p. engine.

Dick Snyder was in charge of Mercury’s propeller engineering in the early ’60s.  “When I took over prop engineering in the early ’60s, I had inherited nothing but low rake (6 degree), 2-bladed props. We had no racing or hi-performance props. “There soon came a time when I fell in love with 15 degrees of rake and 3-bladed props for the added smoothness and a little better acceleration. You typically would lose a small amount of top-end going from a 2-blade to 3-blade prop. The higher 15-degree rake allowed the props to “hold” at greater trim angles for enhanced bow lift and greater hull efficiency. This resulted with even greater top-end speeds than the lower rake 2-blade props,” Dick explained. In 1984, Dick was promoted to Director of Mercury Hi-Performance. So he promoted Bob Hetzel to run Mercury’s racing prop and gearcase shop. “We had quite an interesting development of stainless steel props for racing, followed by replacing bronze for stainless steel on our recreational props,” said Dick. Read more

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Virtual Tour – Part 6: Propellers

A technician puts finishing touches on a 5-blade CNC Cleaver sterndrive propeller.

Checking blade thickness on a classic 3-blade outboard cleaver.

Continuing from Virtual Tour Part 5: Sterndrives, Transoms & Accessories…we will visit the Mercury Racing Propeller Department’s finishing area.

People are fascinated with propellers. The response to Scott Reichow’s Prop School blog series proves people are craving to learn more. Our visitors are a bit surprised when they enter Racing’s propeller finishing area. I think they are expecting to see a number of robotic machines pumping out finished propellers. Nope. What they do see is highly skilled craftsmen creating precision tuned works of art. Each puts their finishing touch on every propeller Racing makes – including our CNC machined Sterndrive Cleavers.

Lab Finished props gave Team Mercury a competitive edge in the outboard factory war days of tunnel boat competition.

Have props, will travel. A classic photo of Mercury’s mobile prop lab during the golden era of outboard factory tunnel boat racing.

The trademark, “Lab Finished,” was created by Mercury Racing back in 1970s – when factory outboard racing required a dedicated Engineering Lab to create specialized props. We have proven through the years that hand-working a prop enhances performance. This is particularly true for props run at elevated transom heights (surface piercing) and higher RPMs where impact-induced vibrations and other nuances are amplified.

Only a small percentage of our propeller line is designed specifically for racing. Our most popular propeller is mostly used for recreation: the Bravo I. We first enhanced performance of this MerCruiser sterndrive propeller by lab finishing them for racing. Read more

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Virtual Tour – Part 5: Sterndrives, Transoms & Accessories

Continuing from Virtual Tour – Part 4: Horsepower Highway…we will follow the assembly of Mercury Racing sterndrives, transoms and accessories.


Mike Riedi inserts the drive shaft on a Bravo One XR Sport Master gearcase.

Mike lowers the Bravo One XR upper housing on the Sport Master gearcase.

Mercury Racing offers a variety of sterndrives fit for virtually any application. Bravo One XRs are enhancements of existing designs while NXT1, NXT6 and M8 drives were designed and developed in-house for Mercury Racing sterndrive packages. The Bravo One XR is a beefed up version of MerCruiser’s Bravo One drive. It was developed to withstand the rigors of offshore racing and performance boating. Our Bravo One XR Sport Master drive targets surface piercing applications. Bravo One XR and Bravo One XR Sport Masters are popular options for boats fitted with 525 EFI, 565 and 600 SCi engine packages. Mike Riedi, who has over 30 years experience building high performance outboard gearcases, also builds Bravo Sport Masters.


Joe Backhaus building a M series transom plate.

Dave Vehrs preparing a NXT6 drive for the installation of the dry-sump oil pump.

Joe Backhaus builds Integrated Transom Systems (ITS) for Bravo One XR and Bravo Three XR drives. He also assembles M-Series transoms used with Mercury Racing  NXT1, NXT6 and M8 drives.

Next door to Joe, Dave Vehrs (when not man-handling our 18-wheel Marketing big rig in the Arizona Desert or Florida Keys) builds the drives to go with Joe’s transoms.

When I first started working here, I attended outboard and sterndrive service schools. Drive building was the sterndrive school’s main focus. A beginner quickly learns the challenge of building a drive – over and over – to get the shimming right for correct gear tolerances. It was with this experience that I gained an appreciation for what Mike and Dave do every day. I’m still a rookie; these fellas are top-shelf pros. Read more

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Virtual Tour – Part 4: Horsepower Highway

Continuing from Virtual Tour – Part 3: Outboard Production…we will follow the assembly of Mercury Racing big blocks – those based on GM’s 502 c.i. platform.

Horsepower Highway

Jon VanDenBogart prepares to install a crankshaft in a CNC machined 502 cylinder block.

Pre-assembled pistons and connecting rods are matched to a designated cylinder block to ensure proper fit and function.

“Horsepower Highway” is where our 525 EFI, 565, 600 SCi , 662 SCi and 700 SCi sterndrive engine family is built. One technician hand builds each engine from a bare cylinder block to a “long block” (with all the rotating and reciprocating bits fitted inside). Sub-assembly work prior to an engine build includes the rotating assembly: balancing a crankshaft,  matching it with a camshaft, pistons, rings, and connecting rods for later fitment into the block.

Horsepower Highway was conceived, engineered and built in-house. It features a unique rail system and assembly fixtures used to transport cylinder blocks along the line. At each station, all the required tools and components are located for assembly. Each technician controls the speed of his build, moving the block along at their own pace. If something doesn’t look right, it is his discretion to stop right then and there. The build begins with installation of a camshaft. Next is the installation of a crankshaft, timing chain and matched piston and connecting rod sets. The bottom end is sealed with the installation of the oil pan.

The engine is rotated on its assembly fixture to enable work on the top end: The cylinder heads are installed; then push rods and rocker arms. Temporary valve covers mask the valve train prior to paint. An intake is the last component installed before the long bock goes to our paint line. Upon return from paint, it goes back on The Highway for installation of a bell housing.  Color matched valve covers replace the temporaries to complete valve train assembly. Transmissions for NXT1 or NXT6 drive models are installed at this point as well.

Jon rolls a 700 SCi long block along Horsepower Highway.

It’s not everyday one sees a Nanna Yeller 565 rolling along The Highway. Mike Rebedew puts finishing touches on the 8.7 Liter long block.

Long blocks for various engine models look similar. One noticeable difference is the intake (long blocks with naturally aspirated intakes are destined to become 525 EFIs or 565s; those with pressure charged intakes will become 600/662 or 700 SCi’s). Custom color long blocks stand out, too. The “dress line” is where an engine get its true personality. Read more

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Virtual Tour – Part 3: Outboard Production

Continuing from Virtual Tour – Part 2: Quality, Paint, and Quad Cam Production…we will follow the assembly of a Mercury Racing OptiMax 300XS outboard.

2-Cycle Outboards

Gary Aman lowers a 300XS powerhead into position for final engine assembly.

Mike Riedi has over 30 years experience handcrafting high performance gearcases.

Consumer, government and race outboards, featuring Mercury’s low-emissions, direct fuel injected 2-stroke OptiMax powerheads, are assembled at Mercury Racing’s factory in Taycheedah, Wisconsin. Consumer models include the 3.0 Liter OptiMax 250 SportXS and the 3.2 Liter OptiMax 300XS outboards. Watch for a future post on the OptiMax JP, an outboard we build for the government.

The competition outboards produced in Mercury Racing’s factory include our 2.5 Liter OptiMax 200XS SST (Super Stock Tunnel) and 2.5 Liter OptiMax 200XS ROS (Race Offshore). However, Racing’s four strokes — the 60 EFI FormulaRace and the Verado 350 SCi — while designed and validated here, are built off-site at other Mercury facilities in order to share common (and expensive to replicate) production processes.

OptiMax 300XS powerheads await their turn on the dyno.

Mike Hammer inspects each cylinder with a bore scope camera.

OptiMax powerheads are manufactured complete, to Racing’s specifications, at Mercury Marine’s headquarters campus — home to Mercury OptiMax outboard production in Fond du Lac, Wisconsin. Upon their arrival at Mercury Racing, a powerhead’s first stop is one of our 2-cycle dynamometers. Upon completing a power run, they move to Racing’s 2-cycle department. There, technicians inspect the cylinders, to ensure proper wear patterns, prior to final outboard assembly. Meanwhile, another technician is working his magic: handcrafting a gearcase that will efficiently transfer 300 h.p. to the water. Read more

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Virtual Tour – Part 2: QC, Paint & QC4v

Continuing from Virtual Tour – Part 1: Intro.… we will visit Mercury Racing’s Quality Control and Paint Line.  We’ll end up in the 4-Cycle Race Shop where technicians build our exclusive quad-cam, four valve sterndrive engine family. Lets go!

Quality Control

Quality Control plays a critical support role in Racing's manufacturing processes.

The automated Coordinate Measurement Machine is the newest addition to our Quality Control room.

Wherever we can, quality control (the discipline) is built into our production processes. Got to build it in; can’t inspect it in. Quality Control (the department) supports these quality processes (trust but verify) — and measures tolerance’s on everything from machined castings, gears, cylinder bores, pistons, crankshafts and anything else used in the production of Mercury Racing products. QC also plays a critical role in the in-house prototype development of new products. This place was buzzing with activity during the development of the QC4v sterndrive engine platform because so much was new — suppliers, parts and processes. Read more

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Ethanol and Older Outboards

Damage to a boat engine carburetor as a result of ethanol at 10% (E10). Photo courtesy BoatUS.

Mercury Racing has received numerous questions on ethanol fuel in older engines. Here is an article from BoatUS, written with input from Mercury engineers (republished with permission), that covers many of the ethanol issues:

A Shotgun Marriage? Ethanol and Old Outboard Boat Engines

ALEXANDRIA, Va., March 28, 2012 — Ever since E10 gasoline (gas containing 10% ethanol) became widely available several years ago, the nation’s largest recreational boat owners group, BoatUS, has received hundreds of calls and emails complaining about boat engine problems. The majority of complaints concern older outboard motors, those made before about 1990. BoatUS’ Seaworthy magazine asked Mercury Marine’s Ed Alyanak and Frank Kelley, who between them have over 60 years of experience, to find out what’s made these decades-old outboards more susceptible to ethanol’s well-known problems and what owners can do. Read more

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Hi-Performance Boat Operation – Part 3: Prep & Drive

Pre-run inspection of a 700 SCi powered DCB catamaran. Photo credit: Tres Martin's Performance Boat School.

Twin OptiMax 300XS outboards rigged on a 30-foot Spectre catamaran.

In my previous post (Part 2) regarding high performance boat operation, I reviewed basic information on rigging fit and function. Now its time to head to the ramp.

While the boat is still on the trailer, walk around for a visual inspection of the hull.  Next, climb aboard for a visual inspection of the interior and engine compartment (motor well for outboards): ensure everything is in place and secure. Don’t forget the drain plug(s)!  Check your other safety accessories: aboard? In secure locations?

Helm of a DCB M35 catamaran powered by twin 700 SCi sterndrives.

Helm of 50-foot Cigarette Marauder with twin 1350 sterndrives.

Once your boat is launched,  review the helm to familiarize yourself with the location and function of all instruments and controls. Make sure the steering wheel, throttle and shift controls are well within your reach and that you are comfortable with their operation.

If your boat is fitted with K-Plane trim tabs, be comfortable with the location and operation of the tab trim switches. The driver needs to know the location and function of accessory switches such as bilge blower, bilge pump, running lights, horn, courtesy lights and related fuses, or circuit breakers. Read more

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Lovin’ Up Our Classic Big Block

These are some of our people who made the 565 happen.

Color optioned Super Silver valve cover caps Racing's exclusive aluminum 2-valve cylinder head.

New for the 2012 Miami International Boat Show — and enthusiastic performance boaters!

Mercury Racing has updated its core, big block sterndrive! Now, the venerable 525EFI has a digital sibling — 565!

We’ve stroked the block to 8.7 liters (or 533 cubic inches), redesigned the cylinder heads, added a second throttle body to the inlet, broadened the torque curve and increased output to 565 horsepower at 5,000-5400 rpm.


Zero Effort digital throttle: the ideal way to control this powerhouse!

Top mounted PCM, TCM and electrical connections makes installation easier.

Mercury Racing’s new 565 runs strong on 89 octane pump gas (RON+MON)/2. It employs dual throttle bodies and electronic fuel injection flowing through a new cylinder head which we designed with improved valve angles for better flow and more precise air and fuel distribution.

Managing operations is a new controller for this engine – the same Propulsion Control Module used on our 1350.

Read more

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The 1959 Glass Craft Aero Dynamic Citation as it looked prior to the restoration.

A custom graphic adorns the top of the replica "alien" engine cowling.

Chris Fairchild is a busy guy. His passion is powerboat racing. He’s been racing tunnel boats for over 20 years.  He not only races his own boats in F1 and SST 120 classes, he also builds and repairs race engines and gearcases. He manages to do this in addition to his “real job” of building custom homes with his father, Jim. So, when he sent me pictures of his latest project, I wasn’t surprised. But it still impresses me that he accomplishes what he does with all of the things going on in his life.

A neurosurgeon approached Chris with the idea of restoring the family boat he grew up with.  The boat started life as a 1959 Glass Craft Aero Dynamic Citation outboard runabout.  The doctor wanted to restore the Glass Craft so he could have something to run on the river during the limited time he is “off-duty.” The challenge was the water levels are too low for traditional outboard propulsion. The doctor asked Chris if the boat could be converted to a jet boat. Chris, always up for a challenge and a journey into the unknown, said, “why not?” Read more

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Hello Handsome! Part 3: Details.














































































The induction system on the 1973 “Champion Maker” needed no styling. Function (here in Doc Magoon’s US-1 Cigarette) was in your face!

































Communicating the technology within. Some technology is simply beautiful on its face. The induction and air balance system of the QC4v platform required only minor refinement to “style” it. It’s just cool – like the 1970s Kiekhaefer fuel injection trumpets from my dad’s “Champion Maker” Class 1 offshore race engines. With QC4v, some minor shaping and angularity masked the required hoses and clamps, but the inlet runners whisper, “You know why we’re here.” Big air!

Both function and movement are suggested in the exhaust manifold styling.

Cast exhaust manifolds, in a world previously occupied by gleaming polished stainless, was a bigger challenge. We opted to communicate the pulse tuning of the exhaust system through subtle relief in the casting surfaces – indicating the pairing of ports and the side-to-side differences. This also helped function: maintaining a high scrubbing speed of the manifold cooling water. Read more

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“Step right up!”

A favorite of the Mercury Racing stable, our 525 EFI. Its stout components make it a tempting target for upgrades.

There are “tuners” out there that offer supercharger kits for Mercury Racing 525 EFI engines (and others). Some of these kits reportedly boost horsepower and torque as much as 50 percent. They reprogram our engine controller to override its logic and limits. Yes, there is more power to be had – for a time. We program our ECUs to keep engines within their physical limits and offer good power with reasonable reliability and durability.

Ah, the joy of performance on the water! This 525 Bravo One XR powered Nordic is a great running and reliable combination.

One tuner just offered a “price reduction.” Their claim is to make power upgrades more affordable. Beware of the sales pitch, “Step right up! It’s on sale!” Alarm bells should be ringing in your head when you hear those words. If you’re tempted by that offer (and your warranty has expired), please proceed with your eyes wide open because just the opposite is the likely result. Here’s why “affordable” may prove very expensive. Read more

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Hello Handsome! Part 2: Methods.

Inspiration from my “wall”: a great looking engine, necessarily buried in frame rails and fenders, is a Ferrari 4.3L V8.


















One of my favorite details: side cooling ducts on a McLaren. Flowing elegance, if a bit too busy.
















Inspiration. There are a multitude of tools in a stylists arsenal. Before any of them can be used, we have to agree to the physical design constraints which define the canvas. Brainstorming basic design alternatives is a prerequisite to an elegant styling execution (not to mention, functionality). It also requires “the eye.” Stylists see things in many places and contexts where most of us don’t. Inspiration can happen at any time. I keep a photo file of appealing details. Inspiration is everywhere: parking lots, race tracks, concourse events, collector displays, air shows, plumbing show rooms – everywhere. My file becomes a wall during a project like QC4v, but settles in a direction, often reinforcing a theme consistent with product history – the DNA. Choosing one design approach sets many things – including the execution journey and styling constraints. Read more

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Hello Handsome! Part 1: How?

1350 on the dyno at Mercury Racing. With the air boxes and covers removed, one can view some of its inner beauty.

Two years ago, I received a call from Skip Braver, owner of Cigarette Racing. He had just received the first 1350 for his AMG Cigarette: “I don’t want your head to explode, but that is one, handsome engine. Just gorgeous!” Thanks, Skip. Flattering. But how did “handsome” happen?

AMG Cigarette: Form follows function. Beautifully. (Photo courtesy of Cigarette Racing)

Function. First, beauty is deep in the soul of Mercury Racing’s QC4v platform, as well as on the surface: it works as intended; it fulfills the needs and desires of its owners better than any engine offered before. In short, it functions as it should (and better than most customers expected). Function defined the structure.

Form. Second, form followed function. I’ve become somewhat infamous for a comment I made back in the 1980s: “Where is it written, that because it is strong, it must be ugly?” This was a discussion with my manufacturing guy at that time, the late Bill Hackbarth. Bill, a stubborn pragmatist, didn’t like the form of the Kiekhaefer sterndrive (now #6) because he couldn’t figure out how to hold the curvacious upper gear housing in a machining fixture. We changed the form, adding a big lug, so he could clamp it tight. When machining was done, we ground that part back off. Propulsion should look good, but… Form follows function. Read more

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Oddities & Rarities – Part 3: Race Power

How many outboards can you lay down in a boat?

Maybe this should be “Part 3 through # n” — since few things are odder or rarer than “one-offs” tried in pursuit of a speed record or race victory. Still, some stand tall above others in sheer audacity. Here are some outboards with an identity crisis.

While it ran, it was fast! Count ’em – six sets of exhaust pipes!

Because of the high power to weight ratio of a Merc 2-stroke powerhead, it was inevitable that Mercury Racing’s Fred Hauenstein would lay some outboard engines down on their sides in his Arcadian Unlimted U-86 and go after inboard hydroplane competitors. Read more

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Alpha Male-Ness Without All The Barking

Mercury wants (and is required) to have exhaust and noise emissions compliant propulsion. By being responsible citizens (you and us), our freedom on the water can continue. Global regulations have caused larger marine engine manufacturers to invest millions of dollars in research and development. In that work, Mercury developed an on-board microprocessor that controls all aspects of engine operating performance – including fuel management and exhaust emissions.  The combination of advanced engine components (hardware), fuel calibration development (software) and extensive testing (more hardware and software) led us to a full line of sterndrives that meet U.S. California Air Resources Board (C.A.R.B.) and Environment Protection Agency (EPA) regulations.  But, as we have learned with experience, emissions regulations are ever evolving.

X-haust Noise Reducer logo: noise in, X, quiet out.

Baja 35 Outlaw with twin 662 SCi’s and X-haust.

Just when we thought our job was done, by meeting the CARB and EPA regulations in place at that time, more stringent ones were being implemented by the European Union (EU) Recreational Craft Directive (RCD). We had to do additional work to create “global” engines that would meet stringent EU RCD exhaust emissions and noise regulations.

We tackled exhaust gas emissions first. The EU662 SCi is he highest horsepower we could attain and still meet the EU RCD exhaust emissions regulation. Also, we were able to adjust fuel calibration on the 600 SCi to make it RCD exhaust emissions compliant.

Then, noise.  Engines, as rigged with a typical through transom exhaust system, didn’t pass RCD noise requirements. Aftermarket mufflers didn’t help. Running exhaust through the prop isn’t an option with our engines: too restrictive. Read more

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Bravo for Outboards? YES!

For those of you who may not know me, I manage Mercury Racing’s propeller department. We offer a wide variety of high performance outboard and sterndrive props. I oversee production and manage our prop offerings. My most enjoyable responsibility is helping customers solve their unique propeller issues.

Pro Finish Bravo I XS outboard propeller.

Allison XB-21 BasSport 2 + 2. Photo courtesy of Allison Boats.

I’ve been getting great feedback regarding our Bravo I XS outboard propeller. The latest is from Allison owners who say it is an awesome prop for their XB-21 tournament bass boats. XB-21’s rigged with an OptiMax 250 Pro XS do best running a 27-inch pitch Bravo I XS. Those who power-up to the OptiMax 300XS say their ride is dialed-in using a 29-inch pitch Bravo I XS. XB-21 owners have found odd-pitch Bravo I XS props provide the best hole shot and bow lift. Read more

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Education (and Tuition)

48 MTI and 1350s during testing.

Sometimes education comes unexpectedly. When special designs or capabilities come together in a unique new way, surprises can occur. This just happened: In preparation for the Miami International Boat Show, MTI was testing one of its 48 Race/Pleasure catamarans powered with Mercury Racing’s 1350s and M8 drives.

Dry sump. I’ve written before about the purpose of dry sumping – efficiency. Here we have a 48 MTI with two dry sump M8 sterndrives. Plus two dry sump, quad cam, four valve engines making 1350 hp each. Between engines and drives, dry sump transmissions. Big power; big expectations!

As people sometimes do, the owner tried propellers from another manufacturer. Whang! Blade gone. We warned that these engines produce big fat monster torque (BFMT); we learned this lesson the hard way, too; we designed a special prop series just to handle it. However, this was not the education – just its preamble.
Read more

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50 Years of Racing merCruisers – Part 2

Racing MerCruisers: 1988 – 2010 (continuing from 50 Years…Part 1)

1988 Superboat World Cup Champion, Don Johnson, with Sterndrives by Kiekhaefer and engines by Gentry.

The deal that wasn’t: Mr. Seger had big ideas, but did not follow through. Ah, what might have been.

First, a relevant side bar: In 1985, a Swiss businessman and offshore racer, Hugo Seger, approached Kiekhaefer Aeromarine (KAM) to design a racing drive. He had tired of his drive failures. We agreed to a deal: KAM would design a drive, he would pay as we made progress, and would become our European distributor.

KAM looked back at the K-600 sterndrive because it was already tooled! But in the dozen years since 1973, we learned a propeller was happier when positioned higher and farther back. Since we dared not start with any handicap, we began to design anew. “Sterndrives by Kiekhaefer” was conceived. Designers, Larry Lohse and Tom Theisen, didn’t sleep much. Me either. Read more

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50 Years of Racing merCruisers – Part 1

Mercury's founder (my co-founder), Carl Kiekhaefer, came reluctantly to embrace the sterndrive concept. But once on board, he never looked back.

2011 is the 50th anniversary of the merCruiser sterndrive. More important to those of us with the speed-on-the-water gene, it is also the 50th anniversary of racing with merCruiser sterndrives. So, here is the first part of the chronology, 1961 – 1987,  and a pictorial flashback: the evolution of the Mercury Racing and Kiekhaefer sterndrives.

Now in its third printing, Jeff Rodengen's book on Carl Kiekhaefer exposed the previously unknown conspiracy in creation of the modern sterndrive.

For a thorough exploration of the modern sterndrive creation, I recommend Jeff Rodengen’s book, Iron Fist, Chapter 26, The Great Stern Drive Conspiracy, pp. 360 – 379. It is a fascinating work of investigative journalism containing creation, deception, disloyalty, honor and captivating personalities of the sterndrive’s history. Here, I’ll focus on the history of merCruiser and Kiekhaefer racing drives in this two-part series.

merCruiser Racing: 1960 – 1987

Sales literature for the first merCruiser with 327 c.i. and 225 hp.

In March 1961 came the first merCruiser – coined from mer (for Mercury) plus Cruiser (for its target market). The idea was to use more powerful automotive-based engines (like an inboard engine) with vectored thrust, trim and steering (like an outboard) to give better performance than a conventional inboard.

This first 225 hp merCruiser sterndrive proved to work well pushing a boat and was more powerful than competitor’s. But it had an odd worm gear and ring gear mechanism to crank the whole drive out of the water – 180 degrees about the crankshaft axis – for corrosion resistance and “prop changes from inside the boat.”

Don Aronow and mechanic, Knocky House, switched from inboards to race merCruisers in the Bahamas 500 and ever after.

Rapid follow-on design work brought the 110 and 140 hp merCruiser I, introduced in late 1961. It was followed quickly by the 310 hp merCruiser III in 1962. The original drive, renamed merCruiser II, was produced until replaced by a new design in 1970 – without the crank-up mechanism. The II and III were the platforms for racing variants.

Twin 225 hp merCruiser IIs powered the 1962 winner of the 184 mile Miami-Nassau "Ocean Power Boat Race." No bolsters. No canopies. No engine hatch. Just go!

By 1962, there was a “Super Speed Master” (SSM) version of the merCruiser II. From inception, factory owned Mercury Racing teams were conquering all comers in offshore power boat racing. That’s where “the enemy” was. Offshore victories told the world merCruiser had arrived. Market supremacy followed quickly.

Read more

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“You Must Have Had Help!”

I’ve had some time to reflect over the Holidays. It was cold and snowy here, so I began dreaming about boating in Florida or Lake Havasu with our new QC4v, 1350 hp engines. Inevitably, that leads me to thinking of the incredibly talented people at Mercury and Mercury Racing who made it happen. Sad how little credit they get for their effort – at least, beyond our hallowed walls. Things I hear make me want to scream, “We have the talent right here!

The QC4v team with their creation just before the Miami Boat Show launch, February 2010.

Whoa! “Quad overhead cams!” And all metric stuff… “Metric equals furrin’, don’t it?” “It looks European.” “Porsche must have designed it for Mercury Racing.” “AMG designed it.” “Lotus…” And so many times, “What block is that based on?” I’ve heard (or read) all of these things, and more.  I’m flattered; that’s good company.  But folks, this was an in-house job.

One thing for sure: Fred K didn’t design it! (OK, I styled it, attended countless meetings about it and did the initial carbon tooling work. And I wrangled the money to pay for it.) No sir, Iclicked nary a mouse anywhere near a ProE CAD station (except once, when I leaned over Tom Immel’s shoulder).

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Dry Sump. Pump it up!

I am pleased to bring you the 4th in a series on the technology of our 1350 engine.

Efficiency. The purpose of dry sumping is efficiency: Put enough oil in the right places to lubricate and cool moving components, but not so much as to produce drag. Then, more power comes out.

The term, “dry sump,” simply refers to scavenging the oil from the lowest point (sump) of an engine – making it “dry.” Except, it’s never really dry. Oil goes almost everywhere and wants to collect wherever there is a low spot. Wherever oil gathers near moving parts, there is not only lubrication, but also risk of drag and even damage.

No tranquility. The oil doesn’t pump gently to the valve train or rod bearings, lubricate and peacefully trickle back down, to make the rounds again. It’s violent in there: Oil goes “weightless” and smashes down when a boat launches and lands. It splashes with every wave impact. It wants to pile on one side, when you round a turn marker. Just think about how your body moves around at speed – and you’re not ducking under a spinning crankshaft! Read more

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Dyno Mighty!

We have an amazing dynamometer laboratory at Racing. The lab is how we know you’re getting the performance and durability you expect. It is independently certified to International Standards Organization (ISO) requirements. Each day, our dynos are put to work: verifying production engine output (video below), validating components, improving quality, reducing emissions or developing power. Although a dyno is helpful for production consistency, it’s indispensable for development. Our engineers and technicians have logged hundreds of thousands of hours conducting dyno testing. They’re pretty good at it.

Moreover, ours is the only lab in the world that can certify exhaust gas emissions on spark-ignited engines over 1,000 hp. Erik Christiansen, our Engineering Director, searched the world to find someone to do emissions testing for us. No one could, so we built our own capability. We are making engines both cleaner and more fuel efficient. We understand dyno processes. Read more

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Sterndrive Losses? Less Than You Think!

Tremendous effort goes into good boat set-up. My conversations about set-up too often turn to power consumed by a drive train,or generated by an engine, and always… propellers. The goal is efficiency – accepting some sacrifice for boat control. Really, your goal is the euphoric joy and adrenalin rush of high performance boating! My goal is to help you get there.

Mercury Racing’s test rig for measuring parasitic losses in drives and transmissions.

Here, I’ll focus on drives. (We’ll cover engine power and props later.) Between engine crankshaft (drive input) and prop shaft (drive output), basic functions are required: gear reduction (so props are efficient); offset of input vs. output shafts (so they’re wet) and ability to change direction (steering and trim are good).

Mercury Racing employs several sterndrives for those functions. Each occupies a unique performance envelope and capacity. Unfortunately, each has parasitic losses: clutch slippage; gear efficiency; number and nature of gear interfaces; U-joint friction; bearing drag; gear oil (quantity, temperature, viscosity and lubricity); and oil windage/pumping losses. So here, drive by drive, are the results of those parasites… Read more

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Go Digital: Drive by Wire!

This is my third in a series about the technology we’ve applied in our new 1350 hp engine.

Computer. It all starts here: The embedded brain of Mercury Racing’s QC4v has ten times the power of our previous PC09 box. That computing power enables far more capability — not just fuel, spark and boost bypass maps — but fine waste gate modulation (learn more:  Big Fat Monster Torque) plus digital throttle, shift and start. Let’s look at DTS.

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Economy of Scale

The more we share (lean on) automotive technology and production volume, the more affordable our products can be. The marine industry is tiny compared to the car and truck world. The high performance market is even smaller. To put it in perspective, GM supplies almost the entire marine industry for a year – performance and mainstream – in one day’s engine production. We cannot (and need not) replicate millions of hours they’ve spent on R&D and manufacturing engineering. We pay for it, a little at a time, in the price we pay for components we buy.

Racing engine refresh cart shows the cam, valve train components, rods and pistons from a 2-valve engine.

General Motors’ big block V8 has served us well – with a relatively low cost platform and many performance parts.  The big block is the backbone of Mercury Racing’s sterndrive products (and most competitors, too). The geometry is simple. The mechanism has endured and evolved for 60 years! Read more

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Big Fat Monster Torque!

This is my second in a series on design features of Mercury Racing’s QC4v engine.

QC4v’s corrected torque is a whopping 1370 lb-ft. Oh, yea!

Torque on our new 1350 is Monster! It rises fast, from 700 rpm idle, and is flat at 1,370 lb-ft from 2,500 to 5,250 rpm and generating 1,350 peak horsepower, before tailing off toward a red line of 6,500. On 91 octane pump gas, not race fuel. Whoa!

(Right to left) Air inlet, compressor, water cooled turbo, and pressure modulation valve.

In other words: Big Fat Monster Torque is more than sufficient to lift the nose of a 48 MTI catamaran, carry it all the way through a hard turn and still plant everybody firmly in their seats for an extended period of acceleration. Just ask my friend, Randy Scism, owner of Marine Technology Inc., about his first test session before the Ft. Lauderdale Boat Show. (Or read, elsewhere on this Blog: MTI Spooled Up!) Read more

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The Valve Train That Could

Cam chain cover hints that quad cams lurk within.

This is the first in a series about design features of Mercury Racing’s 1350 horsepower, quad cam, four valve (QC4v) engine. Throughout the series, I will strive to present unavoidably technical content in non-engineering language.

Bigger Purpose: The only reason to have a high performance marine engine in the first place is to produce thrust from a prop so as to push a boat to: a) go someplace or b) outrun somebody – and come back. Props, drives, transmissions, engine innards and controls all have to do their part, but I skip now to the weakest link in the current high-performance chain: the valve train. (See “Why Rev Limits are…Limits” on this blog.) Read more

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