Comparing Mercury Racing R-Series outboards to Mercury Pro XS models reveals the effort required to power the world’s fastest bass boats.
The same 4.6L V8 four-stroke powerhead serves as the foundation for two series of performance outboard motors – the Mercury 250 Pro XS and 300 Pro XS models and the Mercury Racing 250R and 300R motors. Both are outstanding outboards designed to power high-speed bass boats, but the Mercury Racing R-Series models are really a different breed of cat. Mercury Racing R-Series outboards are the only motors on the market designed specifically to deliver the power, hydrodynamic efficiency and stability required to push the fastest hyper-performance bass boats to their full speed potential, which may exceed 100 mph. These speeds are beyond the capability of a Pro XS package and require a Mercury Racing R-Series package. For the owner of a mainstream tournament bass boat, an R-Series outboard provides an upgrade option over a Pro XS for those boaters craving a top-speed edge and the satisfaction of running the ultimate performance outboard on the water. Let’s compare Pro XS to R-Series to determine which is the best choice for your performance boating needs.
The Foundation
The 4.6-liter 64-degree V8 powerhead features deep-breathing four-valve cylinder heads and a double overhead camshaft valve train. In its Pro XS tune, this powerhead delivers good all-around performance on a variety of mainstream bass boat hulls. Mercury Racing tunes up this already-potent engine with some exclusive components. The Mercury Racing 300R model is equipped with a Racing-designed short-runner intake and high-performance intake camshafts that combine to focus power at the top of the RPM range to maximize the top speed of a light-weight boat. An integrated oil cooler helps keep oil temperature within a desirable zone during extended wide-open runs. A performance-optimized ECU calibration increases the WOT range from Pro XS spec 5600-6200 to 5800-6400 RPM – added RPM range maximizes top speed and improves propping options.
Mercury Pro XS and Mercury Racing R-Series outboards share a number of key features:
Produce full power on 87 octane (R+M/2 or 90 RON) fuel.
Advanced Range Optimization (ARO), a closed loop fuel-control system, utilizes electronic sensors to precisely adjust the fuel mixture for the best-possible efficiency at all speeds.
Transient spark calibration increases torque 5 to 7% during hole shot for unmatched acceleration.
Idle Charge battery management helps prevent battery drain on boats loaded with power-hungry electronics by automatically increasing idle rpm to boost alternator output until batteries are recharged.
Adaptive Speed Control (ASC) automatically maintains engine RPM as load or conditions change due to sea conditions, tight turns or a lower planing speed, and boat momentum is maintained with less-frequent throttle-control adjustments.
A slim-line cowl featuring the industry-exclusive Top Cowl Service Door that makes routine maintenance more efficient – just pop it open for regular engine oil checks and top-offs without removing the cowl. The Mercury Pro XS and Mercury Racing 300R outboards are available with mechanical controls or SmartCraft Digital Throttle and Shift (DTS) controls. The Racing 250R model is offered only with mechanical controls.
Mercury Pro XS and Mercury Racing R-Series outboards are backed by a three year limited factory warranty, with the ability to purchase up to five additional years of Mercury Product Protection coverage.
Racing Midsection Upgrades
All Mercury Pro XS models use the Mercury CMS (Conventional MidSection) with an integral Tri-Ram trim system. In 20-inch versions for bass boat applications, Mercury Racing 300R and 250R outboards also use the CMS but feature high-durometer elastomer upper mounts and solid lower mounts for enhanced engine stability and handling at higher speeds, critical for confident control in the fastest single-engine applications.
Performance Gearcases
Mercury Pro XS models with a 20-inch shaft length feature the Torque Master gearcase with a 1.75:1 gear ratio. The Torque Master gearcase is designed to run partially surfaced and to carry heavier tournament bass boats with maximum speed and control, and is a good choice for mainstream tournament bass boats capable of speeds of up to about 80 mph. For this application, the Mercury Racing 300R model is also offered with the Torque Master gearcase with the same 1.75:1 ratio. For the owner seeking to extract maximum high-speed performance from the fastest bass boats – high-performance models like those from Bullet, Allison and Stroker capable of speeds over 85 mph and in some cases exceeding 100 mph – the Mercury Racing 300R is also offered with the Mercury Racing Sport Master gearcase, a race-proven, surface piercing design featuring a crescent-shaped leading edge to maximize efficiency and speed, and low water pickups for reliable cooling water delivery at high trim angles. The shape of the Sport Master torpedo and skeg are critical for confident handling and control at very high speeds. The Sport Master is offered with a choice of 1.75:1 or 1.60:1 gear ratios to best match both acceleration and top speed to a specific boat design. The Mercury Racing 250R model is equipped with the same high-performance Sport Master gearcase with a 1.75:1 ratio.
Invest in Performance
Final pricing of a factory-rigged outboard is determined by the boat builder, but a Mercury Racing R-Series outboard will cost about $3,000 more than a Mercury Pro XS model with the same horsepower rating. That price reflects upgraded components, extensive development and testing, and close consultation by Mercury Racing experts with the boat builder regarding rigging and propping of a Mercury Racing R-Series outboard. The goal, as always, it to take you confidently to the very limit of any boat’s Wide Open potential.
