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.

Throttle. This is the digital “gas pedal” of the boat and one of two places that the pilot is always hands-on. (No prize for guessing the second one.)

The business end of of the throttle quadrant shows connection to digital potentiometers, producing signals to the brain.

The functional objectives for a high performance throttle have not changed: It should be smooth, responsive, precise, robust and feeling great. Drive-by-wire (electronic) trumps drive-by-cable (mechanical) in every function — especially in boats with two or more engines. The limitations of mechanical execution vanish with DTS: no friction; no degradation with cable kinks, dirt or lack of lubrication; no out-of-adjustment neutral switches and no frozen cables — because there are none. No hassle.

We have added capabilities that were impossible the old way: First, with input from professional boat drivers, Johnny B programmed non-linear throttle actuation to make it feel more logical and progressive with no dead zones. Second, the propulsion control module (PCM) automatically synchronizes two (or more) engines when they’re within 50 rpm of one another. Third, triple or quad engines can be run with two throttles using our shadow-mode logic — the “shadowers” play follow the leader. Fourth, there’s troll control (though you’re unlikely to be fishing – Wait! These work with Verado, too). At low speed, with an optional track pad, you can set a slow running speed, and bump it up or down in small increments — perfect when you must endure no wake or speed limit zones on the Inter-Coastal.

Shift. Digital makes shifting simply amazing. No “thunk” and no grrrrrrind…ever. Just “snick, snick” as you fondle the levers. Moreover, the PCM learns as you shift: Boats differ in weight. Vees are different than cats. Props weigh more or less and have different inertia. The weight of fuel and crew will vary. No matter. You shift a few times and your engines learn to apply just enough throttle, with just the right timing, for perfect engagement.

A solenoid will actuate the shifting valve on this engine headed to DCB.

Shift and 800 rpm idle in neutral drops to 700 rpm idle in gear. Neutral? Back to 800. Forward straight to reverse? “Snick, snick.” It slows, shifts and shifts again. No stalling. No hesitation. No surging. No surprises. (Read what Randy Scism has to say.)

Start. Digital even makes starting easier. You turn the key briefly and let go.  The computer engages the starter just long enough for a purrrr-fect fire-up. Just like an SLS AMG (except SLS has a button and a key). Well, you have an emergency stop lanyard, and a boat load more horsepower, too!

Digital control feels amazing! Everything is so smooth, so well mannered and hassle free, that you’ll feel amazing! It’s OK. Pound your chest now, and giggle. Because, after you hammer the throttles, all you can do is collapse the upholstery foam with your back side and…gasp! For people and engines, deep breathing is good.

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4 thoughts on “Go Digital: Drive by Wire!”

  1. Congrats to the Mercury Racing Team!!!! This is a wonderful accomplishment and hats of to you Fred for getting Brunswick’s support. I’ll never be a 1350 owner but I must say from all the reading I’ve done you all smacked the nail square on the head!!!! If it’s as impressive as the XS lineup the customers will rave! Keep up the good work!


    1. Thank you, NIck. 1350 owners are a very fortunate few, but never say never.

      I am personally honored that Mark Schwabero, Mercury President, and Dusty McCoy, Brunswick’s Chairman were supportive of QC4v. It took some guts to forge ahead through our world’s economy the last couple of years, but that’s when leaders lead.

  2. Glad to know you all at Merc/Brunswick have great leadership as we do here at CAT. Myself and the “guys” here in the group have noticed the shop is always spotless. Very impressive layout and cleanliness is key to these engines living a healthy life. Does the Merc Racing shop offer tours?

    1. We do not provide tours to the public. Under prior arrangement, we do occasionally tour with customers and boat builders.

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