Insight Into MotoGP Engine Tuning


What Happens When It’s Time to Dust Off Old Material

1:52am EST — The following is a re-post from October 29, 2009, explaining some of the recent developments in engine tuning and torque curves.  Also informative regarding Formula1, this is one of those “ah ha!” explanation moments where everything suddenly begins to make more sense and more is right with the world.  Enjoy.

In the December issue of Cycle World, Technical Editor Kevin Cameron posits a simple explanation for why MotoGP is the way it is, at least regarding engine tuning and results in the past few years.  While this article is not yet available online, it should be read as soon as possible.  On Any Sunday, These Days, having found it both fascinating and informative, paraphrases below.

It turns out that a large part of the explanation of the curious Ducati phenomenon of recent years is to be found in new technology.  On the face of it, there is no particular reason that Casey Stoner should be so much faster than his teammates, and the Yamahas ought not post quicker lap times than the more powerful Hondas.  Still, it is so, and Cameron explained why.

He began with an explanation of ” ‘virtual power.’  Rather than shaping the engine’s actual torque curve with cams, pipes and ignition settings, the concept uses rapid, computer-directed movements of the engine throttles to generate a smooth torque curve” (a smoother torque curve would allow the bike to become more rideable, and less likely to surprise the rider with traction issues caused by uneven torque at different rpm).  This virtual power causes the motorcycle to skip the previously required rider’s thought process and translate the throttle position as torque demand.  It is the “computer-driven movements of the throttle plates” that then accelerate the engine.  If the engine flat spots, or the torque spikes, the computer opens and closes the throttle as necessary to provide smooth power, as demanded by the rider.  Similar technology is used in Formula1, and has been for quite some time to great success.

This would be all well and good, Cameron explains, but for the fact that F1 engines use hydraulic actuators on the throttle and easily keep up with the torque demands, even if the engine’s torque curve is choppy.  Unfortunately, hydraulic power is banned in MotoGP.  Instead, the MotoGP bikes are forced to use stepper motors to actuate the throttles.  Unfortunately, stepper motors only work to the best advantage when the natural torque curve of the engine is not terribly bumpy to begin with and the rider has a smooth riding style, thus defeating the purpose of this virtual power to enhance the bike’s rideability.  Apparently, “the smoothness of the base engine remains fundamental.  The harsher the engine, the more often the smoothing-system will fall behind.  The result will be short episodes of unpredictable behavior as the engine reveals its actual torque curve,” according to Suzuki crew chief Stu Stenton.

This explains the Ducati problem in a nutshell.  Stoner has a smooth throttle style, despite his more physical, dirt-track riding style.  Teammate Nicky Hayden, on the other hand, came from both dirt-tracking and AMA roadracing, and his throttle style is much more aggressive.  Combined with the already highly tuned Ducati machine, it is no wonder that Hayden has taken much of the season to get comfortable with his new bike and Stoner has well outpaced his teammates in recent years.

Cameron finished the article with a discussion about the need for more power, and the temptation to tune the engine to increase said power once the software has smoothed the bike and enhanced its rideability.  As the engine is tuned more, the natural torque curve slips past the technological enhancements, forcing the rider to be more smooth in his riding style, and decreasing the bike’s rideability yet again.  It is this that explains Yamaha’s continued wins over Honda, even as the latter has more power and is faster (though, the talent and  extremely smooth throttle control of Valentino Rossi does help).  In the end, to be victorious in MotoGP racing still requires an engine with a smooth base torque curve, and a rider with an instinctive feel on the throttle.

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2 Comments

  1. […] This post was mentioned on Twitter by Chris Connelly, Victoria Reid. Victoria Reid said: Insight Into #MotoGP and #F1 Engine Tuning (old but good) http://bit.ly/6ycGSu […]

  2. Good summary there! Seems like I recall Brawn drivers mentioning this as something tthe ’09 Mercedes F1 engine did a lot better than the ’08 Honda.

    In the FIA technical logs that are posted after each race, you’ll see items like “maximum throttle target,” “driver torque demand map gradient,” and “throttle pedal shaping map selections” that are checked on the cars. This is what that’s about. The throttle maps are controlled to keep teams from using them to implement traction control, which is banned in F1.

    Another old but good dicussion that I read a while back and was lucky to find again:

    http://www.grandprix.com/ft/ft00275.html


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