About Power Needed to Accelerate We feel the engine power as the extra energy needed to accelerate. So let's explore the topic of acceleration. A certain amount of power is needed to attain a certain amount of speed, dependant on bike/rider weight, coefficient of air drag, and area that the bike/rider is displacing. The need for power increases non-linearly as the speed increases. To attain twice as much speed takes more than twice as much power. The green graph below shows the power needed to maintain RPM/speed. The purple/blue graph is the difference between the red graph and the green graph which equates to acceleration power. The illustration below emphasizes what I am saying. The acceleration power is the amount of power exceeding what is needed to maintain the same speed. So it is wiser to look at a graph of that excess power for acceleration instead of just the horsepower graph. Below shows the pipe powerband centered on top of the raw engine powerband (blue). This is very common although not the best setup. The average power in the RPM range between shifts is listed at M244 which is .45 in this case. (The RPM range between shifts is visible by the blue-green overlay over the purple graph.) Below shows the pipe powerband shifted down 1500 RPM. by use of a longer header. This results in an average acceleration power of .49 which is an 8.8% increase. So if you have enough space to design a pipe this way then do so. Click here to download my video on this subject of acceleration power. HOME