Quote:
Originally Posted by M3takesNYC
Not really a huge difference. Its not the M3's gearing that gives it a significant advantage but rather its the high RPMS that allow the relatively low amount of torque to be delivered at a rate that is so fast that it matches a larger amount of torque delivered at a slower rate (335).
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Hum, not entirely right.
Gearing has a direct impact on how torque at the flywheel is converted to torque at the wheels. And it is torque at the wheels that accelerates the car.
What gives the M3 the advantage is the combination of gearing
and torque produced at high RPM.
Quote:
Originally Posted by M3takesNYC
The difference in first gear for example is a multiplier of 13.2 for the 335 vs 14 for the m3. It gets closer through the gears. That is not neglible but hardly what is making up the difference in torque.
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The final drive of the M3 is 3.846 compared to 3.080 for the 335i (you should check your numbers, they don't seem right). This is a 25% advantage in every gear, which is considerable. The fact that the M3 produces power high in the RPM range allows it to use the shorter gearing.
The maximum speed in each gear for the 335i and the M3 are quite similar. However, because of the gearing, the torque produced by the M3's engine is multiplied 25% more than the torque produced by the 335i's engine, yielding higher torque at the wheels. This is what allows the M3 to accelerate faster even if it has less torque at the flywheel.
Quote:
Originally Posted by M3takesNYC
The hardest thing for people to grasp seems to be the effect of RPMS's on horsepower and ultimately torque at the wheels. Think of high RPMS as a way to take a given value of torque and apply the torque more rapidly and at a fast rate which translates into more force delivered to the wheels and thus more torque at the wheels.
Essentially you can take a higher amount of torque and apply it less frequently to accelerate a mass or take a lower torque and apply it at a rate that is much higher to accelerate a mass. This is how the 335 vs m3 works
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A good way to illustrate the relationship of torque, RPM and power is to consider a gearbox. The power at the input and output of the gearbox is the same (assuming no losses in gearbox). However the torque is directly impacted by the ratio of the gearbox. Let's take a 2:1 ratio gearbox as an example at which you input 200lb-ft at 5000RPM. This translates to 190hp (200x5000/5252). The output spins at 2500RPM (2:1 ratio) and the torque produced is doubled to 400lb-ft. The power produced however is the same, 190hp (400x2500/5252).