Quote:
Originally Posted by swamp2
I'm pretty sure the author of CarTest confirmed with me that he included drivetrain inertial effects. I never said it is not important. It clearly is, it translates along with the car and it also takes extra energy on top of that to spin up all rotating components. I just doubted certain details of the math relationships with you.
Other than knowing gear ratios there is obviously no way of knowing how large or what materials (i.e. densities) or sized all of the relevant drivetrain components are. I checked Gillespie, he simply substitutes the so called "mass factor" for not knowing the details about each cars drivetrain. The mass factor is an approximation and certainly does not take into account actual details of the driveline. The mass factor in 1st gear between the 335i and M3 does vary by about 18%. I'll try to check CarTest to see if this "mass factor" is used as part of its acceleration calculation by specifically comparing the M3 and 335i.
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My comment was in regard to the 4000/8000 redline cars with equal power and a totally flat torque curve. The 8000 rpm car's acceleration would be significantly reduced because it had gearing that was twice as aggressive as the 4000 rpm car.
Your CarTech results are absolutely incorrect if they don't show this, and I expect you'll find something in that tool that allows for varying rotational inertia.