Which motor would you want in your car, (for auto cross) Options

[ottox914]

and why...

Lets assume a 2000lb car, and no particular class. Suspension is well sorted, tires correctly sized (big enough but not uber huge).

Motor #1: is pretty pathetic below 4k rpm or so. Between 4K and 7K it will top out at 200hp. Somewhere in there it will top out at 175tq. Valve train and internals will support 8K rpm, so there is a little room above the max hp rpm.

Motor #2: has some power below 3k, definately pulls harder starting there. Starting at 3K it makes 150tq, tops out at 200tq at 6k rpm. Somewhere in there it tops out at 175hp. Engine will rev to 7k rpm w/out blowing parts all over, so you can go beyond the power band if needed.

Lets further assume both cars run LSD, and can run any ratios for the 5 foreward speeds, so the box can be optomised for each motor in this 2000lb car. Both motors drop off rapidly after 6k and 7k rpm.

Which motor would you want in your car and why?

[Dave_Darling]

If we assume that we can change all of the gearing, I would be very tempted to go with the more powerful engine. Remember--the transmission is a torque multiplier, so making torque at higher RPMs with the motor lets you put down more torque at the wheels--assuming you have the correct gearing to use it!!

Power is not just a marketing number. Power is what is used to change the energy of something--in this case, that something's velocity. So more power, assuming you have the gearing to use it, means a greater change of velocity.

Now peak numbers, those really are pure marketing. As Josh2 said, it's all the shape of the curve. Though I mean power curve, not specifically torque curve.

--DD