Lt. Ron "Slider" Kerner
- Jan 21, 2008
- Reaction score
Taken from another board...
Inspired by dred's thread on torque, HP and work, a buddy and I got into a discussion about how people frequently misunderstand torque and gearing. For some reason, we found ourselves looking up dyno charts for various cars and came across one for the E90/E92 M3, which looked basically flat at 260ft-lbs from 3,000 RPM to 8,100 RPM. Given how fast the car is, I figured it had to be geared pretty short. And it is. But what's shocking is how much torque the car puts to the wheels, particularly in first gear.
Below are plots of wheel torque for the E90/92 M3 (peak torque 260-ish-something) and C5 Z06 (peak torque 400ish) versus MPH for the first four gears, assuming shifts at redline. The M3 puts almost 50% more torque to the wheels than the Z06 at low speeds... and the cars are pretty evenly matched after that.
The other plot is torque to the wheels versus MPH for the gears over the entire usable RPM range.
Of course this all discounts weight. But if you convert torque to thrust and divide that by the weight of the car, the M3 still wins in first gear (even with a 600lb weight disadvantage). That's the third plot.
The long and short of it is that most people would probably not describe the M3's engine as torquey (at least when compared to a big 2-valve pushrod V8). But engine torque is pretty irrelevant. Torque to the wheels is really what matters, and in this case the M3 is very impressive.
Maybe this isn't interesting to you guys, but I was bored waiting for a teleconference to start late last night...