Quote:
Originally Posted by Pete_vB
If we're going to bench race let's do it properly... The proper way is to create thrust curves for both cars. You take the torque from the car's dyno and calculate how much thrust results at the wheels by taking the gearing and tire diameter into account. You then divide that by the car's weight (with driver) and you have a thrust to weight ratio, from which you can derive acceleration. Higher thrust to weight is of course better. Do this for both cars you want to compare, for every gear.
Attached is this graph for a 1M with a typical dyno vs a typical manual M3. Compare the two lines- at any given speed when the blue line is on top the 1M is pulling harder, when the red line is on top the M3 is pulling harder...
Now, the OP said 40 mph roll-on. And we see at 40 mph the 1M is pulling 24% harder in 2nd gear, and will pull away quickly. At 60 mph the M3 starts to pull harder; it's slower at this point so it needs to build up speed before it can match the 1M and begin catching it, but at 70 the M3 shifts and the 1M is pulling harder until a bit over 90 mph. From there us the M3 and 1M go back and forth, but at these speeds you really need to factor aero in which will begin to favor the M3.
So not only plausible that the 1M will pull the M3 from 40 mph, but obvious, regardless of what gear the M3 is in. If the drag had started at ~52 it could have been a very close race. As you say it's pure physics, but it's more complex than BHP per ton...
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This is such a keeper post, thanks. I actually remember from early days of 1M, some dyno graphs showing stock 1M and stock M3 together (maybe was Insideline), and it was very interesting to see that the 1M actually produces not only more torque but also more power from idle to around 6350 rpm! After that M3 starts to make both more power and more torque than the 1M, but then the 1M shifts upwards around that point and falls back to its fat torque and power band yet again. It really seems to be hard for M3 especially so for a manual, to catch the 1M till around 160-180 km/h (100-110 mph) or till the end of 1Ms first 3 gears, the trick here is that the 1M needs a good launch which is more difficult to manage than in M3. When the 1M starts in the 4th, the (much) worse aerodynamics also starts to help the M3 catch up and get ahead from then on.
One more time, just another way of seeing the particular strengths and weaknesses of each car. I prefer the 1M but this doesn't make me think that the M3 is not a as good sports car. In fact, they are so different in making power and handling wise, it is surprising that these races against each other and comparos keep going on. Not that they are not fun, mostly they are but still few seem to understand that they really are very different cars despite some shared components.