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      02-27-2013, 01:00 AM   #228
swamp2
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Drives: E92 M3
Join Date: Sep 2006
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Quote:
Originally Posted by Pete_vB View Post
Now even without shifting, the 1M is averaging 11.4 lbs per hp over this speed range with these example numbers. The M3 matches its peak of 11.2, but it averages 12.1. So it's averaging 6% lower power to weight. 8% less power to weight if the 1M shifts. The M3 can't shift to a better gear, 3rd ends before 105.
Thanks for your patience, I think I better understand your point and specifically the more hypothetical nature of the example you have chosen. I've never said that torque or the shape of it is meaningless, just much less meaningful than the best simple figure of merit of peak power (to weight, of course). As well calculating, making sense of units and practically utilizing some integrated form of "area under a torque vs. rpm curve" is quite problematic...

Since, we've already pretty well determined that it is impossible for the next M3/4 to have a 7k+ rpm redline, 400 ft lb of torque and only 415 hp, we should examine a known case. What gives a car like an M3 a better overall performance gain: a 10% increase in peak power to weight ratio (which will realistically probably mean a 5% increase in power at an rpm of redline/2) or a 10% increase in torque, likely at an rpm much lower than redline? Some initial simulations showed these cars would perform very closely in most drag racing related competitions. My simulations were actually surprisingly closer than I suspected they would be.

Of course then I immediately recalled the use of the M3 in the way it really "should" be used. On more of a road coarse / track type setting (of course corner to corner in a canyon, as well, not necessarily on a track per se). Taking into account the mostly correct statement just below:

Quote:
Originally Posted by grimlock View Post
The advantage of higher torque at low rpm (=higher power at low rpm) only matters when you are at low revs, which only happens once from idle, afterwards you are shifting at higher rpm so it becomes irrelevant.
I also ran a bunch of simulations from 20-100, 30-120, 60-130, etc. These cases showed distinct advantage in all cases for the PROPERLY shifted car with 10% more power rather than 10% more torque.

Again nothing particularly wrong with BMW giving us more torque. It is particularly great for drivers who simultaneously demand peak acceleration but will not choose the best gear for obtaining it . I'd simply prefer, for a somewhat more real world speed x to speed y performance (i.e. non-drag race performance gains) more peak hp. With more peak power you do get the near equity in drag racing type of results but get a clear advantage in more canyon/track type of results.

I certainly can not guarantee the universality of such a result but I strongly suspect that for most cars the same general trend will hold on this point.