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      12-09-2011, 08:17 PM   #9
swamp2
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Quote:
Originally Posted by Powerslide View Post
Not only is horsepower relevant - buy also look at how the s63tu has such a huge power advantage at speed versus the s85 - s85 didnt reach peak power until 7750 rpm, at which point the hp starts to go somewhat back downhill again. With the s63tu, you're at 560 hp from roughly 6000 rpm to about 7000 rpm!! Presumably the next generation m3 engine (whether I6 or V6) will also have peak hp and torque over a broad range of rpm's - which in turn means a significant increase in performance beyond what the numbers themselves suggest.

Take the F10 M5 - it has "only" 60 more peak hp than E60 M5 - which doesn't seem like that much. You then take the 200 lb greater weight of the F10, which would seem to further diminish the 60 hp advantage - therefore - the power to weight ratio of the F10 v the E 60 is not much better at all. But nevertheless, the performance advantage is far more significant that the power to weight figures by themselves would otherwise suggest.
I mostly disagree with this.

Certainly average power being higher is better. There is no doubt about that, it is basic physics. However, the importance of the shape of the F10 M5's power curve vs. the E60 M5's, from a practical perspective is basically in the noise. In short peak power is still by far the most important factor.

CarTest simulations (physics based acceleration simulation software) provide the following predictions for the E60 and F10 M5 quarter mile results

E60: 12.2 s @ 118 mph
F10: 11.9 s @ 119 mph

Some of the fastest tested times correpsond nicely with those. These are not supposed to be the best times found nor a detailed statistical average just good solid times from various tests, magazine and private.

E60 M5: 12.3 s @ 118 mph
F10 M5: 12.0 s @ 122 mph

Much like the case of the 335i I suspect the F10 M5 might be a tad underrated given the 122 mph achievement.

Now if we "manufacture" a hypothetical F10 M5 with the exact same peak power but a power curve totally unlike the actual "table top" flat curve above 6000 rpm but like the E60 M5 (or E9X M3) we find this car will run about:

12.0 s @ 118 mph

This is a mere 0.1 second and 1 mph better than the results simulated with the actual shape of the power curve of the production car.

So again, in short, the power and torque curve shapes matter but peak power to weight reigns supreme as the most important indicator of performance.
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Last edited by swamp2; 12-11-2011 at 05:22 PM.
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