Quote:
Originally Posted by grant
Yes, that graph looks VERY impressive. However, it is not really accurate in most any real-world situations. It is created on a dyno where the resistance of the rollers is carefully controlled.
On a real road, it will not look like that in first gear (car will not stay in low revs long enough to build boost to create a torque curve like that). That torque curve would be VERY hard to replicate. Would probably need to be going up a steep hill in a high gear (only way to put the engine under enough load where it stays at low revs long enough to build maximum boost)...
Of course driving up a steep hill at low speed in 5th gear, for example, will produce terrible acceleration, but it will make the torque curve start very early.
It's just a way to manipulate the specs to make them seem more impressive than they really are.
Porsche produces similar graphs for its 911 Turbo. Looks great on paper - not very accurate when driving it (power doesn't come on until revs are much higher than what Porsche claims for the begining of the torque plateau)...
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I know exactly what you are talking about because it is the exact same thing with my MINI. I think BMW claim that the engine produces peak torque of 177 lb.ft. at 1700 rpm (actually, 192 lb.ft. on overboost at the same rpm range). Like you said, if you expect to roast the tires at the lights every time you set off because of all that torque so low down, rest assured that is certainly not the case (although, it certainly can happen if you get a lead foot on the throttle). With a little more than 1600 miles under my belt with the MINI, I can say that under normal driving, the engine doesnt get to peak torque til about 2800 rpm. I would imagine the 135i to be similar. As grant said, you just dont generate any boost in normal conditions by revving the car in neutral and then dropping the clutch. That is the main reason why no matter how hard manufacturers try to eliminate turbo lag, it will still exist in these situations because the turbos need that load to generate their power.