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It is about as relevent as saying giving everything else equal, the athelete with the biggest toe muscle wins a sprint race; everything else is not euqal, and the most decisive part in spriting is thigh muscle. Real world cars have transmissions or transaxles; gear selection, and the design and choice of gear sets take into consideration engine characteristics. Especially this thread is started by a poster speculating on CVT, which has practically unlimitted gear choices within its max-min spectrum.
You are almost always wrong in stating that the way to get max accelearation in your car is at torque peak. Take SAAB 9-5 LPT for example, the torque spec is 207 ft*lb from 1800-3500 rpm; that in typical turbo terms means peaking roughly 215 ft*lb at 2200 rpm. When you engage the 1:1 gear at 2200rpm, you are putting 215 ft*lb onto the final drive gear, ignoring mechanical loss. Now if you would select the 2.1:1 gear at the same vehicle speed, the engine speed would be 4620 rpm, much closer to power peak. We do not have engine torque output spec at 4620 rpm from SAAB. However, from the power spec of 185 hp @ 5500 rpm, we have torque at power peak given as 185 * 5252 / 5500 = 177 ft*lb; combine that with 207 ft*lb @ 3500 rpm, we can get a linear approximation of 192 ft*lb at 4500 rpm. Note this is a very conservative estimate because torque curves are convex, therefore should yield greater value along the curve than on a linear approximation along the cord. So lets say, the torque output is 190 ft*lb at 4620 rpm; driving through the 2.1:1 gear, you get 399 ft*lb onto the final drive, much greater than the previous 207 ft*lb we got from the engine torque peak.
That's as close as we can get to the power peak for the vehicle speed specified by 2200 rpm on 1:1 gear with the 4-speed automatic, which I'm more familiar with. With the new 5-speed automatic, you might get even closer to the power peak by using the new 2.94:1 gear, resulting in even greater accelearation. With continous variable tramissions that the original poster brought up this thread with, it would be rather straight forward to peg the engine precisely at power peak to get the best acclearation.
As I stated earlier, in cars with conventional gears, low-end torque has the advantage in real life driving due to "load factor": gear shift delay and the time engine has to spend in low rpms after gear shift before high rpms are reached. As alluded to by the original poster, CVT will go a long way to attenuate the advantage of low-end torque; now, only if they can make a CVT that can take high engine output. In any case, it's the power rating, not the torque rating that matters in deciding how much acclearation the car gets at given vehicle speed; engineers can design gear sets around the engine torque curve.
posted by 141.157.16...
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