HomemadeTurbo - DIY Turbo Forum - calculating gear ratios based on torque curve

Quote:

Originally Posted by t_cel_t

go get a stopwatch and get in 3nd gear and floor it at 4500rpm and hit the stopwatch untill you get to 5500

then do that same thing from 5500 to 6500

i guarantee that it is almost the EXACT same time.
yes at higher rpms you are doing more 'work' but the engine is not pushing against the wheels any more then it did at lower rpms, its just pushing at a higher speed.

Yes you are exactly right, but like I mentioned earlier, this conversation was started about choosing gear ratios for maximum performance.

Quote:

Originally Posted by MADMAX

100ftlbs at 4000rpms is less energy than 100ftlbs of torque at 8000rpms. The latter allows lower gearin and makes 200ftlbs of torque at the same speed as the subsequent output.

Quote:

Originally Posted by MADMAX

and only assumes the same gear ratios. This conversation is about ideal gear ratios.

But, what you have pointed out is what I said earlier. Shifting at 5500 will make the car slower, because power under the curve is less than shifting at 6500. I mean you guys are answering your own questions about this using real world examples.

Quote:

Originally Posted by MADMAX

Going off of what you are saying, if a motor makes a constant 100ftlbs of torque between 0 and 8000rpms, you could just shift anywhere, cause the torque is the same and the area under the torque curve is the same and the car will be the fastest no matter what.