Quote:
Originally Posted by Shovelman
I must be the first engineer to post in this thread. Here's what you are missing:
Horsepower is torque multiplied by rpm (times some constant to get to the power units of choice). If you shift at max torque or bracketing max torque you are shifting too soon.
Using Math, ex:
torque = 300 and is relatively flat
shift at 6000 rpm
c = .0001 to get to giraffe power
300 x 6000 x .0001 = 180 gp
torque = 300 and is relatively flat
shift at 7000 rpm
c = .0001 to get to giraffe power
300 x 7000 x .0001 = 210 gp
Using gut feel:
the same torque in a lower gear puts more power to the road so stay in the lower gear as long as possible.
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Some engineer always comes along to give the formula for calculating horsepower from torque, as if it explains everything. Unfortunately, it doesn't explain what horsepower actually is. For someone who doesn't understand the physics of energy, the formula provides no insight.
There's nothing wrong with your calculation, expect that it is irrelevant to our cars. Torque is not flat above 5000 rpm, as shown in both the Dynan and Dynojet results, so your calculation of more power at 7000 than 6000 rpm does not match reality.
Finally, your use of torque and power in the same thought contributes to the confusion among people who don't understand the concepts underlying them, which is the source of the common idiocy spouted by journalists that "torque is more important than horsepower". One of the reasons physicists look down on engineers is that often they are so focused on getting results that they don't take the time to fully understand the underlying physics. If you do understand the physics, then you have a professional obligation to use more precise language.