Quote:
Originally Posted by seank
It depends on why you would shift at 8k. If it is to go faster, it does help.
Carrol Smith explained this the best, but I will attempt to give an analogy. If you made a graph showing your hp at all the rpms, you will see something like this (just an analogy, not necessarily your hp numbers): 6500 at 240, 6750 at 245, 7000 at 250hp, 7250 at 255, 7500 at 260hp, 7750 at 265, 8000 at 260hp, 8200 at 255hp.
If you were racing, if you shifted at peak power:7750 you would have at least a 1000 rpm drop and that is being very generous. More like a 1500-2000 rpm drop on most cars. Add all those numbers up between 6750 and 7750.
If you shifted over the peak at 8200 with a 1000 rpm drop, you will only be at 7200 rpms. Add up all the hp numbers.
The number that is the highest is where you should shift to give the most power.
Also, rod bearings are not damaged by running at 8000 or even 10,000 rpms assuming you have adequate oil pressure at those rpm's. Most race motors have an upgraded oil pump, especially the s54. Upgrading the oil pump can also allow you to run a thinner oil and run cooler than stock and it will increase the power output of the motor to the rear wheels. There are other parts of the motor that won't handle 9000 rpm's well, but I won't get into that here.
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This is wrong on many levels, adequate oil pressure doesn't mean rod bearings won't be destroyed by higher RPMS. The OEM bearings are not designed to, and will not live for very long at 10k, even with perfect oil pressure.
As for the shift points, that is a very poor explanation, though it does sort of correlate with the correct. Shift points are wholly determined by thrust at the wheels. Thrust at the wheels is determined by torque and gearing. Essentially what you are looking for is where your wheel thrust in the current gear drops below where it will be in the next, that is the point you shift at. You cannot find this point simply by following your explanation and "adding up" HP numbers.