Shift point

[danc30]

Just received my dyno results on my Keith Craft engine. 622HP and 630 TQ.

My question is, what should the shift point RPMs be to maximize acceleration? The TQ peaks at 4700 and the HP at 5800.
RPM HP TQ
4700 564 630
4900 577 618
5100 591 608
5300 605 600
5500 615 587
5700 621 572
5900 622 553
6000 619 541

[DavidinDurango]

Question cannot be answered without knowing tranny ratios.

You will want to shift so the rpm in the next higher gear (the gear you are shifting into) is at torque peak.

Sounds like fun, keep the rubber side down.

[Steve Bandirola]

Here is the reply to your question from the FFR Forum



posted June 20, 2007 07:56 AM
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I posted a link to an Excel spread sheet calculator that I wrote in another thread.

Here is the link again
http://putstuff.putfile.com/84101/4299774

enter your data in the yellow fields. The transmission ratio's that are already there are for the TKO.
Look at the graph that shows torque at the rear wheels you want to shift when the torque is higher in the next gear than the gear you are in.
The graph gives you speed in mph then look at the speed in gears graph to get rpm.

You can stretch any graph to make it easier to read.

You will need to do your own test to see how much rear wheel torque your car can put down through the tires to the pavement by flooring it at different rpms.

steve

[danc30]

Thanks Steve and David. This helps a lot.

[newBDR]

so, the HP #'s you put in the yellow boxes is at the crank, not rear wheels, right?

[Steve Bandirola]

It doesn't matter, use what ever numbers you have.

Steve