Gear Ratio selection: Torque vs HP

[RonInSD]

As part of the winter rebuild season, I will be building a new motor to the new spec line for my car and I want to look at the gear ratios in the transmission and rear end.

I have been researching on how to best select the best gear ratios to run. I have read different statements about how to make this selection. Some say use the torque curves and some say the HP curve. I am wondering how people are making their selection.

Does any one have a good spreadsheet/program/graph for this select and how this choice is made?

 

[Al Seim]

Power curves are what matter, that's what you are trying to maximize.

 

[EPrill]

Ron-
I'll email you what I used.
Eric

 

[Gordon Jones]

I geared my 1600 for max HP at max RPM and max Torque at the bottom of the gear. Worked out pretty good for me. G

 

[Matt Blehm]

Eric,
I'd like a copy of your worksheet too if you don't mind. matt at mattblehm dot com

still shopping for that perfect dog box that I don't have to replace rear diffs... but that's becoming less and less likely.

 

[disquek]

This might be more work that you're looking for, but I've had great success determining gearing using the Bosch LapSim software.

It takes quite a bit of setup time and you're best served if you can export/import data from your DAQ.

But the results I've gotten have been dead on. In three years, I have never felt the need to change the gears at the track.

Let me know if you're up for doing this and need any help.

-Kyle