If you have a dyno chart, you can graph the HP and torque curves per gear. Graph them on top of each other, and see where the graph from one gear overlaps the graph from the next highest. That crossover point is your shift point. If they don't cross, then shift at redline.

I've got an excel spreadsheet that does it for me (PM me if you are interested).


Really, though, torque and HP are intertwined. HP is just the torque multiplied by the RPM (and then divided by 5250). So putting out 1000 ft-lbs at 1 RPM (0.19 HP) == putting out 10 ft-lbs at 100 RPM (0.19 HP). In other words, HP is how many times you can put out a given torque over a period of time.

That said, I think you want to head towards the max HP number. Why? Because the max HP is your best combination of torque AND RPM combined.

E.g. your best torque is at 1000 RPM, and is 100 ft-lbs (19 HP). (yes, your nissan is now a honda! lol!) You can spin your motor to 10000 RPM, and there it only makes 50 ft-lbs (but now makes 95 HP). So it's sorta making 20 ft-lbs 10000 times a minute instead of 100ft-lbs only 1000 times a minute.

So, to summarize (since I've confused), you should tune to be close to the crest of the HP curve, not the torque curve.

joe