Quote: Originally Posted by
rico's-srt 
you just made less sense than me, in an earlier post you said the equation for figuring horsepower was something (x) and that all hp and torque curves would cross at 5252, how would overlaying both curves help me figure my shiftpoint? furthermore, every car's shiftpoint is at 5252 according to what your saying.
Ok. Let me try to explain this again.
5252 rpm is simply a point in the rpm range where torque= hp (mathematically)
At 2626 rpm torque is always 2X more (numerically) than hp.. Its just a linear relationship.
The hp formula and the shift points don't have anything to do with one another. It was my answer to a different question.
I said that I typically would shift at around peak HP. It's only a general rule of thumb. Sometimes you can shift a bit past peak HP depending on what gear I am in and what my torque curve looks like.
I then said.. the IDEAL way to do it is:
(lets TOTALLY forget about HP for a second).
make 3 runs on the dyno... lets say 3rd gear run, 4th gear run and a 5th gear run. Overlay those charts (just the torque curves) on the same graph.
Since they are based on MPH on the X axis, you will see a point where the end of 3rd gear will torque graph should cross the 4th gear run. It is at that point that torque to the wheels are = and that's when you should shift.
I saw three problems with your initial post.
Quote:
regardless of how the dyno figures the number, its all bullshit, when everyone goes to the dyno, look at the TORQUE line, see where its highest point is, and shift there. thats the fastest your gonna be able to make your car go
1. You didn't account for the torque multiplication of gearing. That's one of the main reasons why you shouldn't shift at peak torque. (unless you have some SERIOUS drop in torque right after peak torque)
2. You didn't account for what torque is available after you have shifted gears (ignoring torque multiplication from gearing). So maybe you have 400 lb/tq at 5000rpm and only 350 lb/tq at 5500. So you shift into a different gear at 5000rpm and encounter only 300 lb/tq at 3000 rpm.
3. You mentioned that your car won't accelerate past your peak torque number, which is not true either. I assume you mean drag limited. A car, given limitless gearing will accelerate until the amount of drag on the car is greater than the force propelling the vehicle (torque). That doesn't mean that a car can't accelerate past peak torque.
Don't take my word for it.. Go to the track and make one run with shifts at peak torque, and another with shifts at peak hp. See what happens to your times.
I'm not sure how else I can explain this to you.
