HPF 2.5 v 3 comparo and shift points.

[InterlagosMcoupe]

By no means groundbreaking, just thought I would share as I'm sure there a few bench racers out there that would get a kick out of it.

I was curious and I do this for a lot of cars using a program I wrote. The charts are basically representations of theoretical acceleration (Wheel torque, does not account for traction aerodynamics ETC) based off a torque curve. In simple terms higher number = higher torque at the wheels (this is in terms of through gearing). I threw in a supercharged e46 I had done in the past for fun.

Interestingly for stage 2.5 it seems shifting at 7kRPM in 4th and 5th is optimal, though the acceleration is very close so it's not absolutely necessary (where the lines intersect indicate that there is higher available acceleration in the next gear if you were to shift at that RPM)

Comparison shows that an HPF stage 3 car has the same acceleration after shifting into second as a supercharged m3 does at its peak in first :woot:.

http://img167.imageshack.us/img167/636/comparisoncopy.jpg

http://img530.imageshack.us/img530/6628/shiftpoints.jpg

[RACEMX-M3]

ok

[SPDu4ea]

http://www.imageviper.com/displayimage/132816/0/wtfrkelly.gif

[zeshon]

That's pretty cool. What did you make the program for? Was this just for your own information?

[HPFMTRE]

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[InterlagosMcoupe]

That's pretty cool. What did you make the program for? Was this just for your own information?

People have been using the same method for ages, I just wrote it so I could tailor it to do exactly what I wanted. I just wish I was a little better in C to ease the input and output.

I did it just as an exercise/learning tool/explanatory tool/comparative tool. Bunch of reasons. It started out as just an optimal shift point calculator but I realized it could be used for much more with a little re working.

Another thing it's nice for is demonstrating how a car will respond to changes in rear end gearing. You can find an optimal ratio fairly easily.


Particularly I dropped in the 2.5 and 3 data because I was trying to decide which to go with, I had read Chris say he liked 2.5 better and that it wouldn't out accelerate stage 3. Obviously theoretically it will destroy it, I'm guessing he meant since 2.5 already is taking full advantage of available traction so going to 3 does nothing but add a little more lag and more lower speed unusable power.

It also does well to explain to people exactly what HP is useful for as a comparative number vs torque by overlaying a low reving high torque high displacement engine over a lower displacement low torque high revving engine.