JWT vs Enthalpy ECU comparison dyno results!! *Another* 400 whp CodyAce Built Car

[jspaeth]

Originally Posted by codyace

While I can grasp your point, wouldn't we also need to figure in a 'time vs RPM' aspec to this? Having more power in a gear is nice, but lets just assume 3rd gear is a 2.5 ratio, and 4 is a 1.0. Even though you'd think the mechanic advantage in power production vs gear would be better in 3rd, could we also not argue that the time in gear in that 1.0 4th be better for total speed? (If this makes any sense)

Or is it just another factor in it all? Or am I just completly wrong hehe.

I could be wrong, but my perception of Newton's laws is that the fastest way to get from point A to point B is to maximize the INTEGRAL of acceleration over the entire trajectory.

This essentially means that you want the most possible acceleration at any point in time possible.

I have done the calculations based upon my dyno chart (and other peoples' will be similar)...

For example.....


Let's say my "dyno" shows that I make 300 ft-lbs at 6000 RPM and 250 ft-lbs at 8000 RPM.



If you do the caluclations, you would find the following "theoretical" accelerations in each gear (in ft/sec^2)...with stock SR/KA tranny and stock USDM 240 4.083 final drive:

6000 RPM (peak torque)

1 - 42.39
2 - 24.27
3 - 16.58
4 - 12.68
5 - 9.68

8000 RPM

1 - 35.81
2 - 20.51
3 - 14.10
4 - 10.78
5 - 8.18


Notice that the acceleration at redline in any gear is ALWAYS higher than the acceleration in the lower gear at the lower RPM (even at peak torque in that lower gear...).


This means that the OPTIMAL way to get from point A to point B fastest is to redline EVERY gear.


Now, in some cars, the torque drops off MUCH faster before redline....in CERTAIN scenarios, it MAY be beneficial to shift before redline.

This would require that the torque made at the NEW RPM (upon upshifting) multiplied by the ratio of the NEW GEAR RATIO/OLD GEAR RATIO is higher than the torque being made if you had just stayed in the lower gear.

Example:

2nd gear is 1.902
3rd gear is 1.308

Ratio of 2nd/3rd is 1.45!!!!

This means if you are in 2nd, and your torque starts dropping off....for it to be beneficial for you to upshift, the NEW torque you would make in 3rd upon upshifting would need to be 45% higher than the current torque you are making in 2nd.

So even if your torque drops off quickly and you are only making 200 ft-lbs in 2nd, you would need to make 290 ft-lbs at whatever RPM you WOULD be in 3rd if you upshifting in order for it to be beneficial to shift.

Summary

Like I said....with GT2871R setups and the shapes of the torque curves they produce out to, say, 8000 RPM or maybe even 8500 RPM, it is ALWAYS beneficial to just keep revving out in the lower gear....



As you can see, even at redline, the lower gear always has better acceleration then the next highest gear at it's PEAK acceleration point (6000 RPM)