High Launch Low Spin

Say the peak torque of your engine is 4000rpms.

Standard gear ratios for 1.8T 6 Speed Quattro.

1st gear ratio is 3.667
2nd gear ratio is 2.053
3rd gear ratio is 1.370
4th gear ratio is 1.032
5th gear ratio is 0.800
6th gear ratio is 0.658

1st gear ratio (3.667) divided by 2nd gear ratio (2.053) x (torque peak) 4000 RPMS = 7144 RPM is the optimal shift point between 1st and 2nd gear...

Shift points:

3.667/2.053 x 4000= 7144 RPM top of 1st gear
2.053/1.370 x 4000= 5994 RPM top of 2nd gear
1.370/1.032 x 4000= 5310 RPM top of 3rd gear
1.032/0.800 x 4000= 5160 RPM top of 4th gear
0.800/0.658 x 4000= 4863 RPM top of 5th gear

Are these calculations correct?

x1rider

The shift point should always give you at least, if not slightly higher than peak torque RPM after the shifting RPM reduction.

ex. with 1rst to 2nd gear

% gear reduction = (from drive ratio - to drive ratio)/from drive ratio
= 3.667 - 2.053/3.667
= 0.44 (44% rpm reduction)

RPM reduction after gear change = shift RPM X (1.0 - % of gear change)

therefore in our case with peak Torque at 4000RPM

Shift RPM = 4000 / (1.0 - % of gear change)
= 4000 / (1.0 - 0.44)
= 7142.9 (not exactly like yours because I rounded a few numbers)

It appears to be correct!!!

diagnosticator1

If the hypothetical torque peak is at 4000 rpm, you want a shift point that results in a after shift rpm between max torque and max hp. Because the redline rpm is 6500, you would never select a shift point that exceeds that redline rpm in any situation. Besides, at least with a stock ECU, the ECU will attempt to prevent over speed, right? Therefore, a 7100 + rpm shift point is irrelevant.
I think you need to factor in the final drive ratio in the calcs, and relate the shift points to overall drive ratio.

diagnosticator1

<ul><li><a href="http://www.bgsoflex.com/shifter.html">Clicky</a></li></ul>

Mrkrad

So if peak whp is from 5000-6000rpm you would want to shift extension so they each successive gear hits 5000rpm and shift soon enough after 6000rpm to drop back to 5000rpm.

depending on your flywheel weight and agility you can do this quite well.

thats straight line performance.

you can run a dyno in each gear to determine your peak whp powerband.

stay in that powerband you will go fastest down the 1/4 mile.

akula-ssh

I think it should be either maximizing torque for acceleration, or maximizing power for speed. Power is the integral of torque when plotted against rpm, so I'd be happy if the calculator is associated with torque instead of power: the integral of power is something not too physical important, I don't believe.

That said, physics aside, the calculator as a tool is still great, for there is no reason it would know whether the user is inputting torque or horsepower

Mrkrad

so if you really want to get nitty-gritty log the g force on your runs and you'll see the mistakes plain as day

diagnosticator1

I grabbed the first Google result that looked like it would be useful. The relation of torque to shift points depending on the shape of the torque curve is key. Selecting shift points to maximize the time/area under the torque curve is optimum strategy.

carl [i has type-S]

<center><img src="http://pictureposter.audiworld.com/32990/shiftpoints.jpg"></center><p>
plot tractive effort versus vehicle speed for each gear.

the point at which the curves for successive gears overlap is your optimum shift point. if the curves don't overlap, then your shift point is redline.

tractive effort is torque multiplied by the gear ratio(s) - don't forget final drive.

vehicle speed is a function of RPM.

i've done curves like this before, and i found that most 1.8T's need to be shifted at redline in the lower 3 gears or so.

the picture is for a stock 1.8T, i believe.

A4Rye

in the 1.8 boost/hp/tq all start to fall off way before redline