mlct

Can someone explain if the Torque channels that Motec records in my 981 Clubsport can help answer whether to shift manually or let PDK do its thing is best? I only downshift in some spots where I know the speed is going to drop otherwise I let PDK shift at red line. Others argue manual "short" shifting is slightly faster. I assume this relates to the "old" question of whether to shift at peak torque or peak horsepower or when the torque in the higher gear will be higher than the current gear. Always heard it is at Red Line in NA Porsches.

I found this document - Motec CAN Channels GT4 Clubsport v1.3 that has this information

Engine Torque Actual - amount of torque actual value of the engine without modifiers from the idle controller, anti-bucking or gear engagement
and
Engine Torque Target - amount of torque demanded of the engine without modifiers from the idle controller, anti-bucking or gear engagement

Thanks

38D

When I short shift my Clubsport or choose a higher gear, it’s not about trying ti out hink the computers optimal shift point. It is merely to allow much more aggressive throttle application. If you are in say 2nd, it can more difficult to get the power down than being in 3rd in certain turns. Across all the various tracks I race, there’s only 2 turns I can think of where I choose a higher gear / short shift (T1 at NJMP, in between 4/5 at VIR).

mlct

Thanks. Good point. I occasionally downshift coming out of Big Bend and going into the Left Hander both at Lime Rock if I know the car will slow under the 2nd to 3rd upshift point which is around 70 mph. Other than those two spots I leave the PDK to do its thing. I cannot remember ever short shifting instead of letting the car go to red line. Two pros who have driven my car, which is modified with a 4.25l engine from Rick Deman, argue that short shifting keeps the car in its power band. I suspect the MOTEC data may help answer this but I have not figured it out yet.

38D

If the computer is shifting to 2nd gear in big bend, you've definitely over slowed the car. Min speed in that corner should be in the 68-71mph range on slicks, and redline in 2nd gear is like 69mph.

mlct

I agree. I know I have blown it when I drop under 70.

Mark

Rick DeMan

A Dyno sheet is your best source of actual TQ data for the 4.25L engine. Here is a similar engine in a 981 Clubsport on the top lines and the stock 3.8L Clubsport in comparison on the lower lines.

These are of course HP and TQ delivered to the wheels/hubs and NOT engine HP and TQ that would be higher.

mlct

Thanks. Rick.

Car is running great.

Mark