Looking for: 911 T - RPM vs speed charts
07-29-2018, 08:27 PM
#31
Rennlist Member
Thanks for the in depth explanation, i think i understand the graph more clearly now. Ill pay attention to see roughlt how far the rpms drop between shifts in the T. Ive noticed they drop pretty quickly unless youre on it and giving back throttle.
07-29-2018, 09:52 PM
#32
This is awesome info and thank you for posting. Just curious how this is determined and what does "optimum" mean - so i understand? Is it for fastest acceleration or best for matching the revs?. Shifts from 1-2-3 are in the peak torque band but not above 4. Just curious if you ring out the first 3 gears to 6500-7000 whether this will be slower than shifting at the optimal shiftpoints shown above
07-29-2018, 10:41 PM
#33
Three Wheelin'
Thread Starter
Torque does work and hp is rate of work. So, not always best to shift a redline, especially when torque is close to the hp output, to get best vehicle acceleration.
Enough here, for further discussion, please see the Racing and DE section of Rennlist, very long discussion thread.
Enough here, for further discussion, please see the Racing and DE section of Rennlist, very long discussion thread.
07-29-2018, 11:19 PM
#34
PDK always shifts at the redline under race conditions 
For example when you engage 2nd (after a redline shift from 1st) - you will be in the meat of the torque band - 450Nm
likewise when you engage 3rd (after a redline shift from 2nd) - you will still be at peak torque - 450Nm
when you engage 4th (after a redline shift from third) - you will still be close to peak torque - 440NM at 5500RPM with perfect symmetry with respect to the power curve (with peak engine power delivered at 6500RPM) thus delivering maximum power under the curve.
Third and fourth are the go to gears on most circuits.
The most important shifting strategy for manuals is knowing when and where to short shift.
For example when you engage 2nd (after a redline shift from 1st) - you will be in the meat of the torque band - 450Nm
likewise when you engage 3rd (after a redline shift from 2nd) - you will still be at peak torque - 450Nm
when you engage 4th (after a redline shift from third) - you will still be close to peak torque - 440NM at 5500RPM with perfect symmetry with respect to the power curve (with peak engine power delivered at 6500RPM) thus delivering maximum power under the curve.
Third and fourth are the go to gears on most circuits.
The most important shifting strategy for manuals is knowing when and where to short shift.
Last edited by groundhog; 07-30-2018 at 12:16 AM.
07-30-2018, 08:51 AM
#35
Rennlist Member
Torque does work and hp is rate of work. So, not always best to shift a redline, especially when torque is close to the hp output, to get best vehicle acceleration.
Enough here, for further discussion, please see the Racing and DE section of Rennlist, very long discussion thread.
Enough here, for further discussion, please see the Racing and DE section of Rennlist, very long discussion thread.
07-30-2018, 10:54 AM
#36
Burning Brakes
Torque does work and hp is rate of work. So, not always best to shift a redline, especially when torque is close to the hp output, to get best vehicle acceleration.
Enough here, for further discussion, please see the Racing and DE section of Rennlist, very long discussion thread.
Enough here, for further discussion, please see the Racing and DE section of Rennlist, very long discussion thread.
07-30-2018, 11:23 AM
#37
Just keep in mind that it is not torque at the engine that is accelerating the car but torque at the wheels. That means gearing is involved and once you go through the numbers you'll find that when you shift to maximize the engine's horsepower, you are also maximizing the torque at the wheels.
07-30-2018, 07:30 PM
#38
Burning Brakes
Optimal gearing is based on multiple factors - engine torque value, engine torque profile, torque at the wheels, rpm, maximum required speed Vs maximum required acceleration, power developed under the curve. Its all a trade off. Torque at the engine is converted through gears to deliver torque at the wheels. Gears are simply torque multipliers
07-30-2018, 08:46 PM
#39
It's not complicated it's pretty simple - the items I mentioned are determinants in the outcome of a vehicles performance whether it be a diesel truck or a race car.
Gears are torque multipliers, engines are machines that deliver torque, gears and final reduction gears deliver wheel torque. The rate an engine delivers torque determines the output e.g. HP.
Gears are torque multipliers, engines are machines that deliver torque, gears and final reduction gears deliver wheel torque. The rate an engine delivers torque determines the output e.g. HP.
Last edited by groundhog; 07-30-2018 at 09:02 PM.
07-30-2018, 11:16 PM
#40
Burning Brakes
It's not complicated it's pretty simple - the items I mentioned are determinants in the outcome of a vehicles performance whether it be a diesel truck or a race car.
Gears are torque multipliers, engines are machines that deliver torque, gears and final reduction gears deliver wheel torque. The rate an engine delivers torque determines the output e.g. HP.
Gears are torque multipliers, engines are machines that deliver torque, gears and final reduction gears deliver wheel torque. The rate an engine delivers torque determines the output e.g. HP.
07-31-2018, 12:03 AM
#42
You're right and my track cars are PDK - so pointless discussion