torque curve question - experts needed
10-01-2007, 04:18 AM
#1
Racer
Thread Starter
torque curve question - experts needed
My 944S2 has been turbo'd and its running a standalone engine management system.
I'm running an approximation of the stock S2 timing - best I could. I noticed on the stock timing map it pulls timing at 5000rpms, which is around peak torque.
Question is now I am turboed around 8psi boost, will that change the rpm of the torque peak and hence my timing retard point?
Whats making me ask is that when I saw a Powerhouse dyno of a 968 16v 3.0 turbos the torque peak was 3500 rpm
thanks
mike
I'm running an approximation of the stock S2 timing - best I could. I noticed on the stock timing map it pulls timing at 5000rpms, which is around peak torque.
Question is now I am turboed around 8psi boost, will that change the rpm of the torque peak and hence my timing retard point?
Whats making me ask is that when I saw a Powerhouse dyno of a 968 16v 3.0 turbos the torque peak was 3500 rpm
thanks
mike
10-01-2007, 04:35 AM
#2
Rennlist Member
Hmm that does seem very low for a 16v tq peak does it not?? Have you had yours dyno'd yet Mike, and where just out of curiosity if you have?
10-01-2007, 07:18 AM
#3
We need to know a LOT more info.
The most important factor will be the turbocharger specs - this will dictate 90% of your torque peak.
The Powerhouse car was low peak because I am sure he put some K27/6 hybrid or another ridiculously small turbo to show boost at low RPM to please all the magazine writers.
The most important factor will be the turbocharger specs - this will dictate 90% of your torque peak.
The Powerhouse car was low peak because I am sure he put some K27/6 hybrid or another ridiculously small turbo to show boost at low RPM to please all the magazine writers.
10-01-2007, 07:51 AM
#4
Racer
Thread Starter
Special Tool, Its a 3.0 S2 engine, running a T04B 60-1 HiFi with a #8 hotside and stage 5 wheel, wastegates a Tial 44mm, stock S2 exhaust at the moment.
Patrick not dyno'd at the moment just been too busy with work, maybe in the next month.
Patrick not dyno'd at the moment just been too busy with work, maybe in the next month.
10-01-2007, 08:02 AM
#5
In this case you need to be VERY careful using stock timing because this turbo willspool fast on your car.
The timing will also then affect the spoolup, so this will not be a once and done timng modification.
You will probably want to rent the dyno for the day to do your WOT timing map.
You will see when additional timing makes no more, or even drops power.
Also - use a high gear.
4th and 5th load the engine earlier than 2nd and 3rd and you don't want to have an overly aggressive timing map in the real world in high gear at lower RPM because you had tuned it in lower gear.
Good luck, you have work to do.
The timing will also then affect the spoolup, so this will not be a once and done timng modification.
You will probably want to rent the dyno for the day to do your WOT timing map.
You will see when additional timing makes no more, or even drops power.
Also - use a high gear.
4th and 5th load the engine earlier than 2nd and 3rd and you don't want to have an overly aggressive timing map in the real world in high gear at lower RPM because you had tuned it in lower gear.
Good luck, you have work to do.
10-01-2007, 08:13 AM
#7
Racer
Thread Starter
I just re read my initial post, forgot to mention that I have pulled about 0.8 degree per PSI of boost in the ignition map so at 8psi I'm about 23 degrees max, I think stock is about 29.
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10-01-2007, 08:14 AM
#8
Rennlist Member
Sorry Mike, I've forgotten but what c/r are you running. From memory you're using stock c/r and cams etc? Or are you using a thicker headgasket to drop the c/r? I would think if it's stock, then 8 psi is at the edge of the envelope and if anything you'll have to retard you timing in places. Have you done anything to enhance the cooling of the fluids in your car?
Again apologies for my vagueness of your build. I've got too much in my tiny mind at the moment. lol
Again apologies for my vagueness of your build. I've got too much in my tiny mind at the moment. lol
10-01-2007, 08:15 AM
#10
Rennlist Member
Ah you beat me to it in your response...
10-01-2007, 08:16 AM
#11
Rennlist Member
PS by the way Duke, what have you done in regards to cooling in relation to your front mount i/c? Sorry for the crosspost, but it's also topical.
10-01-2007, 08:20 AM
#12
Racer
Thread Starter
I am running 10.9:1 CR at the moment, I run the stock ignition map up to 0, then the boost map is dropped 0.8 degree per psi on all the map. So at the 1 psi row each cell from 1500rpm to 6500 rpm is dropped 0.8, then on the 2 psi row same deal again a further 0.8 and so one..
10-01-2007, 08:27 AM
#14
Racer
Thread Starter
oh didnt know that, I roll off more at higher revs at the moment down a couple of psi, for example at 8psi boost I am 23 degrees at 3750rpm, then roll of to a low of 20 at 5000rpm where I thought peak torque was then slightly up to 21 at 6000.