What does PSM really do?
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Intermediate
Joined: Sep 2007
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What does PSM really do?
I have a 06 997 C2 and I was wondering when I turn the PSM off on my car does it disable the rev-limit also? Actually what does happen when I turn the PSM off and why is my car faster with it off?
Just kind of curious………
Just kind of curious………
Racer
Joined: Oct 2005
Posts: 324
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From: Julian, CA
Basically what stability control does is to help the vehicle stay on the drivers intended path in turns. When a driver enters a turn too fast or gets back on the throttle too soon in the turn and exceeds the tire's ability to hold the road through the turn, the vehicle begins to skid or spin. Stability control pulsates the brakes of individual wheels to help "rotate" the vehicle to the driver's intended path. It is basically ABS taken to the next level and it has no effect on the rev limiter. Stability control is a two axis system whereas traction control is one axis system.
I have found the Porsche stability control to be none intrusive and will only intervene if I am not being smooth. I can’t imagine how turning it off would make me faster.
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Joined: Feb 2005
Posts: 10,222
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From: 01776
^^That's a nice explanation.
I think that most people that track their 997s leave it ON. I have only done 1 autocross event with it and never felt hindered by it.
The only time you would want to turn it off would be if your car was 'stuck' either in mud or snow.
That's just my opinion - others might disagree.
I think that most people that track their 997s leave it ON. I have only done 1 autocross event with it and never felt hindered by it.
The only time you would want to turn it off would be if your car was 'stuck' either in mud or snow.
That's just my opinion - others might disagree.
Racer
Joined: Jan 2007
Posts: 350
Likes: 1
From: Huntingdon Valley, PA
All my instructors at DE or autox ask to turn it off because they want me to learn how to drive the car, not let the car do the saving for me.
The only thing that I could add to excellent explanation above is that PSM exhibits itself by braking individual wheels when necessary, ABS and cutting of throttle.
The only thing that I could add to excellent explanation above is that PSM exhibits itself by braking individual wheels when necessary, ABS and cutting of throttle.
Racer
Joined: Nov 2003
Posts: 412
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From: St. Petersburg Florida
I am and have been a DE instructor for many years. We are not running a racing school. I want my students to have every advantage in order not to make an error. I would never have them turn it off. I have never turned mine off. If you do at some critical point it will come back on and sometimes it could be in a braking zone. PSM in stands for PLEASE SAVE ME.
Race Car
Joined: Apr 2004
Posts: 4,159
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From: Chicagoland
It is used by those people who either are unable to drive a car properly or are unwilling to learn. It should not even be used by the most novice of drivers who wish to learn how to handle their car.
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From: 01776
Rev limiter can be disabled by most of the ECU reprogrammers (e.g. Revo, GIAC, etc etc).
HOWEVER, overrev counts are one thing that you definitely cannot hide from Porsche when your ECU is scanned at the dealer.
i.e.
The 6 ranges can be broken down as:
Range 1: 7300-7500 RPM
Range 2: 7500-7700 RPM
Range 3: 7700-7900 RPM
Range 4: 7900-8400 RPM
Range 5: 8400-9500 RPM
Range 6: 9500-11000 RPM
If you disable your rev-limiter you clearly can get into these ranges. It's only a problem in terms of warranty work.
Also, I don't think there's much gain if any to simply disabling the rev-limiter. The stock engine's torque is heading South big time approaching the stock redline, so unless the engine is modified there will be no performance gains. 'Stock' examples of this would be the X-51 Carrera S and GT3 motors which have higher redlines.
Compare max HP figures @ engine speeds (from Porsche) for these naturally aspirated motors:
-C2S 355@6600
-C2SX51 381@7200
-GT3 415@7600
HOWEVER, overrev counts are one thing that you definitely cannot hide from Porsche when your ECU is scanned at the dealer.
i.e.
The 6 ranges can be broken down as:
Range 1: 7300-7500 RPM
Range 2: 7500-7700 RPM
Range 3: 7700-7900 RPM
Range 4: 7900-8400 RPM
Range 5: 8400-9500 RPM
Range 6: 9500-11000 RPM
If you disable your rev-limiter you clearly can get into these ranges. It's only a problem in terms of warranty work.
Also, I don't think there's much gain if any to simply disabling the rev-limiter. The stock engine's torque is heading South big time approaching the stock redline, so unless the engine is modified there will be no performance gains. 'Stock' examples of this would be the X-51 Carrera S and GT3 motors which have higher redlines.
Compare max HP figures @ engine speeds (from Porsche) for these naturally aspirated motors:
-C2S 355@6600
-C2SX51 381@7200
-GT3 415@7600
Racer
Joined: Oct 2006
Posts: 371
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From: San Diego, CA
^^That's a nice explanation.
I think that most people that track their 997s leave it ON. I have only done 1 autocross event with it and never felt hindered by it.
The only time you would want to turn it off would be if your car was 'stuck' either in mud or snow.
That's just my opinion - others might disagree.
I think that most people that track their 997s leave it ON. I have only done 1 autocross event with it and never felt hindered by it.
The only time you would want to turn it off would be if your car was 'stuck' either in mud or snow.
That's just my opinion - others might disagree.
At a dedicated racetrack, it depends. On a low-speed track with lots of runoff, I turned the system off once I knew the track and stated to find it intruding on my attempts to rotate the car for low speed corners. On a high-speed track last weekend with lots of concrete walls and triple-digit cornering speeds, I never turned it off even for one lap. The system is confidence inspiring and it allows a lot more slip angle than the BMW DSC that a lot of people have experienced. I would say it is comparable to Cadillac's system, which also allows the V-series cars to be pushed quite hard before the system intrudes.
The Penguin King
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From: Houston
To date, I've kept PSM on when I've been on the track at DE events. I've gotten as far sideways as I care to without having PSM kick in, and on the few times it has kicked in, I've been happy to see it. My impression is that most of the people who say we should turn PSM off, have not actually driven a 997 to the point where it requires help from a stability management system. I suspect that most of them may be familiar with other similar systems, but not this one. My sense is that if you keep your car well balenced, PSM will not be the limiting factor in attaining low lap times. It's when you get things out of kilter that PSM steps in to help, and when it does, you'll most likely be very glad. I'd love to see a pro-level driver run laps with and without PSM. I'll guess that there would be no difference in times.