Is it possible to over rev an engine with PDK?
06-22-2014, 11:15 PM
#16
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On mine, bumping against the rev limiter with the PDK in manual mode does generate range 1 and range 2 overrevs. I don't know how it determines whether it will be a 1 or a 2 (duration maybe?) but it does generate both. It gets to red line right quick in lower gears and if I'm in normal mode, I have to call for an upshift well below 7400 rpm to avoid invoking the rev limiter. It responds quicker to Sport and Sport Plus mode manual shift requests obviously but it is very easy to get over 7400 in mine in Normal mode.
Below are the six "rev ranges" for the 997.2.
Ignitions at or above 7,500 RPM but below 7,700 RPM are recorded in Range 1; ignitions occurring between 7,700 to 7,899 RPM are recorded as Range 2 ignitions; etc.
Rev range 1: 7,500 to 7,699 = Maximum permitted engine speed exceeded; engine damage possible.
Rev range 2: 7,700 to 7,899 = Maximum permitted engine speed exceeded; engine damage possible.
Rev range 3: 7,900 to 8,099 = Maximum permitted engine speed exceeded; engine damage possible.
Rev range 4: 8,100 to 8,399 = Maximum permitted engine speed clearly exceeded; engine damage probable.
Rev range 5: 8,400 to 8,899 = Maximum permitted engine speed very clearly exceeded; engine damage very probable.
Rev range 6: over 8,900 = Engine damage has generally occurred.
Hope this helps.
Rev range 2: 7,700 to 7,899 = Maximum permitted engine speed exceeded; engine damage possible.
Rev range 3: 7,900 to 8,099 = Maximum permitted engine speed exceeded; engine damage possible.
Rev range 4: 8,100 to 8,399 = Maximum permitted engine speed clearly exceeded; engine damage probable.
Rev range 5: 8,400 to 8,899 = Maximum permitted engine speed very clearly exceeded; engine damage very probable.
Rev range 6: over 8,900 = Engine damage has generally occurred.
06-22-2014, 11:30 PM
#17
Race Director
There is an auto upshift in manual mode...when the acell pedal is pressed all,the way...pass the kick down button PDK will auto upshift in manual mode.
If the PDK is in auto mode then yes, it would upshift.
But with the selector lever in position M (manual mode), there is no automatic upshift at the upper engine speed limit.
Thus if the driver does not back off the throttle or even if he does but the downslope gradient is steep enough the engine RPMs will venture into redline and beyond territory.
But with the selector lever in position M (manual mode), there is no automatic upshift at the upper engine speed limit.
Thus if the driver does not back off the throttle or even if he does but the downslope gradient is steep enough the engine RPMs will venture into redline and beyond territory.
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BGLeduc (01-27-2020)
06-23-2014, 12:14 AM
#18
I agree with mdrums the car will shift even in manual mode. I believe the computer will keep the engine from over revs most of the time. Just as with low speed hiccups ect the computer can make mistakes. Given the right circumstance i.e. just as it shifts down (off gas, on brake, but on decline) you let off brake and you speed up pushing it into over rev range before it shifts again. The computer 99%of the time keep it out of over rev range, but that 1%, just maybe.
06-23-2014, 12:32 AM
#19
Race Director
Take this how,you will...I've been driving PDK since September 2008 and just might have more track miles on PDK than anyone else I know.
You can bounce PDK off the rev limiter.. PDK will not auto shift UNLESS you are in normal mode or press the throttle into the kick down button then even I. Manual mode PDK will auto up shift. I use this feature all the time at the track to either hold a gear and not let PDK auto upshift or have it auto upshift . You can not so called money shift PDK and have damaging over revs....going down a hill won't really do this as you'd have to already be at redline and down shift PDK but it will not downshift until the revs are much lower. As far as being full throttle going down a hill and letting off the throttle...well the engine doesn't continue to speed up! Fuel is cut, less power, engine compression....think about it! I have been all over tracks with elevation changes and this just doesn't happen.
You all can continue to debate this...I'm done hear...just trying to share my experience with PDK.
You can bounce PDK off the rev limiter.. PDK will not auto shift UNLESS you are in normal mode or press the throttle into the kick down button then even I. Manual mode PDK will auto up shift. I use this feature all the time at the track to either hold a gear and not let PDK auto upshift or have it auto upshift . You can not so called money shift PDK and have damaging over revs....going down a hill won't really do this as you'd have to already be at redline and down shift PDK but it will not downshift until the revs are much lower. As far as being full throttle going down a hill and letting off the throttle...well the engine doesn't continue to speed up! Fuel is cut, less power, engine compression....think about it! I have been all over tracks with elevation changes and this just doesn't happen.
You all can continue to debate this...I'm done hear...just trying to share my experience with PDK.
06-23-2014, 09:51 AM
#20
Rennlist Member
Cloudspin,
Below are the six "rev ranges" for the 997.2.
Ignitions at or above 7,500 RPM but below 7,700 RPM are recorded in Range 1; ignitions occurring between 7,700 to 7,899 RPM are recorded as Range 2 ignitions; etc.
Below are the six "rev ranges" for the 997.2.
Ignitions at or above 7,500 RPM but below 7,700 RPM are recorded in Range 1; ignitions occurring between 7,700 to 7,899 RPM are recorded as Range 2 ignitions; etc.
Rev range 1: 7,500 to 7,699 = Maximum permitted engine speed exceeded; engine damage possible.
Rev range 2: 7,700 to 7,899 = Maximum permitted engine speed exceeded; engine damage possible.
Rev range 3: 7,900 to 8,099 = Maximum permitted engine speed exceeded; engine damage possible.
Rev range 4: 8,100 to 8,399 = Maximum permitted engine speed clearly exceeded; engine damage probable.
Rev range 5: 8,400 to 8,899 = Maximum permitted engine speed very clearly exceeded; engine damage very probable.
Rev range 6: over 8,900 = Engine damage has generally occurred.
Hope this helps.Rev range 2: 7,700 to 7,899 = Maximum permitted engine speed exceeded; engine damage possible.
Rev range 3: 7,900 to 8,099 = Maximum permitted engine speed exceeded; engine damage possible.
Rev range 4: 8,100 to 8,399 = Maximum permitted engine speed clearly exceeded; engine damage probable.
Rev range 5: 8,400 to 8,899 = Maximum permitted engine speed very clearly exceeded; engine damage very probable.
Rev range 6: over 8,900 = Engine damage has generally occurred.
06-23-2014, 03:36 PM
#22
I went from a VW with a DSG gearbox which auto upshifted whichever mode you were in. Therefore it was a surprise when driving my 911 home in manual mode slamming into the limiter! So i concur with mdrums, in manual mode it will NOT upshift for you.
06-23-2014, 10:25 PM
#23
Race Director
Unless you are in sport plus mode and press the accelerator pedal all the way and click the button under the pedal...then PDK will upshift automatically no matter what mode you are in.
06-23-2014, 11:56 PM
#24
Three Wheelin'
. This thread is like the quart of milk that's been in your fridge for 6 months. You know it's bad but you just can't stop yourself from checking!
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RexII (02-11-2020)
06-24-2014, 02:29 AM
#25
Race Director
^^^ LOL I know...I got a pm from a friend on this thread and answered him and then checked. Just trying to help you all out. Maybe I such at explaining myself..LOL
06-24-2014, 03:02 PM
#26
Rennlist Member
Yahoo me wasn't even aware there was a button down there and still wouldn't if it weren't for you. So now it is going to be one of those "every time I try to get out, they pull me back in!" kind of deals - what do it do? The button that is. 
06-25-2014, 12:51 AM
#27
Race Director
If you are in normal mode or sport mode then PDK will automatic upshift at ant rpm.
Also in sport plus mode you can aggressively and quickly press the throttle all the way down clicking the button and do a quick downshift.
06-25-2014, 05:58 AM
#28
Sorry but I have a scenario to discuss 
To help illustrate:
Car on flat ground. Car speeds up through 1st gear and reaches redline at 40mph. Engine cuts throttle so car can't gain any more speed in 1st gear.
Car on steep downslope. Car speeds up through 1st gear and reaches redline at 40mph. Throttle is cut, but momentum is in play and gravity takes the car past 40mph. Car is now traveling faster than 1st gear is designed for. Over rev?
PDK scenario:
During autocross, lightly braking on a downslope, I was shifting from 2nd gear to 1st gear, with a heel toe for a higher rev match going into 1st. Brake is completely off as the car releases 2nd gear, where I'm already rolling onto the throttle after the initial kick to get the revs up. As soon as the car engaged 1st, the rears locked up momentarily and put the car in a slide. It felt like shift lock, which I didn't think was possible with dummy-proof PDK. This was with PSM on.
Maybe PDK sensed it and locked the transmission to prevent engine damage, but I remember hearing the rpms sounding unusually high, so I'm inclined to think it was mechanical shift lock from over rev. What actually happened, I'm not sure.
To help illustrate:
Car on flat ground. Car speeds up through 1st gear and reaches redline at 40mph. Engine cuts throttle so car can't gain any more speed in 1st gear.
Car on steep downslope. Car speeds up through 1st gear and reaches redline at 40mph. Throttle is cut, but momentum is in play and gravity takes the car past 40mph. Car is now traveling faster than 1st gear is designed for. Over rev?
PDK scenario:
During autocross, lightly braking on a downslope, I was shifting from 2nd gear to 1st gear, with a heel toe for a higher rev match going into 1st. Brake is completely off as the car releases 2nd gear, where I'm already rolling onto the throttle after the initial kick to get the revs up. As soon as the car engaged 1st, the rears locked up momentarily and put the car in a slide. It felt like shift lock, which I didn't think was possible with dummy-proof PDK. This was with PSM on.
Maybe PDK sensed it and locked the transmission to prevent engine damage, but I remember hearing the rpms sounding unusually high, so I'm inclined to think it was mechanical shift lock from over rev. What actually happened, I'm not sure.
Last edited by 1990nein; 06-25-2014 at 09:38 AM.
06-25-2014, 10:59 AM
#29
Rennlist Member
I'm far from a technical expert but I thought the electronics in 997.2 PDK cars wouldn't allow simultaneous brake and throttle application. I remember reading something to the effect that that limitation could be overcome with a tune or maybe just PIWIS. Someone here will provide a more technical and detailed reply. I'm interested to see what they think. Cheers.
06-27-2014, 03:18 PM
#30
Rennlist Member
What is the "button under the pedal" you speak of, and is it on my Tip?
Tiptronic doesn't allow it, for sure. I thought for a log time something was wrong with the car.
Tiptronic doesn't allow it, for sure. I thought for a log time something was wrong with the car.