Overspeed Question
Discussion
Just wondered if anyone can explain the following seemingly random over-speed numbers:
At 589.7 engine hours
Range 3 - 2,839
Range 4 - 362
At 613.4 engine hours
Range 3 - 2,856 (plus 17)
Range 4 - 363 (plus 1)
At 634.5 engine hours
Range 3 - 2,857 (plus 1)
Range 4 - 364 (plus 1)
This is on a 997 GT2 that I think I haven't over-sped.
Just seems strange to be getting one addition ignition at a time.
At 589.7 engine hours
Range 3 - 2,839
Range 4 - 362
At 613.4 engine hours
Range 3 - 2,856 (plus 17)
Range 4 - 363 (plus 1)
At 634.5 engine hours
Range 3 - 2,857 (plus 1)
Range 4 - 364 (plus 1)
This is on a 997 GT2 that I think I haven't over-sped.
Just seems strange to be getting one addition ignition at a time.
Edited by am0611 on Thursday 27th November 11:38
The 911 Virgin site has some really useful information on this subject.
"The registering and recording of a single ignition at such high engine speed, in our view, is just not possible in the same way that a single ignition in, for example, Rev Range 4 can't follow a single ignition in the previous rev range. In order to pass in to a higher bracket of engine speed the engine must complete at least a full engine revolution, a minimum of 3 ignitions."
"The registering and recording of a single ignition at such high engine speed, in our view, is just not possible in the same way that a single ignition in, for example, Rev Range 4 can't follow a single ignition in the previous rev range. In order to pass in to a higher bracket of engine speed the engine must complete at least a full engine revolution, a minimum of 3 ignitions."
I had exactly the same issue on my 997gt2. Single ignitions in 2 different rev ranges, and ignitions when I was sure I had not over revved the car.
The problem with the 2 compared to the 3 is the added torque, so the way it revs quicker, and the much lower rev limit.
I'd be very surprised if anyone has a 7gt2 with no rev range issues.
The problem with the 2 compared to the 3 is the added torque, so the way it revs quicker, and the much lower rev limit.
I'd be very surprised if anyone has a 7gt2 with no rev range issues.
Glad it is not just my car.
Owners/Buyers/OPC's should be aware of the problems of using this "snap-shop" data to make decisions on selling, buying and warranty (including asking for compression tests...).
I'm glad I am now keeping an eye on this and every time (for the last 3 visits) I go to the OPC, I get a periodic picture of the over-revs for my records. Having this data makes the car look better than it initially looks on the surface.
Compare (a) & (b) below
(a) Without periodic data - Engine Hours: 634.5, Range 3: 2,857 (last at 633.4), Range 4: 364 (last at 633.4)
This could be seen as a car that has been over-revved recently with problems to come.
(b) With the periodic data
Range 3 can be seen to have had 2,839 at 246.0 hours (no data before) but since has run nearly 390 engine hours with only 18 more, including at least one erroneous reading
Range 4 can be seen to have had 362 at 199.2 hours (how many are erroneous I don't know) but has since run nearly 435 hours with 2 single erroneous hits at 597 & 633 hours.
As you can see (a) and (b) look very different prospects but are the same car...
Owners/Buyers/OPC's should be aware of the problems of using this "snap-shop" data to make decisions on selling, buying and warranty (including asking for compression tests...).
I'm glad I am now keeping an eye on this and every time (for the last 3 visits) I go to the OPC, I get a periodic picture of the over-revs for my records. Having this data makes the car look better than it initially looks on the surface.
Compare (a) & (b) below
(a) Without periodic data - Engine Hours: 634.5, Range 3: 2,857 (last at 633.4), Range 4: 364 (last at 633.4)
This could be seen as a car that has been over-revved recently with problems to come.
(b) With the periodic data
Range 3 can be seen to have had 2,839 at 246.0 hours (no data before) but since has run nearly 390 engine hours with only 18 more, including at least one erroneous reading
Range 4 can be seen to have had 362 at 199.2 hours (how many are erroneous I don't know) but has since run nearly 435 hours with 2 single erroneous hits at 597 & 633 hours.
As you can see (a) and (b) look very different prospects but are the same car...
Edited by am0611 on Thursday 27th November 11:49
Totally agree on your points.
1) A reading of 1 in a range is likely an error. It's impossible to achieve a single ignition in RR4 with only 1 in RR3 at the same timestamp after all...
2) The evolution of the RR data is critical in car assessment. Even porsche say that 200 hrs run time post an ignition count in RR3-6 warrants no 'investigation' for warranty purposes!
The whole OverSpeed thing is over egged as ever but I can understand the need for it. Just a shame that one size doesn't fit all.
Is the GT2 limiter higher than a standard car based on the same block?
If you had, for example, a C2S with X51 and a limiter adjusted (as per the factory spec) to 7550 rpm then you can get into RR2 without hitting the limiter and RR3 becomes 'as common' as RR2 on a non X51 car. Doesn't seem reasonable at first glance but obviously the same parts of the engine are spinning faster etc...
1) A reading of 1 in a range is likely an error. It's impossible to achieve a single ignition in RR4 with only 1 in RR3 at the same timestamp after all...
2) The evolution of the RR data is critical in car assessment. Even porsche say that 200 hrs run time post an ignition count in RR3-6 warrants no 'investigation' for warranty purposes!
The whole OverSpeed thing is over egged as ever but I can understand the need for it. Just a shame that one size doesn't fit all.
Is the GT2 limiter higher than a standard car based on the same block?
If you had, for example, a C2S with X51 and a limiter adjusted (as per the factory spec) to 7550 rpm then you can get into RR2 without hitting the limiter and RR3 becomes 'as common' as RR2 on a non X51 car. Doesn't seem reasonable at first glance but obviously the same parts of the engine are spinning faster etc...
Alpinestars said:
The only problem is that anyone wanting an OPC warranty on if will need a leak down and compression test because of the RR3 data.
Yep, I bought mine with 14 ignitions in RR3 in 2012, because of these over-revs Porsche compression tested it in March this year at my expense before it could have further extended warranty. They were happy to warranty it for 2 years when I bought it but the conditions have changed since then. It's a shame that if you want to hedge against big bills you have to play this game with Porsche. I probably won't renew the warranty again next year as this stuff winds me up and the reality is I'd probably send it to Fearnsport for an engine rebuild anyway rather than let an OPC crack the engine open.Yep, gave up the warranty 4 years ago. All down to frustrations with Rev ranges, compression test requirements, having to use N rated tyres & crappy Porsche batteries that died frequently in the heat of Dubai.
Run mine warranty free with non-N rated tyres & non standard battery. The money I saved on batteries, tyres (not running semi-slicks that need to be changed regularly), warranty & compressions testing is sitting in my bank account for that day when I need to spend some cash on the car.
Buyers choice for me, my risk I know but I prefer that rather than supplier dictate which I hate.
Run mine warranty free with non-N rated tyres & non standard battery. The money I saved on batteries, tyres (not running semi-slicks that need to be changed regularly), warranty & compressions testing is sitting in my bank account for that day when I need to spend some cash on the car.
Buyers choice for me, my risk I know but I prefer that rather than supplier dictate which I hate.
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