996 turbo boost question
Discussion
Before I go to my Spanish OPC (whom I have mixed experience of) I thought I would ask here.
Just got the car back after a long time following instillation of a new gearbox/clutch (Ouch ! ) attempts at repairing it via a Spanish "specialist" that the OPC have used in the past, having failed.
It is an x50 which had a REVO chip-job done on it shortly after I acquired it.
Seemed to be running well, boosting from 2000rpm as it did before, and felt generally OK. I wanted to give it a good blast on an autoroute though , just to check all was bolted together properly.
Caning it away from a peage I thought that it didn't feel so manic through the gears as before, so tried (traffic permitting ) to see where it was lacking.
1st & 2nd felt normal for the very short time it takes to accelerate through them. 3rd OKish, but not quite as scary as I remembered, in 4th it normally gets to the rev limit TOO quickly but now it seems to be tailing off above 5000rpm. Tried a few full throttle accelerations in 4th & found that the boost builds to 0.9 Bar (which was more or less what I normally saw after the chip) but approaching 5000rpm the boost started to reduce ending up about 0.3 Bar by 5500-5700.
I haven't driven it much recently, but unless my memory is deceiving me I seem to remember it being very difficult NOT to hit the limiter in 4th if accelerating hard.
AFAIK the fuel quality of my last 98 octane fill-up was OK, no other signs of malaise, but it just seems to have lost that fizz it had before through 3rd & 4th.
Finding a gap in the traffic & keeping the foot down I managed 280clicks (175mph) indicated, but it took a lot longer to get there than I remembered from the last (distant) time I got it that high.
Just wanted to pick your collective brains before I entrust it (again) to the OPC.
Just got the car back after a long time following instillation of a new gearbox/clutch (Ouch ! ) attempts at repairing it via a Spanish "specialist" that the OPC have used in the past, having failed.
It is an x50 which had a REVO chip-job done on it shortly after I acquired it.
Seemed to be running well, boosting from 2000rpm as it did before, and felt generally OK. I wanted to give it a good blast on an autoroute though , just to check all was bolted together properly.
Caning it away from a peage I thought that it didn't feel so manic through the gears as before, so tried (traffic permitting ) to see where it was lacking.
1st & 2nd felt normal for the very short time it takes to accelerate through them. 3rd OKish, but not quite as scary as I remembered, in 4th it normally gets to the rev limit TOO quickly but now it seems to be tailing off above 5000rpm. Tried a few full throttle accelerations in 4th & found that the boost builds to 0.9 Bar (which was more or less what I normally saw after the chip) but approaching 5000rpm the boost started to reduce ending up about 0.3 Bar by 5500-5700.
I haven't driven it much recently, but unless my memory is deceiving me I seem to remember it being very difficult NOT to hit the limiter in 4th if accelerating hard.
AFAIK the fuel quality of my last 98 octane fill-up was OK, no other signs of malaise, but it just seems to have lost that fizz it had before through 3rd & 4th.
Finding a gap in the traffic & keeping the foot down I managed 280clicks (175mph) indicated, but it took a lot longer to get there than I remembered from the last (distant) time I got it that high.
Just wanted to pick your collective brains before I entrust it (again) to the OPC.
They told me at the time (5 yrs ago) 510 or so, generally I think most remaps yield about 50 hp + or so.
Could this also be a symptom of dodgy divertor valves ? the car has less than 70,000ml but is now 10 & a half years old , and is on (AFAIK ) the originals, which I am led to believe deteriorate with time & could be replaced with (improved) original parts or aftermarket billeted variety.
Could this also be a symptom of dodgy divertor valves ? the car has less than 70,000ml but is now 10 & a half years old , and is on (AFAIK ) the originals, which I am led to believe deteriorate with time & could be replaced with (improved) original parts or aftermarket billeted variety.
Edited by the other me on Wednesday 3rd October 09:58
Could be, apologies I forgot about them! We fit forge divertor valves to a lot of cars, mainly for longevity purpose rather than any amazing improvement in the car.
Might be worth having a dig around to make sure they have fitted all the hoses around that area, and on the intake piece itself.
Might be worth having a dig around to make sure they have fitted all the hoses around that area, and on the intake piece itself.
Passed by my (Spanish) OPC. They sent me out with a mechanic who wanted to test the car 
fairly obvious he wasn't too used to Turbos, let alone chipped x50's.
He was very impressed & pronounced it fine (which it is up to a point) saying it was one of the quickest he had driven.
He judged the boost tailing off at higher RPM as being normal ( his "official" explanation, it is a geometric turbo & as the revs increase the engine takes over from the turbo, the boost reduces to protect the turbo & the engine)
Unless my memory is playing tricks on me the acceleration was a lot more manic before, & avoiding the Red line in 3rd & 4th was almost as precarious as 2nd. I think my recollection of the sensations does not deceive me.
OPC say they can connect a diagnostic & check for faults, they seemed less enthusiastic about checking for leaks, and I have serious doubts about their ability to identify a stuck wastegate/dodgy diverter valves. . . . don't really know whether I am wasting my time with them asking anything.
Any other Ideas of likely problem ? Oh, and does anyone have any experience of Kotniks in Barcelona, they are not too far from me if anyone could give them a big thumbs up.
Generally, the car is going fine, but just doesn't measure up to my recollections at the top of the rev range.
fairly obvious he wasn't too used to Turbos, let alone chipped x50's.He was very impressed & pronounced it fine (which it is up to a point) saying it was one of the quickest he had driven.
He judged the boost tailing off at higher RPM as being normal ( his "official" explanation, it is a geometric turbo & as the revs increase the engine takes over from the turbo, the boost reduces to protect the turbo & the engine)
Unless my memory is playing tricks on me the acceleration was a lot more manic before, & avoiding the Red line in 3rd & 4th was almost as precarious as 2nd. I think my recollection of the sensations does not deceive me.
OPC say they can connect a diagnostic & check for faults, they seemed less enthusiastic about checking for leaks, and I have serious doubts about their ability to identify a stuck wastegate/dodgy diverter valves. . . . don't really know whether I am wasting my time with them asking anything.
Any other Ideas of likely problem ? Oh, and does anyone have any experience of Kotniks in Barcelona, they are not too far from me if anyone could give them a big thumbs up.
Generally, the car is going fine, but just doesn't measure up to my recollections at the top of the rev range.
) just wondered if any of the "contributors" on threads earlier today had any "new" ideas on thisGassing Station | Porsche General | Top of Page | What's New | My Stuff