advice sought: over-revving in 997.1 Turbo

[stumcnu]

Hi All

I'm in the process of viewing a 997.1 Turbo and have just had an independent PPI carried out. Most of the findings are straightforward 'cost to replace' items, so nothing scary.

However, there is evidence of over-revving as follows:

- Range 4 x 7 at 608.6 hrs
- Range 5 x 2 at 608.6 hrs
- Range 6 x 1 at 606.7 hrs

The car is now at roughly 630 hrs.

Other than the above findings, the car is pretty immaculate.

So I have two questions:

1. What is the 'worst case scenario' if the over-revving goes bad? I presume it's a replacement enginge?
2. What would PH-ers do in my position - buy or walk away?

Any and all advice greatly appreciated.

Many thanks,

Stuart

[mm450exc]

I had a turbo with

Range 4: 3 ignition
Range 5: 2 ignition
Range 6: 1 ignition

If you do the math that's just a fraction of a ms. Still have OPC or independent to a full check on it.

[Magic919]

Too recent for me. I'd look elsewhere.

[pete a]

While i think that there is too much of this over rev nonsense with Porsche's compared to any other car you buy, that looks like a major mis shift not that long ago, bearing in mind thay made thousands of 997 turbos you wont struggle to find another one that has not been buzzed into range 6.

walk away and find another one.

[stumcnu]

Thanks all so far. So one 'buy' and two 'walk away' opinions so far.

Can I just check: can even just one single rev into range 6 be enough to cause fatal engine failure (in theory)?

And also, I'm just waiting to confirm the current total operating hours. If this was at 730 rather than 630 (which it might be), would that change anyone's opinion?

Thanks again!

[Sexual Chocolate]

stumcnu said:

Hi All

I'm in the process of viewing a 997.1 Turbo and have just had an independent PPI carried out. Most of the findings are straightforward 'cost to replace' items, so nothing scary.

However, there is evidence of over-revving as follows:

- Range 4 x 7 at 608.6 hrs
- Range 5 x 2 at 608.6 hrs
- Range 6 x 1 at 606.7 hrs

The car is now at roughly 630 hrs.

Other than the above findings, the car is pretty immaculate.

So I have two questions:

1. What is the 'worst case scenario' if the over-revving goes bad? I presume it's a replacement enginge?
2. What would PH-ers do in my position - buy or walk away?

Any and all advice greatly appreciated.

Many thanks,

Stuart

I have nothing to add about rev ranges but ... those look to me like the previous owners last hoon.

[IMI A]

Run Forest run. I walked away from a GT2 recently which had RR 5. Find a car without the dreaded over revs if you can or with no ore than RR3

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[Soov535]

What the choc sex man sed.

Looks like a final hoon to me.


Rev range 6 = run away.

[sleep envy]

I would suggest that the numbers are wrong, there's no way you could get 1 rev in range 6 and 2 in range 5.

[Ian_UK1]

It's impossible for those recorded 'over-rev' stats to be correct!

2 reasons:

1) It would simply be impossible for an engine to accelerate all the way through RR5 to RR6 and back again in 1 ignition either way - or 1/3rd of one rotation of the crank. At say 7500 rpm (just guessing the RR5 rpms, so don't shoot me down in flames) that's .00266 of a second. .00266 of a second, each way, to accelerate then decelerate all that rotational mass by 1000 rpm is not going to happen.

2) The above's irrelevant anyway. There are only 2 RR5 ignitions recorded in total. Notwithstanding the rotational acceleration that breaks the laws of physics, one of those ignitions would have had to have happened as the crank accelerated into in RR6 and (at least) one more would have happened on the way down again at 606.7 hours. That being the case, how the hell can the RR5 recorded at 608.6 hours have happened? There must have already been 2 recorded by that time from the previous 'over-rev' (and in reality a lot more, had a real over-rev happened that didn't break the laws of physics). So the 608.6 time stamp HAS to be false.

What you're looking at here's a glitch in the over-rev recording algorithm in the ECU. Wouldn't be the first time, won't be the last.

Edited by Ian_UK1 on Tuesday 24th June 15:43

[sleep envy]

Agree with Ian, as ever a little knowledge is a dangerous thing...

[stumcnu]

Eek - some interesting information to work through here.

I understand only the basics of this RR stuff, but isn't another theory that:

- The RR6 was a 'change down' over-rev = (+1 RR6)
- On the way back down from the RR6 overrev it clocked at RR5 = (+1 RR5)
- Then there was a separate 'change down' over-rev in RR5 (i.e. one that was between 7,900 and 9,000 so not enough to buzz into RR6) = (+1 RR5)
- Therefore 2 in RR5 and 1 in RR6?

Or have I got totally the wrong end of the stick?!

What would people do - get another ECU read-out elsewhere?

Cheers

[sleep envy]

It's impossible to achieve those numbers as the engine can't spin that fast to achieve them.

[Junior Bianno]

^^^ Whether it's a mistake/glitch is sadly irrelevant. They're on the ECU now, and short of major software surgery they ain't going anywhere. When you come to sell it many dealers won't touch it, and private buyers doing checks such as you have are likely to walk away. Unless it's a serious bargain and you're up for the potential dramas, then there are plenty of other, lower hassle options, to choose from.

[Ian_UK1]

stumcnu said:

Eek - some interesting information to work through here.

I understand only the basics of this RR stuff, but isn't another theory that:

- The RR6 was a 'change down' over-rev = (+1 RR6)
- On the way back down from the RR6 overrev it clocked at RR5 = (+1 RR5)
- Then there was a separate 'change down' over-rev in RR5 (i.e. one that was between 7,900 and 9,000 so not enough to buzz into RR6) = (+1 RR5)
- Therefore 2 in RR5 and 1 in RR6?

Or have I got totally the wrong end of the stick?!

What would people do - get another ECU read-out elsewhere?

Cheers

The numbers in each rev range represent the total number of ignitions (3 per revolution of the engine) that took place whilst the engine was in a particular speed range - not the number of times the engine was in that speed range. Being a total, they are also cumulative.

[Far Cough]

Junior Bianno said:

^^^ Whether it's a mistake/glitch is sadly irrelevant. They're on the ECU now, and short of major software surgery they ain't going anywhere. When you come to sell it many dealers won't touch it, and private buyers doing checks such as you have are likely to walk away. Unless it's a serious bargain and you're up for the potential dramas, then there are plenty of other, lower hassle options, to choose from.

Exactly what I was thinking ..... You , the seller , trying to convince the next bloke thats its all ok. Or at the very least having this whole confusing and ambiguous conversation.

Those numbers do look like a final trackday or similar. If the ECU has incorrectly interpretted the over rev , will a main dealer be able to understand this fact and replace the ECU or wipe it clean ???

[Isysman]

I think this is so stupid. I understand what people are saying about it but it's just so stupid that people have to take this into account. Only a history of constant ragging would put me off buying. Not one instance of the car being over revved.

Do other car companies even have this facility?

How is this information gathered, what software?

[Alpinestars]

Isysman said:

I think this is so stupid. I understand what people are saying about it but it's just so stupid that people have to take this into account. Only a history of constant ragging would put me off buying. Not one instance of the car being over revved.

Do other car companies even have this facility?

How is this information gathered, what software?

Not only is it 1 incident, it's also about 1/100 th of a second in RR 4.

What would be interesting is what the over revs in 1 and 2 are, which should give a better indication of how the car has been driven. And also the average MPH.

[mikem7709]

Those numbers wouldn't concern me in the slightest. The figures for the lower rev ranges will give a better indication as to how it's been drive .

[stumcnu]

To answer the question about RR1 to 3:

RR1: 2,032 @ 608.8 hr
RR2: 436 @ 608.8 hr
RR3: 67 @ 608.6 hr

Just to say - I'm now totally confused about the advice being offered! It ranges from "run like the wind" to "don't worry about it"...

Any final thoughts?

I need to make a final call by 0900 tomorrow...!

Stuart