Over revs - is this ok / to be expected / normal???

[peteA]

Looking to buy my first 911 and want a 997 - looking at a car and the OPC carry out an inspection part of which is a video. In the video they show the diagnostics read out including the recorded over revs.

Thoughts?

[v8ksn]

If the OPC did it, ask them if they are willing to give the car an OPC warranty

[isaldiri]

for the non gt cars, rev range 1 and 2 would be recorded at the rev limit so you would expect a fair number there but very few after which seems to be the case.

[S1MMA]

ranges 4 - 6 look like they may be spurious, I'd expect range 1 for hitting limiter and maybe some range 2. Range 4-6 on any car is a definate put off, but values of 1 or 2 ignitions doesn't really mean anything.

[Porsche911R]

yep that's a monkey shift alright at 905 hours, I am shocked an OPC can sell it unless it's had a bore scope check but then they would offer that as a back up on the car sale.

4, 5 and 6 look odd and prob false.

but 905 hours some ones miss shifted imo and hit 3 ,2 and 1 all at once.

3 used to be an OPC pass but they changed the rules and now any in range 3 is a warranty fail unless you get a bore score done and extra checks.

cars prob fine as the engine can take it, just hassle to sell and warranty later.

Edited by Porsche911R on Friday 4th November 18:52

[peteA]

Spoke to the Opc briefly - thoughts are the 4-6 events are probably cocked up downshifts and the rest are 'normal'? We agreed to discuss again on Monday but they said that enough time has elapsed since the events that is was probably ok but for a warranty they would need to do a compression test as a matter of course which sounds reasonable.

I'm not necessarily after a warranty just some reassurance that the recorded data is par for the course if you like.

You don't buy a sports car to tootle about but on the other hand it would be good to know it's not been thrashed every time it's been driven!

Any further thoughts greatly appreciated

[peteA]

Porsche911R said:

yep that's a monkey shift alright at 905 hours, I am shocked an OPC can sell it unless it's had a bore scope check but then they would offer that as a back up on the car sale.

4, 5 and 6 look odd and prob false.

but 905 hours some ones miss shifted imo and hit 3 ,2 and 1 all at once.

3 used to be an OPC pass but they changed the rules and now any in range 3 is a warranty fail unless you get a bore score done and extra checks.

cars prob fine as the engine can take it, just hassle to sell and warranty later.

Edited by Porsche911R on Friday 4th November 18:52

Thanks 911R

Not for sale at OPC but I've paid for them to inspect the car

Interesting so far - no major issues, nothing that can't be sorted / fixed but obviously the over revs came up during their investigations

[Milnsey]

peteA said:

Thanks 911R

Not for sale at OPC but I've paid for them to inspect the car

Interesting so far - no major issues, nothing that can't be sorted / fixed but obviously the over revs came up during their investigations

Maybe look elsewhere as good chance it’s been thrashed from cold start also

[Porsche911R]

Milnsey said:

Maybe look elsewhere as good chance it’s been thrashed from cold start also

rubbish.

the cars got very low rev ranges in range one so it's not been thrashed at all, looks like 1 missed shift in 968 hours, that's it.

you see cars with rev range 1 in the 20/30 thousands count wise.

[Slippydiff]

Milnsey said:

good chance it’s been thrashed from cold start also

Though every chance it hasn't been either.

[peteA]

How could you tell from the over rev data alone?

I've loads more info including speaking to the previous owner via the V5 (no vested interest in the car so no reason to lie?) who said the car was great and no bother and wasn't aware of any over rev issues. He traded the car for another Porsche which backed up by the no plate history in the HPI check info. He said the previos owner was a lady...not sure of the significance / relevance of that comment...?

Thanks 911R - your comments make sense

Think I'll have a better chat with the OPC next week and take things from there.

Thanks for the useful comments + keep them coming!

[Milnsey]

How many times would you have to hit the limiter to get 850 ignitions in RR1?

[peteA]

This is true - the number are ignitions right? So how many times does this equate to in terms of prolonged redline?

Should of said the car is 2008 Carrera 2S with approximately 30k and for sale in the low £30k's.
I'm guessing at this age a Porsche warranty is not relevant and to be honest this is not the point of my post. The car has been on the OPC inspection test drive and was fine. The overall report highlighted only minor issues.

I'm more interested in if low over revs are typical - these are sports cars at the end of the day and I'd expect them to be driven enthusiastically but also looked after?

I'm struggling to see how the engine could revved to over 9000rpm and survived intact! The other issue is I could buy one with no over revs, miss a gear and crest my own over rev log! I can peddle a car but I'm not perfect!

The over rev topic is putting me off and this coming after 15 years or so of TVR Ownership including a speedsix car! Sorry to labour the issue if this something you Porsche guys have discussed on multiple occasions.

I'm keen to become a 911 owner but want to find a nice one but even then I also fully accept the potential IMS, etc issues, it's not like I'm looking for any guarantees as such

[Porsche911R]

anonymous said:

[redacted]

911 v quote RR 4,5,6 look false readings when a full engine revolution is a min of 3 ignitions ?
And Rev range 2 does not mean 3 separate occasions !

It means it's spent 1/2 a second at range 2
The Rev range 3 is a tenth of a second.

As I said one missed shift at 905 hours. That's backed up by only 1.1 seconds at RR 1 in total life of the car.
This would cause no damage and Rev range 3 was ok with Porsche for 20years !

The issue is understanding the Rev ranges and coming to sell the car on to people who don't hence it's too much hassle to buy a car with RR 3 done and said all and these cars find there way to non Porsche dealers after being rejected by the OPC 1st then the top indies.


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

Edited by Porsche911R on Saturday 5th November 09:17

Edited by Porsche911R on Saturday 5th November 09:25

[Hexanchus]

Yes, the rev range events are ignition counts. There are 3 ignitions per rev so this car had less than one revolution in ranges 5 & 6. At 9 or 10k rpm that's less than 100 microseconds. The range 5 & 6 events are so brief and over 200 hours ago that if the engine has good compression now you can forget about them. If the OPC knows about the rev ranges and provides OPC warranty after test I would not worry about it as the engine is covered.

All the other lower range events are over 50 hours ago.

As an aside I'm not sure that rev1 are due to hitting rev limiter. I've hit limiter several times and the rev 1 events have not changed.

For more details of this topic see:

http://www.911virgin.com/porsche/rev-range-informa...

[hunter 66]

PeteA , maybe your are searching so hard as past TVR owner you are used to unreliability ........ Having against raced them in GT races ...... finishing was a feat ...... mis-shift over-revs happened in the old days with H patern boxes ......and if after the next few corners all was good you forgot about it ..in a Porsche.

[Hexanchus]

anonymous said:

[redacted]

Ok fair enough. Probably does make sense to find one without any of the upper rev range events so the OP gets one without any question marks in future. I'll try not to hit the rev limiter in future!

[The Surveyor]

I'm just reading through this and I'm confused....

Range 1 - 2 can occur during normal spirited driving and isn't a concern.

The upper ranges are a concern as they show that the engine has been used beyond what most buyers, and OPC's would see as being acceptable. Peters potential car shows that for a couple of milliseconds, it's triggered the upper ranges, which as they are so brief, can't actually be genuine readings.

However, despite being unlikely to be genuine readings it makes the car a poor buy?

Does this mean that there are loads of second hand 911s out there that have experienced a recording glitch on their soft wear that's also sliced a huge lump off their value, or is this very rare?

[Adam B]

I understand why the OP is being thorough, but there is so much knee jerk over-reaction written about rev reports on threads like this, especially as false readings are common.

From memory my PPI by 9e showed plenty of 1s, some 2s, and a couple of 3 and 4

9e said nothing to worry about at all, they also did a pressure test (as they always do for a PPI not due to the rev range results).

Prefer to trust the likes of them and 911V (their guide is good)

[Adam B]

anonymous said:

[redacted]

Nope

At 911Virgin our purchase policy prevents us from considering a car with engine over rev activity beyond the rev limiter within the last 50 operating hours...... The ability to separate genuine incident from an erroneous recording is critical. In general terms we would consider the registering of less than 10 ignitions within a given range to be no cause for concern. 10 ignitions represents fractions of a second, insufficient time, in our experience to cause damage.