Porsche 991.1 Carrera S rev ranges - Page 1 - Porsche General - PistonHeads UK

Hi, I have a 718 GT4 but am looking into buying a used 991.1 Carrera S. I found the perfect car at a Porsche Center with all the right options (manual, sunroof, PSE, Sport PASM, full leather dash...). However, the car has 14 ignitions in rev range 4 at 900 operating hours (total operating time is 1700 hours). The Porsche Center says that a pressure test was done and everything is fine. The car also comes with one year Porsche Approved warranty. 1. Should I make the jump or walk away from a car with rev range 4 ignitions? 2. What would be the effect on the resale value? Dominique

If you look at 911v you will see that rev ranges 1 and 2 are normal to the limit, rev range 3 and 4 are a concern but only in the last 200 hours if a compression test shows a problem, otherwise all is good. If sold by an OPC the warty supports the car, and in fact the rev range 3 is very narrow ... 200 rpm ? Only 5 and 6 are a concern. It's worth mentioning also that this is ignitions, so 1.5 ignitions per rpm on a six cylinder engine ?? I have seen 3 but that feels illogical to me ... Chris

Ok, thanks for the information, and good to know. However, I don't get the fact of the 1.5 ignitions per rpm when the car has 14 ignitions in range 4... You mean that the ignitions in the DME readout should always be a multitude of 3, because per cylinder bank the 3 spark plugs ignite simultaneously? (6 cylinders so 2 x 3 ignitions on one full rotation)

I thought it was 3 ignitions is one rotation of the engine, but it doesn’t have to be a multiple if 3 as it may not have completed a full rotation. There’s a formula for working out how long in seconds it equates to, but 14 or whatever is a tenth of a second? Anyway, checked and warranted by an OPC would be good enough for me. I’ve seen a car with ignitions in RR6 recently that was fully warranted as well, i think this sort of thing can be overblown, and sometimes the numbers are spurious.

six cylinders with a four stroke to me should be 1.5 ignitions per revolution ... but 911v say 3. Either way, 14 ignitions is very few revs and a very short time at around 7000rpm ... 115 revs per second guesstimate ? Maybe it is a spurious error anyway ?

The impact on the engine physically and then resale value are two slightly separate issues. Given the time interval, probably no physical harm done if indeed the ignitions are real (false recording of a few ignitions is a known thing). But ignitions recorded in DME are ignitions recorded in DME and will probably narrow resale market in future. How much? Who can say. Probably not massively, maybe not even materially. But some traders, for instance, say that they won't buy a car with anything at all over range 2. Incidentally, extended leather is standard on all regular 991 Carrera and Carrera S sold in the UK, so not an option per se.

The full DME report shows that the overrevs occurred at a single instance (all ranges at 900 operating hours): range 1: 185 range 2: 45 range 3: 20 range 4: 14 range 5: 0 range 6: 0 So I guess this only happened due to one slight miss-shift, for the rest I don't think the car was driven aggressively.

So that's 800 hours ago, the engine has been compression tested and the OPC will put an extended warranty onto it. Some people are frightened to cross the road ... but almost everybody does ... I wonder how many cars have less than this (with so few, if they are real).

anonymous said: [redacted] Thanks for the clarification !

I wouldn’t worry about it. I bought my 997.1 turbo with a report showing 1 ignition in range 6 from an OPC. This was 9 years ago, car had been pressure tested by the OPC and warranted ever since until last year. No issues whatsoever. As others have said, the 911V site provides great info on this topic.

Dominique997GTS said: The full DME report shows that the overrevs occurred at a single instance (all ranges at 900 operating hours): range 1: 185 range 2: 45 range 3: 20 range 4: 14 range 5: 0 range 6: 0 So I guess this only happened due to one slight miss-shift, for the rest I don't think the car was driven aggressively. Just to add some clarity to your statement, the last event added some to the cumulative totals; there were likely earlier events but the run-time of the last addition is recorded '@ operating hours X' You can only add to each range in turn starting from 1; so to get to 3 you must go 1, 2, 3, 2, 1 - so one should always be higher than 2 which should always be higher than 3. There have been cases where individual additions occur on multiple ranges - these are considered implausible and render the record unreliable therefore discounted from checks. For better context, comparing data from multiple records on the same car can highlight the erroneous occurrences. Also worth knowing: Rev flare at gear change near the limiter can add some - even to Tiptronic / PDK equipped cars - but they are exempted from check as the driver CANNOT over-rev personally. Edited by Pope on Saturday 11th June 09:07

RR1-4 fine. I wouldn't worry. Its on RR 5 and 6 were engines have been potentially buzzed and I wouldn't touch these cars without a leak down test.