sbbarnett

I'd appreciate it if knowledgeable people here would double check my interpretation and conclusions based on the over rev data from a car I'm considering making an offer on:

2005 911 Carrera S Cabriolet (Manual)
Current operating Hours: 2295.4
DME Range 1: 11325 @ 2292.9
DME Range 2: 301 @ 2289.0
DME Range 3: 29 @ 1337

Interpretation:

Over 7300 RPM for approximately 30 seconds about 3 operating hours ago
Over 7500 RPM for approximately 1.2 Seconds about 6.4 hours ago
Over 7700 RPM for approximately 0.1 Seconds over 950 Hours ago

Conclusion: Current owner thrashed the car a little a few hours ago, but nothing too serious. Given the lack of other issues found during the PPI, nothing here to cause me to run away from the car.

Skwerl

The hours just indicate the last time it brushed into that range, and the counter is cumulative over the life of the car. That is, it could have just been 10 revs in range 2 at 2289 hours. In any event, "thrashed" is probably a bit harsh and that report shows nothing to worry about IMO.

Be sure to also calculate average MPH using the mileage/engine hours and make sure it seems realistic.

sbbarnett

You're right, thrash is too harsh - probably colored by the fact that there was a bunch of race track rubber accumulated on the tires during the PPI that was not there when I test drove the car a few days prior.

I calculated the average MPH as 21MPH - seems low, but we are in the SF Bay area...

qikqbn

other key factors are how many total miles on your car and what is the average speed??
You really just want to get a feel for how many hours and mileage since last high range 3+4

Here are the range specs:

A 997-1 DME records the following rev ranges:
Range 1: 7300-7500 RPM
Range 2: 7500-7700 RPM
Range 3: 7700-7900 RPM
Range 4: 7900-8400 RPM
Range 5: 8400-9500 RPM
Range 6: 9500-11000 RPM

In your case this is how you should read it..

2005 911 Carrera S Cabriolet (Manual)
Current operating Hours: 2295.4 This is total hours your car has been operating. like an odometer, but based on time/hours of operation..

Number of ignitions in that range @ What Operating Hour it was recorded Last.
DME Range 1: 11325 @ 2292.9
DME Range 2: 301 @ 2289.0
DME Range 3: 29 @ 1337


As you can imagine a single ignition cycle can be milliseconds at high rpm. The fact that it has been almost 1000 hours since the car was in Range 3 and it only had 29 ignitions means that no damage was made whatsoever from that over rev. The biggest problem with extreme over revs is the stretching or weakening of engine parts due to extreme forces. Usually the damage from an over rev is seen within a few hours of the over rev. The longer the car drives after the last extreme over rev, then the possibility of any damage done by the over rev diminishes as time marches on.

Based on what I am seeing on your car DME report. There is nothing to worry about here. If anything, I would say this guy was just enjoying the car as it should be.. I would not blink twice at this DME report.

Heck... If you just are at a stop and in neutral gear and mash the throttle and bounce off the rev limiter you will not cause any damage to the engine, but you will record several Range 3 + 4 just by bouncing off the rev limiter. Our engines will bounce on the rev limiter close to 8000 rpm all day long! Range 4 + 5 may be a concern, but it all depends on how many ignition cycles and how many hours have passed since the engine was in those ranges. For example. A few ignitions in a range 5 may not be much of a concern if they happened over 1000 hours ago and the car is still running strong. It may have been a missed shift in to a wrong gear, but was caught just in time before any real damage. Any range 6s and I would be very concerned. Most likely something got stretched, but maybe not enough to damage the engine or throw it away. Still may have plenty of life left in it, but I would look for something else if I saw anything in Range 6 since there are a lot of cars out there with babied engines.

Skwerl

I agree with almost all of your post, but for accuracy's sake, range 4s are usually induced mechanically by a missed shift unless you have a really aggressive ECU tune that raised the rev limiter by a lot.

sbbarnett

Thank you for your detailed response.

qikqbn

I agree. Range 4 are most likely missed shifts. Range 5+6 definitely a missed shift, no question.

Although I may be a bit more forgiving of a range 4 for guys who admit they track their cars and race. I would probably expect to see several range 4s on a car that has been tracked a lot. It's not hard on the track to bounce off the rev limiter when the adrenaline is pumping. That's why it's good to talk to the previous owner and have them explain any dme report findings. The insight could be very helpful in making your decision.

As I said, in your specific case... I would not worry about that report. Yet , for peace of mind on a 2005. I would seriously consider an ims bearing upgrade at the next clutch replacement. I know it's a rare failure, but 2005's have very easy access to replacing those bearings so it would make sense to plan for that in the future. just my humble opinion

Meursault88

I am always amazed that these cars designed to go 180mph end up averaging 25mph over their lifetimes. What are we doing here?????? (grin)

LexVan

Or a high speed spin. Very rare. Can happen. But, since you like accuracy.

Buzzard95023

Thanks for the comprehensive information. I am considering purchasing an 08 Turbo with the following over rev information
Range 1- 27769 /1345.7 hours
Range 2- 8457 /1345.7 hours
Range 3- 2235 / 1345.7 hours
Range 4- 440 / 1345.6 hous
Range 5- 4 / 1342.4 hours
Range 6- 0
Total hours 1345.6
Seller has done some enhancements such as EVOMS evt-670 tune, so I assume the stock rev limiter is not in play. 47K miles
How risky is this purchase

saabin

Those numbers don't look horrible for a tuned turbo, but it seems like someone thrashed it into a range 5 ( >7900 RPM) just 3 short hours ago.. How does the rest of the car check out?

cwheeler

I'd be cautious. Driven hard in the last couple hours. Range 5... was it the owner? Test drive? Does the owner no longer care what happens cause they are selling?...

Fullyield

The car has been tracked extensively.

Bkrpdx

I also have a 2005 Carrera S Cabriolet 6-Speed, mine with 44391 miles on it (FWIW it is a late 2005 - April - and as validated by the engine number - M97/0168512474 - it has the later IMS bearing). It was in for a service so I asked them to run the DME / overrev report. Some of the data which it revealed are:

Range 1: 2873, operating hours: 989.800
Range 2: 126, operating hours: 916.500
Ranges 3, 4, 5, and 6: 0

Operating hours Counter: 1381.000.

I bought it at 35,xxx miles, which I calculate to mean I have done about 21% of the miles, which loosely equates to 290 hours, or it was at about 1090 hours when I bought it.

I read all of this as meaning: (1) I have never over-revved the car. (2) the prior owner (I am the second owner) did not spend a lot of time near redline.(3) It has averaged 31 mph in its life, which is relatively high, likely meaning a lot of freeway driving.

Is this an accurate understanding? Are there any other data on the report which I should be looking at for possible concerns?

Thanks!

B.

Elonash

I think you should read again at the counter and historical principles. This is not the logic conclusion to it indeed.