DME rev report

[flynavyj]

What would be your guys thought in this report?

Range 1: 959 at 692.1 hrs
Range 2: 60 at 692.1 hrs

Total time on engine: 708.8 hrs

[particlewave]

Range 1 = redline. The car hit redline for about 319 crankshaft revolutions (or about 3 seconds, depending on model).
Range 2 = over redline. The car was over redline for about 20 crank revolutions (or about 0.2 seconds)

Both occurred 16.7 operating hours ago.

[Anker]

Range 1 is not an issue, the car was built for that and the fuel cutoff prevents the revs from going higher.

Range 2 is bad. Usually happens when you downshift at high revs. When you release the clutch the transmission pulls the revs above the red line. Even 20 crank revolutions can fatally damage the engine. I was in a DE last year when a Cayman inadvertently downshifted to second instead of upshifting to fourth. Less than 20 crank revolutions, but the engine was toast!

[Dave80GTSi]

A year ago I had an LN Engineering dual row ceramic IMS bearing installed by the only LN-certified installer located in the State of Ohio.

Here was their initial review report, as noted on the repair order:

---------
Camshaft Deviation: #1=(-2.20), #2=(-0.89)
Over Revs "Range 2" = 1092/617.9h (>7800)
Total operating hours = 975.4h

NOTE: Vehicle did not meet minimum standards for
IMS Retrofit pre-qualification due to prior over revs
in ECU and does not qualify for warranty program.
Owner was informed prior to repairs and agreed to
proceed acknowledging that there is no warranty for
the following repair by LN Engineering.

----------

Since the over-rev time point was well before my ownership, there was obviously nothing that I could do about it, and so I went ahead with the repair as noted.

[The Radium King]

meh. i have some old overrevs on my car (and know the exact shift that caused them) and engine is fine. checked the filter for metal bits after and all good. porsche sets the rpm limit where it does because the hydraulic lifters can't respond fast enough at high rpms - the result in an interference engine is pistons meet valves and catastrophe ensues.

that's my car. if i were buying a car with this report i would at a minimum use it as a bargaining tool. again, typically if the engine running fine then all ok, however you can't really trust the oil filter check in this situation as the vendor might be cagey and changing the filter just prior to test drive (been known to happen).

[flynavyj]

Did some more online digging, that shows Range 1-3 as essentially normal on the Cayman. Above range 3 and you start running in the possibility of mechanical damage.

1-3 being into fuel cutoff, however above that is mechanical over-revving of the engine exceeding approximately 7900 rpm.

BTW - Do appreciate the replies, and am passing all info along to my friend. He's been searching for a bit, and has sent three cars for PPI's during the last six months. Two out of town, and now this one near home. Says car is very clean overall, one owner...obviously one of the biggest concerns on this rev report is that the over-rev was so recent in the car's history.

One he'd checked out before this, had considerably more overruns, but they were long in the vehicles past, and the PPI inspector stated that he had no concerns on the reliability of the engine moving forward considering the history of engine since the over rev, and the total time on the engine.

We shall see what he does.

[The Radium King]

ah, depends on the year of the car. early cars only had two ranges - at rev limiter and over rev limiter. later cars have i think 6 ranges.

[flynavyj]

Originally Posted by The Radium King

ah, depends on the year of the car. early cars only had two ranges - at rev limiter and over rev limiter. later cars have i think 6 ranges.

Yea, this is a later model car. There were no revs above stage 2, and only those sixth ignition cycles in stage two. I’m thinking this is a non event at this point.

[356Guy]

Well if you didn't bend valves then the risk is over stressed rod bolts is it not?

[The Radium King]

i'm sure there's all sorts of things that can break. my understanding is that the hydraulic lifters are the limiting factor and catastrophic failure point. and if it didn't fail at the time of the incident, then it most likely wont. remember also - 60 ignition cycles at what, 8000 rpm - is that .2 seconds?

[flynavyj]

Originally Posted by The Radium King

i'm sure there's all sorts of things that can break. my understanding is that the hydraulic lifters are the limiting factor and catastrophic failure point. and if it didn't fail at the time of the incident, then it most likely wont. remember also - 60 ignition cycles at what, 8000 rpm - is that .2 seconds?

Yea, about two tenths of a second...my friend is thinking this happened right about the time the guy decided it was time to sell it. LoL...It's always funny, as we tend to LOVE manual transmissions, but this obviously is the biggest concern of driving a manual transmission car hard. LoL...we'll see what he decides.

[thstone]

It wouldn't be any worry for me. These engines can take a lot more than that.