steepsnow

Hi All,

I recently had an engine die. Some of you may have commented on the related thread that is a general discussion about engine failure and my present options. However, the 16K RPM header may get a few people to chime in on this specific subject.

I was told by the first shop that the computer on the car said I hit 16,000rpm. ...thus the engine death was therefore the dreaded "money shift." (mis-shift)

Based on the situation, this implies that I was shifting from 2nd to 3rd - and mis-shifted into 1st at high RPM (6800). I do not think I made that shift - or any shift. I believe that I was in third gear before that track section.

Could such a mis-shift cause a 16,000RPM condition?
...even at red-line limiter engaged at about 7200 RPM


I'm sure there must be some money shift stories out there...
What gear were you in/planning to go to?
What happened to the car at that instant?
What damage was externally visible?
Did you get a report of how high the RPMs got?


...the rest of my story:

I am hearing a lot of conflicting information from shops regarding the potential cause of the blown engine. I called a couple other shops about a second/third opinions and they have told me that 16K RPM would not be possible and even if it "could happen," the heat would have caused molten metal, most likely a rod would have been thrown or other visible external damage and there should have been much more oil loss.

Note: when smoke came billowing out of the tailpipe, there was no "lurching" of the car, violent, loud noises, etc. There was also no oil dropped on the track - only out the tailpipe and minor seepage under the engine.

Have a great day!

htny

I'm not sure that 996 DMEs record anything more than Type1 and Type2 for overrev, followed by a number which, if I remember correctly, represents the number of overrevs (counted per stroke per cylinder I think?)

If I were a betting man I'd say it was counting it off the crank position sensor for the amount of time the tach registered over a pre-determined redline

I don't believe it has a time variable stored at all, so I don't know how they could say anything about rpm

ltc

The (type 1) rev limiter works by cutting ignition/fuel to limit revs, thus in a (type 2) mechanically driven over rev, it would be worthless, since the engine is being forced to rev mechanically (thru the wheels/transmission/gears).

Given the circumference of the tires, the speed and the gear ratio (owner's manual), it should be straightforward to calculate engine RPM under these conditions.
There are also online calculators that do this function as well.

porsche52

No way in Hell that engine hit 16,000 rpm!! The guys at the first shop are idiots! Colorado? What track? What dealer/shop did you call first? PM me with more info! I'm a Tech at the dealer in Littleton.

redridge

did the engine die at the track? or later on... money shifts are usually instantaneous.

steepsnow

Instant death! Smoke screen that could make James Bond proud. (more than I have ever seen from a car not on fire). Oil and coolant in tailpipe.

So, to confirm the actual RPM is NOT recorded in the DME?
...just the Type 1 or Type 2 condition?

BTW - High Plains Raceway
at the Prairie Corkscrew (Turns #13,14,15)

Meister Fahrer

Nobody else has commented, but there's no way that you jammed it into 1st gear at high rpms.....

ivangene

why does it really matter what the final rpm was (BTW 16k sounds awful rounded or guestimated) - it was maybe a miss quote from a tech who "remembered" a number wrong and blurted it out...for all you know he could have been watching some motorcycle show and a brain cell connected after that last toke and the 16k just came out of the mouth unobstructed by a counter point imput from someone who knows better but didnt want to make them all look stupid so he just kept his mouth shut....

OH

anyways, sorry about the engine, what are your plans... options...
GL

steepsnow

What do you mean?
Is there some type of lockout for shifting from 2nd to 1st at high RPM's?

Jake Raby

Sounds like the ECU had limited 16,000 sparks during it's life leading up to the big over rev.. This is very possible, I see cars all the time with 10-12K over revs in their counters.. My test car has 47,00 occurrences logged!

If the shop doesn't know how to read the DME correctly they damn sure don't need to be working on your car!

Ahmet

I think you could shift into 1st from a high rate of speed, but I don't see that as a likely mis-shift, finding 2nd instead of 4th is the common mis-shift, not 1st instead of 3rd...

Anyway, it's just about impossible that your engine actually saw 16000 rpm, but it may have seen say 10-12000rpm. I've seen and even rebuilt engines after an over rev of that nature. Some run OK for a time before showing symptoms, others don't, but I don't imagine your rods would've stayed intact at 16k rpm.

Tippy

Its basic math.

Take the % difference between 2nd and 1st (gear ratios) and then multiply that by redline.

That is your max RPM.

No way you hit 16,000RPM though.

steepsnow

The reason I am digging deeper here is that the shop is claiming that I blew the motor with a missed shift. I believe that I was in third the whole time - specifically not shifting through that track section to practice my braking point and car balance. ...in fact focusing on braking for the entire lap.

They had just done work on the car: 1) RMS replacement and 2) clutch replacement. This work was done within about one tank of gas of the engine smoking. Thus, the shop has $$$ motivation for putting the blame on me. From what I am reading here, the 16K is not possible, nor is it a "reading" that can be taken from the engine.

They said multiple times that they pulled the info from the DME and it read 16k RPM. This was not an offhand comment. I did not believe that I did the mis-shift, so I kept pressing him in our conversation, he kept saying the 16K RPM computer data proved I was at fault.

Since the shop has at the very least "exaggerated" the RPM data - or worse lied about it, the next question is whether they shop could have made a mistake with the RMS or clutch replacement that could have caused the engine to fail??? The second part of that question - is there some type of diagnosis that could prove I missed the shift or the shop made an error?

Obviously, I have read about random engines "grenades," however, the actual numbers are very low for the amount of cars produced (clearly a topic heavily discussed already...). So, there is a third option here, the coincidence that car just happened to die 10 days after work was performed and the shop is trying to protect itself.

Car condition prior to ending failure:
This car was in great shape, 80K miles, well maintained (recent 75K service + all records), I had it for the past 10K miles. It was strong and consistent as 1/2-time daily driver (in CO good to have an SUV as well), with frequent mountain trips and 6 track days this summer. The RMS leak was repaired within a couple weeks of noticing the problem. It always passed pre-tech for DE events without a hitch.

Thanks again for all of the input!

steepsnow

x= 1st gear = 3.82
y= 2nd gear = 2.20
r= Redline = 7200 RPM

(x/y) * r = 12,501 max possible rev for "redline" mis-shift from 2nd to 1st

That seems like enough to kill the motor, but certainly not 16K!

Torontoworker

If you downshifted from 3rd into 1st you would have been off track backwards with a lot of tire smoke added to the engine smoke! Sounds like you need an independent look see inside that engine (post-mortem!) as it *sounds* highly suspicious that the engine blew just after work major work being done. I'd have it towed to a dealer and have a full report in writing concerning what they have found. It might pay off if they find something *missing*, installed *wrong*, *wrong part* etc. You might have some leeway on cost recovery of the repairs (or reman unit) or they may find nothing and your only out an inspection fee.