DreamCarrera

Wow, based on the information provided by the link either:

1.) There is a lot of misinformation being given on this thread/board

OR

2.) The 996 TT has a different system for counting type 1 and 2 over-revs.



P.S. The posters in the link, which is taken from a 996 TT board, claim that any over-rev which exceeds the 996 TTs redline, even by 1RPM, constitutes a type 2 over-rev. That is scary news for all of you 996 TT owners out there and possibly for us normally aspirated 996 owners as well.

wross996tt

Correct...that is why I posted the link.

redridge

what misinformation had been given? Am I missing something? An over rev is just that, 1 or thousands of RPM over the redline?

The point is in level 2, is that the dme sees an over rev and tries to stop it from happening but cannot because the user put it in the wrong gear and the momentum of the car is now driving the engine past the redline. That is not good and raises the flag on reliability of the engine.

Wether it is a TT or N/A an over-rev is just that.

DreamCarrera

What misinformation? You're kidding, right?

Not to single him out, but UCrazyKid's posts on this thread give a very different view of what constitutes a type 2 over-rev when compared to the explanation given in the link. Not to mention the fact that the numerous other similar threads on Rennlist contain differing info. This is not an issue where opinion is the deciding factor, there is a set numerical value where the cars computer registers a type 2 over-rev. If there is contradictory information being given, which there is, then some of it is invariably misinformation.

As far as I can remember, not one of the threads about over-revs on the 996 board mention that exceeding the redline, even by 1 RPM, constitutes a type 2 over-rev. If this is the case then those of use who drive our cars hard are most likely putting type 2s on the engine, which is a little scary. I always just assumed that type 2 over-revs were not registered until the engine exceeded about 7,500 - 7,700 RMP or so.


Of course, all of this assumes that the information contained within the linked thread is correct.

Palting

I'd have to agree that the link sounds and looks authoritative, but lacks a certain credibility. It's one guy, quoting interviews with unknown "experts", going against what is reasonable to reasonable people.

wross996tt

Actually your information is WRONG...or misinformation, sir. Read the link. A type II over rev. can occur without missing a shift (or putting it in the wrong gear). This will create a type II, but not the only way. The information in the link has been corroborated by tuners and there is actual data to back it up....so stop your conjecture.

Palting

I don't know, Statman. That claim by the link seems quite illogical. The logical thing is that type 1 means likely no engine damage. The engine was protected by the rev-limiter. Type 2 means there is likely engine damage. The rev-limiter was overwhelmed, which is what would happen if you mistakenly downshifted to 2nd when you meant to upshift to 4th after hitting red-line at 3rd. Or, it could also be because the rev-limiter was either disabled or the chip was messed with by, you know, tuners. Then it would also logically follow that these tuners will give propaganda to say that a level 2 over-rev can happen just by shifting normally and means nothing. Wait a minute, didn't you say the data was corroborated by, ah, tuners?

No. I stand by what has been said before, and what sounds logical. Type 1 means the engine is probably OK. Type 2 mans the engine went significantly beyond the safe rpm range and may have sustained damage. Otherwise it would not make sense to make a distinction between the 2. Anything else is misinformation.

BTW, red line for NA 996 is 7200 rpm. My tachometer says so, and my Porsche manual says so. Anyone want to argue with my 2 experts?

Miller_arch

I agree with Palting.

I know the 993 also has a rev limiter, I hit it a couple times by not shifting out of first gear in time. The gas is retarded to the engine and it looses RPM when you reach a certain point. I have not hit the rev limiter on my 996 yet but it seems the rev limiter on a 996 would work the same way as a 993; pretty basic computer technology now days.

I have read about blown engines because of a bad shift on the track, I would understand that to be a type 2 event for a 996. It seems easy to understand how not all type 2 events are severe enough to blow an engine. It’s very plausible to have many Type 2 events while driving aggressively at high RPM's…that’s is not allowing the computer management system to retard gas flow before a severe RPM event takes place.

The ECU on the 996 seems to record both events and is able to distinguish between the two. If the computer records a certain rpm without retarding gas flow...a type 2 event. But that's just a logical guess on my part how it works.

redridge

That link doesnt make sense whatsover...

"Type 1 = hitting the stock 6750rpm limiter.
Type 2 = ANYTHING over that 6750 rpm limit.
It's that simple."

I dont see any real data to back up that comment...

You can believe this if you want. But if your car rev limiter works, it is impossible to go way pass redline at extended period of time... that is what the cuttoff is for and is a failsafe method for your car. The only way to run past your limiter at extended periods if you are in the wrong gear. The DME can easily detect this over rev based on speed and rpm... then it is flagged by the dme.

Go ahead an try it, see if you can reach 7800-8000 rpm... not likely. I bet you can do it downshifting in the wrong gear though.
Believe what you want...

wross996tt

First, the argument is not about at what rev the over-revs occur...just about how a type II can occur. This is the misinformation. The data has been collected by several folks that have recorded Type II's when there was NO mis-shift.

We are not talking extended period of time...do you have any idea what the time is for 100 type II over revs to be recorded? Less than .1 second...

Actually I am going to believe Stephen at IA (and also the technical expert for turbos for Porsche's website and Panorama magazine) and Kevin at UMW who rebuilds turbos and engines way before I believe you who have no credentials whatsoever. That goes for you too mr. Palting.

wross996tt

BTW...for the record, I don't care what you believe...if you want to vote (or agree with someone else) on what is technically correct, that is your prerogative. I just think you should be clear when you are stating an OPINION vs. FACT.

Peace.

Palting

OK. I'll bite. Point me to the right website or scan and upload what Stephen (Stephen who?) and Kevin (Kevin who?) had to say about type 2 vs type 1 over-rev. Then, we can talk about it. None of this name dropping. I want to see or hear directly from an acknowledged expert. I'm serious. I really want to hear from true experts and truly learn the facts. Not alleged quotes and what someone heard from someone who know someone who is an expert.

Ray S

A very fair response...

wross996tt

RTF link...
I'll do better...call them. I am of course slanted by the turbo side of things and perhaps this is the difference.

IA, Stephen
alsosee Stephen PCA

UMW, Kevin
Stephen Kaspar & Kevin Matwichuk...perhaps you should read more instead of typing. Stephen was in the thread I posted (porschePHD).

Here is another link for you...notice I also challenged the original poster.....

Rennlist over revs.

Palting

Like I said, these guys are tuners, statman. They talk about raising the rev limiter, erasing recorded type 2 over-rev records. I am not as savvy as they are, but they are talking about cheating on the car designed parameters. That is what they do. They may even be good at it. They can raise the rev limiter to allow the car to run into a level 2 over-rev with little effort. They like to say no biggie, that it's normal. But the chances of engine damage increase when you start pushing the engine beyond what the original engineers intended.

I can definitely say this. I have inadvertently hit that rev limiter at full throttle in 1st and second gear in my car. I have recorded type 1 over-revs. I have never missed a shift. I have no recorded type 2 over-revs. Maybe I just don't hit the rev limiter often enough, or my car doesn't have enough power to generate momentum to reach a level 2 over-rev just by flooring it. Maybe I need to check more often, as this was 2 years ago and only 4 years on track. Maybe a turbo can hit level 2 just by flooring it because it has more power.

I also definitely have this to say. A PPI is soooo important when you buy a used Porsche.
Level 1 = no biggie. You can buy the car.
Level 2 = beware!! The engine may have gone 1 rpm or 5000 rpm beyond designed limits. Go look at another car.