Every day we hear members requesting interpretation of the DME (Over Rev's),what that means and how to interpret them.

This is an informative post and by no means an expert one. Please correct me if i am wrong.

The idea of this post is to relieve some of the unnecessary jitters and myths that are attached to these over revs. Yes i know there are many other clean cars to choose from but that's not the point. The point is to educate the people and make them under stand what it is and let them make the decision rather than saying : Any thing over range 3 " is a big no no "

Anyway, i am close to ending my search for a 997 TT and here's what i have learnt over the pass several weeks about the DME.

One thing for sure, it is indeed a very useful tool and is definitely helpful in evaluating how the car has been driven in the past.

This is a 2 part post: In first, i will try to explain different sections and the significance of running this DME report and in second we will discuss some of the points :

Part 1: Some of the information you can get from these report are as follows:

1)- Engine Red line


2)- Ignitions :

There are 3 ignitions in 1 revolution and there are 120 revolutions in a second. That means there are 360 ignitions per second.

Significance:

Say a car has 110 ignitions in range 3 so by doing the maths, it seems like the engine went pass the red line only for .3 of a second. So how significant would that be ?

Similarly, you can add all the ignitions in all the ranges and be able to get the time that the engine has spent pass the red line.

3)- Operating hours:

Operating hours can usually tell you how the car is driven and when in the engine life the damage was most likely done.

Significance:

You left the car with the dealership for some service work and you decide to run a DME report prior to picking up the car. The report can tell you that the total operating hours e,g are 250 and if there was an over rev that occurred say at 249 hour, was more then likely happened at the dealership.

On a side note, i recently went out looking for a TT and my local dealership handed me the keys to an '09 TT. I took the car out with out the sales guy so what if i had driven the car spiritedly and had a bad mis-shift 5-3 So got my point


4)- Ranges:

For future reference of rev ranges for 997.1 Turbo together with a classification of the expected engine damage.

Over rev events are documented as follows in the VAL (Vehicle Analysis Log):

Rev range 1: 6,740 -1 ... to 6,940 -1
⇒ Maximum permitted engine speed exceeded; engine damage possible.

Rev range 2: 6,940 -1 ... to 7,140 -1
⇒ Maximum permitted engine speed exceeded; engine damage possible.

Rev range 3: 7,140 -1 ... to 7,340 -1
⇒ Maximum permitted engine speed exceeded; engine damage probable.

Rev range 4: 7,340 -1 ... to 7,840 -1
⇒ Maximum permitted engine speed clearly exceeded; engine damage probable.

Rev range 5: 7,840 -1 ... to 8,940 -1
⇒ Maximum permitted engine speed very clearly exceeded; engine damage very probable.

Rev range 6: over 8,940 -1
⇒ Engine damage has generally occurred.


Significance:

Porsche usually uses this information to time the damage esp if there's claim on the warranty. Porsche can deny the warranty claim, if the engine damage was done with in the 70 hours of the Over revs. Most sources say it's the over revs in ranges 5-6 that counts but who knows what PCNA comes up with.

I have talked to quite a few guys in the tuning industry including but not limited to Porsche service advisers as well as the master techs and the general census is, if the car runs fine then it's fine

I have also seen it myself where Porsche has certified these cars with over revs even in range 5 so if those are so catastrophic, why would they even certify them ?

5)- How's car driven:

By dividing the actual mileage with the operating hours you can get an average speed of the car. For example the car has 25,000 and there are 1425 engine hours with the value coming out at 18.

Similarly if the car has 15,000 miles on the odo and the engine operating hours are say 100, it should raise some red flags as they should correspond to each other.

Once again the general census is:

< 30: garage queen, mostly short trips
30-50: Mostly highway driven
> 50: Could have been aggressively driven/tracked

Part 2: So bottom line is:

Would you pass on a car that is mint, nicely optioned, has 25,000 miles and passed the PPI with flying colors. However the DME, reads some thing like :
Range 3: 340 at 340 hours
Range 4: 140 ignitions at 175 hours
Range 5: 105 ignitions at 175 hours

Operating hours 975

Discussion:

I think there was just one incident where the guy probably had one mis-shift that was caught pretty quickly ( .68 th of a second) and since the car has covered 800 more engine hours since then with out any issues, runs flawlessly and passed the PPI so why ignore this car ?

a)- Considering how many of us buy manual cars ( M3's/M5's/EVO's/Ferraris etc but have we ever ran this sort of Over rev reports on those cars ?

b)- Has any one ever personally seen a damaged engine in a street driven car with these over revs ?

c)- Why would PCNA even both certifying cars with range 4-5 over revs ?

d)- How many people track their cars so you think they all have perfect DME's. You think they never hit the red line or had a mis shifts ? I have even talked to race shops and they all tell you the same, they see these over revs all day long but the cars are still running fine.

Come on guys, these are some of the strongest engines out there and are meant to be tracked and driven.

All i am saying is, these over revs should NOT be an automatic no no in an other wise beautiful car.

 

excellent post, well done Quick. This should be a sticky so that any further questions people have about over revs can just be directed to this post.

...and Rep pts for you!

 

Can Tiptronics have over-revs? I have heard yes and no.

 

1234

 

Over all very nice post. But missing, most important to me, is how are these over revs caused? Because I want to drive my "super car" to the limit of "super car" happysause fanfare, but not dmg it or cause other people think I did if I want to sell it later But I am pretty sure I will stick with my car for a long time ^_^b

 

What about on a car with PDK?

 

1234

 

How is this possible, my stock car shifted buy itself at rev limiter, and when the revs are too low, it downshifts. The tiptronic/pdk only shifts when it is possible, How can you overrev it? I think in this situation they cannot blame the driver, as the machine does the work.

Unless of course it is tuned...

 

Very good detail to present to us. Thanks.

 

Great post!

 

If you have the Tip set to manuel. You could be in 3rd and accelerate hard into 4th but screw up and down shift to 2nd instead. That might do it.

 

excellent post thanks for sharing !

 

1234

 

Also, keep in mind on a tuned car with the RL raised, the entire range is thrown off at all error levels.

 

Great post. I just got a DME report back this morning on a possible purchase and let me share some numbers with all of you.
#of ignitions range 1
62 64.6 hrs
# of ignitions range 2
10 30.3 h

range 3-6
0

Operating hrs 66.800
Miles on car 2,100
GT3 rs
what do you guys think? From the explanation on this post it looks good, right?