Gen 2 bore scoring feedback requested

[bazhart]

Just to make a plea for anyone with experience of a Gen 2 bore scoring failure to assist our research by contacting us.

We have now received a damaged car, engine parts and feed back from a few UK based specialists that has been extremely helpful (thank you guys!). We have measured all the parts and analysed the failure causes with 3.8 Gen 2 engines.

At this stage we don't know how many are likely to be affected - probably less numbers than Gen 1 and probably at higher mileages.

What makes it difficult to assess is the small numbers - yet we hear of a lot more engines being replaced (rather like the early stages of Gen 1 problems).

The Gen 1 was relatively easy to analyse - weaker thin cylinder material with larger forces on it leading to cracking, changes to piston coatings being less resistant to wear, a bearing system that was often inadequate.

The Gen 2 is far better made - should be almost bullet proof - yet there seems to be one technical area of concern.

Problems that relate in some way to the number of complete thermal cycles the engine goes through (probably regardless of mileage) and impossible for manufacturers to reproduce since it require a full heat to fully cold cycle to be reproduced "x" number of times with a lot of sample vehicles - so if and when it occurs - it is often too late to alter the production or find a sensible solution for from them.

It would help me enormously - not so much to find the cause (as I am certain I understand that) but work out the numbers and predict the ages and mileages if anyone who has had any experience of a failure World-Wide - would send me the following information.

(1) Where did the piston score (one side or both sides and in the centre of the piston thrust face or either side?).

(2) What age was the car?

(3) What mileage di it occur at?

(4) Which bank did it occur on?

(5) which cylinder failed?

(6) what capacity was the engine?

This request is absolutely not scare mongering nor seeking business - because we are going to provide a solution in any case as we believe there will be a small but steady stream of similar failures over time. We are also working at capacity anyway and numbers of M96/7 Gen 1 engines are not diminishing.

It would help if those who cannot wait to deflect my simple request and turn it into some other issue kindly leave this particular post for serious and reliable answers - they will not make any car score a bore - but they will help speed up the provision of a solution and minimise the cost for anyone who does experience it - however few that will turn out to be.

Thanks,

Baz

 

[Martian]

On a side note Baz, are Gen2 engines starting to show coking around the valves due to the architecture of the design?

 

[DynoMike]

Baz, are you aware that some BMW models such as the 320i Sport suffer with the same bore scoring? A friend of mine had to have his block changed by BMW as a result, from his description of the failure it would appear to be very similar to those experienced by Porsche.

My thinking is that due to sheer volume sales, looking into those failures may cross pollinate with the Porsche failures? i.e., more of them doing higher mileages and heat cycles which may help furnish you with more information.

It's just a thought that's all, but I realise that there is a huge difference between the engine styles so may be a non-starter for you. However if it turned out to be a metallurgy or piston skirt coating problem, this may help your knowledge base.

Mike

 

[Phil 997]

Good luck getting the data Baz , nice to see proactive solution seeking for the few cars that may suffer this issue. keep us posted on your findings and the solutions you come up with. presumably your recommending the same preventative measures as the Gen1 :thumb:

warm up fully before going over 3000 revs.
use millers nano.
fit LTT.
Change oil at more frequent intervals that just at service time.
Drive in the correct gear ,which is an interesting one for PDKs as they have more gears than the tip and because of the hippies saving the world rush up through the gears as quick as poss and this is going to add load to the engine demanding power when in high gears, so are there any PDK remaps that owners should be thinking about ,the car stays in more of a suitable gear for the speed ,given they are sports cars and not big old long distance cruisers so are more likely to be given hard spurts of power more frequently . :thumb: :thumb:

 

[Alex]

Following with interest.

It surprises me in this day any age Porsche (even back 10 years ago) didn't fit a data collection system in all their cars, collecting engine data:

RPM vs. Temp over time.

Not hard to do and would provide some amazing analysis for fault finding engine issues.

It would tell people a hell of a lot more than mileage does.

 

[Johnd52]

so are there any PDK remaps that owners should be thinking about ,the car stays in more of a suitable gear for the speed ,given they are sports cars and not big old long distance cruisers so are more likely to be given hard spurts of power more frequently . :thumb: :thumb:

I set the car to sport mode in the warm up phase and then drive gently below 3000 rpm. It hangs on to lower gears longer but does not stress the engine.