Wayne Smith

Jake acknowledges that his photos (and analysis?) are nearly identical to Baz's.

Does this imply that scoring in the 997.2 9A1 motor has not been a problem?

So are we down to ...

1. Warm up is critical (try to get the cylinder walls heating as quickly as the pistons ... no low temp thermostat?).

And

2. Noiseless LSPI affecting the bearings?

Maybe toss in chain tensioners for good measure?

This sounds like cylinder wall damage due to faulty injectors is not such a concern.

Am I missing something?

Thanks again for everyone's input.

bazhart

Thank you. With 9 years of knowledge on this problem - can we then see a picture of both sides of the bore and piston and what was the result of your measuring them?

Baz

SpeedyD

Okay, so we have 4 cases of bore scoring documented in the rennlist poll.

9,000+ 997.2 cars produced

Disproportionate number of people would come to the forum to complain if something went wrong (this IS the internet) so let's just say we assume the sample size is 3,000 or a third of the cars out there (remember, the total owner universe is likely 3 or 4 times as large making this a relatively conservative figure).

So that would suggest a failure rate of 0.1%. Not 1% not 2% or 3% but 0.1%. Even if we get ultra conservative, including the selection bias inherent in posting on a topic like this (when financial impact is severe disproportionate number of people will vent online) we are still talking a fraction of 1%. That includes cars that were tracked, started in extreme cold, not following warmup procedures, etc.

How on earth does this thread continue to get traction? Preventative measures? Preemptive measures?

If anyone is diverting any mental energy to this exercise for a 997.2 they are massively irrational.

okie981

You answered your own question earlier in your own post, ...because this IS the internet. For me personally, it's curiosity, wanting to understand cause and effect, and wanting to learn. I find materials science fascinating, always have. I've seen your posts in other threads and understand your desire to minimize the thrashing of the 997.2 and other Porsche cars using the 9A1 engines. I believe posts I've seen that make claims about the "serious design problems" (or similar comments about the 9A1 engine ) are uncalled for and a disservice to the community, both current car owners and prospective future owners. I wish those types of comments could be suppressed, but I also believe in having an open forum within the rules of Rennlist posting.

Having said all that, I think the shock tower failures that have occurred on 981/991 GT cars is more of a concern to the ownership community than the 9A1 engines. Go to the GT4 forum, there is a sticky there now, and a thread titled "shock tower failure", IIRC. The typical cost to repair that cast aluminum part when it fails is around $30k, and so far people have relied on insurance unless it occurred on track with no track insurance. The same GT4 forum started a failure database about 3 years ago on the now recalled 3rd gear transmission failure. Affected production ranges of cars are having transmissions replaced under warranty. I doubt there were be a recall to reinforce the shock towers, but we shall see as the years pass by. You can see when that thread started, it was believed to be a freak occurrence. As more have occurred, maybe not so freak.

doclouie

It keeps getting traction because after reading all 43 pages from the beginning I want to know how it ends. It is like a good book. I am invested now so as far as this thread will go I will be there. LOL.

HenryPcar

With all the mind-f@@king going on, eventually brain-damage will inevitably develop.

SpeedyD

I am all for learning and there is no benefit of a head-in-sand approach to real issues. But, and this is a big juicy but, it really does a disservice to current and future owners to distort facts. The facts are that the failure rate in the real world is statistically insignificant. In fact, it is such a low failure rate that the only logical conclusion today with the existing facts, is that the engine design is extremely robust and reliable.

The way the facts get distorted (or more precisely, obscured) is when conversations go in circles over a couple of anomalies, as though this provides evidence of a systemic issue, and when there is fear mongering. There is certainly fear mongering going on (and I think you accurately described the sorts of comments I've seen). It is unfortunate that this is the case as it just leads to confusion for enthusiasts reading these posts who may not be aware of the facts due to the level of attention given to what is essentially a non-issue.

Of course the onus is on everyone to self-educate when forming an assessment of the facts and risks, but we know that in the real-world this can be difficult (many unfortunate examples in the spotlight today...) It is just unfortunate that this community is adding to that distortion.

Bruce In Philly

You got it... it is ours to self educate....

Hey, the internet is not new, forums are not new. Blaming threads like this for killing resale values are simply not accurate. There are many many sources of information when buying a car... and the market will know. It did before the 'net.
Anyone who reads forums and then panics is a moron. They would never buy anything.

Peace
Bruce in Philly

edomund

SpeedyD, I’m more in line with your thoughts. A big reason this thread has gone on for 43 pages is because of all the misinformation. If the builder came out and stated what he did today (basically he’s seeing similar things as Baz) we would have had a conclusion to the cause of failure a long time ago. Instead he offered possible theories with little to no data to support the claim and then was secretive about his conclusion on said theory. Every time this was done it created 10 pages of conversation about something that is not a significant factor (ie. LSPI, fuel injectors, liner material). This is a big disservice to the knowledge base this forum provides to us as owners as well as people google searching about a prospective purchase. This forum is one of the main sources of info about Porsches. Before I bought mine I read many threads on here. There’s really no other place to go on the net that has the wealth of knowledge this forum has. If the facts are not accurate here then it does have an effect on perception about the cars.

What I’d like to see going forward is an effort to stop misinformation from disseminating, then being repeated as fact, and then becoming internet fact. Also maybe we can consolidate the findings, so in the future this thread can have some value. People will likely not read all the pages as we have so it would be helpful to distill the info.

1. Failures of 9A1 engines are very rare statistically and hoards of failures are NOT imminent.
(It’s been 10 years since the first ones went into service and the weaknesses would have already shown themselves as the M97/M96 engines did in a shorter time frame. Jake confirmed this.)

2. Failures are typically seizures and or scoring from a combo of improper warmup, tight tolerances, and some block movement.

3. LSPI is not a significant factor. ((Until someone shows some evidence of a damaged engine part (not bearing wear) this should stop being considered an issue with these engines.) (Wayne Smith, as far as I know there is no inaudible detonation. It’s literally an explosion before the spark plug igintes the fuel mixture, the knock sensor picks it up and most of the time you can hear it with the naked ear if you are listening for it.))

Wayne Smith

Sorry. I was being tongue in cheek with my inaudible LSPI comment. I guess that may not have been obvious to everyone. Thank you for clarifying the apparent absence of LSPI in the 9A1 motors.

From what Baz said (all failures have been seizures) and with Jake agreeing (his photos were identical) it would appear that bore scoring is not a factor either. So I'd take that off your list.

So we're down to cold motor seizing and it would appear there is a way to minimize that risk.

It seems worn out chain guides may be our biggest real world issue which admittedly hasn't gotten much (if any) ink on this Forum.

That leaves a pretty clean record for the 9A1.

okie981

I log data on my engine during track sessions, and sometimes around town, using a Cobb AP. I see timing pulled at various times on various cylinders, sometimes for several seconds at a time. I see more timing pulled on cylinder #1 than on any other cylinder, and not just a little bit more. I never hear audible knocking or pinging or rattling. I think the only reason the ECU would pull timing is if a knock is sensed. I see timing pulled during around town driving when it would be very easy to hear anything resembling a knock or detonation. I'm puzzled about this. Can anyone explain why timing would be pulled but no pre-ignition sounds heard?

rtl5009

Because the knock sensors are calibrated to be very sensitive. They can detect knock that you cannot hear and retard the timing before it ever gets “bad”.

saabin

What octane fuel are you using? The knock sensors are pretty sensitive and I would assume any knock detected would be very high-frequency. I would imagine the ECU would work to prevent it from getting to the point where it could audibly be heard.

Petza914

What are you running for motor mounts and transmission mounts - OEM or stiffer aftermarket. Stiffer mounts can make the knock sensors pick up non-engine vibrations from the chassis like they're engine knocks and then pull timing.

SpeedyD

Bruce, note that I never commented once on resale values in my commentary on this topic. In fact, resale values have been increasing while this topic has blossomed on here. I agree with little or no correlation between the two.

But for those who do come onto a forum for self-education, it is difficult to separate fact from fiction (or legitimate posts from trolling). Many new potential owners need answers to much more basic questions and can get blindsided or overwhelmed by the significant participation in this non-issue topic. I say non-issue because I am governed not by irrational fear but by reality - and the reality is that a 0.1% or 1/1000 failure rate points to zero systemic issues with these engines, engines that are often driven to 50,60,100k+ miles. Ferraris often see less than 100 or 200 miles per year and the vast majority don't cross the 20k mileage mark in their first decade. Plenty of issues with bent rods, cracked manifolds, etc, for Ferraris that, for the same vintage, do not materially outperform these Porsches. And with service costs that add up to a replacement engine in the same period of time...

The behavior on this topic by many is akin to people buying lottery tickets each week and having an expectation of winning the jackpot, and making that their main retirement plan. Worrying about a 1/1,000 occurrence makes no sense except for those who have planned so irrationally in the first place that it would cause them financial ruin.