997.2 3.8 Engine Failure
04-23-2019, 11:12 AM
#646
RL Community Team
Rennlist Member
Rennlist Member
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.
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.
The "press" is stating these cars are the best deal out there..... get one, address the issues... and you got a great deal. Truth? I dunno.
Peace
Bruce in Philly
04-23-2019, 12:29 PM
#647
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.))
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.))
However, I do believe there are a few things to note to give Jake et. al. the benefit of the doubt. At some point in this thread, one of the vendors from the Rennvision videos did note that they had put together an engine to conduct specific testing. I would image all of these theories are being tested to be either debunked or proven as fact. Nice to see a company putting their money where their mouths are. As we know, "testing" takes time.
Second, coming from the world of B7 RS4s (a bit cynical on this given the background) that saw failures due to leaking and/or failed injectors, these are parts that are largely overlooked. No manual has a recommended interval for fuel injectors. The reality is though, direct injection is particularly tough on wear items given the much higher pressures and a service interval for injectors should be determined and injectors considered a regular wear item for DFI owners. Atomizing fuel at 15,000 psi is a different league compared to port injection with what? 100 psi?
04-23-2019, 12:49 PM
#648
Rennlist Member
That and modern cars have lots of sound insulation, not to mention the injectors and high pressure fuel pump emit lots of noise themselves. These engines are noisy and it's the knock sensor's job to distinguish what is knock and what isn't, but most owners will not hear detonation or knock.
04-23-2019, 01:58 PM
#649
I agree.... but to our responsibility to inform ourselves... it is not just these forums that have strong opinions (or apparent opinions), it also comes from other sources. My indy, now retired, was a Porsche shop foreman for many years and then opened his own shop. He bluntly said really bad things about these M96/M97 engines.... really bad and told anyone who asked. Was he accurate? Did he have skewed data? Was he just a fear monger? I dunno.... a data point I guess.
The "press" is stating these cars are the best deal out there..... get one, address the issues... and you got a great deal. Truth? I dunno.
Peace
Bruce in Philly
The "press" is stating these cars are the best deal out there..... get one, address the issues... and you got a great deal. Truth? I dunno.
Peace
Bruce in Philly
That said, I agree with you 100% on having multiple sources, though it is important for those sources to be unbiased or minimally biased. I am a biased source of information if I am selling or contemplating selling a car. Someone in the process of buying a car and negotiating around that has a different set of biases. Someone selling related service that benefits from eyeballs in their market (for that exact service or not) all have different inherent biases.
04-23-2019, 02:15 PM
#650
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On the subject of LSPI and whether or not you can always hear when it occurs to any degree, I want to know the answer to that question. I know what I see in my data logs and that I never hear audible knocking/rattling/pinging/popping, nada. But the ECU is sensing something or otherwise it wouldn't be retarding timing on a per cylinder basis. And why is cylinder #1 the most affected? Is it LSPI?
04-23-2019, 02:18 PM
#651
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OEM mounts everywhere. Nothing is loose in the engine bay, on the engine, or in the suspension. I check regularly. I'm under the car after each track weekend.
04-23-2019, 03:23 PM
#652
Rennlist Member
I'll preface this with the statement that the 9A1 engine has shown itself to be very good. It does have a few known issues, but most will live a long life and actually wear out. In track duty they have been bulletproof with no wear other than timing chain stretch, but only after hundreds of hours of track only service. No one hear is saying the 9A1 engine is a bad engine.
The purpose of this thread is to try to understand the failure, however rare, and what steps can be taken to minimize these types of failures.
There is more beyond the pictures. Bronz's failure is more than just cold start scuffing. It's been glazed over, but the piston from the cylinder with scoring had a collapsed skirt. Secondly, the surface was getting smoother on cylinder #2, likely indicating it was next in line to score, which it did have some scuffing but the piston had no measurable wear, pointing to the loss of exposed silicon particles on the bore.
I don't have an answer as to why the piston skirt was collapsed other than perhaps it was just a bad piston, but I did state we had seen this bore in M96 and M97 engines without scored bores,which resulted in increased piston to cylinder clearance indicated by audible piston slap, but perhaps they were not driven long enough to end up with visible scoring on the pistons and bores, like in this instance with Bronz's engine.
I cannot say whether or not the piston and bore scored because it cold-seized first which then caused the piston skirt to collapse or because the alusil matrix could no longer support the loads and there was metal to metal contact, which I explained in a previous post, but I will summarize again.
The surface finish measurements on the bores best tell the tale of long term wear performance and match up the available research on the topic of hypereutectic blocks and how they wear. The pistons and rings ride on a triofilm made up of anti-wear additives deposited on a super-fine aluminum matrix that supports the raised silicon particles. Oil located around and between the silicon particles provides a hydrodynamic film that prevents metal to metal contact.
When the silicon is fractured and folded over, it gets ploughed into the aluminum matrix that supports it, mixed with the tribofilm. Eventually, you end up with an insufficient distribution of silicon particles to support this system and that's when metal to metal contact occurs (and scoring).
This is the same with any engine with Alusil or Lokasil and why we see other engines with Alusil bores also score, not just Porsche engines.
What is most important to me in all of this is the ZDDP plays a huge part in preventing wear, as does the film strength of the lubricant used.
My takeaway from this thread is that a full SAPS oil should be used, shorter drain intervals are recommended, and care to operate engines when cold at low loads and rpms until they are sufficiently warm is critical, and on the far extreme, added cooling and oil capacity is needed on vehicles that will see hotter climates or track use.
Remember, scoring is rarely seen in the transaxle cars or in a 3.0SC, all that used Alusil, so operating temperatures (all these engines ran much cooler than modern engines) and also used thicker oils with higher levels of ZDDP (and less detergents).
We need more R&D to find a tribological solution to slow the progression of normal alusil wear as there is strong evidence for the addition of moly to the oil on direct injected cars for its antioxidant properties and also its load carrying ability.
Lastly, determining a realistic service life or time in service for injectors is needed to prevent wash-down of bores which leads to rapid wear, which again, can occur with any type of engine or cylinder composition.
For those on the forum who are angry about how this thread has lowered the value of their car, is fueled by capitalist money hungry pigs, or believe that because I own a business that precludes me from being a reputable source on this topic, please take into consideration that I didn't have to measure anything nor take time to share those measurements. Likewise, I've spent thousands of dollars on SAE papers and to gain access to technical research documents on this topic, let alone hundreds of hours to read them all, so that I can with certainty make comments that are based in fact and backed by research, not because I stayed at Holiday Inn Express last night or because I read it on the internet.
The purpose of this thread is to try to understand the failure, however rare, and what steps can be taken to minimize these types of failures.
There is more beyond the pictures. Bronz's failure is more than just cold start scuffing. It's been glazed over, but the piston from the cylinder with scoring had a collapsed skirt. Secondly, the surface was getting smoother on cylinder #2, likely indicating it was next in line to score, which it did have some scuffing but the piston had no measurable wear, pointing to the loss of exposed silicon particles on the bore.
I don't have an answer as to why the piston skirt was collapsed other than perhaps it was just a bad piston, but I did state we had seen this bore in M96 and M97 engines without scored bores,which resulted in increased piston to cylinder clearance indicated by audible piston slap, but perhaps they were not driven long enough to end up with visible scoring on the pistons and bores, like in this instance with Bronz's engine.
I cannot say whether or not the piston and bore scored because it cold-seized first which then caused the piston skirt to collapse or because the alusil matrix could no longer support the loads and there was metal to metal contact, which I explained in a previous post, but I will summarize again.
The surface finish measurements on the bores best tell the tale of long term wear performance and match up the available research on the topic of hypereutectic blocks and how they wear. The pistons and rings ride on a triofilm made up of anti-wear additives deposited on a super-fine aluminum matrix that supports the raised silicon particles. Oil located around and between the silicon particles provides a hydrodynamic film that prevents metal to metal contact.
When the silicon is fractured and folded over, it gets ploughed into the aluminum matrix that supports it, mixed with the tribofilm. Eventually, you end up with an insufficient distribution of silicon particles to support this system and that's when metal to metal contact occurs (and scoring).
This is the same with any engine with Alusil or Lokasil and why we see other engines with Alusil bores also score, not just Porsche engines.
What is most important to me in all of this is the ZDDP plays a huge part in preventing wear, as does the film strength of the lubricant used.
My takeaway from this thread is that a full SAPS oil should be used, shorter drain intervals are recommended, and care to operate engines when cold at low loads and rpms until they are sufficiently warm is critical, and on the far extreme, added cooling and oil capacity is needed on vehicles that will see hotter climates or track use.
Remember, scoring is rarely seen in the transaxle cars or in a 3.0SC, all that used Alusil, so operating temperatures (all these engines ran much cooler than modern engines) and also used thicker oils with higher levels of ZDDP (and less detergents).
We need more R&D to find a tribological solution to slow the progression of normal alusil wear as there is strong evidence for the addition of moly to the oil on direct injected cars for its antioxidant properties and also its load carrying ability.
Lastly, determining a realistic service life or time in service for injectors is needed to prevent wash-down of bores which leads to rapid wear, which again, can occur with any type of engine or cylinder composition.
For those on the forum who are angry about how this thread has lowered the value of their car, is fueled by capitalist money hungry pigs, or believe that because I own a business that precludes me from being a reputable source on this topic, please take into consideration that I didn't have to measure anything nor take time to share those measurements. Likewise, I've spent thousands of dollars on SAE papers and to gain access to technical research documents on this topic, let alone hundreds of hours to read them all, so that I can with certainty make comments that are based in fact and backed by research, not because I stayed at Holiday Inn Express last night or because I read it on the internet.
Last edited by Charles Navarro; 04-23-2019 at 04:47 PM. Reason: Typo
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04-23-2019, 03:40 PM
#653
Three Wheelin'
Refer to the area right below the oil ring.
Let's take a step back and review all the pictures put forth on this thread.
What is intriguing to me is the scored piston skirt that shows scoring right beneath the oil ring. What I cannot understand is that the oil ring's task is to scrap residue oil from the cylinder walls and yet the area right beneath the oil ring on the piston skirt have scoring.
Commonsense tells me that the piston skirt is way smaller than the oil rings and yet scoring is evident on the skirt right below the rings. I'm not talking about the base of the skirt which shows scoring due to piston slapping and rocking on the up/down movement, but the area right under the rings which the piston shouldn't even have contacted the walls of the cylinder due to the rings there. Perhaps some knowledgeable folks here can explain why this is happening.
Last edited by HenryPcar; 04-23-2019 at 04:17 PM. Reason: Include a picture
04-23-2019, 04:38 PM
#654
Racer
For those on the forum who are angry about how this thread has lowered the value of their car, is fueled by capitalist money hungry pigs, or believe that because I own a business precludes me from being a reputable source on this topic, please take into consideration that I didn't have to measure anything nor take time to share those measurements. Likewise, I've spent thousands of dollars on SAE papers and to gain access to technical research documents on this topic, let alone hundreds of hours to read them all, so that I can with certainty make comments that are based in fact and backed by research, not because I stayed at Holiday Inn Express last night or because I read it on the internet.
04-23-2019, 04:44 PM
#655
Rennlist Member
Refer to the area right below the oil ring.
Let's take a step back and review all the pictures put forth on this thread.
What is intriguing to me is the scored piston skirt that shows scoring right beneath the oil ring. What I cannot understand is that the oil ring's task is to scrap residue oil from the cylinder walls and yet the area right beneath the oil ring on the piston skirt have scoring.
Commonsense tells me that the piston skirt is way smaller than the oil rings and yet scoring is evident on the skirt right below the rings. I'm not talking about the base of the skirt which shows scoring due to piston slapping and rocking on the up/down movement, but the area right under the rings which the piston shouldn't even have contacted the walls of the cylinder due to the rings there. Perhaps some knowledgeable folks here can explain why this is happening.
Once the piston skirt is collapsed, it's like throwing a hot dog down a hallway, especially with this much clearance, as the rings, piston, and bore are subjected to loads and wear that they aren't designed to handle.
Engine Labs has a good write up about this:
https://www.enginelabs.com/engine-te...s-arent-round/
04-23-2019, 09:15 PM
#657
HenryPcar, I think that you are assuming that the oil ring cannot be compressed all the way into the land. Apparently it can, therefore there is damage right up to the base of the oil ring land.
04-23-2019, 09:36 PM
#658
Three Wheelin'
04-23-2019, 09:43 PM
#659
Three Wheelin'
Thanks for taking the time to reply Charles.
04-23-2019, 10:54 PM
#660
