[Bulti]

Maybe the oil in the inlet has something to do with it. I read that 'auto-ignition' of oil droplets could cause detonation.

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[Waylander]

Now that's a mess, melted piston,

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[MCL968]

That is an amazing amount of damage. I really can't reconcile that to a single cause. Number 4 piston looks like it's had a flame path working down the side for a while. I wonder of the injector was running lean and combustion temps increased due to that, or possibly a piston squirter clogged and the piston skirt overheated.

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[flash]

i'm inclined to think it's a combination of things, not the least of which could be an oiling issue.  dirty oil (read thin oil)  high rpms and boost can make for some heat.  that could have fragged a ring.  that's what the damage looks like it came from.

 

the injectors are new, and the mapping was overly rich.  i did that deliberately because i couldn't get it to redline to test it.  i played it safe by backing off a lot of timing up top, and making it really rich up top.  it should never have gone lean.  that being said, i don't know if the AFPR failed or the pump was weak, or any number of other possible fuel issues.

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[ds968]

Doubtful the oil was a key factor here, or perhaps a just a little - the car has always consumed so much oil, for the last year I was dumping a new quart in it every 300-400 miles, so the oil was constantly " recycled " with fresh oil . Yes maybe I did not change the filter in the past year, but in terms of the viscosity I'd guess at least 75 % of the oil in there had less than 3 k or 4 k of miles on it. However, I have been using 10-40 , and maybe that's not ideal ; am told 20-50 is best . And speaking of oil, given what has happened with piston / cylinder 4 ,mat least we now know what's all that oil in the intake suddenly came from ..

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[flash]

that's actually probably an incorrect assumption, though it "sounds" like it should be that way.  the problem is that the dirty part of the oil would stay in the sump, and while you added "clean" oil to it, thereby diluting it, there were dirty parts that stayed behind.  also, because i set that thing so rich, i would guess the oil needed to be changed every 5k.  if a ring was bad, even sooner.

 

it could have been consuming oil due to a worn part like a ring.  i don't see a lot of coking going on in there, but it is possible.

 

if there was a worn part that was generating friction, it is imperative that there be clean oil.

 

i'm not saying this was the cause, but it sure could have contributed.

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[Rap]

So when will your car be fixed and back on the road?

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[ds968]

Tough to say, the estimate was about 3 to 4 weeks from the day they start working on it , but with the replacement block variable in the mix and / or who knows what else might have to be sourced, it could last a bit longer . I'm not really in a rush, even though I'm generally an impatient person, with this issue I'd rather have them take all the time they need to check everything " while in there " and end up with as good of an engine as can be built.

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[Rap]

Sensible!

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[jfrahm]

My concern for the mixture (and timing) would not be the WOT map but rather the cruise and lighter throttle situation which should be closed loop.  That's a spot where you can detonate a boosted engine to death without hardly noticing.  The driver might be thinking they are taking it easy by staying out of WOT.  In traffic with a lot of throttle adjustment there can be some boost spikes and tip in and lift throttle detonation. 

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[flash]

doesn't happen - ever.  unlike every other kit out there, i fixed that with proprietary software.

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[94SilverCab]

It's Bush's/Obama's fault !!!

 

Jay

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[MCL968]

I am guessing that the flame path down the side of the piston put a ton of combustion residue into the crankcase, which packed up the filter, starved the bottom end, and culminated in the melted ring groove and piston ring in the crankcase. I don't think these motors are so fragile that a little detonation would create that level of mayhem in such a short period of time. There was a lot leading up to this level of failure. I would want to interrogate the oil pump too and see of something got in there and trashed the drive. I would also like to see the sump and the oil pickup screen. There might be some clues there as well.

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[flash]

we saw the filter which, unless it was installed incorrectly (pretty sure i installed it, so i don't think so) clearly showed that something had gotten in there.

 

i agree that detonation was not likely the issue.  i think it was a lubrication failure issue, which coupled with the high rpms and boost, resulted in things going awry.

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[ds968]

# 4 also gets hotter than the others , as it receives the least amount of coolant back there , right ?

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[MCL968]

You may be right about #4 running the hottest. I do recall that some 4 cyls have the hardest time cooling the center cylinders because of the coolant flow and the proximity of the cylinders to other heat sources. After looking at the pictures a number of times, I would almost be willing to posit the idea that the piston was flawed when it was cast. It looks like the head was collecting oil carbon for a long time, which could have resulted from a damaged piston and poor ring fit in the ring lands.

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[ds968]

What the heck is all that brown stuff - residue / rust left under the head gasket ? Some areas are far more concentrated than others, I wonder if that's an indication of the gasket's condition in certain spots ( it was fairly new, less than 2 years and not even 25 k mi on it ) or after what happened and all hell broke loose , those spots could be from what knows what other things ..?

We know the PO had the head machined / shaved but no record of just how much, and what gasket the shop put in there ; a regular gasket would have bumped up the compression, and IF that was the case, it would have been yet one more factor pounding on the final coffin nail ...

I showed the photos to my mechanic, he said in all his years he's never seen a piston that mangled in any Porsche , BMW, or MBZ ..

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[jfrahm]

It does not look all that unusual to me but I have seen broken ring lands due to detonation, melted pistons from N2O misadventure, tossed rods, etc.  You can overlook the stamping damage from the chunks of ring and ring land in the bore.

 

https://www.google.com/search?q=detonati...s&tbm=isch

 

Shop your pics around on some Turbo boards and get some opinions.

 

Lubrication failure usually seizes the cams first as they run with no proper bearings and gall up.  I'd also expect to see more scuffing in the bores.  At any rate I'd shop the pics around or get someone who drag races turbos to look at it in person.  Send pics to Sid if you have no other ideas.

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[ds968]

Holy crap !! And I thought my piston and cylinder looked like someone threw a grenade in there, those photos are downright frightening . I'll run the photos by my buddy who races a serious ( LMP-style ) 911 Porsche and manages to blow up his engine just about every other race - he rebuilds everything himself so while that would suggest ( to me ) that he's not that great of an engine rebuilder, lol, he's probably seen every variation of destruction, cause and effect , so we'll see what he has to say. Although, he's running a 30 boost engine ( IIRC ) so " just slightly " over a D1R SC , lmao , this not sure a proper comparison or conclusion can be drawn as to what was the most probable leading culprit leading to my engine's damage . But does not hurt to get more opinions and probabilities just so we know what the shop working on my car can check and test before everything gets buttoned up.

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[flash]

i have never seen cams seize up on any engine.  i've seen plenty of lubrication failures on other engines though.  when i've seen them, it has been cylinder lubrication failure about 20% of the time, rod bearing failure about 30% of the time, and main bearings 40% of the time.

 

i really do not think this had anything to do with detonation.  there were so many safeguards built in that it would be hard to imagine them all failing.  between the timing i pulled out, the fuel i added, the lower redline (all more than with the highly successful 6 speed setup) and then adding in the OEM knock sensors and timing retardation there, it is all but impossible for detonation to be at play here, unless something failed (injector, pump, etc)

 

if there was detonation, it was caused by something else going wrong.  it's just impossible if everything was working.  that's what i would be looking for.  i would not be looking at what led to this situation, not what caused the specific damage.  it doesn't matter what damage the bomb did.  it matters what lit the fuse.

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