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Manley's took a beating... Piston Damage.

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5150DSM

Supporting VIP
856
3
Jan 5, 2004
Sacramento, California
Well, my pistons are done... again. I'm not entirely sure what happened but the tops of 1-2-3 show some serious heat. I was doing a quick teardown to refresh the bottom end before I strapped on all the parts I've been buying for my build. http://www.dsmtuners.com/forums/dsm-build-journals/450595-high-hp-street-strip-91-eclipse-gsx.html

When I cracked the oil pan, I found RTV squeezed out into the pan; there were bits of it floating in the oil and my pick-up screen was covered with debris. (I had another shop reseal my pan last year when I was on vacation. :ohdamn:) There was a little bit of metal on the oil surface and a chunk of aluminum laying in the bottom of the pan. The chunk ended up being the rear main housing, apparently a pan bolt was overtightened which broke off a piece of the housing. I cracked the caps fearing the worst... and found the the bearings were fine, normal wear, no signs of damage. :confused: So, I proceeded the knock the slugs out of the bores and saw this:

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Now I need rod and main bearings, rear main seal and housing, all new bottom gaskets and a new set of forged pistons. Focking fun. Well, I aint broke yet, pockets or spirit. I got on the phone with Paul at JNZTuning and described my needs, he promptly told me what he could do for me and within an hour and 3 calls (me buying more shit) we got it worked out. Picked up all the little shit, bearings, gaskets and such and grabbed me a set of Wiseco's in 9:1. Also grabbed a Magnus heat barrier gasket and that stupid little BSPT fitting for the FFOFH -4 feed. I got a smokin deal and JNZ was super easy to work with (as always) these guys have always taken care of me and I just want to say thank you. On a side note, the other shop didn't give me any grief and covered te majority of the parts; I ponied up for the pistons because I felt like my tune probably had more to do with the damage than the RTV.
 
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Is this what a 14:1 AFR at 25psi looks like?? LOL
 
According to my wideband, I was always in the 10-10.5:1 range, too rich but I was fighting the factory ECU and never got quite where I wanted. PTW was .0035, ring gap was .019 top and .022 second ring.
 
There was definitely a ton of heat in your combustion chambers for the piston tops to be white.

Oh yeah, I don't doubt it but funny enough the valves andthe plugs look absolutely fine. I need to get my wideband calibrated to make sure my reading are accurate. Also, it's only the upper edges on the intake side of 3 pistons that got smoked, number 4 looked fine.
 
I wonder if the turbulance associated with using a 1G intake manifold on a 2G style head created an erratic burn pattern causing the above ugliness?
 
That s a theory... Sounds a bit far fetched but im stumped too. They look like the were colliding with something its so bad. Low octane gas on accident? your knock cel would have been lit up though.

nvm you are running eth. Which at 10:1 would be ridiculously rich.
 
That s a theory... Sounds a bit far fetched but im stumped too. They look like the were colliding with something its so bad. Low octane gas on accident? your knock cel would have been lit up though.

nvm you are running eth. Which at 10:1 would be ridiculously rich.

The mods in my profile are for the current build. I was running a MAFT, pocketlogger and a wideband on a E3 at the time. AFR's were stupid rich but I was only running pump (91) for the last 300 miles of life. (last time I had the head off) At that point there was no damage on top and compression was good, 180 across, no signs of anything abnormal. Whatever happened, happened in the last 300 miles, which was when I switched over to the Hyundai (2G) head. The head and a composite gasket were the only things different during the time the damage occurred. As far as the damage to the sides and ring lands, it looks like someone beat on them with a hammer but the bores don't look beat up at all, there's only minor scuffing.
 
Wow those pistons got f'ed up. Do I dare ask how the cylinder walls look?!

The cylinder walls are fine, just some minor scuffing, nothing that won't hone right out. I'm going .020 over with the new pistons as well so a bore job is in order.
 
I wonder if the turbulance associated with using a 1G intake manifold on a 2G style head created an erratic burn pattern causing the above ugliness?

Lots of people have done that before though. I think I'd be looking more at the fuel system than anything else. It's just weird that #4 was fine when the other three got that hot. btw been following your build thread keep it up!
 
Lots of people have done that before though. I think I'd be looking more at the fuel system than anything else. It's just weird that #4 was fine when the other three got that hot. btw been following your build thread keep it up!

Yeah, I'm reaching on the manifold theory. Fuel system consisted of an EVO IX pump and EVO VIII injectors on a stock auto FPR. IJDC's were in the 89-92% range at WOT and AFR's were silly rich. (According to the suspect wideband) I just can't figure out what the hell beat my pistons to shit without damaging anything else in the motor. I've never seen pistons bashed like that without accompanying damage. Maybe I dropped a hammer in the block last time I had it open... who knows? I plan to contact Manley and see if they want the pistons for analysis; I'm not pursuing any kind of warranty or material failure claim. I just want to know what the fock happened to my motor. Maybe they will figure it out and let me know what not to do in the future.
 
If you stuck stock bore pistons in a stock bore motor without getting your piston to wall clearence correctly(I am 100% postive your Manley's require more the the .002" that a stock piston requires), you likely swelled those pistons right into the cylinder walls. It sure looks like they were scuffing horribly whether is be from being over sized(likely) or not enough lubrication.

The crowns of the pistons do not lie. The motor went lean. It is possible it was lean for quite some time and it over heated the whole pistons and made it swell that way. That is a possibility. But, I suspect you would have melted a hole in the piston before things got that bad.

The rings broke from so much friction against the cylinder walls from when that piston swelled. I have seen them break from major detonation and a really poor tune as well.
 
If you stuck stock bore pistons in a stock bore motor without getting your piston to wall clearence correctly(I am 100% postive your Manley's require more the the .002" that a stock piston requires), you likely swelled those pistons right into the cylinder walls. It sure looks like they were scuffing horribly whether is be from being over sized(likely) or not enough lubrication.

The crowns of the pistons do not lie. The motor went lean. It is possible it was lean for quite some time and it over heated the whole pistons and made it swell that way. That is a possibility. But, I suspect you would have melted a hole in the piston before things got that bad.

The rings broke from so much friction against the cylinder walls from when that piston swelled. I have seen them break from major detonation and a really poor tune as well.

Thanks for the input, it's appreciated.
PTW was .0035". I know the motor got lean, I know it got hot. The things that have me stumped are:
Why did 1-2-3 get smoked and 4 was ok? (scuffed but not destroyed) Why did my wideband not pick up the obviously lean condition? If lubrication was an issue, why are the cylinder walls barely touched; additionally, why do the bearings show only normal wear. Why, if I went so lean, are my valves not burnt and why do my plugs show an even light tan color? How did the sides and skirts get so beat without damaging anything else in the motor?
 
If you stuck stock bore pistons in a stock bore motor without getting your piston to wall clearence correctly(I am 100% postive your Manley's require more the the .002" that a stock piston requires), you likely swelled those pistons right into the cylinder walls. It sure looks like they were scuffing horribly whether is be from being over sized(likely) or not enough lubrication.

The crowns of the pistons do not lie. The motor went lean. It is possible it was lean for quite some time and it over heated the whole pistons and made it swell that way. That is a possibility. But, I suspect you would have melted a hole in the piston before things got that bad.

The rings broke from so much friction against the cylinder walls from when that piston swelled. I have seen them break from major detonation and a really poor tune as well.

Stock bore drop in pistons are smaller than oem, to bring the ptw clearance into their spec range.
 
The pistons are aluminum and the cylinder walls are iron. Not too hard to figure out why the pistons took more damage than the walls. When we have melted motors in the past, the pistons always look horrible and leave aluminum behind on the cylinder walls. I could have been a single timing event that caused the damage to the piston crowns. That could explain why not all pistons look like that. I don't know about you, but I don't watch my wideband. It could have happened in the blink of an eye and you would never have seen it, even if it registered on your wideband display. Remember, they read unburnt fuel, not fuel mixture.

Bearings usually take a beating with severe detonation or pre-ignition as they are hammering down on the rotating assembly. A lean condition does not have the force detonation does. If you have stainless steel valves, that could explain why they do not have damage as that is a pretty tough metal. Again, a lean condition will be confined to the pistons and combustion side of the cylinder head.
 
I wouldn't be surprised if my timing got seriously advanced. Fighting the factory fuel curves with a MAFT I was always leaning out the settings to try and get out of the 10:1 range. I imagine the signal reduction got my timing up there and like biglady said, it happened too fast for me to catch it on the wideband. Unfortunately I don't have any logger data because as soon as I picked up Link, I shot my Palm with a .45. I didn't know at the time that I might need to review the logs, car was running great when I took it down to go bigger. Oh well, it's always fastest right before it blows up. At least I got everything to fix this on the way, my project isn't going to die because of it... Just my bank account.
 
Did you use the same PTW clearance on your rebuild? and do you think that it played a factor in the damage? would you go with a wider ptw clearance and higher Ring gap in the future? I have a similar build in reference to ptw clearance and was considering taking it back to the machinist to go .0045 or even .0055 PTW
 
How lean were you running this thing? Also, whats your piston to wall and piston ring gap clearance?
Piston to wall doesn't matter, Look at the top of the piston it was seriously lean! A lean condition will destroy any piston,, I do take my hat off to the manley for withstanding this abusive lean condition with total destruction. I hope you get her up an running soon and look into what's causing that lean condition.
 
Did you use the same PTW clearance on your rebuild? and do you think that it played a factor in the damage? would you go with a wider ptw clearance and higher Ring gap in the future? I have a similar build in reference to ptw clearance and was considering taking it back to the machinist to go .0045 or even .0055 PTW
FYI I run a piston to wall clearance of .0047 engine been taking a beating for almost a year.
 
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