arnout Posted June 13, 2005 Share Posted June 13, 2005 This weekend we were tuning a car of a customer when we heard a big bang and the engine died. At the workshop I thought we broke a rod because of the hole in the oil pan: http://www.supras.nl/iB_html/uploads/post-3-59671-DSCF0015.JPG We started to dissassemble the engine and we found debris in the intake runners: http://www.supras.nl/iB_html/uploads/post-3-57465-DSCF0017.JPG The exhaust runners had way smaller debris; so the debris went from the intake to the exhaust http://www.supras.nl/iB_html/uploads/post-3-57498-DSCF0025.JPG Lifting the head we saw most of the stuff was on the 6th piston. See the pistons; very nice blackish so no signs of a lean burn http://www.supras.nl/iB_html/uploads/post-3-63385-DSCF0001.JPG and now what?!? The 1st piston is completely gone! So the rod didn't break http://www.supras.nl/iB_html/uploads/post-3-63425-DSCF0004.JPG ah.. found the piston: http://www.supras.nl/iB_html/uploads/post-3-80319-DSCF0001.JPG Even the oil pump was toast: http://www.supras.nl/iB_html/uploads/post-3-80420-DSCF0010.JPG Now the question: Anyone want to share his thoughts on what could have happened? The engine was in very good condition and it was tuned properly. We then installed an AEM peak and hold driver and retuned it. The piston went at around 1 bar of turbo pressure with A/F of 11.5 and EGTs no higher than 900 celcius. The car has all the stuff required for the AEM ECU, so HKS DLI, IK24, and the turbo is a PT67 GTQ. Injectors are the siemens 850cc on the PHR dual feed (2x walbro) rail. Link to comment Share on other sites More sharing options...
Whitelightning Posted June 13, 2005 Share Posted June 13, 2005 Strewth. Act of God ? Never seen that b4. Link to comment Share on other sites More sharing options...
b_have Posted June 13, 2005 Share Posted June 13, 2005 Scarey strange. Never seen a piston completely desintigrate like that. I would look for signs of a breakage on the induction side. maybe a pressure sensor icv? Don't think this is a heat/lean/det issue. Link to comment Share on other sites More sharing options...
adi2009 Posted June 14, 2005 Share Posted June 14, 2005 holy $hit. Link to comment Share on other sites More sharing options...
Terminator Posted June 14, 2005 Share Posted June 14, 2005 Good old fashion metal fatigue. Any clues in the head or was it shot blasted by the shrapnel? Link to comment Share on other sites More sharing options...
JohnA Posted June 14, 2005 Share Posted June 14, 2005 Metal fatigue leaves quite obvious signs behind. However, I don't see how these powder remains can help point in that direction --- you'd need to look at the surfaces where the breaking started. Feken ell, I've never seen a piston fail more catastrophically. Is there no larger chunk left? At 1 bar with that sort of fuelling (and decent intercooling I'd imagine) explosive detonation is not likely (but you never know) Were the pistons newly fitted after a fresh rebore or something? Link to comment Share on other sites More sharing options...
Ian C Posted June 14, 2005 Share Posted June 14, 2005 Looks like it spontaneously exploded/shattered and surely that can only be an unfortunate flaw built in from the factory? -Ian Link to comment Share on other sites More sharing options...
paulrenn Posted June 14, 2005 Share Posted June 14, 2005 Agree with IanC, manufacturing defect in the piston, he says without any shred of evidence... Link to comment Share on other sites More sharing options...
dandan Posted June 14, 2005 Share Posted June 14, 2005 What cams and headgasket were you running? Max rpm? Can we see some pictures of the head and what's left of the valves and combustion chamber? Link to comment Share on other sites More sharing options...
Gaz Walker Posted June 14, 2005 Share Posted June 14, 2005 Wow. Thats a mess. Link to comment Share on other sites More sharing options...
Bobbeh Posted June 14, 2005 Share Posted June 14, 2005 Thats impressive! Link to comment Share on other sites More sharing options...
Wez Posted June 14, 2005 Share Posted June 14, 2005 Wow, Whats an AEM peak and hold driver? Where was the EGT probe located to read approx 900deg? What ECU was this using? If its an AEM ECU did you have internal logging turned on, if so you could download to get a better idea of what happened? Wez Link to comment Share on other sites More sharing options...
eyefi Posted June 14, 2005 Share Posted June 14, 2005 probably the magnetic sump plug Link to comment Share on other sites More sharing options...
Ian C Posted June 14, 2005 Share Posted June 14, 2005 An FSE valve and an earthing kit should sort that out. And I'm disappointed no-one has volunteered T-Cut as a quick fix yet -Ian Link to comment Share on other sites More sharing options...
eyefi Posted June 14, 2005 Share Posted June 14, 2005 was it a big chunk of piston thet left through the oil pan? i'd reckon there is something wrong with that cylinders injector or aem's control of that injector. Link to comment Share on other sites More sharing options...
Ian C Posted June 14, 2005 Share Posted June 14, 2005 Hmmm, but even det can't do that to a piston without an inherent weakness in it surely? I mean there isn't a bit left bigger than a 10p piece (or whatever coinage they use over where Arnout is ) -Ian Link to comment Share on other sites More sharing options...
TLicense Posted June 14, 2005 Share Posted June 14, 2005 Debris in the intake runners and on no. 6 when it's no.1 one that's gone??? Is it possible that it's ingested something? What shape is the turbo in? Link to comment Share on other sites More sharing options...
Alex Posted June 14, 2005 Share Posted June 14, 2005 Blown out the exhaust and then sucked back in via the long duration cams? Link to comment Share on other sites More sharing options...
Chris Wilson Posted June 14, 2005 Share Posted June 14, 2005 Looks like it's eaten something to me and it's a mechanical failure. Link to comment Share on other sites More sharing options...
Ian C Posted June 14, 2005 Share Posted June 14, 2005 How about #1 shatters and a lot of chunks go back into the intake plenum simply by explosive force and the valves being open, and the airflow and possibly g-forces from being under acceleration pushes the chunks to the back of the plenum, to promptly be hoovered up by #6. Is there debris in the intake plenum at the back as well? I'd imagine the turbo isn't too happy, that's a lot of shrapnel. Any oil galleries may be contaminated too, although how much of the whole engine is recoverable may be debatable... -Ian Link to comment Share on other sites More sharing options...
Alex Posted June 14, 2005 Share Posted June 14, 2005 Was the engine running a filter? Missing any spanners?! Link to comment Share on other sites More sharing options...
paul mac Posted June 14, 2005 Share Posted June 14, 2005 Looks like it's eaten something to me and it's a mechanical failure. to fail that catastrophicly i'de be with Chris on this, if you look at the shape of the intake if something was ingested it would hit the back of the plenum and then drop down into number six at the back Link to comment Share on other sites More sharing options...
JohnA Posted June 14, 2005 Share Posted June 14, 2005 I'm feeling physically sick. this is the stuff of nightmares... Link to comment Share on other sites More sharing options...
TLicense Posted June 14, 2005 Share Posted June 14, 2005 Yeah but there's a hell of a lot of debris, all of which would need to get out past the inlet valve, plus I can't think of anything that would cause a piston to explode on the inlet stroke?? When I asked what state the turbo was in, I was thinking more as in was the compressor wheel in one piece? If it's not I would suggest either a failure there, which has been ingested and visited no.1, or something has been through it. If the compressor wheel is in good shape, and I can't imagine much of anything else being left in the inlet tract between the turbo and inlet plenum (??) I'd be really stuck for an answer. Link to comment Share on other sites More sharing options...
JohnA Posted June 14, 2005 Share Posted June 14, 2005 If no foreign object is found present, and nothing is missing from the inlet, then maybe it's worth investigating the ignition curve. If for some reason ignition was waaaay off nasty things could happen. Even if the map looks OK, how do you know that the rest of the ignition chain executed the map properly? (just a theory) Link to comment Share on other sites More sharing options...
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