Vaporized a piston this weekend!

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.

Strewth.

Act of God ?

Never seen that b4.

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.

holy $hit.

Good old fashion metal fatigue.

Any clues in the head or was it shot blasted by the shrapnel?

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?

Looks like it spontaneously exploded/shattered and surely that can only be an unfortunate flaw built in from the factory?

-Ian

Agree with IanC, manufacturing defect in the piston, he says without any shred of evidence...

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?

Wow. Thats a mess.

Thats impressive!

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

probably the magnetic sump plug

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

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.

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

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?

Blown out the exhaust and then sucked back in via the long duration cams?

Looks like it's eaten something to me and it's a mechanical failure.

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

Was the engine running a filter? Missing any spanners?!

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

I'm feeling physically sick.

this is the stuff of nightmares...

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.

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)