Munched Piston (PICS) - What the hell caused this?

[MS112]

cast iron piston aye

Were they cast aluminium? I thought the head may have been aluminium with cast iron pistons (in reference to the molten aluminium balls). My mistake.

[IN 05 NT]

i have simillar marks on piston 3 and 6....both of those cylinders destroyed some spark plugs about 3 moths ago.....after a backfire

no ceramic left around the electrode.....

other than that mine lok fine..

[stradlater]

no ceramic around your electrode is bad news though mate.

Also, if you want a 1g running, Andrew Vibert has several. (CVAP)

Actually, better still, if you need std 1g bits, I have several...

[wiseco7mgt]

cmon guys the reason is really simple........a loose object(electrode tip,bits of metal,e.t.c)cause marks all over the piston as it gets bounced around ,consistant marks in and around a small area on a piston useally mean detonation,lean conditions.detonation can cause many different effects not just melted looking dents,how about showing some pics of the inside of the head and the effect it had on it.?next time check your compression ratio and tune ,tune,tune before boost.and yes i have made the same mistakes and found ways around them.if anyone wants to see whata bit of metal does to the inside of a combustion chamber just ask ill show you a head i took off a while ago that looks like someone took to it with a jackhammer.

[oldcorollas]

not metal.
ceramic from around the electrode. the insulator.
when these break, they form sharp edges.
look at the sharp edged indentations on the piston, and the metal that has been squashed past the edge of the piston..

perhaps detonation will occur at the squish area.... but a square edged piece of ceramic insulator will definitely make the marks here, and the corresponding marks in the combustion chamber... (where were those pics?)

the ceramic doesn't have enough inertia to make marks all over the piston, and is not big enough to be physically squashed elsewhere in the chamber (to make marks in piston)

i would love to see the pics of the other head you have.. do you know what the foreign object was? are there bits of it still stuck in the indents (like here) ?
not doubting your experience, but curious to see other examples (of detonation, where the spark plug has NOT broken)

anyone got pics of detonation damage that left square marks (of course, detonation could be the reason the spark plug died and fell to bits also )

[wiseco7mgt]

in my case the metal was a 12mm bolt the apprentice left sitting on one of the pistons and forgot about when he stuck the head back on.didnt hole the piston amazingly but chopped the head to bits,bent the valve guides ,valves and valve seats.turned the 12mm bolt into a flat bit of steel as thick as a 10cent piece.
when i looked at the 1gs piston top the marks look very consistent to a certain area on the piston.marks on both sides.and not anywhere else.was the plug checked before the head was removed?im very curious.

[stradlater]

OC: Will check the head. I'm pretty sure there's equal marks on the head.

[stradlater]

Ok, well guess what I found.

A) the marks in the piston match marks in the head

B) the piston that got marked is number 1

C) the insulator in number 1 was 'gone' off the spark plug

D) there is ceramic lodged in both the head and the piston

and

better still

E) ceramic has gone through the turbo and has bent the turbine wheel blades..

Also, the other engine I pulled apart, had a smashed ring and consequently a smashed ring land, but surprisingly not a marked bore in sight.

a few key pics.











A bunch more interesting and useful pics..

http://stradlater.com/celica_gallery/folder/2007-02-25

[wiseco7mgt]

old corrollas was spot on.......good call dude.

[jeffro ra28]

Those bearings are farked. Watever engine they came out of had a hard time on detonation!
The broken piston is typical of slotted oiling hole. Half descent pistons are drilled rather then slotted.
Its a shame about the turbine tho!

[stradlater]

Yeah, the bearings are from the 'old' engine, the one I first ran, and it doesn't surprise me that it's damaged, it coped a beating.

But the turbine is a rather big shame..

[IN 05 NT]

i'll try and get some pics up of what mine looks like,

2nite or tomoz.

[kickn5k]

The close up on the top ring land also shows signs of detonation. The piston runs hot and fatigues at the weekest point as jeffro ra23 said the slotted part.
As your in vic there are a heap of good turbo reco`ers about. We usally use Kyp at ATP.
They are in "Murrenbeena" gotta love tradesmen trying to spell. haha
on princess hwy. But if your on the north side of the city, then im not too sure.
Good luck with it all. Hoping to see her go Jarrad "the nobbler" Speaks highly of the old celica.

stu.