what could cause this?

[tydon]

had a mate buy a car with a stuffed motor and after ripping the heads off to look at pistons found this

[Kiwi_Fozze]

owch... that\'s nasty

[boon]

I\'m going with det, but that\'s just me.

[tydon]

 boon said:

I\'m going with det, but that\'s just me.

what is DET?

[lachlan]

detonation . not enough fuel / too much timing . melts the alloy

[Kiwi_Fozze]

detonation , or pre ignition

basically, petrol exploding on compression stroke, as opposed to after the spark plug has ignited it.

it\'s BAD.

[tydon]

ooooh not good this motor was supposedly doing late 10sec 1/4 Miles according to previous owner and major engine work..

and was apparently not long rebuilt before this happend lol..

[Guest]

Really lean isnt it? Like blowtorch style. Piston looks stock not major mega $ but I would have no idea tbh.

[tydon]

yeah a engine rebuilder had a look at these and said they were non sti pistons

[WRXONP]

Those are sti pistons

The spark always ignites on compression stroke wnce timing is measured btdc (before top dead centre)

But yea other statements are true - that\'s caused from det - det is like a hammer on the piston - igniting way to early and trying to push the piston down when it\'s forced upwards can cock the piston over - brakes ring lands - although that looks pretty melted also so running pretty lean

[Kiwi_Fozze]

wasn\'t running a FCD by any chance was it?

[boon]

 tydon said:

ooooh not good this motor was supposedly doing late 10sec 1/4 Miles according to previous owner and major engine work..

and was apparently not long rebuilt before this happend lol..

Sounds more like it was being flogged to death - probably with a chur boost tap to make it lean out like that

[funkytown]

 WRXONP said:

Those are sti pistons

could be aftermarket or factory pistons from that view anyway. there is no way to tell

[bc5rs]

i just ripped into mine and same thing my lift pump died so i had not much fuel and bang slowly ,

[loganrasti]

 bc5rs said:

i just ripped into mine and same thing my lift pump died so i had not much fuel and bang slowly ,

ripped into. Yeh probably a good description of what you would do david

[bc5rs]

 loganrasti']

[quote name='bc5rs said:

i just ripped into mine and same thing my lift pump died so i had not much fuel and bang slowly ,

/quote]ripped into. Yeh probably a good description of what you would do david

stay focused on the topic and less on being a twat logan