Re: burnt pistons!
 

ran your a little wider

Re: burnt pistons!
 

After thinking about it for a minute, keep the ring gap the same, hone your cylinders out to around 0.005" or .127mm. Basically, you want to run at or a bit more than the factory wear as possible. Most factory toyota turbo cars run about that. Doesnt sound like alot, but it makes a difference.

Scorch, what did the cyl walls look like? Can you catch you fingernail on the marks? Basically, can you hone it out?

Re: burnt pistons!
 

i have new block now. not sleeved like the last time. just honed it. my old block didnt have any scratch on it. the resleeved block gave. dont know why. still dont know why my pistons are burnt on the intake side only.

Re: burnt pistons!
 

Pre-ignition/lean mixture started and heats up the piston beyond the knock threshold. First thing the air/fuel mixture hits when it enters the chamber is the intake side of the piston, from there its just a domino effect of the piston being kept hot, and burning itself from continuous pre-igniton of the mixture, until you lose compression in the chamber. By that time its too late.

I would also consider having your injectors cleaned. All it takes is one sticky injector to help it on its way out.

EDIT: BTW, Honda-tech doesnt have tech. They cant build hondas much less a 'yota. ;)

Re: burnt pistons!
 

hitchhikkr,

thanks man,
maybe the the old 450cc dsm is the culprit. i just changed my injector to 750cc. ill check the new 750cc for spray and flow pattern also.
but really i never had detonations before. 11afr at fullbost.

Re: burnt pistons!
 

Detonation and pre-ignition both have disasterous results, but you rarely get burnt pistions from detonation, usually it looks like it got beat with a hammer. The lack of pock-marks on the piston is a dead giveaway.

You can have a lean mixture and not detonate, pre-ignition leaves no fuel left for the detonation to occur after the plug fires.

Re: burnt pistons!
 

You suck dude, you didn't take pictures of the piston skirt, etc, so I can't be 100% sure.

Looks like there's pitting around the sides of the piston crown, right above the first ring. Might be some oil coming across causing pre-ignition, might be a bore that's too tight causing heat to linger in that area, bunch of stuff really.

Re: burnt pistons!
 

that was my first reaction. some oil going to the pistons. ill try to take a better picture. ill get som shots of the block also

Re: burnt pistons!
 

what do you guys think of bore fuel wash?

Re: burnt pistons!
 

I finally found the piston clearance spec. On a GZE it should be 0.0047" - 0.0055".