motor is 14:1cr,85x89 Lsvtec tuned on e85, not sure what went wrong, ran good but started making a noise and decided to pull apart to see and just found all this mess. motor was still running very good, no smoke or nothing, just made the noise. I want to know if this head is still useable, the most detnation is on chamber 4, chamber 3,2,1 seems fine, but all the steel seats are still in great shape on all 4 chambers...

chamber #4


chamber #3


chamber #2


chamber #1


chamber #4


Piston #4


Piston # 4 Intake side skirt


Piston # 4 Exhaust side skirt

 

what went wrong is your motor was running very lean. Your tune wasn't giving it enough fuel and things got quite hot, expanded into the cylinder walls. May have had a little too much timing as well.

 

That sounds reasonable. Maybe not enough cam duration?

 

no, more like said above, too little fuel. did you check it on a wideband? also with compression that high the time HAS to be altered for the given fuel. on the pistons it's possible piston to wall was a little tight. everyone usually errs on the loose side for a performance build. that means for a cast piston .0015 to .0020. if you went under .0015 that could also have been an issue.

the head is an easy fix. standard abrasives porting kit, die grinder, smooth the chambers and you're good to go. probably could run it as is if you wanted to. still 1hr doing clean up would be worth it

man, you can see how hot it was just by the dome of the piston.

 

looks like a heat issue that lead to detonation. Detonation was not the initial cause.

 

this is the cam/spec that was used in the engine

Intake Primary: 11mm lift with 250deg duration
Intake Secondary: 11mm lift with 250deg duration
Intake High cam (VTEC): 12.9mm lift with 305deg duration.

Exhaust Primary: 11mm lift with 250deg duration.
Exhaust Secondary: 11mm lift with 250deg duration.
Exhaust High cam (VTEC): 11.9mm lift with 315deg duration.

 

none of which matters if the engine wasn't tuned properly or clearanced correctly. the heat actually appears to be tune related. look at the dome. the side of the pistons may or may not have been caused from heat expansion, still, i would guess the PWC was too tight and the engine was not tuned.

 

If the engine was clearanced the same on all cylinders then PWC is not the cause of the damage. 00_Red is right the motor ran lean, in one cylinder. The most likely cause is injector failure not the tune.

 

thanks guys, this motor was build by a very reputable engine builder, im thinking it ran lean and mess it up.

 

What changes(if any) did make to your fuel system to run e-85? Was it tuned on summer or winter blend?

 

actually that's a good point, if the other pistons don't have any wear and it's specific to #4 the failed injector or {failing i should say} theory makes a lot of sense.

 

only change was the walbro 255 fuel pump and rc750cc injectors, everything else was stock oem. tuned during fall.

 

wouldn't the #4 chamber run leaner than the rest because of its location closest to the TB?

 

No, the number 3 is the cylinder which typically runs hottest.

 

curious as to why it runs the hottest?

 

hell if i know, could be manifold design? it's the reason you run the #3 bearings the loosest as well

 

Firing order is the main reason. 1,3,4,2,1,3,4,2.

Cylinder 3 fires and then each cylinder as side of it fires 1 after the other. No other cylinder gets that treatment.

 

never heard that theory. but that is interesting.