CroteTurbo

I just pull my engine apart cause I got low compression on one cylinder.
175,170,135,170

One the 135 cylinder, the piston look like that
there's a small dot on the ring land, you can feel it with your nails. It cause a scratch in the cylinder and on the piston. black **** and carbon was in this small hole. I like to know if there something i can do to reused those pistons.



There is also a small crack on the ring land, don't look to bad but it leave a small line in the cylinder also.


I'd like your opinion.
I want to put them in a new block, with new rings.

CroteTurbo

Oh and the engine has 65k km turbo ~10psi t3t4.
The pistons are SRP 9.1 81.25mm

92redhatch

change the pistons just in case. If its giving you lower conpression then buy new ones.

non-VTEC

we have all see pistons in MUCH worse shape. and for a boosted engine with 65K+ i would say they look pretty good.

take them to a machine shop and have them measured. if they seem to be re-usable just install a new set of rings......but in all honesty these days the price for new honda pistons is pretty cheap compared to many other makes/models.

i would buy new pistons if you plan start a new build....

CroteTurbo

In fact they are forged SRP pistons.
I'll try to show them to a machine shop, and maybe polish the ring land a bit to see if I can get rid of this small hole.

I don't want the sleeve of my next engine to be like that.



In fact I'm not 100% sure that the scratch on the sleeve is causing my low compression. I don't have time to chek the valve now, maybe the pistons/sleeve have nothing to do with the low comp.

Thanks

0morgan@synapse motorsport

if u clean that up wont u need an 81.5mm piston anyway?

JDMs1eeper

how deep is the mark? will it hone out? You may be able to get by with a rehone. (cant really tell in the pic how deep that mark is) Get a fresh set of rings and buff out that side of the piston. (is that some sort of blimish on the piston?) You would be surrprised but a boosted engine isnt that picky about being all that "tight". Your dealing with much more heat/power so it should seal up fine. (within reason) Try to run the hone on it, see if it clears up.

good luck, hope you have a good 07'.

snaileg

ya how deep is that cut? from what i can see it looks very deep so you would have to send it to the machine shop and bore it out to the size you want but if that cut is to deep you wont beable to run your stock 81mm if you just wanted to rehone it or something

CroteTurbo

No if I reuse that block, I will for sure bore it out to 81.5mm with new piston.
The mark in the sleeve is kind of deep, I don't think that it will go with a hone.
But I might use my piston in an other block, that was my main concern.