Swapping Forged Pistons same rings

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Aug 26, 2014 | 03:06 AM

#26

blackeg

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Joined: Feb 2003

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From: schooling kids in ny, usa

Re: Swapping Forged Pistons same rings

Quote:

Originally Posted by NotARacist

The second pic just looks like burn damage from a dead head gasket. The first pic straight up looks like a crack in the head.

yeah could we get a closer pic of that. i 3rd the leaking headgasket on the block

Sep 1, 2014 | 08:14 AM

#27

RevRipe

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Joined: Jul 2013

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Re: Swapping Forged Pistons same rings

Quote:

Originally Posted by wantboost

looks like the headgasket could have been on the way out... or previous marks from a gasket failure.

who knows lol

The black stuff was just head gasket flakes on the head and block. Head has already been resurfaced and pressure checked its good to go. GE is decking the block for me. The leak was so small I don't think I could the find it.

Sep 1, 2014 | 08:31 AM

#28

RevRipe

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Re: Swapping Forged Pistons same rings

Quote:

Originally Posted by wantboost

I can already tell from pics that your p2w is too tight. that much scuffing tells me your motor is around .003-.0035 which is too tight for a turbo motor, much less a high compression e85 turbo motor.

it needs to be around .004-.0045 at minimum to avoid scuffing like that... .0035 might be fine for an NA motor but FI puts wayyy more heat into the motor resulting in increased piston expansion and stress on the piston which gets transferred to the skirts.

any turbo motor with forged internals I've ever had setup at .0035 scuffed skirts and walls bad, regardless of motor brand/model.

my sr20det @ .0035 making 350 scuffed
my vg30dett @ .0035 making 680 scuffed
my last ls/vtec @ .0035 making around 500 scuffed.

a lot of the high compression turbo guys here started out at .0035 and had scuffing issues, they've since gone higher, most around .0045 with no issues. it might slap a little more on cold start but that's about it. higher power/compression generally dictates a looser motor

but that's my .02

So I came up with another theory about how I scuffed the walls so bad. I was running E85 all motor for awhile and at one point I had tuning issues due to an ecu problem and my afr's went very rich. I read that the ethanol in the fuel can break down the oil faster than gasoline and leave you with scuffed cylinder walls real fast. I also had excessive wear on several of my bearings which goes with this as I had some fuel in my oil from that incident. I recall smelling ethanol when I drained my oil. It wasn't for very long but I guess it doesn't take much. This one of those times this hobby is rough on my wallet

I just bought a set of 84.5mm wiseco pistons for the rebuild. I have been trying to figure out my ptw going forward so I don't scuff up my cylinder walls again. I was thinking 0.035 and will loosen to 0.040 when the coating wears off ?