4g54 Pistons

[d3v147]

I recently cracked a ring land in my Sigma (4g54, Astron 2). I have cleaned up the crank and replaced all the bearings. I purchased replacement rings; but they were made of brittle black iron rather than the shiny steel like ones it came with. On installing one of the no.2 rings, it actually cracked. I am not sure whether I should just use and old ring there or attempt to find another single. I don't really want to but a whole set. My other concern is that if they are that brittle and the engine knocks a bit (due to boost) will they shatter? Also a bit concerned about the tiny lip at the top of the bore with new brittle rings.

If I could find some pistons with decent ring lands and compression ratio (8.5-9 ish) then I'd bother to get the engine rebored; otherwise this is just meant to get it going again until I can get a 4g63 working; as the parts are a lot cheaper and available for that platform.

I would greatly appreciate any advice that doesn't involve spending ludicrous amounts of money.

[Philby1973]

I have been told that Toyota 3F pistons fit. They are 94mm bore.

[Superscan811]

I am not sure whether I should just use and old ring there or attempt to find another single. I don't really want to but a whole set

NO.. don't use the old rings.

My other concern is that if they are that brittle and the engine knocks a bit (due to boost) will they shatter?

Not likely, It's the top of the piston that takes the brunt of the detonation.

Also a bit concerned about the tiny lip at the top of the bore with new brittle rings.

Definitely possible. It happens quite regularly when a young hoon purchases an old car that has been driven by granny for the last 25 years and never revved above 3000rpm....

If I could find some pistons with decent ring lands and compression ratio (8.5-9 ish) then I'd bother to get the engine rebored

VW pistons, do some research and you will find they are a good match, and cheap..



THE MOST IMPORTANT QUESTION

I would greatly appreciate any advice that doesn't involve spending ludicrous amounts of money.

How much are you wanting/prepared/capable of doing yourself, AND, how much are you wanting to spend?



Cheers.

[d3v147]

Fixed a while ago. Used original block, pistons out of an old motor, new rings, new bearings, honed bore and linished crank.

Had some problems with a blocked oil return (long story) and then a non sealing head gasket but it's going fine now at about 15 psi.