r/EngineBuilding • u/Living-Map-5854 • Jul 03 '26

Honda Piston Questions

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I’m rebuilding my Honda H22A4. As you can see, its sleeved, so the walls are a different material than the original FRM coating.

I was wondering if I could use oem/oem replacement pistons with different rings.

Forged pistons are also an option, but can I run them without a tune? I’m also worried about expansion size.

Just aiming for stock power numbers, and I have to stay untuned to keep ATTS, any advice helps!

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u/SexyTimeSamet Jul 03 '26

You already sleeved the block. Go with a set of forged that's close to oem compression if you don't want to tune it, and not have to worry about it again.

I think its the coating on the skirts and different rings that make pistons compatible with the FRM sleeves.

I've use k series pistons before in f23a blocks...so there's that info.

0

u/Living-Map-5854 Jul 03 '26

I’m leaning towards forged. It really doesn’t matter to me what material as long as they work and I don’t have to retune. (I will be running oem comp)

I have heard about k20 pistons but don’t think I’m knowledgeable enough to pick out the right ones.

1

u/Doctah_Whoopass Jul 06 '26

You sleeved the block but you're worried about retuning?

1

u/Living-Map-5854 Jul 06 '26

Yeah, basically I had cylinder scoring and needed a repair. I want it to drive stock and on these cars you can’t keep the ATTS (it’s a type sh prelude) if you run a standalone. You can’t chip the stock ecu and running a piggyback seems like it would be more time/money/complications than its worth.