eddie7978

i talked to someone about rebuilding an engine
tbey said they have to hone it and put oversized pistons in
now my question to you is would that change to compression ?
would i need to get it tuned after? is there a way to use the same pistons?

pogeeboy27

iTrader: (3)

Yes it will increase compression slightly.

To maximize power potential you would want to get it tuned. But if you are running a stock tune, then you are probably ok.

If the shop recommends oversized pistons, that usually means the cylinder walls are damaged in a way that over-boring is required to fix it. So no you won't be able to use your old pistons or ones that are the same size.

eddie7978

well they told me that's what they do for a full stock oem spec rebuild

pogeeboy27

iTrader: (3)

Ask the shop if the cylinder walls were damaged in any way. If not then request to have them simply hone the walls so you can either reuse your stock pistons or purchase new ones.

jdblock

If that is what they do, then let them do it. Many reasons why over boring and installing larger pistons is needed. Taper, out of round, just to make the new build last a long time. The more you can control the better.

pogeeboy27

iTrader: (3)

OP, what's the condition of the motor and why do you need a rebuild?

TomCat39

It's not just damage that requires a rebore, wear will cause that requirement too. Over time the taper and the out of round will get beyond maximum specification in which case you have to rebore to over size. There is actually no damage to the walls, just the shape will not reseal properly as well as cause piston slap.

The engine in my car I highly suspect they only honed and threw the original pistons in with new rings. Not only does it sound like the engine is tearing itself apart but it sometimes msifires (doesn't fire) at times and sounds like a subaru. Car runs but I honestly do not know how long it will. Seller claimed it was "rebuilt" but obviously not to spec.

eddie7978

i saw they sell oversized pistons that are oem honda .. i never knew that i wonder why

TomCat39

So the engine can be rebuilt twice without going with third party pistons that usually require third party rods.

motoxxxman

oversize oem pistons will not increase compression enough to make any noticeable difference.
no you do not need to tune.
yes oversize pistons are required in ALL proper rebuilds in order to ensure the cylinder walls are in brand new condition, for the reasons tomcat gave above. wear.