overbore?

[clark_486]

how far can you overbore an a20 block and what does that work out to as far as total displacement. [2.0 to a 2.x]

[ghettogeddy]

id say .50 is about as far as you want to go

http://www.csgnetwork.com/cubicinchcalc.html

that should help you calculate the displacement

[cygnus x-1]

Stock displacement is 1955cc or 1.955L. The largest oversize pistons I've ever seen off the shelf were 1.50mm over, which is 0.060". That would make for a displacement of 2027cc or 2.027L.

C|

[MessyHonda]

boring out doesn't always bring power...you have to add compression also

[ghettogeddy]

Stock displacement is 1955cc or 1.955L. The largest oversize pistons I've ever seen off the shelf were 1.50mm over, which is 0.060". That would make for a displacement of 2027cc or 2.027L.

C|

ive just read that for this block .50 mm is about as far as you want to go

[cygnus x-1]

ive just read that for this block .50 mm is about as far as you want to go

No argument there. If you look on ebay though you can find cheap ass replacement pistons that are 1.5mm over. Kinda scary if you ask me. That would be a blown head gasket waiting to happen. Interestingly Honda only has 0.3mm oversize pistons available. So that's as far as they think you should go.

C|

[ghettogeddy]

No argument there. If you look on ebay though you can find cheap ass replacement pistons that are 1.5mm over. Kinda scary if you ask me. That would be a blown head gasket waiting to happen. Interestingly Honda only has 0.3mm oversize pistons available. So that's as far as they think you should go.

C|

ya but some things can bend just a little

[clark_486]

cool. all good points. just checking different avenues if i ever have/want to rebuild.

[cygnus x-1]

ya but some things can bend just a little

Of course. After all, I had my A18 bored 2.7mm over, turning it into an A20. But then that's all the A20 really is; a bored out A18.

I did this because the A20 block I was going to use needed at least a .020" rebore and I wanted to use OEM Honda pistons. But they aren't available that large so I decided to punch out the A18 block.

But anyway, to the OP. Boring out an A20 for more displacement is not worth the effort.

C|

[gfrg88]

i believe bobbafet is the only one that has gone .50 or something like, i think... i think he has an a21a1 now lol.. and hes not sure how that's going to hold up...

[rjudgey]

If you are trying to fix up a badly damaged engine that is going to be stock it will be fine but if you are doing this for performance or to turn into performance engine than stick with stock or the next Honda piston size up .25mm from stock. As the others have said compression is more important and if you go bigger more problems with stress and gaskets become a factor. And don't use cheap pistons get honda or aftermarket forged ones if this is going to be a performance engine.