mattie170

Got a golden eagle sleeved block and I'm wondering what the biggest diameter piston people would run. 700-800bhp is the most I'll run. It is already 88mm so thinking about going up to 89mm for more response but still able to rev it.

Cheers in advance

s2000Junky

Ive got one thats 89mm. But I think ive seen as high as 90mm max.

If your concerned with engine response, your better off with a smaller/lighter piston, not larger. If your boosted, you can overcome displacement with boost. A larger piston will generally deliver more trq and hp but at some cost of rotating mass, slowing down the response and eagerness of the engine to spin.

Steven622

The wider the piston the less sealing surface area you have with your head. Adding an extra mm or two barely adds a few grams and isn't something you'd notice, especially since the factory assembly is actually somewhat heavy.


So in summary, smaller is better because of the increased sealing surface area, especially at higher manifold pressures.

SlowTeg

I'm not familiar w/ the f20/f22, but have experience with other hondas. As the previous poster said, just be careful going with too large a bore because it could lead to trouble with the headgasket sealing. I'd probably err on the side of caution and go with the smaller bore.

Prokaw875

90mm is max bore, arguable that 90.5mm is being done now too in the all motor scene. As far as for a boosted application goes I would always stay as small as possible to keep the walls around the firing ring thick as you can to support more power. If you have to overbore I would try and go with 88.5mm before you go to 89mm. Keep a little meat on the bone. Plus if you blow it ever again you can hone it once more and not have to resleeve the block.

mattie170

Thanks for the replies. I want off the self pistons to get the engine back together ASAP so 88.5mm is more custom. The block is copper ringed also so the sealing should be fine. I have a spare block which I'm sleeving myself so it doesn't bother me about getting another use out of this block. Also means I can still keep my 9k rev limit but add more cc to spool the turbo faster whilst on track(circuit).