Another effort at deshrouding the mystery of the F20B. Mine is in my DD right now, so I can't take it out and play with it like I want to...

Anyhow - does anyone know the bore limits on the F20B? People say it is the same as a H22/H22A block... but how much the same? Stock bore is 85mm... any way I could bore it out to 89? Even with some fancy ductile iron sleeves? Just thinking it would be a cool way to bump up to 2.2 liters displacement while maintaining killer rod/stroke ratio for high revving.

Just looking for some more low-end torque in my NA build...

 

I believe that it is possible because all h and f engines should have the same distance between the bore centerlines of each piston. However as a rule of thumb boring and engine will increase top end hp while stroking it will increase bottom end torque.

 

I'm running 87mm pistons in my f20b block...but that is Benson Sleeved. With sleeves you can go as big as you want...without sleeves i'm not exactly sure...
It is essentially a destroked obd2 h22a block (not obd1 which had smaller mains, etc).

 

well sleveeing it is the right way to bore them out .,

the only reason the h22 is 87mm is becuase of the FRM coating to help with the thin cylinderwalls.

i too cant wait to slevve and bore out to 90mm , but that so far away from now lol

 

thanks guys.

I am pretty sure most of the pro shops doing sleeves, including golden eagle, benson, etc. recommend max 87mm for boost and max 89mm for NA on H blocks. guess I gotta be pretty sure of my decision first on NA vs boost, given the investment.