I've got a b20 that's been bored over to 84.5, and i plan on putting in some high-comp. domed pistons. do i need to have the combustion chambers on the head enlarged to handle the pistons?

any info would help. and does anyone have an idea what your average machine shop would charge to have this service done? thanks.

 

Why would you enlarge the combustion chamber? That would pretty much negate the gains seen by adding high cr pistons, so my answer is no.

 

what i'm trying to say is that b18b's and b20's use the same heads. but b20's have a 84mm bore. that's 3mm bigger then everything else in the b-series family. so i'm assuming that the combustion chamber in every b-series is sized to handle 81mm pistons. b18a/b and b20's use flat topped pistons, so the size of the combustion chamber shouldn't matter. what if you put domed pistons into a b20?

i've heard of people having this done before, so that's why i asked.

 

you don't have to have the chambers opened up to accommodate the 84.5mm bore BUT it will help in combustion flow and efficiency along with a good head port job.

it all depends on how much power you want to make and how much money you are willing to spend..........

hope this helps.
good luck

 

thanks non-vtec. good stuff.

any idea how much this service would run?

 

any good machine shop with GOOD experience in honda heads should be able to do this no problem. there must be some around your area.......as for the price.........depends on the shop doing it........basic port job can range from 300-500 bucks and good extensive head work can run you over 1000 bucks......it all depends on shop and the quality of work.....

your other options are to send them to the experts at head porting/modification (portflow, endyn, import builders, etc.....) if you check out their websites they might have prices available for you........