to end a arguement between this guy at a "shop"<<<Uncle Bens ricer town place. the guy said that you don't have to do anything to the head if you get oversized pistons, so what about that. Isn't it obvious that you have to match the bottom of the head to the Circumference of the bore on cylinders. Correct me if im wrong. Im talking about maybe 85mm sized pistons

 

Yes you should for optimal power but it isnt nessicary, B16 head (81mm) b20 bottom end (84mm) people do it all day long no probs if you want to go ahead if you don't nothing is going to hurt it

 

so it doesn't matter, i thought it would cause some major engine damage if you don't match up the bottom of the head w/ the Circumference of the block. So are there any noticeable gains if doing so or any problems that may arise

 

yeah, it'll definetly make a difference. The sharp edges on the head can be a possible source for hotspots that may cause detonation. If you dont do it then you can still use the head on a normal bore engine in the future. But if you do it the head will be limited to big bore engines only.

 

OK, for example; i get a b16a2 swap in there and i want oversized pistons and a bottom end done. I can just take off the head and don't worry about the valve area being to small and not matching up to the oversized pistons. im still confused about all this and im trying to learn this stuff.

 

like in this pic in the upper right corner doesn't the circumference of the bottom end of the head have to match up w/ bore on say an engine like this. Thats the problem im having because if the bore is bigger than the unmodified head i obviously think that it will break. Please clarify more thank you.

 

the pistons do not make contact with the head. the piston's edges do not go above the deck of the block, therefore that is why you can run a b20 block with a b16 head. It is not necessary to modify the head, which is why most guys do not do it.

 

thanks