So I keep reading about sleeved B series blocks bored to 85mm when you guys run them do you do it on a stock combustion chamber (81mm or whatever it is) or you do you guys get the head machined to accommodate the extra 4mm?

 

I believe stock sleeves are good up to 500hp and they can be honed to fit

 

That's not at all what he asked, Forrest.

This question would be better suited in the FI section, but I believe most people go with the stock combustion chamber.

 

I would imagine with stock combustion chambers and 85mm bores, you'd want to calculate your piston-to-deck height very carefully lol.

 

Wouldn't that cause like detonation gaps tho? Since both diameters do not correspond.

 

After 82mm the combustion cambers should be opened up to match bore.

 

I run a 85mm block with a 84mm chamber head

 

Not necessary to open up the cylinder head chambers. You'd have to make sure to check for piston-to-deck height for clearance, as Ryd2TheMax said below.

 

This came from the EJ/EK section didn't it?

Typically people open up the bore of the combustion chambers as well... some don't, however it doesn't make much sense not to do it unless you're broke or something.

Like they've said, it can cause issues with clearances depending on things

 

I can understand you will get more swirl into the combustion chamber with such a small squish.