Hello,

I'm running a LS block with p30 OEM pistons, shot peened rods, fresh cylinder hone, micropolished crank, etc etc. The block is in the shop. It's an 81.5mm 1.8L

I want a slight bump up in CR from my b16 head.

I was able to get some cheap flat faced Buddy Club p1 valves to help.

I will be running a full Buddy Club valve train, and SK2 pro2 camshafts.

I was wondering how much can I mill the head to raise CR. What is a safe amount of CR increase I can realistically expect from milling the head a bit.

Thanx in advance
B

 

You can get an idea of your compression ratio with this:

http://www.zealautowerks.com/bseries.html

 

The rough rule of thumb is for every .010" removed, it'll bump your compression ratio up by .2 Many people start by running a thinner head gasket before milling the head. Compression is only one small part in making power, increasing the airflow through the engine by haveing the head professionally ported and matching supporting mods is the way to go.

 

You can mill quite a bit off those heads, there are some people that have milled them so extensively that the quench pads are flush with the deck.

You already have a pretty decent CR with the setup you described. I wouldn't raise it anymore.

 

Milling a head means that the next time you go to rebuild it you might not have enough meat on it to cut it flat. Then you're out a good head.

 

Put it together now and check piston to valve clearance and that will tell you how much you can take off. CC your chambers before and after. It is a better way to raise compression than adding big domes on a piston. I would say your only obstacle is the piston pocket depth of that particular piston.

 

excactly the procedure i followed trying to determine much we can mill the head of my mates GSR.

degreed PRO1's combined with stock JDM GSR slugs came out to be 0.108 V2P clearance, indicating we could easily mill 0.07 of the head increasing the CR by 1.3 points. more then we want obviously because with the flat faced valves he would reach over 13:1 CR on a streetdriven nitroused GSR

only correct way to determine tough how much you can mill
degree the cams, clay it, measure it!