Going to start my rebuild on the Mini Cooper S soon. It has the Helix turbokompressor kit http://store.helix13.com/helix-turbokompressor-kit/. I'm looking to upgrade the head gasket. Would anyone recommend the head gasket made by Cometic( which is .0027 kicker than stock)? Looking to upgrade the piston for CP or JE, but keep stock bore because I don't know how he stock pistons will hold up. I've set the boost to run 15 psi, but he S/C helps build boost so quick- it usually will gig 21 psi before the boost controller kicks in. The motor is built to be able to run up to 30 psi. Any other suggestions would help. Thanks.

 

when changing pistons in a car that is outputting a fair amount more than stock you really should go for the 1 size overbore (.020 Overbore i think)

it just makes sure your cylinders are completely round, have a good hone, and everything is as tight and tidy as it should be.

as for head gasket, if you get a thicker one you really should deck the block or head to make up the difference.

You cant (well rather shouldn't) just ***** nilly add space inside your motor. A thicker head gasket will drop compression just a tad if you need it to run that "one more psi", but as a general rule they are made to go into cars that have had to have their heads decked flat due to they were slightly warped, and the thicker gasket makes up for the missing material.

 

Thanks for the input. I will be removing the engine completely and getting the engine dipped and clean- along with replacing the clutch. When the Helix kit was installed about 6-7 years ago, it did get a port and polish and titanium valves and springs installed. I guess while it'll be at the machine shop- I'll talk to them about decking it and boring the motor for bigger pistons. The reason why I'm doing the rebuild is because recently- the vehicle had excessive white smoke coming from the PVC valve and doing some research indicates a possible blown head gasket. Im not too tech savy, but I'd like to get the car running to get it out my garage. Lol