So, I'm going to be swapping heads and putting a stock one on my car (to comply w/ rules for TimeTrial or the class(es) I'm interested in racing with). However, we're allowed to bump up compression by up to 0.5 points. I figure my options are to a) mill the head before installing it, or b) install a thinner than OEM headgasket.

Since I'll be replacing the headgasket when I swap the head anyway, I figure I might as well go with option B, which is a less "permanent" solution. However, before I do that, I'd like to hear from people that have had a thinner headgasket installed for more than 15K miles or so (particularly Spoon, since that's what I'm looking at).

Has anybody run a long term test with one of these?

 

heard they will give way sooner. but I'm thinking you could make it 15K miles with the spoon gasket.

 

dont feed him that junk


you will be perfectly fine, a thinner headgasket isnt going to kill your motor
it barely raises compression

 

All nice thoughts, but has anyone actually used one? Looking for firsthand data, not hearsay.

 

thinner gasket = less gasket material to seal the head THUS better chance of leaking. This is just a very general rule of course.

I personally would mill the head and do it right, if for some reason you need to raise compression later you can do a thicker head gasket anyway. Better yet get the correct pistons etc. but ya.

-Greg

 

that doesnt make any sense

theres no less material to seal the head, the surface material that faces the head and the block are exactly the same, the gasket is just less layers, it will seal exactly the same

if your racing, you dont want to do anything permanent like milling the head just for a small bump in compression when you can just get a headgasket, just in case somthing happens later, if you mess up the motor, if you overheat and warp the head, you will still have enough material on the head and block to mill and deck back into specs

it whould suck if you mill your head now, and then overheat on track and warp your head and go to have it milled back to spec and you dont have enough material to be able to do it

you cant mill the head to much

 

Dont you get small timing issues from milling? Or do you replace the timing "chain" when you do this also?

 

The Spoon will raise compression by ~.3. I know of one motor that has one installed for the last 10k miles so far without issue.

 

I had a spoon HG in for about 40k miles, no issues.

 

Carbon >

Thinner head gasket = less physical material to crush.

I'd fully agree on the head milling part as far as giving some "just in-case" it's the same way I feel about boring out cylinders past 87mm etc. No "OOPS" room.

Still the seal of a gasket is based on it's ability to fill the gaps, a thinner gasket means it can't fill as big of a gap, simple as that. Now the better the machining the better the seal, theoretically a PERFECTLY milled head wouldn't need any gasket to seal.

-G


******* Curious what was the power gain after a tune with the +.3 CR change.