milling specs

[mavisky]

i'm wondering how i could know how much milling my head will raise my compression. is there an equation i can follow, standard differences, or anyone with any experience?

thanks for any help you have to offer.
~kyle

[BatmanGSX]

I don't think anything beyond minor resurfacing can be done with a DOHC head. This is because the distance between the centerline of the crank and the cams will change. The whole T-Belt system, including the width of the gear teeth, was designed around that specific distance.

If you mill a DOHC head you need to get a gasket that is thicker, then you would see minimal change in compression.

Anyone care to second this?

[dsm4eva]

To accomplish this, most people will mill quite a bit of material off the deck surface. I would imagine .100" of an inch would be a good number to use as an approximation. They will then use different thicknesses of metal head gaskets for fine tuning of the CR. To pull all this off and to keep timing correct, you absolutely need to use a set of adjustable cam gears.

[Le Talon]

We're talking NT, right?

A local member raised his compression to about 11 to 1, enough to give him 220psi compression per cylinder. All he did was to remove material from the block, the head and made the valves grooves in the pistons deeper. This engine has been running for more than a year now and it is still going strong.

The only problem were the AT trannies that would fry after 6 months. Now, the new owner is doing a MT conversion.

I think he ran an 16.10 on an ailing AT tranny. I'm pretty confident this car will be good for 15.50 once the MT tranny swap is complete. Not bad for a low buck NT project...

[galantvr41062]

I know when I get my head race preped(after exaust and rebuild tranny) I am going to install a set of ajustable cam gears, I will also mill the head more on the exaust side to bring the intake valve higher in the combustion chamber. I know that some company changed the angle of the intake valve 3deg. up on a v-6 and gainded almost 70hp, thats alot just by changing the angle of the intake valve. If you guys think a standered amount to remove on the head would be .100" I would take .08" on the intake side and .120" on the exaust side and possably use the stock mistu head gasket(I herd someone was runing a 9 on the stock one) but I will research more and more and do more calculations to find out how much to remove and the head gasket I will need to run a Mutt level5 at 30psi and NOS(200shot) just thoughts I have any thoughts on this would be great.

~John
LSE Performance Engineering and Design

[dsm4eva]

Le: was this guy having to run race gas with the upped compression?

[verserv]

well european 1g dsm owners have a stock 10.4:1 compression as to the u.s 9:1 they also have 15 more hp stock. on gas 93 and up their. you can easilly do 10:1(NTLaser has done that on here) and probably even 10.4 like euro without adjustable cam gears. all this is nt i am speaking about. I am doing the same procedure and am also having trouble figuring it out.