Pat Burton

Has any one stacked two Cometic MLS head gaskets together to lower their static compression? I know stacking sounds bad but the MLS gaskets are basically stacked gaskets anyways. I just didn't know if this has been tested on a boosted motor.

I am sitting at 10.0:1 and would love to be in the 9's or even 8's. I am getting my heads machined and going to gain about 5cc in the combustion chamber.

LilJohn

And exactly whats leading you to want to reduce the static compression?

Pat Burton

I want to lower my static compression so I can increase my volumetric efficiency and allow more boost without spark retard.

ss1

iTrader: (32)

You can buy Cometics in almost any thickness you can imagine...within reason.

dschmittie1

iTrader: (64)

I think stacking gaskets would be a bad idea. what fuel are you running and how much power are you looking for. My current motor is 10:1CR running E85 My last motor was 9.9:1CR on 93 and Meth.

Pat Burton

Just talked with a guy from cometics. He said they can do a 0.140 mls gasket. That will get me down into the 8.xx:1's. Right now im running a 10.0 with 11 lbs of boost. Im looking to build around 20lbs. Im hoping to get into the 8's with a 383. Anyone know of a better compression ratio to run from experience? Im running 110 shell unleaded gas.

qqwqeqwrqwqtq

Yes, leave it at 10.0-1 unless you're trying to reduce power and response.

Pat Burton

Hmmm. I've read different articles saying that you should run a lot lower CR's if you are trying add a lot of boost. So what is the optimal CR if the engine was at 10.0:1 at 11 lbs of boost when I am trying to get around 20 lbs. I was running a p600b and now I'm switching to an F1-R

chasgiv3

iTrader: (1)

If you want to run big boost on pump gas then that's a different story. But at 110 I don't see an issue.

dschmittie1

iTrader: (64)

I have seen 16 psi on my 10:1 385 cubic inch motor on E85 powered my 3400lb car to an 8.79@158 Saturday. I plan on turning it up closer to 20 psi next season

Pat Burton

What is your guys's IAT's? I'm not planning on running meth or nitrous. I run a water to air intercooler that keeps my IAT's below 100 degrees F

dschmittie1

iTrader: (64)

No Meth and a cheap E-bay air to Air intercooler my IAT's are 140ish

Pat Burton

Damn thats not bad for air to air... Is 10.0 what many people run? I just want to be on the safe side because it isn't too hard to slap on a thicker head gasket. I was thinking about hittin 9.5:1 just to be safe. I guess there is more factors that just CR, like cam and valve events and keeping the heat down. So I guess I could stick with 10.0:1 and try and keep the air cool? Any other insight?

dschmittie1

iTrader: (64)

I know of an Outlaw drag radial car that was a 427 with 10:1 CR and saw 40 psi

jridenour31

I don't see the point of this at all. 10-1 is fine for boost. Dynamic is more important anyway.