Head Gasket: thinner the better?

[theCSXmachine]

I've got a stock thickness Cometic head gasket because i'll be running up to 26 lbs/boost. I've also got a custom Cometic head gasket that is so thin it's scary. I've heard the thinner you go the less chances you have of blowing a gasket. If this is true, does it have any negative affects like more of a chance of blowing something up instead? Thanks...

[TheVoyager]

Genrally when you up the boost you want a thicker head gasket. A lot of people stuff a head shim under there along with a head gasket. The shim is .020" thick. This lowers the compression. Mine has been ok.

The only way your headgasket will blow is if the bolts were not torqued right. It doesn't matter what thickness it is. I've seen the stock gasket with two .020'' shims take over 20 PSI.

[theCSXmachine]

well the machinist building my longblock didnt want to see the sheet with torque specs i printed up, he better have it right, maybe i should retorque them?

[toddipoo]

Quote:

The only way your headgasket will blow is if the bolts were not torqued right

No No No

Blowing a headgasket is caused more by detonation than anything.
High compression on a turbocharged engine is a big no no.
The thinner the headgasket the more compression it will add. If you run high comp and then up the boost your going to not only blow a headgasket but more likely a piston to chunks of metal.

Thats why non turbo cars that swap on a turbo run less than 10psi because they dont want to blow up there engines.

-toddi

Quote:

Originally posted by toddipoo No No No Blowing a headgasket is caused more by detonation than anything. High compression on a turbocharged engine is a big no no. The thinner the headgasket the more compression it will add. If you run high comp and then up the boost your going to not only blow a headgasket but more likely a piston to chunks of metal. Thats why non turbo cars that swap on a turbo run less than 10psi because they dont want to blow up there engines. -toddi

High compression is a big no no on turbo engine because of pump gas. You can run high compression, and high boost as long as you have the right octane. You don't have to fear blowing a headgasket.
Non-turbo cars can't run more than 10 PSI for 2 reasons. 1 is a non-turbo car naturally has higher compression than a turbo car and cannot be run on pump gas with high boost. 2 is the internals were never meant to be boosted anyway. I have never seen a head gasket fail on a boosted N/A car. I have seen however snapped connecting that ventilated the block. And melted pistons of course, but gasket was still intact on both.

The thinner head gasket is more dificult to blow. However, if the thinner gasket raises compression too much then that is bad.

[mopar2ya]

Have the shop tell you what thickness you need to get 8:1 compression. Its a good all around number that lets you run enough boost to kick some but on the street and you dont need 4billion octane at the track to run mid 25 psi at the track, unless your Larry J, Mr. 22 psi on 93 pump gas without knock....

As far as the Cometic gaskets is concerned you wont blow it from compression or boost, BUT detonation is your enemy, its far worse than high boost.

Wallace

[Marcus86GLHS]

while higher octance does reduce detnonation, higher octance gas cannot fully protect an engine...what blows head gaskets, destroys bearings, breaks pistons, etc., is, specifically, cylinder pressure (CP).

CP is effected by comp ratio and other factors, and, when detonation occurs, CP spikes dramatically....but yes, you can break a motor w/ too high comp ratio, despite using very high octane.

[mopar2ya]

Technically CP does break parts, but detonation is what increases that pressure exponentially. I can run the same 25 psi of boost and same advance with 105 octane and all is good, if I say put in 91 pump gas the detonation would greatly increase the CP with the same boost and spark advance and break parts. Typical flame travel is about 280 ft per second and detonation is around 540 ft per second, which is like a sledgehammer hitting the piston top.

Sure to much of anything can break something, then again fuel certainly can strech those limits. Diesels run 16:1- 18:1 CR and routinely run pressures that would grenade a gas engine. New semis have 80 psi boost gauges in them, then again Diesel fuel doesnt combust like gasoline, its Cetane rating rating is actually its inability to ignite. It requires pressure and heat to make it work.

So you must have components made to take increased strees and fuel sufficent to control the flame travel, as long as those are kept in balance your life will be peachy.