Thickest head gasket for boosted car?
Thickest head gasket for boosted car? What is the thickest head gasket I could run on a TT 347? I see Cometic offers a .074 gasket, would this be ok to help drop CR?
thanks
thanks
A little general, but I get what you're saying. Ideally when you design an engine you take quench distance into account. "The general feeling is that the total quench or squish distance should be about .040". The quench distance is the compressed thickness of the head gasket plus the deck clearance. The quench area is the flat part of the piston that would contact a similar part of the head if you had .000 assembled quench height. In a running engine, the .040 quench height decreases to a close collision between the piston and the cylinder head. The shock wave from the near collision drives air at high velocity through the combustion chamber. This movement tends to cool hot spots, averages the chamber temperature, reduces detonation and increases power. The shock wave also provides better fuel/air mixing, and this allows the fuel to ignite better and burn faster. A faster burning fuel charge means less timing is required for optimum power output." (Internet link, but closed it before sourcing)
To calculate quench distance you take the compressed head gasket thickness and subtract how much the piston is out of the hole or add for in the hole.
To calculate how much your piston will be out of the hole take:
((.5 x stroke) + rod length + compression heighth) - deck height
LS1 block deck height is usually a generally accepted 9.240 inches.
To calculate quench distance you take the compressed head gasket thickness and subtract how much the piston is out of the hole or add for in the hole.
To calculate how much your piston will be out of the hole take:
((.5 x stroke) + rod length + compression heighth) - deck height
LS1 block deck height is usually a generally accepted 9.240 inches.
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I have .067" with no problems.
my engine is a 347 with flat top pistons cut down to give a 8.9:1 CR with 69CC chambered 6.0 liter heads.
they are cometics, which i have reused quite a bit (4-5 years), next time the heads come off though i probably will be going back to a stock .054 thick mls gasket to bump my compression up a tad as i want to start tuning with e85 and might help with a slightly higher CR.
my engine is a 347 with flat top pistons cut down to give a 8.9:1 CR with 69CC chambered 6.0 liter heads.
they are cometics, which i have reused quite a bit (4-5 years), next time the heads come off though i probably will be going back to a stock .054 thick mls gasket to bump my compression up a tad as i want to start tuning with e85 and might help with a slightly higher CR.
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I would do that as a last resort. The best option is getting pistons sized to hit your desired static compression level. Next would be using heads with larger combustion chambers or opening up existing head chambers.
Keith
Keith
What is the compressed thickness of the GM 5 layer MLS gaskets?
Thats what I am running with Stage3 LS6 heads and -25CC dished pistons. I am trying to get a total idea of the compression on my 408.
Thats what I am running with Stage3 LS6 heads and -25CC dished pistons. I am trying to get a total idea of the compression on my 408.
I have .067" with no problems.
my engine is a 347 with flat top pistons cut down to give a 8.9:1 CR with 69CC chambered 6.0 liter heads.
they are cometics, which i have reused quite a bit (4-5 years), next time the heads come off though i probably will be going back to a stock .054 thick mls gasket to bump my compression up a tad as i want to start tuning with e85 and might help with a slightly higher CR.
my engine is a 347 with flat top pistons cut down to give a 8.9:1 CR with 69CC chambered 6.0 liter heads.
they are cometics, which i have reused quite a bit (4-5 years), next time the heads come off though i probably will be going back to a stock .054 thick mls gasket to bump my compression up a tad as i want to start tuning with e85 and might help with a slightly higher CR.
yea I agree, but if I can get away with safely running a extra thick gasket to drop some more compression, than Im interested in looking into this.
Keith
no that is not true, the ohio boys have ran an o-ringed head with an mls gasket, and have had good success with it.
I have .067" with no problems.
my engine is a 347 with flat top pistons cut down to give a 8.9:1 CR with 69CC chambered 6.0 liter heads.
they are cometics, which i have reused quite a bit (4-5 years), next time the heads come off though i probably will be going back to a stock .054 thick mls gasket to bump my compression up a tad as i want to start tuning with e85 and might help with a slightly higher CR.
my engine is a 347 with flat top pistons cut down to give a 8.9:1 CR with 69CC chambered 6.0 liter heads.
they are cometics, which i have reused quite a bit (4-5 years), next time the heads come off though i probably will be going back to a stock .054 thick mls gasket to bump my compression up a tad as i want to start tuning with e85 and might help with a slightly higher CR.
Bro-with a 347, -2cc releif and a 6.0 head that should put you under 9.7CR. I don't think you would have any issues with a gasket as thick as .080 thou-I have seen alot of the blower guys do it with success. What Slowhawk suggested is a very good idea as well-just put in a cam with more overlap. I wouldn't go too low on the CR-compression and boost can make sick power when done right!
Well I went ahead and bought a cheap set of 317s that I'm going to put a good set of springs on and sell my TEA 853s. With them on the combo it wouldve been around 10.3-10.5:1 CR. I thought that was a little excessive and figured I'd be better off with a set of 317s and the thickest feasible safe gasket or o-ring combination that had been proven before to get the compression down to around 9.5:1. I won't be boosting over 14 lbs though more than likely.