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What head gaskets to use? turbo LSx

Eagle

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Paging TCG vendors with opinions on this...

I'm fairly certain I lifted a head or two awhile back while pushing ~20psi on the street. Ran a compression check and its only clocking in around 90psi/cyl, a couple as low as 75psi.

I'm running Akerly and Childs Xtreme rings, which were gapped for a medium nitrous shot. I tried finding my notes from when I filed them down to see what they measured, but I couldnt locate them. So IIRC, top ring is .038 and 2nd ring is .042. They were clocked 180* when installed.

Back to the head gaskets... pretty sure I need to get new gaskets. Right now, I'm running ARP studs and GM 6.0L MLS gaskets which were installed dry on a freshly surfaced pair of heads. The studs were installed to ARP spec, but it turns out many people install them with another 10-15lbft past spec... can anyone confirm this?

Not sure about cometic (heard that they have sealing issues if the block isn't freshly decked), but I've been hearing about LS9 gaskets... something about them being 7 layers and "better" than 6.0L 3 layer MLS gaskets.

Thoughts?
 

redevo58

Regular
Apr 3, 2010
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Stay away form cosmetic they are junk. Everyone no matter what type of vehicle who ive heard that installed them always complain about them leaking. Im 95% sure the ls9 gaskets are a 4inch bore same as the 6.0, and they are made to handle boost(how much more that 550rwp?) I would start with a new set of arp head studs and the ls9 gaskets.
 

Larry@AMS

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Jun 20, 2011
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it sounds like you have done some research and seem to be on the right page :)

20psi, iron motor, ARP studs & stock heads has been done often, but tuning is very important as anyone knows. I would be sure to have the head decks surface checked again while off.

GM 6.0 MLS or GM LS9 MLS would be my suggestion

I will agree that most tend to go a bit further with ARP's revised head stud torque recommendation of 80ft lbs. The use of oil or lube will change the recommended torque as well by approx. 5 ft lbs. I say go 90 in an application like yours.

good luck and if you need anything feel free to call or email me anytime

[email protected]
630-549-8919
 

Eagle

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Stay away form cosmetic they are junk. Everyone no matter what type of vehicle who ive heard that installed them always complain about them leaking. Im 95% sure the ls9 gaskets are a 4inch bore same as the 6.0, and they are made to handle boost(how much more that 550rwp?) I would start with a new set of arp head studs and the ls9 gaskets.

For the price you pay for cometics, you would expect them to be decent... but I've heard too much about them to risk it.

it sounds like you have done some research and seem to be on the right page :)

20psi, iron motor, ARP studs & stock heads has been done often, but tuning is very important as anyone knows. I would be sure to have the head decks surface checked again while off.

GM 6.0 MLS or GM LS9 MLS would be my suggestion

I will agree that most tend to go a bit further with ARP's revised head stud torque recommendation of 80ft lbs. The use of oil or lube will change the recommended torque as well by approx. 5 ft lbs. I say go 90 in an application like yours.

good luck and if you need anything feel free to call or email me anytime

[email protected]
630-549-8919

Larry,

Thanks for dropping by. Would you know the installed height (thickness) of the LS9 gasket vs the LS6 gasket? I think I'll shoot you a PM here in a few min... :D

I wish I had these problems......

Good luck and it sounds like there are some experienced people in here to help.

Thanks, Aaron. You too could have these problems... you get into a new car yet? Got your eyes on anything in the near future?
 

Pressure Ratio

....
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Glen Ellyn
Dan,

Are you using ARP "Ultra Torque" when you torque the nuts on the head studs? That stuff makes a big difference in the way the hardware moves. It will allow the threads and hardware surfaces to have less friction than oil. This leads to less of a false reading on the torque. It is pretty cheap and well worth it.

The Cometic gasket does get a bad rep for leaking. They are very specific as to what they want for a surface. Not only being real flat but also the kind of finish on the surface of the block and heads. But done right they work well. I know many people who run them with great results. My car has them in the motor. They have been on there for over 3 seasons now. Not a drop of coolant on my motor. That is with running upwards of 32# of boost some times. So Cometic gaskets can work. Many people prefer the Felpro MLS gaskets as they have additional sealer around the water ports. They have a better rep for working with less than ideal surfaces. I have seen them used with great results as well. That being said I think you should stay with the GM gaskets as well. They seem quite durable in applications I have seen them used in.

If all your issues are behind you get it tuned again and then hit the track. Data log and tune from there. Good luck!
 

daturbosix

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ive used cometics on toms bbc, and my 6cyl. no issues. felpro MLS on another turbo lsx combo, and tonys n20 sbc, and my turbo sbc, and my dads n20bbc... its a crap shoot. to me, they are the same..... i cant say either is better than the other.
 

Larry@AMS

Regular
Jun 20, 2011
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0
For the price you pay for cometics, you would expect them to be decent... but I've heard too much about them to risk it.



Larry,

Thanks for dropping by. Would you know the installed height (thickness) of the LS9 gasket vs the LS6 gasket? I think I'll shoot you a PM here in a few min... :D



Thanks, Aaron. You too could have these problems... you get into a new car yet? Got your eyes on anything in the near future?

no problem

.051ish for Ls1/Ls6 stock MLS gasket

Dan,

Are you using ARP "Ultra Torque" when you torque the nuts on the head studs? That stuff makes a big difference in the way the hardware moves. It will allow the threads and hardware surfaces to have less friction than oil. This leads to less of a false reading on the torque. It is pretty cheap and well worth it.

The Cometic gasket does get a bad rep for leaking. They are very specific as to what they want for a surface. Not only being real flat but also the kind of finish on the surface of the block and heads. But done right they work well. I know many people who run them with great results. My car has them in the motor. They have been on there for over 3 seasons now. Not a drop of coolant on my motor. That is with running upwards of 32# of boost some times. So Cometic gaskets can work. Many people prefer the Felpro MLS gaskets as they have additional sealer around the water ports. They have a better rep for working with less than ideal surfaces. I have seen them used with great results as well. That being said I think you should stay with the GM gaskets as well. They seem quite durable in applications I have seen them used in.

If all your issues are behind you get it tuned again and then hit the track. Data log and tune from there. Good luck!

I'm with this guys above info as well.:smile:
 

Pressure Ratio

....
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Nov 11, 2005
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Glen Ellyn
Years ago when graphite head gaskets were all that were around O-ringing was a big help. But with the new MLS gaskets there is less of a market for them. The O-ring set up works well and is an option when building a complete motor. But being Dan is just replacing the head gaskets in the car there is no easy way to O ring the block.

Like Larry said, the MLS set up should be fine. Because the MLS will take a lot of abuse until you melt them. If you melt them you have more issues to worry about than the head gasket. So sealing will not be a issue with a good tune and no parts failure.

If the failure is due to lifting the head that is not because of the head gasket. It is due to the clamping of the head to the block. If it is lifting the head no matter what head gasket you have it will be a issue. Figure out why it is lifting the head, fix that issue and the head gasket will last for a long time to come. But like any thing else, if you abuse it enough it will fail. Just have to match the right parts and tune to make it live. Which is not always easy either. haha

Dan, Did you run a leak down test on the motor? A lot of times you can hear the escaping air. if the coolant bubbles in the radiator you know it is a water passage issue. If you hear it out the PCV, throttle body or exhaust it all tells you some thing else. I prefer a leak down over a compression test any day. You learn a lot more from it. Might be worth doing one.
 

Eagle

Nemo me impune lacessit
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Mar 1, 2008
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Years ago when graphite head gaskets were all that were around O-ringing was a big help. But with the new MLS gaskets there is less of a market for them. The O-ring set up works well and is an option when building a complete motor. But being Dan is just replacing the head gaskets in the car there is no easy way to O ring the block.

Like Larry said, the MLS set up should be fine. Because the MLS will take a lot of abuse until you melt them. If you melt them you have more issues to worry about than the head gasket. So sealing will not be a issue with a good tune and no parts failure.

If the failure is due to lifting the head that is not because of the head gasket. It is due to the clamping of the head to the block. If it is lifting the head no matter what head gasket you have it will be a issue. Figure out why it is lifting the head, fix that issue and the head gasket will last for a long time to come. But like any thing else, if you abuse it enough it will fail. Just have to match the right parts and tune to make it live. Which is not always easy either. haha

Dan, Did you run a leak down test on the motor? A lot of times you can hear the escaping air. if the coolant bubbles in the radiator you know it is a water passage issue. If you hear it out the PCV, throttle body or exhaust it all tells you some thing else. I prefer a leak down over a compression test any day. You learn a lot more from it. Might be worth doing one.

I'd love to, but don't have the tool to do so. I have a compressor, but that's about it.

Nope. Still rocking a neon.... So I'm shopping and looking at some ls-powered and srt powered cars. :noes:

Good luck with the ls9 gaskets. :bigthumb:

LS powered and don't look back! :nutz:
 
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