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Heads lifting under boost: avoid?

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Old 06-26-2007, 12:35 AM
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Default Heads lifting under boost: avoid?

How do you guys running alot of boost (im looking to run 20-25lbs on a six liter iron block) avoid lifting the heads on "stock" LSx blocks (IE not the 6 bolt per cylinder LSx)?

Is it not as common a problem as i think? happen just every so often? ways to combat it?

Thanks

Dom
Old 06-26-2007, 07:07 AM
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i tried some fel-pro mls gaskets and they had the same results as the gm 6.0 mls.

i guess the o ringing which i've never really paid attention to would be the next thing.
Old 06-26-2007, 07:58 AM
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O-ringing the heads will help a lot. I have my TEA heads o-ringed to use with a iron 6.0L block. I am using using Fel-Pro PT-6166 gaskets.

The next thing( mostly likely the true first time ), a very good tune.

Keith
Old 06-26-2007, 09:34 AM
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My 7.9:1 346 is an aluminum LS6 casting, and has seen 18-26 psi. I am running a set of GM MLS head gaskets.

I think the key would be to run aftermarket head castings that would offer the best clamping capabilities, and run a safe amount of timing with a given fuel.

I think a vastly more experienced tuner/racer like Mike Brown or Kurt Urban would talk about how a lot of timing can roach head gaskets. I think Mike Brown has push head gaskets past the limit a few times, and knows when it becomes a problem.
Old 06-26-2007, 09:57 AM
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I agree with PSJ. I run GM MLS head gaskets and L19 studs. I have never had a problem with a boat load of nitrous or boost. My nitrous setup had 6.0L heads and my current setup is with AFR's.



Originally Posted by Pro Stock John
My 7.9:1 346 is an aluminum LS6 casting, and has seen 18-26 psi. I am running a set of GM MLS head gaskets.

I think the key would be to run aftermarket head castings that would offer the best clamping capabilities, and run a safe amount of timing with a given fuel.

I think a vastly more experienced tuner/racer like Mike Brown or Kurt Urban would talk about how a lot of timing can roach head gaskets. I think Mike Brown has push head gaskets past the limit a few times, and knows when it becomes a problem.
Old 06-26-2007, 10:04 AM
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Setup and tuning will tell how long a head gasket will last.I had a car running 18lbs and just 2 degree's more timing would lift the heads.If you left it back the car would run forever and was only down 10rwhp on the dyno.
Old 06-26-2007, 11:48 AM
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my car pushes water at 17psi on the track 20 on the street and 23 on the dyno.. go figure.
Old 06-26-2007, 11:51 AM
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Originally Posted by MIGHTYMOUSE
my car pushes water at 17psi on the track 20 on the street and 23 on the dyno.. go figure.
that is a really wierd difference!
Old 06-26-2007, 11:59 AM
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its kinda proportional to the load and the time spent under that load
Old 06-26-2007, 12:13 PM
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I know it was due to different loads, but I had to laugh at the numbers because the one we would LIKE to push at the track is the one on the dyno, lol.
Old 06-26-2007, 12:25 PM
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I think the LS1 head "lifting" phenomenon has more to do with detonation under load than with the amount of boost. Although, I'm sure there are some instances of extreme cyl. pressure and even 'cupping' of the head surface between studs.
Old 06-26-2007, 12:44 PM
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I started to push a lil water @ 20 psi with stock castings(317) and 6.oL Iron block with standard ARP head studs on GM MLS gaskets....
Lifted the heads with a lil more boost then that
20 psi was w/ 23 degree's of timing on C16...
O-Ringing the heads and copper gasketing as i type this...
New heads will be an aftermarket casting with a thicker Deck.

Kyle
Old 06-26-2007, 02:25 PM
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got a question guys...i understand o ringing the heads but do yall mean the block also? if not how does this keep the water from seeping under the flat surface of the ring to the block? doesnt make sense? are the rings slightly deeper than the groove your putting in the head?
Old 06-26-2007, 02:32 PM
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O-ringing the heads and block helps provide extra cylinder sealing and pressure containment. The o-ringing on the block side consists of a grove machined into the block. The o-ring in the head sits in the block groove. Doing this combo requires a special head gasket.

Mainly people, including myself, only install the o-ring in the head. This only requires a graphite composite gasket to be used. When used with head studs and good tune, it seems to hold quite well.

Keith
Old 06-26-2007, 02:37 PM
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I haven't been to the track yet but I'm over 20 psi with a F1R, stock LS6 castings-pump gas with 1 can of Torco accelerator and a dual nozzle meth setup. Car has made over 900 rwhp and i'm still on the same head gaskets. Timing is 14 degrees up top. Car hasn't pushed a gasket yet, even with a bunch of lean outs after 5500. Knock tables are completely stock and i have yet to record any knock on my logs. Could it be the way the centri ramps up in boost why it's surviving? Fuel octane is supposed to be at 105 with the Torco and 116 with the meth? My IAT's are 90 degrees at the beggining of the pull and 65 at the end of the pull. If it does spit out a gasket I would like to o-ring the heads but what is the correct procedure and what gaskets to use?
Old 06-26-2007, 03:15 PM
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holding on the track is where it matters. hits on the street or dyno are way easier

i have aftermarket castings, and have conservative timing and conservative octane... i also beat on it hard at the track..

back when i didn't use to do so.. gaskets would last a long long time at higher boost levels and more timing on less octane.
Old 06-26-2007, 03:46 PM
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Originally Posted by eb02z06
Could it be the way the centri ramps up in boost why it's surviving?
Yes. Turbo's are much harder on head gaskets than centerfugial superchargers cause your're at peak boost for thousands of rpm, rather than just at peak rpm.
Old 06-26-2007, 04:03 PM
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MMouse, have you had to change hg's since you debuted the new ride?

My car went thru one set of hg's a few years ago, but that was probably due to the lack of proper timing when I first set up my old FAST system.
Old 06-26-2007, 04:47 PM
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yes. the hgs were fresh when i wrecked the old car and have put on set on a month ago since the engines been in the new car

i think its been enough now that the head and block needs to be surfaced.. but nothings wrong with the bottom end so hate to take it apart
Old 06-26-2007, 08:17 PM
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Originally Posted by NA$TY-TA
I started to push a lil water @ 20 psi with stock castings(317) and 6.oL Iron block with standard ARP head studs on GM MLS gaskets....
Lifted the heads with a lil more boost then that
20 psi was w/ 23 degree's of timing on C16...
O-Ringing the heads and copper gasketing as i type this...
New heads will be an aftermarket casting with a thicker Deck.

Kyle

Ill definitely be using copper gaskets and probably just go ahead and o ring the heads, but why a thicker deck?

I was probably going to go with some ported L92 or dart heads to save a bit of cash...


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