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Max boost on regular 4-bolt heads?

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Old Jun 14, 2008 | 03:21 PM
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Default Max boost on regular 4-bolt heads?

On a proper forged setup, what would be the max boost you can run on a ported factory 4-bolt casting before you have to worry about head lifting?
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Old Jun 14, 2008 | 04:01 PM
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I know a guy doing it at 18 with a d1sc . I would like to know what people that are running more are doing to keep the heads down
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Old Jun 14, 2008 | 04:36 PM
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Im interested also to see how much before pushing water.Im sure aftermarket castings help
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Old Jun 14, 2008 | 04:47 PM
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Texas Speed is running there LS7 280cc heads @ 18psi on there twin turbo car. Stll has not lifted.
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Old Jun 14, 2008 | 04:58 PM
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Why dont you go with aftermarket Casting??? Budget build???

17-18psi IMO After that you'll have to worry big time.

Mighty mouse 20+psi with a litttle head lifting If I remember correctly maybe he will help.
Also Kp Ran 18psi with F1A 346ci without any lifting.
Hunter with His TT.

BTW all of them were running AFR 255 I really cant remember Anyone that ran 18+ psi with Factory casting.
Lots people say its all in the tune.
lol
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Old Jun 14, 2008 | 05:10 PM
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Ill see how these tea tfs heads do once i turn the boost up here in a few weeks
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Old Jun 14, 2008 | 05:58 PM
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Originally Posted by venom ws7
Why dont you go with aftermarket Casting??? Budget build???

17-18psi IMO After that you'll have to worry big time.

Mighty mouse 20+psi with a litttle head lifting If I remember correctly maybe he will help.
Also Kp Ran 18psi with F1A 346ci without any lifting.
Hunter with His TT.

BTW all of them were running AFR 255 I really cant remember Anyone that ran 18+ psi with Factory casting.
Lots people say its all in the tune.
lol
PSI doesnt mean much, a detuned 20psi wont push water and a hot 15psi tune will. It also depends on your cam, compression, exhaust etc, pushing water is more of a function of cylinder pressure and detonation, whats on the other end of the intake valve means very little. I have ran factory 98 heads well in the 9s and havent pushed a drop of water with composite gaskets @ 19psi with 10:1 compression or so but thats with no timing and a hooker cat back so it wasnt making a ton of power.

18psi with the F1A and AFR heads and GM MLS gaskets would push some water here and there with the LS6 block, maybe a cupful, this LS2 block so far hasnt pushed any even with the F1A maxed out but I havent ran it in any good weather so its making a lot of power, I'll see what happens when it cools off out but so far the LS2 block seems to be holding a little better. Unfortunately I have no plans of a bigger blower or turbo so thats as fas as I can go
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Old Jun 14, 2008 | 07:15 PM
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After pushing a little water....at what point would you be concerned about gasket integrity ?

Ive been logging system pressure in my header tank. I had a little rise last weekend, and lost a very small quantity of water, so Im sure I had leakage of some sort. Circa 17psi in the header tank.....Usually its 10-12psi on a warm day.
After my last run, water temps also rose to almost 220degF, which is some 20-25degF higher than normal.

At home, and back to some cooler weather and road use....system pressure remains at around 7-8psi, even with a few 3rd and 4th gear blasts down the road.
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Old Jun 14, 2008 | 07:24 PM
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Thanks for the info Kp.

thats why I love LS1TECH learn something new everyday.
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Old Jun 14, 2008 | 08:21 PM
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Originally Posted by stevieturbo
After pushing a little water....at what point would you be concerned about gasket integrity ?

Ive been logging system pressure in my header tank. I had a little rise last weekend, and lost a very small quantity of water, so Im sure I had leakage of some sort. Circa 17psi in the header tank.....Usually its 10-12psi on a warm day.
After my last run, water temps also rose to almost 220degF, which is some 20-25degF higher than normal.

At home, and back to some cooler weather and road use....system pressure remains at around 7-8psi, even with a few 3rd and 4th gear blasts down the road.
When I start seeing carbon building up, looks like exhaust, between the block and heads I put new gaskets on. I have never really seen any elevated temps on any logs, even on a 90 degree day on a 2nd back to back pass it will seldom get over 200*F. Typically a 1/4 mile pass I try to start at 180 and when I let off its 184-185, thats even with some water-pushing.

With the LS6 block, 5.7 GM MLS gaskets and small bore AFR 225 heads made it the longest for me.
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Old Jun 15, 2008 | 03:33 AM
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My cooling system is at its limit on a warm day even in slow moving traffic. My radiator is a decent size although perhaps still not big enough, but being totally blocked by the IC, which is only about 1.5-2" in front of it, is far from ideal.

As it is now, with 2 fans covering a fair amount of the core, and all 4 steam ports in use, on a warm day, temperature can remain in control during normal driving, and total stop traffic. But its just about doing it.

When I was racing at the weekend, I fitted the coldest stat I could due to the temperatures, but without proper forward motion airflow thru the rad, temperatures still remained higher than ideal.

Im presently on LS6 block ( in use for some 3+ years now, and second hand when I got it ) new 5 layer MLS and TFS 225cc heads ( large bore )
Last rebuild I did get the block machined. Limited ( ie. crap ) machinists here mean the deck is flat, but the smoothness was far from ideal
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Old Jun 15, 2008 | 12:57 PM
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Originally Posted by stevieturbo
My cooling system is at its limit on a warm day even in slow moving traffic. My radiator is a decent size although perhaps still not big enough, but being totally blocked by the IC, which is only about 1.5-2" in front of it, is far from ideal.

As it is now, with 2 fans covering a fair amount of the core, and all 4 steam ports in use, on a warm day, temperature can remain in control during normal driving, and total stop traffic. But its just about doing it.

When I was racing at the weekend, I fitted the coldest stat I could due to the temperatures, but without proper forward motion airflow thru the rad, temperatures still remained higher than ideal.

Im presently on LS6 block ( in use for some 3+ years now, and second hand when I got it ) new 5 layer MLS and TFS 225cc heads ( large bore )
Last rebuild I did get the block machined. Limited ( ie. crap ) machinists here mean the deck is flat, but the smoothness was far from ideal

I would take rough and flat as opposed to warped and smooth.
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