l92 heads lifting???

van383 · 10-24-2009, 06:01 PM

427cu 10psi heads wanting to lift, running arp bolts not studs.. 14 total timing and 11.5 a/f.. wtf.. l92 things? need studs? how they keeping these things dwn or are they at that boost??

veee8 · 10-24-2009, 10:46 PM

Been there done that. Even with ARP studs and GM LS9 gaskets, I still was never able to keep them from lifting. If you wanted to keep the L92/LS3 port arrangement and intake manifold, get a set of the new MAST/Performance Inductions aftermarket L92 heads. Practically any set of decent aftermarket castings will be way better at sealing then the GM L92's. You will be way better in the long run.

Louis · 10-27-2009, 12:08 AM

Sounds standard issue with LS3 castings. We push water Naturally aspirated in endurance racing

venom ws7 · 10-27-2009, 02:32 AM

Quote:

Originally Posted by veee8

Been there done that. Even with ARP studs and GM LS9 gaskets, I still was never able to keep them from lifting. If you wanted to keep the L92/LS3 port arrangement and intake manifold, get a set of the new MAST/Performance Inductions aftermarket L92 heads. Practically any set of decent aftermarket castings will be way better at sealing then the GM L92's. You will be way better in the long run.

How much boost were you running when you lifted the heads???

Quote:

Originally Posted by Louis

Sounds standard issue with LS3 castings. We push water Naturally aspirated in endurance racing

N/A

What is the compression of the engine?? 8000RPM??

Exotic Performance Plus · 10-27-2009, 05:43 AM

So far, this Hummer has not had a problem at 14 psi with the LS3 heads lifting, hopefully our luck holds out. We are using ARP head studs. http://www.exoticperformanceplus.com...Car.php?car=56 Bob

veee8 · 10-27-2009, 10:15 AM

Quote:

Originally Posted by venom ws7

How much boost were you running when you lifted the heads???
.

N/A

What is the compression of the engine?? 8000RPM??

Above 12 psi it would push a little, above 14 it was big issue

z28boysteve · 10-27-2009, 12:24 PM

Wow didn't know about the Mast heads.. 12 degree L92s with a .750 deck and 370 CFM per port as CNC'd! Count me in! Going to let others test em out first, if they can hold a gasket better I'll buy a set!

veee8 · 10-27-2009, 01:00 PM

Oh I guarantee they will hold gaskets a 100 times better then GM castings. They are a proven design, and now have a few neat upgrades over the previous ETP stuff. The MAST L92's are very similar to the small bore LS7 heads that Performance Inductions offers.

z28boysteve · 10-27-2009, 01:27 PM

Im thrilled to find out about these things! I can pay $2600 and swap ALL my valvetrain, including my custom stainless and Inconel valves, and my GMPP Intake and custom rails etc etc right over and save a bundle of money! Ill be able to see what this LQ9 can really take! :-D Going to have it O-Ringed though and fill it while I'm at it. Can't wait to step up to my 101 and NOT have to build a new motor lol.

Louis · 10-27-2009, 01:29 PM

Quote:

Originally Posted by z28boysteve

Im thrilled to find out about these things! I can pay $2600 and swap ALL my valvetrain, including my custom stainless and Inconel valves, and my GMPP Intake and custom rails etc etc right over and save a bundle of money! Ill be able to see what this LQ9 can really take! :-D Going to have it O-Ringed though and fill it while I'm at it. Can't wait to step up to my 101 and NOT have to build a new motor lol.

Good find!! Thats 100% the truth there!!!!

OUTLAWZ RACING · 10-27-2009, 04:52 PM

Any body using the mast heads???

lt1camaroman93 · 10-27-2009, 06:07 PM

Hmmm.. I'm gonna have to look into these Mast heads.

LSX Truck · 10-28-2009, 02:11 AM

how is this happening? what kind of bolts you using?

z28boysteve · 10-28-2009, 04:20 AM

4 bolt heads get deflection, alot of it under boost, L92 and LS3 are the worst.. Studs help, but marginally. It's a common issue.

Those Mast heads aren't due for sale for about 2 more weeks I guess. Im going to wait 3 or 4 months to get a set to see if they hold gaskets better for sure or not.

Louis · 10-28-2009, 11:22 AM

Quote:

Originally Posted by LSX Truck

how is this happening? what kind of bolts you using?

The decks of the LS3/L92s are thin. Its a 199$ casting, its hard to go wrong NA, but on boost, they make great power, you just cannot keep them on the motor with out it pushing water above 700-800 rwhp.

We are forced to run them in our series, so we have find ways to cope with the issues. Its pretty simple, and we have it down pat, just requires a lot of head gasket swaps, and then adding water at certain hour intervals during the race.

I have some neat data on water pushing that I have learned in the last 2 months, Ill gather that in the next few days and make a new post.

z28boysteve · 10-28-2009, 12:25 PM

Performance Inductions says the new head is about the same as the old ETP LS7 Heads I guess with an LS3 Intake port and bolt pattern basically. My valves won't work in the new heads but that's trivial. What matters is I don't have to shell out another $2,000 or more for another custom intake and fuel rails and do a bunch of BS for LS7 heads... They also flow 370 CFM per port in the "medium" bore valve arrangement (2.165,1.59) which isn't too shabby really.
These heads should be a good step up for me, or anyone looking not to do a max effort motor, but something that still kicks some ass. Going to beef up my LQ9 some more next freshening and shoot for 1500HP to get my feet wet in the big HP realm.

afattitude · 11-01-2009, 11:23 AM

Quote:

Originally Posted by z28boysteve

4 bolt heads get deflection, alot of it under boost, L92 and LS3 are the worst.. Studs help, but marginally. It's a common issue.

Those Mast heads aren't due for sale for about 2 more weeks I guess. Im going to wait 3 or 4 months to get a set to see if they hold gaskets better for sure or not.

4 bolts? I'm confused. I thought the L92 heads had the same number of bolts as all the others? What is the real different between the mast casting and the normal GM casting? Will these 6 bolt heads fit on the LQ9 block?

z28boysteve · 11-01-2009, 11:49 AM

4 bolts per cylinder, same as all the other GM heads. However the number of bolts per cylinder isn't the most important thing. If your clamping down your head and right below the nut or bolt head there is a water jacket, well your not getting as good a clamp as if it was solid aluminum below it all the way to the deck. The way the heads are designed has alot to do with how well they hold down. As well as the number or fasteners, and the deck thickness.
GM's new LSX has additional bolt bosses cast into the block below and above the cylinder adding two more fasteners per cylinder. World has done the same in their warhawk blocks (with thier own 6 bolt pattern), and ERL offers conversion services which will add them to factory aluminum LS blocks by means of machining and welding. a 6 bolt head may be utilized on a stock block, but with only 4 fasteners... If you ask shawn @ VA speed he will tell you though that 1500 HP is capable through a 4 bolt block, and he claims it's survivable but I can't testify myself weather or not that's true but Fireball99 can.

beavis · 11-01-2009, 10:45 PM

I've gone as high as 15lbs with my L92's with no problems. I'm running 8.9:1 compression.

Louis · 11-02-2009, 10:33 AM

The issue is that when you take a REAL street car, that gets DRIVEN, not a 1/4 mile at a time, that is when you will have problems.

Going to a FRESH, no mile head will extend the longevity, as long as the block and tune up are good.

As soon as it starts to move around, cylinder pressure might go up, bad gas, high heat, you name it- Something that shows ZERO signs of damage, and all of a sudden, it will push water.

It may take a 30, 40, 50, 100 mile drive to see it happen. Garage queens may never ever see it. drag racers may only see it in the puke tank. They can just top it off and go another round or 5 before they need to tear it apart....

The "pushing water" issue is out there, most dont understand it or even know its happening, but I can tell you its probably happening more than people want to admit. If you are building a NEW foundation and plan to make big hp ( 700 at the wheels plus) I would HIGHLY recommend going 6 bolt for pure reliability sake. Is it over kill? Sure, some will call it that, but the minute you have to tear it down and put fresh gaskets on it, thats when its NOT over kill.

are there things that lead to it pushing more than others? Sure! BIG area under the curve turbo cars ( read- peak tq at 3-3500) will push WAY earlier than a centri car, who makes peak tq at say 5500 or 6k....

Any big power adder cars that come through here from here on out will ALL be 6 bolt, no questions asked. Period. If I put my name on it, and I stand behind it, I wont be experimenting with what so-and-so says will work across the country.

Louis