L92 heads

[bangbangskeetskeet]

Ok so just wanted to know a couple things.
How big are the chambers on the L92 heads.
Also how much can I mill them down?
What would the compression be with L92 heads and a 4.03 bore with a stock 6.0 stroke and a factory thickness head gaskets?
And lastly how well do you think a set of L92 heads with some port work and a mill and valve job would do with nitrous compared to a set of 243's also with some port work and a mill and valve job?

[tanz45]

I am gonna go GMFullsize on you.......

What are you stupid? Search button don't work!?!

Tired of spoon feeding info to everybody!



Sorry, I don't know bud.

[bangbangskeetskeet]

I am gonna go GMFullsize on you.......

What are you stupid? Search button don't work!?!

Tired of spoon feeding info to everybody!



Sorry, I don't know bud.

I hate you.
I tried the search button but couldn't find anything about the chamber size.

[tanz45]

Found 70cc on google, is that right?

[bangbangskeetskeet]

Maybe I'm googlin wrong....can't seem to come with anything.

[mean05]

Found 70cc on google, is that right?

yes

[fullthrottle]

If you check the gmpp website and view their catalog I think in the acrobat reader download, it will give you some info on those heads. As for milling I think I remember something about their deck being thinner. Anyone else know about that?

[mean05]

L92 heads have 72cc chambers and that the L92 heads have a very thin deck (thinnest of all LS heads) and not to deck them. They flow really well out of the box but at the cost of deck thickness. And depending on the setup and cam... the piston may have to be cut or else piston to valve slap will occur. Lot's of variables with these heads on some setups that make power

[bangbangskeetskeet]

Ok well I did a little more looking and ran some numbers.
From another thread...every .006" you mill that's about 1cc...so using that formula milling .020" would take away 3.3cc bringing the chamber to 66.7cc. Milling .030" takes 5cc bringing the chamber to 65cc.
Also I was looking for gasket thicknesses and found some say use .043" and some say .060" so too that into account also. Along with different piston selections...flat tops or dished (-8cc).

So here are the numbers:
Milled .000" w/ .060" gasket and flat tops = 10.19:1
Milled .000" w/ .043" gasket and flat tops = 10.61:1
Milled .000" w/ .060" gasket and -8cc = 9.39:1
Milled .000" w/ .043" gasket and -8cc = 9.73:1
Milled .020" w/ .060" gasket and flat tops = 10.58:1
Milled .020" w/ .043" gasket and flat tops = 11.03:1
Milled .020" w/ .060" gasket and -8cc = 9.7:1
Milled .020" w/ .043" gasket and -8cc = 10.07:1
Milled .030" w/ .060" gasket and flat tops = 10.79:1
Milled .030" w/ .043" gasket and flat tops = 11.26:1
Milled .030" w/ .060" gasket and -8cc = 9.87:1
Milled .030" w/ .043" gasket and -8cc = 10.26:1

That's a lot of typing on my iPhone.
Anyway back to my OP...we know with P&P the L92's out flow just about everything so what are the thoughts on these vs. 243 heads on a nitrous motor?

[bangbangskeetskeet]

L92 heads have 72cc chambers and that the L92 heads have a very thin deck (thinnest of all LS heads) and not to deck them. They flow really well out of the box but at the cost of deck thickness. And depending on the setup and cam... the piston may have to be cut or else piston to valve slap will occur. Lot's of variables with these heads on some setups that make power

Of course you would post this while I was doing my research and typing that ^^^ out