Milled L92 Heads...?
09-11-2009, 05:14 AM
#1
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Milled L92 Heads...? By anychance does anyone know how much I would be able to mill down some L92 Heads to run on my 6.0 LQ9 Motor(Flat Top Pistons), Torquer V2 Cam(Maybe MS3 later).... I wanna raise the compression on my motor. Currently I have 243's on my LQ9.
09-11-2009, 06:41 AM
#2
I wouldnt mill them at all. I cant tell you anything specific because names of camshafts means nothing. Specs are what people need to help you, not names.....
I milled my L92 heads .030 and couldnt fit bigger than a 219 duration intake lobe and Im sure your cam choice is bigger than that. It also depends on the lobes on those cams, I have an LSR cam with LSL lobes which are fairly aggressive. If you get a lazy/slow cam you might be able to fit a little more. Remember, True flat top + gigantic intake valve = not much PTV, mill the heads or change to thinner intake gasket = even less!!
Hot Rod Mag just did an article with 5 Comp cams and unmilled they mentioned the biggest they could fit. I dont remember what cam it was though... Look it up if you want, they made 525ish FWHP IIRC.
Either way, you MUST check PTV with any camshaft install, because your paying the bill if it crashes no matter what anyone says on here....
I milled my L92 heads .030 and couldnt fit bigger than a 219 duration intake lobe and Im sure your cam choice is bigger than that. It also depends on the lobes on those cams, I have an LSR cam with LSL lobes which are fairly aggressive. If you get a lazy/slow cam you might be able to fit a little more. Remember, True flat top + gigantic intake valve = not much PTV, mill the heads or change to thinner intake gasket = even less!!
Hot Rod Mag just did an article with 5 Comp cams and unmilled they mentioned the biggest they could fit. I dont remember what cam it was though... Look it up if you want, they made 525ish FWHP IIRC.
Either way, you MUST check PTV with any camshaft install, because your paying the bill if it crashes no matter what anyone says on here....
Last edited by SweetS10V8; 09-11-2009 at 06:46 AM.
09-12-2009, 06:14 PM
#4
You would have to notch the pistons, it can be done, how much I don't know, depends on how much piston material you have left to notch.
I would just get a set of different heads if you want to up that cr a bunch.
09-12-2009, 06:51 PM
#5
Wrong.
Guy on ls1gto just got 23rwhp and 16rwtq by doing nothing more than milling the heads .0030 and running a thinner gasket. Info is here...
http://www.ls1gto.com/forums/showthr...=1#post6024970
Guy on ls1gto just got 23rwhp and 16rwtq by doing nothing more than milling the heads .0030 and running a thinner gasket. Info is here...
http://www.ls1gto.com/forums/showthr...=1#post6024970
09-12-2009, 09:58 PM
#6
Its an opinion, I cant be wrong. 
I would rather have the PTV clearance for the option of a larger camshaft. It depends on what you want....
The heads already flow well, matched with a good cam will make great power. Compression is one of the last things on my list of importance for a street vehicle. 10:1 is perfectly acceptable for a decent street engine.
I would rather have the PTV clearance for the option of a larger camshaft. It depends on what you want....
The heads already flow well, matched with a good cam will make great power. Compression is one of the last things on my list of importance for a street vehicle. 10:1 is perfectly acceptable for a decent street engine.
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09-12-2009, 11:53 PM
#8
You could measure your current head surface to valve depth on your heads and then compare that measurement to the new L92 heads. Doing so will give you a good idea how much change you have with just a head swap. You would need a micrometer style depth gage for accurate results.
So, if there is a .050” difference between the two heads and your current camshaft clears, it would seem reasonable that you can mill off .050” safely. Check a couple valves on each head as sometimes there are variances.
I had about .066" milled from a set of 243 series heads and still have room on -14cc pistons. Another .018" will come off in the future. The pistons and valves are clayed for clearance with a .037" gasket. Specs on the camshaft are below.
So, if there is a .050” difference between the two heads and your current camshaft clears, it would seem reasonable that you can mill off .050” safely. Check a couple valves on each head as sometimes there are variances.
I had about .066" milled from a set of 243 series heads and still have room on -14cc pistons. Another .018" will come off in the future. The pistons and valves are clayed for clearance with a .037" gasket. Specs on the camshaft are below.
09-13-2009, 07:17 AM
#9
Your theory would be more likely true if he were keeping the same heads and same cam.
I always check PTV with a solid lifter, adjustable pushrod, checking spring, and a dial indicator
09-13-2009, 11:27 AM
#10
And if you would reread his original post, he wants to raise the compression.
09-13-2009, 12:25 PM
#11
Check how far the pistons are above the deck first, measure all of them, they can vary. This will help you determine everything else. LSx based engines are between .004 and .010 above the deck.
The flat tops will cause you issues because valve reliefs, get some cut and you can do what you want.
The flat tops will cause you issues because valve reliefs, get some cut and you can do what you want.
09-13-2009, 01:48 PM
#12
OP has a 364ci engine. So why on earth, would he care about running a "larger" camshaft? "Larger" camshafts have been proven to barely make (and in a lot of cases not even) the #'s that "smaller" to "midsized" camshafts when coupled with a 6.0 bottom end and L92 heads.
And if you would reread his original post, he wants to raise the compression.
And if you would reread his original post, he wants to raise the compression.
Like I said, from my personal experience when I milled .030" I couldn't go larger than a 219 duration on my intake. "Larger" then refers to cams larger than 219, say 220-228(ish).
He may want to raise compression, but he most likely can not with those cam choices because of piston to valve clearance.
09-13-2009, 02:13 PM
#13
I make 525 whp with milled L92's and a 242/246 custom cam. on a stock 6.0L bottom with valve reliefs. I picked up 55 whp with a very mild port job, milled heads and the change to this cam from a MS4...
it can be done. Mine are milled .070" and compression is around 11.0. I also run a GMPP l92 intake and a edelbrock elbow.
Car runs 11.0's at 125, 3775 lbs. 6 speed..... heads can be made to work.
it can be done. Mine are milled .070" and compression is around 11.0. I also run a GMPP l92 intake and a edelbrock elbow.
Car runs 11.0's at 125, 3775 lbs. 6 speed..... heads can be made to work.
09-13-2009, 04:45 PM
#16
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How Do I Make A Big Cam Fit With Optimum Compression?
Maybe this will answer some of your questions. Its a pretty decent write up on fly cutting. It answered alot of mine. Hope this helps.
http://forums.corvetteforum.com/c6-t...mpression.html
Maybe this will answer some of your questions. Its a pretty decent write up on fly cutting. It answered alot of mine. Hope this helps.
http://forums.corvetteforum.com/c6-t...mpression.html
09-13-2009, 08:12 PM
#17
Your trying way too hard here.... stop trying to start fights and start helping people......
Like I said, from my personal experience when I milled .030" I couldn't go larger than a 219 duration on my intake. "Larger" then refers to cams larger than 219, say 220-228(ish).
He may want to raise compression, but he most likely can not with those cam choices because of piston to valve clearance.
Like I said, from my personal experience when I milled .030" I couldn't go larger than a 219 duration on my intake. "Larger" then refers to cams larger than 219, say 220-228(ish).
He may want to raise compression, but he most likely can not with those cam choices because of piston to valve clearance.
You know what my cam specs are and they are much, much larger than yours and I milled .0030, run the stock gasket and I am fine.
And I am trying to help
You are the one telling him that if he mills the heads he can't run anything larger than the cam you run.