6.0L question on compression
07-25-2010, 11:37 PM
#1
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6.0L question on compression I'm new to the LSX world so be easy on me lol. I am installing a 01 6.0L into my 89 Formula and currently have the engine down to the long block. Engine has 60K on it. Looks like it has a few more miles then that only which worries me. My goal is 400 RWHP . I already have an LS6 intake for it and a TF 228/230 585 585 cam. I am thinking of just going though the motor with new bearings bolts and rings. Keeping the stock rotating assembly. How much power am I going to be loosing by staying with the stock pistons but with the heads milled a little. I assume I'm going to be around 10:1 Thoughts?
07-26-2010, 08:52 AM
#2
It depends on which 6 liter you started with, an LQ4 or LQ9.
The 4 will have dished pistons and the 9 will have flat tops.
I cant remember right now what the stock compression is for either of them, but obviously the LQ9 wont need as much milling to get 10:1.
The 4 will have dished pistons and the 9 will have flat tops.
I cant remember right now what the stock compression is for either of them, but obviously the LQ9 wont need as much milling to get 10:1.
07-26-2010, 07:41 PM
#6
Not sure what you will lose, but if the heads are already off, it might make sense to sell your 317s and buy a set of used LS1 heads. They will bring your compression back down. I bet you would almost break even after you sell your 317 heads.
I am not very familiar with all the different castings, but I think all of the LS1 "car" heads have the same valves as the 317, and they're all aluminum too. There are a bunch of castings, and not all are created equal. You could also use the LS2 or LS6 heads if you were willing to spend a little more money.
I am not very familiar with all the different castings, but I think all of the LS1 "car" heads have the same valves as the 317, and they're all aluminum too. There are a bunch of castings, and not all are created equal. You could also use the LS2 or LS6 heads if you were willing to spend a little more money.
07-26-2010, 08:51 PM
#7
You may have to mill quite a bit to get to 10:1 with the 317s...they do flow well though.
If you use 241s, you'll be right at 10:1 with a stock head gasket. If you use LS6 heads (243s/799s), you'll be at roughly 10.26:1 with a stock head gasket. Not sure if you want to spend any more money on heads at this point, though. 241s are cheap, but they don't flow as well as the 317s. LS6 heads would be your best bet, but you'll have to spend $400-$500 for a set.
If you use 241s, you'll be right at 10:1 with a stock head gasket. If you use LS6 heads (243s/799s), you'll be at roughly 10.26:1 with a stock head gasket. Not sure if you want to spend any more money on heads at this point, though. 241s are cheap, but they don't flow as well as the 317s. LS6 heads would be your best bet, but you'll have to spend $400-$500 for a set.
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07-26-2010, 10:00 PM
#9
With your horsepower goals, I would get some of the ported ls6 heads from Texas Speed or similar vendor. They flow 300 cfm, will raise the compression to over 10:1 and are only 1300 bux or so. These would almost assure that you reach your goal with that cam.
07-27-2010, 06:37 PM
#11
Keep in mind, if you spend $500 on a set of stock LS6 heads, you'll probably be able to turn around and sell your 317 heads for about $250. That might be the easiest way to get the compression!
How much do you have to mill your heads before stock pushrods don't fit anymore?
How much do you have to mill your heads before stock pushrods don't fit anymore?
07-27-2010, 09:59 PM
#12
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Does it matter if its ls2 or ls6 heads? I see both under 243 castings. I finally pulled my heads tonight off the LQ4. Heads look good. Bores looks awesome with the cross hatch still there. Can I get the 243's mill 10 to clean and run the 585 lift cam with no PTV problems?
07-27-2010, 10:04 PM
#13
My 243s are milled .010 and I had the cam in my sig spec'd for my combo with a prerequisite of no flycutting. Keep in mind, though, its the duration on the cam you need to worry about, not the lift. It's all about the valve events on the camshaft when it comes to PTV issues, so I'd definitely clay it and check to be sure...but I'd do that with any cam install.
07-27-2010, 10:44 PM
#14
Does it matter if its ls2 or ls6 heads? I see both under 243 castings. I finally pulled my heads tonight off the LQ4. Heads look good. Bores looks awesome with the cross hatch still there. Can I get the 243's mill 10 to clean and run the 585 lift cam with no PTV problems?
I installed that same cam in a carbed 10.5:1 5.3, and we easily got 7500 out of the old girl, no valve float, with 918's. now 5.3 intakes are 89 grams, but even the heavier valves should be good to 7000 with a set of 918's. You can also shim the springs to get a little more pressure out of them if you plan on really cranking it. A .015-.020" shim should get you a little extra seat/open pressure w/o messing with coil bind, since both sets mentioned are good till .625.
You should easily hit your goal if you use 243/799 heads. They like a nice valve job, so if its in your budget, get that done while they see the machine shop.
07-27-2010, 11:10 PM
#15
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Yea, I'm looking hard for a set now. My buddys friend works for TEA which is down the street from me and hes always coming acorss heads for dirt cheap. He texted me about a deal hes got so i'll see what happens when I see him tomorrow. Is there any other heads I should look for?
07-28-2010, 08:31 PM
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Ok I just bought a set of 243's from the classifieds lol. This LS stuff is like a drug. Going broke lol. Luckly enough. I sold alllll my SBC parts and I'm still in the green. I havent had to spend my own money yet.
