My ls1 recently threw a rod, so I decided it was a perfect time to upgrade to a 6.0. I just picked up a complete low mileage, lq4 with the 317 heads. My original plan was to just use the short block and reuse my stock 241's, and change over my 231/237 cam. I figured the 241's would make more power, but some of my buds are saying to simply mill the 317's and use them, because they would make more power, is this true? I would love to buy some after market heads, but that is simply not in the budget right now. My car made good power before (393rwhp untuned) I don't wanna do all this work and make the same or less power. What should I do?

 

You could get a good valve job on the 317's and mill them down to 65 cc's (.030)or so with a .40 cometic gasket . That will give you around 10.5/1 compression and still have more ptv clearence sinceits a dished piston.

I have 241's at only 10.3 to 1 with stock gaskets on my lq4 in my trans am and it pulls hard with an f14 cam.

 

I love my AFR's on my LQ4... but since your on a budget milling your heads should give you a good power gain by lowering the compression. Just make sure your PTV clearance is good. Which it probably will, since you have the dished pistons and all...

 

I used my 853 with a stock gasket. I'm not sure the cr but with a Trex it makes good power and pulls real good. I don't know how much rwhp it made with the LS1 but now it makes 400/389.

 

You'll probably have to mill more than that to get the 317's down to a small enough chamber. Usually is .006 mill for each cc removed. To go from 72 down to 65 is .042" mill. At that point, you might start losing flow from increased shrouding.

If you could find someone with LS6 (243) heads looking to go FI, it would be a good swap for you. 317 and 243 head ports are nearly identical, but you get a smaller & better combustion chamber in the process. If you can't swap, they've been going about $400 around here, still way cheaper than aftermarket...

 

I thought 317's were 70 cc. Thats what I was basing it on.

 

My brother is on the same boat as you.He has a 04lq4 with 317heads also,but his pistons look flat at the top and not dish shaped or anything that would make the piston lose compression .So what does he have LQ4 OR LQ9.

 

lq9 has flat tops

 

Yeah that's what I thought also but I thought the 04 6.0 were lq4 and the 05 and up were lq9.And they told him it was a 04 lq4 block with 317 heads.

 

No they were around all the same years, the LQ9 came in a the Denali/Escalade and the LQ4 came in the work trucks/vans

I'm in the same boat as you man, for now i am going with the 5.3 heads and using a stock gasket for 10.9:1 compression. I hope to move on to the L92 heads when i have the money to build the block and maybe stroke it to 408ci.

 

So most of you guys are against using the 241's?

 

the 241 head can make power, are they ported?

 

No, they are bone stock, looks like i might be better off to sell both sets of heads and put the money towards a good set of aftermarket heads. Some of the patriot heads seem to be reasonably priced. I know they probably wouldn't be the best, but i would think they would be better than ported factory heads?

 

[QUOTEI know they probably wouldn't be the best, but i would think they would be better than ported factory heads?[/QUOTE]

PP ARE ported factory heads.......

 

Patriot are just CNC'd factory castings they will do your set of 241's for $600, they can also add enlarged valves and dual springs if you want.

 

We were installing LQ4 6 liter marine engines through 2008 model year. In 2009, GM supplied the LY6 VVT with Econtrols ECM, rated @ 409hp @5600.

 

Apart from my brothers 6.0 I have a 408 that's going to be running the Gmpp ls6 60cc cnc ported and polished heads.I know they are going to hold me back some hp but its just that I bought them years ago when there wasn't that much competition.But oh well maybe when I get some extra cash ill invest in some better flowing heads.

 

I am putting a set of 5.3 truck heads on my 04 LQ4 shortblock but I have had a set of hollow stem intake/sodium exhaust valves put in the 5.3 heads simply because the 5.3 heads have a smaller intake valve in them than a ls1/2/6. Also the 5.3 has the same port as a LS1 head does much like the 317 (6.0) and the LS6 heads share the same port design. So with that said when you put a set of valves in the 5.3 heads they will flow better than a LS1 head mainly from the valve job. And my head porter told me that a 5.3 head with LS1 size valves and a valve job would flow better than a stock LS6 head. All of that has cost me roughly around $300 mainly because I already had the LS6 valves sitting here as spare parts. Also the compression hike over all other LSx heads. Stock 5.3 heads are right around 61.5cc IIRC

 

What do you guys think about the 5.3 patriot heads, they sell for 1100 bucks, ported and have larger valves, and 63cc chambers, what kind of compression would that give my 04, lq4?

 

317's have 71cc combustion chambers, fwiw. Take your 241's, have them milled .015 to give approx 64cc combustion chambers, have a valve job done, and call it a day until you can have them CNC'ed. If you can have them CNC'ed now, go ahead.