What would be more cost effective? (If the motor being built is a LQ4 6.0L)

Taking the set of stock LQ4 heads, trying to find a good price on springs and valves, then having them milled to around 65cc (if possible).

or

Try to get a good deal on a set of 243 castings.


I am still young in my knowledge of LSX engines. I'm trying to do as much research as possible before starting my project. Sorry if anything in here is outrageously impossible, wrong or inaccurate. Thanks.

 

i say stay with the 6.0 heads since you have them, I did , had mine milled .25 an a valve job along with 918's in them. The 241's will bump your comp up over the stock 6.0 heads, but the 6.0's flow better then the ls6's

 

What did .25 bring your combustion chamber cc to? I don't mind the bump in compression, it won't be a daily driver, so running premium won't be an issue. The LS6 243 casting should have the same int/exh port volume as the LQ4. The 241 casting is listed less, so I could see how it wouldn't flow as well, but the 243 should be the same. How much do you have tied up in the heads? Thanks.

 

243 and 317 flow the same!!!

i would find 243 and use those. i sold mine for 450 to a buddy only 8200 miles on them and that was with valves

 

merk7408 richard at WCCh for 1300 can do a valve job with all new parts and mill the heads for 1300. Might want to call him. This will then outflow the ls6 heads and have any compression you desire. He is a sponsor and very knowledgble guy to talk to. Just make sure you have time to listen to what he says cause it will take you a min to take it all in. LOL

 

I have about 350 tied up in the heads, I am not sure on where my comp is at and don't have the form or flow numbers to tell ya. Quick I was almost certain that the 317 flowed better then the 243's, guess I was wrong lol.. I still would go with the 6.0's and have them done if you already have them

 

yea sorry to break it ot you that the 243s and 317s do flow the same

just like the 5.3s and 241s flow the same even tho the 241 have a larger intake valve

 

I have learned some things by reading a few LSx based books, articles, etc., however there always seems to be contradictions. Let me know if something is way off.

Valve size is common on all LSx based engines; 2.00" Int / 1.55" Exh

4.3L, 5.3L, and LS1's have 200cc Int and 70cc Exh ports

LS6 and 6.0L's have 210cc Int and 75cc Exh ports

To me the 6.0L and LS6 heads should flow about the same. I know with any upgrades you should change the valve springs. I am not looking for crazy horsepower at this point, so the LS6 style springs should be adequate. Not a daily driver, so milling the heads to increase compression for extra HP would be acceptable. So, with the exception of the different style (not size) valves, you are basically building a set of 243's right? I am not going to have the budget for $1300 heads so squeezing every little bit of hp for the least investment is what I am after. So the question remains, $450-500 for a set of bolt on 243's or is it possible/practical to build a set out of 6.0's for less?

 

4.3 is a 6 banger head, 4.8 and 5.3 have smaller intake valves

 

I think the LS6 heads flow a little better. I know the LS6 head has a better combustion chamber design. I also think it wouldn't be wise to try to mill the 317 heads down to the size of a LS6 chamber. Thats too much IMO.

If I had my choice, I'd run the LS6 heads.