Sport Side

iTrader: (6)

dang, seems like there aint to many ways to raise compression on a 5.3 besides diggin in to your motor. Not a big deal if your runnin boost but for us NA runners. ill have to go check out those heads you were mentioning,

thanks

1LEThumper

You could always have them milled a couple thou and that would bring the comp up some just make sure you are watching your piston to valve clearance.

Sport Side

iTrader: (6)

yea thats also a possibility. I wonder where i could get some head work done over here on the south east? (round jacksonville area)

Ryan, those heads you were talkin about sound sweet with the 59cc that should bring up my compression like you said.. thanks for you guys help..

Ryan23silverado

iTrader: (1)

Sorry for confusing you man I think it was when I said the Patriot Perf. LS6 'style' heads are really welded up LQ9 heads to increase compression ratio. The LQ9 heads start off with much more cc volume than a 5.3L head to begin with. Having the weld in the LQ9 head increases compression (of that LQ9 head) in general.

**Since the 5.3L heads are the smallest combustion chambers of the LSx family style of heads to begin with, the only way you will be able to increase compression ratio by doing a head swap would be to mill the 5.3L heads down some. Also, like 1LEThumper stated watch your piston to valve clearance when you do this if you go with a high lift cam. The more you take off of the bottom of a head, the closer it moves the valves to the piston when it is at Top Dead Center. You would have to get pretty radical before this would be an issue though.

Sport Side

iTrader: (6)

ok, i thought stock 5.3L heads are 61cc. wouldn't the patriot heads at 5.9 bump your compression a lil or no?

how much does it cost to mill some 5.3L heads?

Flyer

iTrader: (1)

There is a sticky thread in one of the F-bod forums about the head volume and CR.

Ryan .. those LS6 heads, can you get yours down to 8.5 with those heads? Were there any chamber work done on them as far as smoothing them out or anything? I am SERIOUSLY thinking about a set of these for my truck. I have to decide if I'm gonna build a motor or not first.

Trevor @ Texas Speed & Perf.

iTrader: (3)

I see a lot of discussion on Patriot's cylinder heads, so I thought I would jump in with some information that might be useful and of interest.

Patriot's stage II 5.3L cylinder heads are a HUGE bang-for-the-buck! As mentioned, the 346cid guys like the 5.3L heads due to the smaller combustion chamber. Patriot does perform some chamber work that does open up the overall size of the chamber slightly. The chamber work helped to pick up exhaust flow by 10 cfm, so it is well worth it! The downside is that it will open up the chamber some, so you will see a slight decrease in compression ratio. It would be right around .25 of a point. You could easily shave the cylinder heads to offset the larger chamber and even increase the compression ratio over stock. Patriot will shave your cylinder heads however much you want for no added charge. Shaving .030" off will raise your compression ratio about .4 of a point over stock, so taking .030" off of Patriot's 5.3L heads with the chamber work should put you around .1-.15 of a point higher than stock. Shaving the heads do decrease piston-to-valve clearance, but I have yet to see a camshaft in a truck large enough to cause clearance issues. If you're in doubt, just give us a call. We'll be glad to go over a setup with you.

Patriot's stage II LS6-style cylinder heads do start life as LQ9 6.0L cylinder heads. The LQ9 heads do have the same port design as the LS6 cylinder heads. The only difference between the two heads is the size of the combustion chamber. The LQ9 heads come from the factory with a 72cc chamber vs. the LS6's 64cc chamber. Patriot welds the chamber up and then sends the cylinder heads to Canfield Cylinder Heads for heat-treating. Once they are heat-treated, the heads are sent back to Patriot to be ported and assembled. As mentioned, you can get a 59cc combustion chamber with the stage II LS6-style cylinder heads. However, if you're bolting these heads on a 4.8L or 5.3L, I would not recommend them. They're not going to net much power over what you would see with a stage II 5.3L cylinder head. The smaller bore size won't take much advantage of the stage II LS6-style heads.

As for Patriot's valve springs, they did have some spring problems early in the game. They are no longer using the 1.43" diameter single springs that they were having problems with. They now use a new stock-diameter dual valve spring on all of their stage II cylinder heads that are good up to .650" lift! Patriot also uses titanium retainers, stainless 2.02" intake valves, and stainless 1.57" exhaust valves. I would not hesitate to use Patriot's valve springs. There are customers running over .610" lift on them with no problems.

Please don't hesitate to give us a call if you have any questions. We can put a complete heads/cam package together for you that will work well with your setup and for your needs. We have heads/cam packages starting at $1829.99 with Patriot stage II 5.3L cylinder heads, your choice of camshaft (including custom-grinds!), TSP hardened pushrods, and Rollmaster timing set. We also offer GM bolt and gasket kits that will include all of the necessary items needed for the swap. We are constantly working on our website to get more parts up, and we have a completely new website currently being designed! It will be more user-friendly and a lot more complete with full explanations and pictures.

Let us know if you have any questions.

Trevor
Texas Speed & Performance

Sport Side

iTrader: (6)

Thanks for clearin up things..
very helpful