lq9 heads

[sliverado rst]

i took off my heads to find a bent valve, broken spring an rocker, so to not make the whole project a loss i wanted to try and get some more power out of the heads, is it possible to run bigger valves in the stock lq9 heads? i was going to send them out and get new guides and seals, probably a 5angel valve job, but since one is bent i figured id replace them all, i don't want to deck them because im running 8psi of boost and id probably be making too much compression, i was considering a port but it probably wont do much with magna charger intake. any input would be great thanks

[diablotruck]

You can run 2.02 int. with 1.57 exhaust but it will require some machine work to the valve seats. With this done you will need some port work done to match the new oversized valves. Being that you are FI milling the heads much is not such a good idea because it will decrease the amount of boost you can run with the same octane rating you were running before. As far as port work most of your gains will come from working in the bowl area and the short side radius of the ports especially the exhaust. mario

[sliverado rst]

<div class='quotetop'>QUOTE(diablotruck &#064; Jun 17 2007, 05&#58;20 PM) [snapback]97062[/snapback]</div>

You can run 2.02 int. with 1.57 exhaust but it will require some machine work to the valve seats. With this done you will need some port work done to match the new oversized valves. Being that you are FI milling the heads much is not such a good idea because it will decrease the amount of boost you can run with the same octane rating you were running before. As far as port work most of your gains will come from working in the bowl area and the short side radius of the ports especially the exhaust. mario
[/b]

who makes the valves? and i wont need to mill the heads for valves correct? the compression is too high as it is

[diablotruck]

manley. that is the same size used on patriots. no milling of the deck is necessary for valve install but the valve seats will have to be worked by your machine shop for proper seating along with a valve job. pocket porting will also be needed to maximize airflow with the bigger valves if not there wont be as much gain as possible.(bowl blending) As you probably already know good springs are a must with FI as the valves are having to work against the boost to close. With good springs you will see an increase of 1-2 in/vac and more top end as valves close quickly and you minimize bleeding off of your precious boost in the overlap portion of the valvetrain cycle. mario

[sliverado rst]

i just got the manley cato. it says the make those valves for ls1/ls6 heads, can i use those or are they different?

[diablotruck]

patriots are stock castings ported by them. The valves will work with all GenIII engines. mario

[sliverado rst]

i will order the valves soon, thanks