Need advice on heads for 04 lq4 6.0

**ROMERO98Z28** · 02-22-2011, 04:28 PM

I want 425-450 hp but need advice on heads and cam?? Got ls6 intake and my 98 z28 motor and am on a budget

**Firebirdjones** · 02-22-2011, 05:50 PM

You can stick with the 317's they come with and reach your HP goal with just a cam. They are basically patterned off the LS6 heads, they just have a larger combustion chamber, that coupled with your dished pistons gives you a 9.4:1 compression ratio.

Even a tighter combustion chamber LS6 head would only bump your compression to 9.94:1, you would have to mill to get anything higher. But you would gain nothing in flow,,,,that is unless you went with a set of ported heads.

**ROMERO98Z28** · 02-23-2011, 07:57 AM

So the stock 806,241,??the compression am not trying to run high price gas like 93 plus grade

**youngrigo** · 02-23-2011, 08:24 AM

I would throw some 5.3 stg 2.5 heads on that that will bump the compresion up!

**Firebirdjones** · 02-23-2011, 12:04 PM

Did your engine come with the original heads? In 2004 from what I can tell they had either 317's or 035's. I just bought a complete 2004 LQ4 myself and it has the 317's on it.

The 806 and 241 numbers are for the LS1 heads with a much smaller combustion chamber. Not to mention they are the older style LS1 heads that are not patterned off of the LS6 castings. (smaller intake runner size and round exhaust ports)

**ShiftyCapone** · 02-23-2011, 01:34 PM

You could always mill the heads for a little bump in CR. I would do that and or find a set of LS6 castings. The jump in CR is noticeable per dyno results published in an LS rebuild book (name escapes me right now). Easy power is always good.

**Firebirdjones** · 02-23-2011, 03:18 PM

Originally Posted by ShiftyCapone

You could always mill the heads for a little bump in CR. I would do that and or find a set of LS6 castings. The jump in CR is noticeable per dyno results published in an LS rebuild book (name escapes me right now). Easy power is always good.

Yep, would be cheaper to mill the original heads, since the 317/035's are already an LS6 casting with larger chambers.

**Sid447** · 02-24-2011, 09:21 AM

Originally Posted by ROMERO98Z28

I want 425-450 hp but need advice on heads and cam?? Got ls6 intake and my 98 z28 motor and am on a budget

Doing it on a budget is easy enough,

leave the heads as they are (un-modified) and fit a set of LS6/LS2 valvesprings pn 12586484.
Find yourself a good condition small cam e.g. ZO6 cam (204/217 .550/.550) or something similar.

Then all you need is a good professional tune.

A couple of us bought a 2004 LQ4, fitted a set of C-C 918 v-springs, a used Lunati 220/220 .558/.558 112LSA cam a really well done tune and it was great, really woke a 2,500kg 4x4 up.

**ROMERO98Z28** · 02-24-2011, 01:49 PM

My lq4 came with the 317 heads still got them,so the 9.4 cr is good for 89 grade gas?or maybe 87 gas?? And still make hp&tq

**Firebirdjones** · 02-24-2011, 06:29 PM

9.4:1 compression is actually very tame for an aluminum headed engine.

I'd much rather see 10:1 with an aluminum head which would still run on cheap gas even with a mild cam.
Personally, if I were going for more power, you could bump that to 10.5 or even 11:1, with a larger cam that would bleed off some cylinder pressure anyway, and a good tune, you could run on 91 pump gas easily and make big HP with the right cam and heads.

Going to be difficult to make the power you want on 87 octane. I personally don't even run that stuff in the lawn mower.
I've seen this done on the dyno with a well thought out combination and a sharp tune, but to save 10-20 cents at the pump it's alot of effort for little gain.

Higher elevations play a roll, higher up you can get away with lower octane levels. If you are close to sea level it's more difficult.
I built a 455 pontiac for my father a few years back, with aluminum heads, 10.5:1 compression with a very large (by you alls standards) 264 at .050 roller cam,,,and a good tune, it made just over 600 HP on the dyno with 89 octane.