ok, thought it would be best to start a new thread about the heads 243s milled that Im thinking about putting on my LQ9. I could always mill my 317s .030 I thought but then I will be just a tad about what some 243s would do.

So I want every hp per cube out of this engine. NA, that said, would I be okay to purchase some 243s and what do I need to mill off of them?

I run 93 octane. But I want this engine to be atleast a 11.1 motor.

 

Sub'd

 

Looks like 243 milled .030" would give you about 10.75 CR with GM gaskets. You could get close to 11 with .040" Cometic gaskets.

 

U be around 10.9-11.1 not milled cuz it basically be an iron ls2 then and milled 30 it be around 11.7-11.9

 

its amazing how you always have a answer Im searching for in my threads. This sounds about right to me, cause I know the lq9 with 243s would be a iron ls2. So basically, what Im getting at is Milling the 243s to .015 to get around 11.4-5 compression for a street NA beast?

and how would that compression work my Lunati Camshaft:

Advertised Duration (Int/Exh): 272/278
Duration @ .050 (Int/Exh): 222/228
Gross Valve Lift (Int/Exh): .567"/.567"
LSA/ICL: 113/109
Valve Lash (Int/Exh): Hyd/Hyd
RPM Range: 2000-6600

 

.010 milled 317 heads and a .040 gasket will be around 10.6 ish and a dynamic compression of 8.45 ish with your cam of choice. Which about the max you want to run on pump gas.

No need to go with 243 heads because you would end up with to much cylinder pressure, you would need a larger cam to bleed some of that off.

 

you mean 317 heads right?? See this is why I asked questions.. That cam is already ordered and what Im going to be using. I was not sure about even switching to 243s as its essentially the same as the 317s. I would prob just mill my 317s. .020 and run the .040 gaskets.

save my coin, for the ls7 lifters, chain, springs, TBSS intake and 102mm tb. Trying to get my best bang.

 

Yeah 317... my bad. Its been a long day.

The cam will be fine, just you don't need to mill them .020 because you will not be able to run the timing you could with them just milled .010 Basically it will be more prone to detonation.

But with .020 milled heads and .040 gaskets you will be around 10.87 compression and a dynamic compression of 8.6 You could run 93 pump gas @ that compression but your really pushing it and would be no better of power wise then if you just milled the heads .010

 

Bingo in a nutshell... Lots of food for thought. Im thinking of not even milling the heads, now, and just runing the .040 gaskets. And saving even more coin. If I stay untouch milling, is that the gasket of choice?

My tuner has a good bit of timing in her right now... so dont want to compromise that...

 

That is another option!

Yes the .040 gasket is what I would run, it will give you a good quench.

You would be sitting @ 10.36 ish compression with a dynamic compression of 8.2 ish, it is on the safe side for 93 octane but not the crazy safe side lol Your still optimizing your setup.