denmah

iTrader: (2)

before i do this for research
what head gasket should i use, the 6.0 truck one, a ls1 5.7 gasket?

stock 5.3 truck gasket?

i actually have ls9 gaskets for that iron 370 im building but i would throw them on this motor if they fit for a trial

chiaj144

iTrader: (4)

I'm running the ls9 on my 5.3 with the stock heads. I don't see the 317's being any different.

denmah

iTrader: (2)

ok, i used a compression calculator and saw itll drop me to about 8.54 CR

i dont mind running 25lbs of boost though, so i guess this will be an interesting test.

a4ls2goat

Head studs?

denmah

iTrader: (2)

i have a set of ARP bolts and studs i could use. either or...

not sure if dropping the compression a whole point is worth it...

like i said i don't mind winding up this 80mm and pushing this 5.3 as high as the ignition system will let me go.

what do you guys think.

2lucke4u

my vote is to let her eat!!!!!!!!!
5.3's are cheap and the test will yield great knowledge or at least a great story

a4ls2goat

I say go e85 instead add studs and bump up the boost.

HRHohio

Could have them milled to bring it back up to 9.5, or even 9.0 CR.

denmah

iTrader: (2)

ill need diff length pushrods then right?

a4ls2goat

It's not good to have them milled, specially for that much boost.

fastcars95

iTrader: (9)

Because of deck thickness ?

HRHohio

Ahhhhh, right.... I'm thinking you're correct.

(Subscribing... also just picked up a 5.3 to drop into my "new" '72 Camaro.)

Was thinking of having the stock 5.3 heads ported and put in larger intake valve... ala "Hot Rod Magazine Big Bang Theory" "The stock 5.3L heads were ported by Total Engine Airflow and received larger intake valves and an appropriate spring upgrade." Link: http://www.hotrod.com/techarticles/h...g_bang_theory/

I'm using that article as my inspiration, but I was thinking of milling the deck so it wouldn't be a dog down low...
===============================

"Because of deck thickness ?"

In a way... milling 317s down decreases piston to valve clearance. Limits the use of "BIG CAMS". But if you're using a moderate boost friendly cam, you can probably mill .020 off, get the compression back to 9.0, and still be clear. (I haven't run the numbers, so I'm just guestimating... don't hold me to it!
Plug the numbers in your calculator and see what it spits out.

fastcars95

iTrader: (9)

Its pretty easy to measure for pushrod length. Summit sells the tool for something like $10.
The hotrod story is what sealed the deal on me parting my procharged LT1 to build an LS.

HRHohio

Crazy, huh... I was like, "I'M DOING THAT!"
(of course, I'll be keeping it at a moderate 750 rwhp for longevity)... for now.

c0ncEpT

iTrader: (4)

You think you have trouble building boost on the footbrake now. Just wait until you go down to 8.5....

JAX04

iTrader: (17)

Exact reason why the 317s i have sitting in the corner are not on my 5.3 as we speak. And i would not even considering milling them for anything other then getting them back to true. Just my .02.

EDIT: However, you do have nitrous dont you Denmah?

oneoverwrx

iTrader: (1)

I would use the ls9s and your head studs. I would also have them checked for flatness(minimum amount milled) need a good surface to seal properly. You can reuse the studs when u do your 370 and the gaskets are 90-100 a pair, they are worth using. I have them on mine, skinnies has them on his. Just use them.

I thought a 5.3 with 71cc chambers yielded closer to 9.0-1 oh well. Boost>compression. You will probably not have to run any more boost as the amount of flow you will get will take the power up a lot. Good luck.

denmah

iTrader: (2)

yeah i might not throw these on, i didnt think it would drop them a whole point, whew that might end up being a 3 steps forward 2 steps back thing

oneoverwrx

iTrader: (1)

Just went and did a comp calc and got 9.1:1.

You might have entered the 4.8 stroke to end up with 8.5:1. I would re check your numbers. 3.779 bore 3.622 stroke 71cc chamber .....flat tops? If you are using dished pistons that might get you to 8.5:1. Wasn't thinking about that. 8.5:1 isn't that bad. I think you are worrying too much about your compression. Those heads will pick u up a
Ton of power regardless of the compression.

denmah

iTrader: (2)

Yeah I think I have a flat topper I'll probably try them anyway after this weekend they are supposedly great breathers