The engine in my 01' SS recently threw a rod, so I'm gonna replace it with a 6.0 truck engine. Here is my plan, I'm on a tight budget, so I'm planning on finding a low mileage short block, and putting my low mileage stock ls1 heads on it, and also installing my cam and valve train, what kind of compression ratio would I have? I'm hoping to find an lq9, since from what I've found, already have a higher comp ratio than the lq4, or would I be better off with the lq4? A friend of mine even suggested using the 6.0 heads, would these heads make as much power?

 

**All are with stock .055 gasket (unless stated otherwise)**

LQ4 has 9.4:1 (dished pistons -6cc)
LQ9 has 10:1 (flat top pistons)

LQ4+241's = 9.7:1 (66cc heads)
LQ9+241's = 10.4:1 (66cc heads)

LQ4+5.3 heads+.040 gasket = 11:1 (route i am going ) (59cc heads)

The truck heads flow about the same as the LS6 heads they just have a larger chamber ~72cc ( i believe) so they will yeild the same power, after being milled for a smaller CC.

This calculator gives a rough estimate of where you will be, it even take the gasket volume into account.
http://www.csgnetwork.com/compcalc.html

Here is the stock heads list and their specs.
https://ls1tech.com/forums/advanced-...ume-vs-cr.html

 

You will lose power with the 241s on the 6.0. Pull the 317s off the engine and have them milled .040"

 

Will that clear Piston/Valve clearence with the LQ9 pistons ??? what size head gaskets ??


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Question:

What are all the different head gasket thicknesses that are out there? What companies and etc?

If there are different thicknesses and bore sizes this can affect compression ratios.

Question:

Will the stock valve springs on 317s or 241's be OK with a stock LS2 cam?

 

I'll check the links, but also wanted to go ahead and ask the question.

 

Piston to valve is something you always have to check. In the end there is no one to blame but yourself if you screw up your engine. But with a stock LS2 cam there shouldn't be any issue at all, it basically when you get into larger aftermarket cams.

There are a few aftermarket companies like Flat Out, Cometic, Felpro, etc. They make gaskets in various thicknesses and bore sizes.

A lot of people, including me, just use GM head gasket which are multi-layer steel like the aftermarket gaskets. You can find thier specs in the GM performance parts book on pg 210 Im pretty sure. You can download it as a pdf online.

The valvesprings might not work on the LS2 camshaft which has .525" lift. Ive seen many stock valve springs where the stock valvesprings wont even take .525" lift. You can get a set of the yellow Z06 valvesprings that are good for something like .550 or .570" lift for about $70. But I wouldn't really run them on much of an aftermarket performance camshaft.

 

Thanks for your reply.

I am curious as to replacing the Lq4 cam with the LS2 cam. How much of a benefit would it be? Sounds like it may just be around 15 to 20 horse.

I have a GM book and have looked up the numbers, but do not remember them. I need to look at them again.

 

Yes, I know about piston to valve clearance.

 

The GM MLS gasket is .051" compressed. It's also much easier to install than the Cometics regarding deck prep. Seeing as you're on a tight budget, the LS2 should be a nice little bump. I'd do it.

 

OK, then would you bump the compression up with the head gasket and or mill the heads?

I believe the LQ4 compression is 9.4 to 1. Is that enough for the LS2 cam?

I think the LS2 cam had 10 to 1 compression.

Truck will mainly be used for hauling, a improvement over the 4.8. I hope for around 380 to 400 torque and 375 to 400 horse with the LS2 cam.

Truck has a 5 speed and 3.42 gears.

Your opinion?