novajess1972

iTrader: (1)

Ordering a 408ci rotating assembly for my 6.0 liter. How do I know which pistons to choose? Flat top, dished, domed, +/- cc?

Not a car noob, just a noob at putting a LS engine together from scratch. This is going into my 72 Chevelle...replacing the 454 that's currenty in there.

What I have selected so far. Just clueless as to the benefits of choosing a different pistion.

6.0 LQ9 Block
Lunati Forged Crank
Lunati 6.125" H Beam forged rods w/ARP 2000 bolts
Mahle 4.03 -4cc flat top?????
Clevite coated main/rod bearings
TSP Stage 2.5 Head and MS3 Cam

KCS

iTrader: (20)

Depends on what compression ratio you're looking for. I have a little spreadsheet I built when I'm spec'ing that stuff out, but there are plenty of online calculators to help you get close.

novajess1972

iTrader: (1)

I'm not looking for anything radical. Just a stout motor pushing around 500ish to the wheels on pump gas. No power adders in the immediate future just yet.

Is my current piston selection okay? Would Wiseco 4.03" -3.0cc flat tops also be okay?

Thanks

KCS

iTrader: (20)

If you plan on using heads with less than 64cc chamber, I'd say no. 64cc chambers will put you at ~11.75:1.

novajess1972

iTrader: (1)

Which should I choose to lower the compression?

litle88

iTrader: (20)

11.75 is perfect, that will give you free hp and tq. I'm 12.25 on 93

But what 2.5 head do you have or planning on getting? The 5.3/6.0/Ls6? They vary combustion sizes. If you have them already what is your chamber size?

KCS

iTrader: (20)

A dish and a small chamber is best as far as the combustion chamber is concerned, but that doesn't mean you should mill a stock 5.3L head to get the smallest chamber instead of better heads that have bigger chambers.

You need to get a realistic idea of what heads you plan to run before you decide on a piston.

novajess1972

iTrader: (1)

Directly from TSP website:

Precision Race Components LQ9/6.0L 72cc Stage 2.5 Cylinder Heads Fully CNC Ported & Assembled With Stainless Steel 2.02" Intake Valves, 1.57" Exhaust Valves, & PRC Dual Valve Spring Kit with Titanium Retainers, Rated to .650" Lift. Kit Also Includes TSP Hardened Pushrods & Your Choice Of Camshaft!!

litle88

iTrader: (20)

With 72cc chambers and a
4.0 bore
4.0 stroke
.051 compressed GM mls gasket w/ 4.02 bore size
Flat top pistons
"0" deck height but its never that
I came up with 10.97

I used this calculator
http://www.wallaceracing.com/cr_test..._redirect=true

If I were you IMHO I'd get a piston with like a -4cc valve reliefs for Ls1/2/6 style
Like these http://www.texas-speed.com/p-1108-ma...00-stroke.aspx
Then you can check ptv clearances and mill the heads to an 11.5/11.75 for some nice free TQ for your ride. TSP I'm sure can tell you how much to mill, I'm sure they've done this many many times. Just my .2

litle88

iTrader: (20)

Or combination mill and .040 cometic gasket. Just my .2 bud.