Ok so long story short was running in SD (Bought the car and it had previously had an SD tune, but CEL was never turned off for it) and one of my O2's failed, but since the CEL was always on I never knew. Engine went way too rich and washed out the rings. So building a new motor sooner than I expected.

Ok so I know I'm gonna go with a 6.0L iron block, LQ4/LQ9. And here's what I'm thinking so far:

LQ4/LQ9 block machined as needed 4.000-4.030in bore
Factory 3.622 stroke crank
Callies Compstar 6.125in Rods

Now my question is I'm not sure what pistons to go with, I'm eventually planning on going forced induction with either an APS twin turbo setup or a TTi single since they're both around the same price. With that said, one of the local guys thought I could build it for stock compression using factory LS1/LS6 heads, and then go with some 72cc 6.0L or if I can get them 72cc L92 heads, dropping the compression to 9.5:1n when I go FI a couple years down the road.

I was looking at Diamond or Mahle pistons. What's everyones thoughts on this? What size reliefs or dish am I going to need to get my desired compression?

Also the car has an ASA cam in it right now, love the cam and the power but the car doesn't like to have the A/C turned on in the summer lol. What would be a good cam to go with, that will give me good n/a power similar to the ASA with a noticable lope, but not require me to switch it out right away when I go turbo.

I'm going through withdrawals and need to start piecing this car back together so I'm not missing out again next year.

Thanks everyone

 

To get a final compression of 9.5, you'll need to find out what parts are required. Roughly speaking, take the volume of the cylinder, and divide by your desired compression ratio minus one.

(4.03/2)^2*3.1416*3.622 = 46.2008
46.2008/(9.5-1) = 5.4354

Now figure out what makes up that volume
Positive deck volume = (4.03/2)^2*3.1416*(-.007) = -.0893
Gasket Volume = (4.06/2)^2*3.1416*.045 = .5826
5.4354 - (.5826 + (-.0893) = 5.4354 - .4933 = 4.9421

Convert that volume to cc's 4.9421 * (2.54^3) = 80.98 cc

So to get 9.5:1 with a 72cc head, you'll need a 9cc dish

Doing the math for a smaller head, you could get as high as 10.95:1 with 59cc heads, and have your 9.5:1 later when you put a 72cc head in place.

Also, the ASA cam is probably not a good choice for a turbo, but you may as well run it for a while until it's turbo time, then replace it with a specific turbo grind at the time the rest of the swap is done. If you are already going to swap heads, why not just do the cam then too?

 

Sweet thanks.. so judging by this and from what I've been searching through various vendors... Probably going to be a custom piston order?

 

You won't need a full custom piston, you can have a shelf piston modifed to 9cc dish. Less expensive way of doing it.

let me know if you need a quote

Fraser

 

If you're going TT go with low compression. 8.8:1 sounds like a nice number to me

 

I was going with the 9.5:1 as I wasn't really planning to go more than 600rwhp-ish I would think that would be plenty low for pump with meth injection wouldn't it? Or should I really go lower?