Hey guys so I have a 2000 lq4 has new pistons in it. I was going to go turbo so I went with dished, however plans changed no turbo going in at the moment. So the dish is .050 and I have a sloppy stage 2, supporting valve train. So my question is what will be my best bet for heads to bump compression without swapping pistons? Don’t really want to run the 873s because I know there will be no real gain.

 

Find some 243/799 heads.
If using stock 6.7cc dish pistons, you will be at around 10;1 compression with aluminum 243/799's compared to stock 9.4:1 compression with the cast iron 873's.

 

Excellent that’s what I needed to hear. Don’t have to mill them down though?

 

You wouldn't have to mill the 243/799 heads. You might want to, but that would depend on what you plan on doing with the motor. If it's going into a truck or SUV, I would put the 706/862 heads on it. The 706/862 heads with the sloppy stage 2 cam will make lots of low-end torque. It would also make a good daily driver in an F-body with highway gears.

 

I agree the SS2 camshaft likes compression and the specs say 10.5 minimum.
I ran the SS2 in a SBE LQ9 with 317's stock 10.2 compression and it ran pretty good.

 

I’m dropping it in an 85 t/a so maybe I’ll see about a set of 243s. There are some 317s around my area but if that would drop the compression then stock for stock I might just look for the 243s.

 

What fuel you looking to run in this? E85 likes compression! Some CNC ported 862's with a 2.00 inch valve and now you have the best of both worlds.

 

I was planning 91 we don’t have 93or anything close to where I’m at. We’ve been getting more e85 around

 

The two options listed are both decent:

I don't know what that dish translates into for CC's.

706/862 heads from a 4.8 or 5.3. Better if you have them CNC ported, and go 2" intake valve. On a standard LQ4 dished piston, these get you to around 10.6-10.7:1 CR, I believe.
243/799 heads get you to about 10.2

Now, you can also go with a 0.040 or 0.045 head gasket, this gets you tighter quench and smaller effective chamber size. And you can mill. And do combinations of these things.


From another post on here:

Here is a stock bottom end LQ4 compression calc breakdown using stock LS2/LQ4/LQ9 Head Gaskets:
72cc - 9.47:1
71.06cc (stock 317 chamber) - 9.56:1
71cc - 9.57:1
70cc - 9.67:1
69cc - 9.77:1
68cc - 9.87:1
67cc - 9.98:1
66.67cc (stock LS1 241/853) - 10.01:1
66cc - 10.09:1
65cc - 10.20:1
64.45cc (stock LS2/6 243) - 10.26:1
64cc - 10.31:1
63cc - 10.43:1
62cc - 10.55:1
61.15cc (stock 5.3 706/862) - 10.66:1
61cc - 10.68:1
60cc - 10.80:1
59cc - 10.94:1
58cc - 11.07:1
57cc - 11.21:1
56cc - 11.35:1