I'm 12.2:1 compression on 91 spraying a 325-350 shot with c16 fuel in a 1 gallon stand alone fuel cell.
If you have a wiseco +12cc dome piston with an ls9 head gasket and stock unmilled ls3 heads that will give you a 11.9:1 compression.
Bad thing is that there's not like middle of the road piston that'll net you around mid 11:1 or so. But with my compression ratio on 91 octane I don't get any detonation at 28 degrees where I make where I make most my power. Good thing about having 15 degree ls heads you don't need all the ignition timing like an sbc head needs to make your peak power.

 

Also the Mahle pistons are a forged 4032 whereas the Wiseco are a stronger 2618 forged material, also have a better ring package along with having thinker ring lands for a nitrous engine.

 

Ok called mahle today and with stock ls3 heads and .051 gasket I'm at 10.2:1
If I use .041 gasket at 10.4:1
Stock gasket and shaved to bring chamber to 64cc Im at 10.9:1

The Wiseco LS1 +12 pistons will get me 12:1 but also cost me $250 more.

Yet again at a cross road.

I think I just get my heads shaved and call it a day. This is after all a truck and not a race car.

 

compression makes a world of a difference expecially with these heavy trucks

 

Ok Im back looking at these....My heads starting to hurt LOL

What are we talking in HP gains?

 

30-40 hp

 

$250 more to upgrade pistons

$6.25 / HP is a Win in my book.

 

There ya go lol

 

you wont regret it.

 

First I would Like to thank dirt track racer 81 for me bugging him with PMs for a few days here.

I contacted Justin and Geoff about going 12:1 and this is what I got back.

From Black Bear
Just got off the phone with Geoff at EPS and he also said my Cam was not made to go that high. He said if I would have called and said I want 12:1 he would of had a totally different Cam Made. Reason is that on big cams the Intake valve is open longer on compression stroke where it pushes Air back into the intake which cause less Volume of Air to be compressed.
He said he would have to sit down and run the numbers on my Cam but off the top of his head he thinks the Cam I ordered from him will be the happiest at 11:1. Anyone down the road reading this for sure give Geoff at EPS a call for all Cam questions. I have 4 pages of contacts from looking for parts and Geoff is the only guy that talked to me other then giving me a price.

My cam Specs are 222/230 112 +3 .628/.604

So Im going to mill the heads and use smaller gasket to try and hit 11:1 with the mahle pistons. $125 to mill the heads from my Shop.