How to get 11.1 compression in a LQ4
09-18-2009, 07:58 PM
#1
How to get 11.1 compression in a LQ4 My LS1 just spun a bearing so i figured i would build an LQ4 to make better numbers. My question is since the LQ4 is gonna get new rings and bearings since its already gonna be in short block form what else do i need to do to to the internals to make 11.1 compression. Use flat top pistons? I know the heads can be milled to bump up the compression but im not sure if i want to mill a set of heads to have my cam options pretty limited after that. My car needs to pass smog since im in CA anyways so i will probably put in a TR224 but who knows. So if you guys can help me out with the compression question that would be great. 
09-18-2009, 09:46 PM
#2
Def gonna need flat tops. Whatever compression depends on piston choice and combustion chamber size. Smaller combustion chambers for a given piston will yield higher compression. You need to find a piston to match whatever heads you decide to go with. I would suggest 243 castings vs the 317's because it's the same exact head but the 317's have a larger 72cc combustion chamber while the 243's have 64cc (I think).
09-19-2009, 03:34 AM
#3
i was probably gonna run the PRC stg 2.5 ls6 heads. or the PRC 215 heads that texas speed sells since they are in my price range. does anyone know what a good set of pistons would be? and is it worth buyin forged ones? i want to run a 100 or 150 wet shot on the car but it was to my understanding that the lq4 internals are pretty strong? my goal is to have a low 12 second 1/4 mile car on street tires(12.1 or 12.2's) but have a car that hauls *** on the freeway
09-20-2009, 05:29 PM
#16
speed pro pistons pressed to stock rods, 1/5/1.5/3.0mm rings. i assembled the engine. using clevite bearings, cam bearings were installed by machine shop. and i assembled the rest, degreed cam etc.
pistons and rings are less than 400$
09-20-2009, 05:43 PM
#17
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Def gonna need flat tops. Whatever compression depends on piston choice and combustion chamber size. Smaller combustion chambers for a given piston will yield higher compression. You need to find a piston to match whatever heads you decide to go with. I would suggest 243 castings vs the 317's because it's the same exact head but the 317's have a larger 72cc combustion chamber while the 243's have 64cc (I think).
09-20-2009, 07:25 PM
#18
nope, the pistons are made to be pressed to stock rods, engine was align honed for proper spec, rods were honed with arp bolts, tq plate honed,decked .006. just basic machine work.
speed pro pistons pressed to stock rods, 1/5/1.5/3.0mm rings. i assembled the engine. using clevite bearings, cam bearings were installed by machine shop. and i assembled the rest, degreed cam etc.
pistons and rings are less than 400$
speed pro pistons pressed to stock rods, 1/5/1.5/3.0mm rings. i assembled the engine. using clevite bearings, cam bearings were installed by machine shop. and i assembled the rest, degreed cam etc.
pistons and rings are less than 400$
