If this is your daily or mostly street driven truck, I would opt for the higher CR. I am currently running 11cc pistons with 241 heads for a 9.74 SCR with ~11psi. I had the shortblock built with the -11cc pistons with the intentions of lowering the CR with a head swap to add more boost in the future but my plans may change. I think I am going pully up to 15psi then I may actually increase the compression when I get a new set of heads depending on what I see at 15#.

 

If you want max power go the lower compression route. If you want better driveability, go with the higher compression route.

 

What he said ^

For highest output Boost > CR

 

hell mill the heads a bit, and throw a thinner headgasket on it, bump it up to ~10:1 and then you can run it like that till you feel like you need more, and then go to a meth kit. higher comp works better for blowers anyway right?

 

IMO low compression high boost.

 

Well...I'm running 9.3:1 CR and 10lbs of boost w/ meth. I can tell u first hand that the low compression is costing me a good chunk of ponies. I'm not so sure shaving my heads wud do the job either and I'd prob have to change pistons for diff dish/and change heads to get closer to 10:1 - which seems to be what everyone tells me is ideal...but frankly ITS FOR SALE so 550rwhp is where it'll stay - I cud be driving a nice Italian model for what I've spent on this thing!!!!

 

3rd that. On a heavy vehicle, the high compression route will make it more driveable off boost. I'm assuming you are going to get a more Centrifugal friendly (wide LSA) cam once you rebuild so that may also kill some of your bottom end also so I see why you are leaning that way.

The LC version will ultimately make more overall power and with your PC pullied to hit say 17-18lbs, boost will come on a lot faster so the decrease in low end torque may be moot in a 2WD truck.

The quench will not be a factor when you are running a lot of boost. All that air being forced into the cylinder will be you all the swirl you need. Keeping the quench tight will help when your out of boost and cruising.

What is your piston height on your 370? I think I may be running the same pistons (Wiseco K444X05 -11) on my shortblock and my piston height with a stock crank, new GM 6.0l iron block and Lunati Pro Mod rods is .004 in the hole. With my AFR 225 72cc heads and a GM LS9 .053 head gasket, I'm hitting 8.94:1. I'd like it to be a little higher but milling the heads to 70cc only raises me up to 9.11, 68cc bumps it to 9.28. I'd rather keep the deck extra thick.

Rick

 

how can anyone answer this question with that avatar you got going on? nice!

 

no clue really on what my CR will be but it is a 4" stroke with 4.030 bore and -20cc dish
and 72cc heads...

can someone tell me what i will be at...
i'm sure the 91mm will do fine i'm just curious...lol

 

Around 9.15 for 0.051" head gaskets