I am building a gsr right now. The motor spun a rod bearing before i had got it. I replaced the crank and had a mechine shop check everything out and all looks good except for the gsr rods so i got a set of p72 type r rods from a friend. Another friend said that he could press the gsr pistons on my new rods and ended up screwing the pistons up some how. They look like they were droped on the ground. So i have a set of PR3 usdm b16 pistons and a set of PR4 b18 pistons. with the ls pistons i will be 9.49 to 1 and the pr3's 11.28 to 1. The motor will be boosted soon. I know the comp is high with the pr3's for boost but are the ls pistons weaker or will it be ok. the motor has a ported gsr head, ctr cams, skunk 2 valve springs, retainers, intake manifold and cam gears. thanks for the help

steve

 

if u have *****/money u go for the 11+
if ur cheap/poor you go for the 9ish comp

 

Werd 11+ is danger zone for a stock boosted motor though. I think i'm even going to be pressing my luck at a 9.7:1.

 

The ringlands probably wont last with the pr3's, I don't really wont to pust my luck with the pr3's because i am pretty good ar blowing motors up. So is p72 gsr piston stronger than a pr4 ls piston? I will go find a set of gsr p72 if they are stronger and they will make the turbo spool sooner. Witch piston will i get more power from? I know that i can run more boost with lower comp but will i see more power with higher comp and less boost?

steve

 

if you got the PR3's in with the 11:1 comp...just go all motor...unless your wanting to boost then go with the ls pistons to lower your compression ...if you go high comp with boost ...youll end up seeing your head pop through your hood....

 

Cast is cast...they're really not meant for boost to begin with. And especially if you have a tendency of nuking motors, go with the lower c/r. Only thing you'll really gain with higher c/r and lower boost is more heat and more than likely more detonation if not properly tuned. Take our advice...go with the lower c/r. Don't worry about the PR4 pistons not taking the beating...they will. I cracked a sleeve before any of my pr4's went and they still look minty fresh Ringlands will go with enough abuse, but it's more of an inherent problem with d-series pistons.

 

Ls pistons it is then. Thanks for all the help

steve

 

your intake valves will hit the ls pistons.

 

How so? Ls pistons should sit further down in the deck than the pr3's and p72's If that's the case, clay it out then and make sure first.