This goes out to the guys running a gsr block with ls crank, I understand that you need to use the ls length rods and I know that the aftermarket b series pistons are all the same except for the valve reliefs for different engines(pin placement is the same). I have gotten mixed answers on this subject in my quest. It would make sense to me that for a high compression build to use the gsr pistons for the extra valve relief clearance but for a low compression build does it matter? should i get the gsr or ls pistons? pistons will be cp.

 

I would like to know the same answer. More specifically I have a GSR block, LS crank, Eagle LS rods, and I would like some pistons that would net me around 9.5:1 to 10:1 compression for strong off boost power.

 

Well, I guess if I were to go through the trouble of doing this great build, i would not use an OEM piston at all for a boosted setup, whether I had the OEM pistons there or not. that's what the marketplace is for... Otherwise, check your Wiseco,Arias,JE,CP piston catalog for the LS/VTEC hybrid section. (it will say LS block with B16 head, or some similar description.) the compression that they dictate from that setup will be about where you would be if you used an LS crank, LS Rod, B16 or GS-R head

 

pistons will not be factory most likely going with cp's, did you use the ls or gsr pistons in your build? forced induction i assume

 

The block that I am building now is a GSR with an LS Crank, I am using GSR Arias Pistons.... would of ran the GSR's if it was a low, mid or high comp setup.

I can tell you that flat top shelf Arias Pistons with a GSR head/block, LS Crank/Rods and a stock size gasket will net you around 10.8:1

In my opinion I would always take a piston that gives me the most P/V clearance that way if you ever swap in a high lift cam and your running OS valves you will have a little more room.

 

10.8:1 is a wee bit high for boost for my preference, but thanks for the info.

Sorry to the OP, as I don't want to seem like I'm hi-jacking your thread. I'm just interested in the same information you are.

 

no problem...

 

I was giving you a reference point for their Flat Top Pistons, most of you guys will run a piston with a dish, which drops the compression ratio.

I am running 10.8 because my car will only get E85 or race gas.

 

i have seen several high compression turbo builds that are very strong..like you said on e85 its very tempting

 

It can be done on pump too but there is alot of risk involved and little room for error, a bad tank of gas and you could be in for some problems....

 

Personally a lower compression motor is a more happy motor.. I would stick with something in the 9.0:1 to 9.5:1 range just to be safer. And I also like the choice with CP's not bashing other companies but I personally use CP's and haven't had a problem yet (knock on wood)

 

http://realstreetperformance.com/store/acura-honda-38/

Real Street Performance..They have rod and piston combos for a great price..alot of reputable brands too! If you email them, they can get you some CP pistons with the LS rods you need for the same price as GSR/GSR combos!

 

bump for some more opinions...looks like gsr is the way to go for low and high compression

 

Aftermarket pistons are the sam for gsr or ls the compression will be slightly different but if u order a 9:1 gsr or ls pistons u will get the same piston.

 

I'm currently running eagle LS rods with ls crank and SRP gsr pistons in a gsr block. its roughly 9.3:1 compression ratio. havent had a single issue and the srp pistons dont expand as much due to higher silicon content so less piston to wall sfor a tigher quieter start up

 

I used a CP piston that was for LS/VTEC at 9.7:1. When you choose from the site, choose as though you were doing an LS/VTEC conversion to get the dome height correct for the compression you want. I never went by "LS" or "GS-R". I went by the specifications of the piston, I guess.

 

thank you sir...

 

imo you just need a super strong flat top. 11ish : 1 is perfect.

 

for 93 pump maybe E85

 

i am running a gsr block and i am using the ls eagle rods, and forged pistons.. you also use all ls acl bearings... main and rod bearings ls.. and thrust washers as well.. that is all you have to know to put the ls crank, pistons and rods in a gsr block.. that is what exactly what i did and it is working fine..

 

im using the cp dished pistons in my mixmatched motor(includes ls crank and eagle rods in jdm gsr block).

 

Why are you running LS mains in a GSR block? Who told you to do that?

 

main bearings in the b series are all the same.

 

My fault you are definately correct.... All B mains are the same bearing

 

If you're not using OEM pistons, it won't matter. All will have releifs made for oversized valves. The 0.5mm oversize and extra stroke will increse CR by .2-.3 points last time I checked, but with the larger CC size it will only be .1-.2 points.

If you use OEM pistons, you're limited to what the LS rods can do, so the higher compression won't harm anything. You won't be running huge power anyways.