so i bought some pr3 81.25mm pistons for my gsr build but the block has to be milled due to a chip in one of the cylinder walls. but come to find out need bigger ones so, i decided to change my pistons to p73-AO doing this to lower the compression to 11.1:1 give or take. But does anyone know if they make 81.5mm oversiezed. also where to buy these if so.

my setup

gsr block
ls crank with ls rods with arp
gsr head resurfaced 0.07
skunk2 high compression valves
Skunk2 retainers
skunk2 springs
skunk2 pro 2 cams
oem 3 layer gasket

 

why in the hell are you using the weaker LS rods? you do realize the extra displacement is literally worth 1-2hp and ft/lb?

p73-a0 is an american ITR piston, check with your acura dealer if you want to use it. another trick to bring compression down is either

A: using ferrera valves which are dished slightly more than the oem
B: blend the chambers which can buy you a cc or two via removing casting flaws and smooth the sharp edges

anything up to 11:5-1 to 11:8-1 can be tuned pretty easy with a full timing map

in fact you could probably do 12:1 with those giant pro2 cams.

still think you're nuts for not using the gsr crank and rods in an engine that's going to 10k rpms

make sure you gram balance the bottom end on a spintron and run the bearings on the loose side of oem spec

 

I do realize that they are weaker but ls rods have been used in many turbo setups. That is why I put the ARP rod bolts for some insurance. i would like to have got different ones but cutting costs in someplaces. I choose the usdm version of ITR pistons to keep the CR a littler safer as this will be my everyday vehicle with a little kick

im also going to be using skunk2 intake
Question?
will the Ls throttle body hurt me?
And
does anyone know of a cheap remake of the Itr pistons in the 81.50mm size i need. and what good brand?

and I choose to use the ls crank because the gsr crank i have needed to much more work to save. while the ls crank just needed a micropolish, as well as gain a few more hp and tourgue.

 

well i got my 81.5mm itr pistons for inline four. so: www.inlinefour.com There probably the best shop in cali for honda/acura.They have ctr/itr domes usdm and jdm types from 81.25, 81.5,82mm and have the special head gaskets for those sizes ,cause the factory gasket is only good for a 81.25mm oversize. Hope that helps

 

you're using cams that might make it 40k miles for a DD?

well, the cams will go longer but that is such an aggressive lobe that it puts a lot of stress on the seat and guide

 

well thats the plan im sure by the time i hit that 40k mark i will go turbo and change my hole setup again anyway so im not to worried about it.

thanks gsr tom looks fresh

 

Pro2s are to big for you're setup. I am surprised no one stated this yet. It will make good top end butt low end and mid range????? Ill let more experienced guys talk.

 

Why do you say that its to big? for a everyday driver?

 

No not for everyday drive. Just You dont have enough CR to make the pro2s function properly. They will make great top end power butt most likey mid range and low end will suffer. Like i said. Let other more experienced ppl chime in like all motor.