CRXguy_88

iTrader: (7)

I have a B17a1 complete bottom end and a B16a head. I want to switch the pistons out for some higher compression ones but i'm unsure of what to use. Should I use CTR (B16B's) P30 or PR3's? whichever one is recommended, will i need any work done rod, block, crank or head wise? will my clearance be ok with the head? Any input would be great thanks!

hoga113

Get the B16B piston, if you want higher compression, the stock bore all the same for B16, B17, B18, other job for the bottom, depend whats wrong with it, ask the machine shop after they take it apart and measure it, and the B16 head its better than the b18 already coz its have bigger combustion chamber, your combination there it's called the poorman type r. But if your still want to pass smog get the USDM Type R piston.

CRXguy_88

iTrader: (7)

thanks for your input. but now looking at my post i meant will anything need to be done internally with those pistons or will they just drop and go.. not if there's anything wrong w. my block in general. just want to make they'll work fine. and I don't have to worry about smog testng here in KS I'm going JDM! lol

jdmboyef9

The B17 has the same head as a B16...PR3. Also the B17 and B16A share the same block. The only difference is slightly different crank and rods. Check out Zealautowerks.com for a compression calculator to help you better understand your setup and different combos with stock parts.

As far as a B16 head being better than a B18C P72 head because of the larger combustion camber...that is some of the worst info I have heard. The larger combustion chamber in the B16 head lowers compression. The GSR has what's called quench pads that are designed to increase compression. The B16 simply flows better. Many head builders actually weld in these quench pads onto B16 heads to increase compression. Don't always believe what people say on here because they clearly have no clue

CRXguy_88

iTrader: (7)

I already know all the differences in the crank and pistons in a b17. I know they are the same block just asking which pistons would ppl recommend and if anything would need to be changed internally with either of the pistons or if will drop and go.. because i believe i read somewhere if you went w. b16b's you have to shave the rods or something that's why I'm asking.

DCRB

id go with b16a's (pr3?), keep it pump gas friendly

hoga113

sorry I put B18, what I mean is GSR B18, not the type r one.

CRXguy_88

iTrader: (7)

what would be the highest compression ratio i could run normal pump gas on just fine. and i calculated pr3's w. a 2 layer gasket at 11.02 to 1 and a normal 3 layer at 10.7 to 1...

zrickety

iTrader: (1)

i'm running the b16b pistons, calculator puts it close to 12:1. yes, the rods had to be shaved just slightly for those pistons. everything bolted in and runs great on premium gas.

b17power

b16B

CRXguy_88

iTrader: (7)

ok so I calculated...

B17 block
B16 head
B16B pistons
OEM 3 layer gasket.... 11.361 to 1


Would that be pump gas friendly?


or could it be possible to squeeze 11.695 to 1 with a 2 layer gasket?

12.05 with one layer? lol


Thanks, guys

DCRB

honestly what's going to matter the most is the tune. aren't type r's around that compression stock?

jdmboyef9

As stated above Tune tune tune. And that does not mean chip because that will ruin your engine. I ran 13:1 on pump gas but it had a lot of timing pulled out. Stock basemap I would stick with B16A pistons because you don't want to ping

Deetz

stock itr compression....

usdm- 10.6:1

jdm- 11:1