Hey guys, new to this site, i usually stay on clubcivic but I posted on there and got no answers so I figured id try here and see if anyone could help me out.. I have a Jdm b18c in my 96 civic. Im currently in the process of rebuilding and I was told that putting PR3 B16 pistons in would raise my compression.. Used a compression calculator and found the compression to come out to 11.3:1 . I was just wondering if bumping my compression from 10.6:1 to 11.3 would require me to have to tune my car? And are there are fitment issues at all when doing this? Ive read that you must take off about 1mm from each side of the b18 rods for the pistons to fit, just wondering if anyone can shed some light on this for me? Thanks!

 

shimming the rods, yes, tuning yes. want to be a normal honda guy? dont tune it, throw it together, hit vtec.

 

LOL

use the stock ecu for a turbo motor etc....


anyway, as for the op. those compression calcs can be off, especially if they don't have domes correct or chamber volume.

if you have a jdm gsr that means p72 rods which happen to be the same rod in the jdm itr and a p72 head. the pr3 has a larger dome than the p73-00 pistons and those give you 11:1-1 with a pr3 head which has larger chambers than your p72 head. steve at hmotors online has some authentic honda jdm itr pistons new in the box which will fit the p72 rod with no modification and should put you in the low to mid 11s for compression with that p72 head. i could have sworn the pr3 pistons with a gsr head were just under 12-1, i could be wrong of course but double check the cc's and calcs

also be real with how much compression you use. the engine will be more efficient and get better mpg as well as burn cleaner if you can use a full timing map versus having to pull timing to prevent detonation. 11:1 works just fine on 91 octane but higher than that on a 100deg day, especially if you run the car hard or have 3 friends stacked inside is asking for pinging/detonation

i had a stock jdm itr, stock ecu etc. on a hot day it would ping under load. personally i wouldn't want to go much higher than low 11s for a street car

 

Thanks for getting back to me guys. And yeah, I dont plan on going higher then that anyhow, but I think im jus going to hold off on them anyhow if its gonna be that much work and money.. Im better off buying hondata and just saving to get my low comp pistons and rods for next winter.. I plan on boosting it but the pr3's were BNIB for a decent price so I thought, hey whynot if its cheap and easy but its too much work for what its worth for one season.. Thanks for the help though!

 

if you're boosting it leave the 10:6-1 compression and run e85. car will be extremely responsive as long as you leave it around 300whp

if you want big numbers that's sleeved block, manley turbo tuff rods and forged pistons.

i would assume if you change the pistons you're going forged and if you do you'll have to have the block professionally honed to get that extra piston to wall clearance which means a complete tear down

 

Id liked 9:1 comp. Yes forged pistons and rods for sure.. Their going to be the first thing I purchase, even before any turbo gear, that way I know the chances of it blowing up on me are slim.. I only want 300ish on 10psi if possible, but i want to feel comfortable driving it, i dont want to have to worry about it detonating on me.. and honestly I have no idea where i can get e85 around here.. I live on the east coast of Canada and all we have for **** gas is 93 octane i believe.. and the tear down doesnt bother me, because im hoping to buy an 06 si for a daily this summer so having the car in pieces shouldnt be an issue!

 

all depends on the turbo and manifold you to know if 300 is possible at 10psi. you should be close with anything from a 5431e cea to a GT30x if you go garett. the guy i sold my old car to has a 3071 on a stock R motor and it's pretty wicked.

even if it takes a couple more pounds 9:1 with 93 octane shouldn't have any problems at 12-14psi provided the timing isn't too crazy

if this is a street car be thrifty with your choice of pistons. 4032 alloy expands less and that means a longer ring life and less rattling when cold. the supertech or mahle pistons can be setup at .0030 to .0035 PWC. with wiseco or the hardcore 2014 race pistons you're at .0045

 

I was planning on going with a boostflow ramhorn manifold along with a garrett gt35r turbo if possible, hadnt really made my mind up on any of the pistons or anything like that yet.. Im just starting to research all of this stuff and make sense of it.. And to make matters worse, the mechanic who I bought the motor from along with one of the guys he works with are trying to convince me to go all motor.. lol, so im a little torn at the moment.. Ive always wanted boost, just because to me it seems easier to make power and be faster, but with an all motor build id like to be anywhere from 220-250whp on pump gas. I guess at this point im just looking for opinions wether I should go boost or N/A and what the pros/cons are of both..