BC_Garage

I'm in the process of rebuilding my 98' B18c1 to put into my civic. It's been bored .25 over and I'm at the point of ordering pistons. Wanted to shoot for around 190whp somewhere in the future but I know I need to bump my compression so I am thinking about putting USDM ITR pistons to raise the CR to 10.8:1. Here in California we have to BAR the motor by the state ref in order to avoid major fines. Tuning is out of the questions but my question is will the motor run correctly with the ITR slugs and no tune on a stock obd2 GSR ECU. I've been reading some say It'll be completely fine at stock timing with stock ECU and others say it won't. Can I get away with driving on it for a while with no tune. I will beat on it some and won't be doing headwork for probably about a year.

Cynical 1

why not tune it on an obd1 ecu, and smog it on the obd2?

or, run an obd2 type r ecu...

just my thought. someone with more knowledge hopefully will chime in...

BC_Garage

Yeah my point is I want to use the OBD2 GSR ecu if I can. Everything is stock besides the USDM ITR slugs. Will it run perfectly fine on that ECU I want to clear that up.

m_shake

My odb1 gsr ecu ran a more aggressive setup then that and passed California bar and smog

mouab18c1

iTrader: (5)

My old setup with ITR pistons bored .25 over in a gsr block/stock head ran like **** on an obd2a GSR ecu. Converting to obd1 and get it tuned is your best bet.

BC_Garage

Let me ask this then? is the .8 bump in compression worth it or can I make decent power with stock GSR pistons. I really don't want to get it tuned because I cannot pass BAR with a chipped OBD1 ECU.

00Red_SiR

you should be fine unless you ran some big cams with larger primaries. In other words, go with the JDM ITR pistons and go for 11:1, as long as you're running something like ITR cams, you should be fine.

BC_Garage

I will be using USDM ITR pistons not the JDM ones only shooting for 10.8:1 CR. I will be using a completely stock GSR head. My question is will it be a problem running those pistons with no tune and still beating on it occasionaly when the motor is broken in.

00Red_SiR

If you're running stock GSR cams then honestly I don't see much of a problem using a stock ecu.

BC_Garage

^^That's what I thought and I've heard a few people say you can run the ITR pistons in a completely stock GSR with stock timing and stock ecu with no problem and I've heard others say it'll run like **** or will lose power.

I don't want to rebuild the motor and then **** it up or use the ITR pistons untuned and have it make less power than a stock GSR.

mouab18c1

iTrader: (5)

Mine personally did not run smooth, driveable but it's not worth rebuilding to just have it run so so.

BC_Garage

So from sounds of it untuned itll make less power than a stock gsr

m_shake

Mine had a ported and shaved head(bout 11.2:1) itr cams and a s2 intake manifold. With the stock ecu and s2 manifold there was a noticeable flat spot in the mid range...but passed smog so I was happy

OH_1fstgsr

iTrader: (2)

I ran USDM ITR Pistons in my GSR on the OBD2a ECU for around two years. It only ran into trouble when it was really hot. Like it is right now. Can't remember the code it would get.
If you don't have to do this I wouldn't recommend it.
I don't have the before tuned numbers, around 160ish but once it was tuned it made 171whp/128wtq.

BC_Garage

^^ Wow those are nice numbers when it's tuned was that a completely stock GSR with ITR pistons. I think maybe I will tune it and then just put in obd2 ECU when I want to smog and BAR the motor. When you ran it untuned did it still pull hard or did it run bad.

OH_1fstgsr

iTrader: (2)

Yes it was. Completely Stock GSR Head. Hondata S300 in an OBD1 P72 ECU with harness modified for IAB.
The bolt on's:
DC Sports 4-1 header
Comptech Exhaust
Stock Cat
AEM GSR CAI

angryhillbilly

just get a tune. its the right way to do it. or get a hondata with a program that has worked well on similar motor builds.

or make ur build more like a type r. get type r cams and a skunk2 IM. then run a obd2 type r ecu.

BC_Garage

If I chose just to use GSR pistons how much WHP can I make with a good set of cams?

00Red_SiR

That compression level limits your cam selection to not much more than a typical stage 1 cam.

BC_Garage

So then in your guy's opinion its worth getting the ITR pistons in the GSR and spending the extra money to get it tuned and maybe put the OBD2 ECU in for smog and to BAR the motor

mouab18c1

iTrader: (5)

Correct!

BC_Garage

Okay then I'll do that. I don't want to break it in on the dyno I have no way to tow the car to the dyno shop. Do you guys think it'll be okay if I break it in on the street normally and then have the shop tune it.

.25 oversized p73 pistons & rings
new OEM Main & Rod bearings.
All gaskets replaced including valve seals
Hondata Intake Manifold Gasket
ACT 12 lb flywheel
Exedy Stage 1 Clutch
Comptech Intake
DC Header
Everything else is stock

Will this be okay to break in on the street for maybe 5k and then take it to get tuned?

mouab18c1

iTrader: (5)

Breaking it in on the dyno or street is up to you as long as you do it correctly.

BC_Garage

So then driving that setup is not a problem with messing up the engine the problem is that it won't make the most power that it should

igorka_91

iTrader: (1)

from personal experienced. rebuilt my b18c1 with usdm 81mm slugs with 114 kmiles on it. has 34 k miles on it. out of those 34 k. about ~25k miles were driven/raped/abuse on a stock obd2 gsr ecu with wot AFRS inthe mid 14s . ~5 k were on a crap tune and now about 4 k on a good tune. Passed smog with it with flying colors. The only thing that you will have to break in is your rings. I would get it dyno tuned/broken in. Your engine will get stronger and stronger as the rings seat fully.