BC_Garage

I want to make 200whp on my B18c1 that I am currently rebuilding. I have a choice of going with stock GSR pistons or USDM ITR pistons which I know will bump compression to 10.8:1. I know that it will be extremely difficult to make 200whp with stock GSR compression but my problem is that I want to BAR the motor therefore I cannot tune the motor, I need to use a stock GSR ECU. I know itll run fine but wont make the most potential power but will my emissions be effected. The state REF will check my ECU so will running these ITR pistons in a stock GSR pass emissions with no tune on a stock p72 ECU.

rhymeshark916

Good luck. You need a brand new OEM GSR cat. conv. if you want to have a chance to pass the sniffer. B16 pistons, forget about it.

spAdam

iTrader: (1)

P73-A00 pistons will be nice in your motor. P30s will be too much.

PyroProblem

Besides lowering the knock threshold, how does slightly higher compression affect emissions?

If a/f stays close to where its supposed to be, your getting a clean burn, and your cat is doing its job, I don't see how a little more compression would hurt emissions. There are several high performance vehicles from the factory with over 11:1 cr, some even 12:1 cr.

OP- Would it be possible to run an ITR ecu? I have no idea what is required to BAR your engine, but if USDM ITRs can pass, you should too.

If an ITR owner ever had his head resurfaced, this would raise compression also, but it wouldn't prevent it from passing emissions would it?

00Red_SiR

Emission of NOx increases with an increase in compression ratio. With a lower compression ratio, the premixed burning is high due to a longer delay resulting in lesser production of NOx in naturally aspirated engines. With an increase in compression ratio, ignition delay reduces and peak pressure increases resulting in high temperature which causes larger amounts of NOx formation.

Resurfacing a head would alter the compression ratio marginally and still keep Nitrogen Oxides levels within the acceptable range, assuming the emission controls are working properly on the car. Bumping the compression ratio up by roughly .6 might still be ok if tuned properly but I'm guessing that over a 1 point increase may get snagged in emission testing?

Other stock engines that run high compression engines probably have more elaborate (expensive) emission equipment that can handle the increased emissions (I'm assuming).

PyroProblem

Ahhh, I see...Thanks!

m_shake

My old crx had a b18c1, ported endyn head, itr cams, s2 intake mani, usdm itr pistons, and a stock obd1 p72 ecu ...with a fresh oem gsr cat the car ran almost all zero's on the test

BC_Garage

I dont think I have to get a GSR cat cus I have a 98 civic ex and the cat is under the car. I cant run a p73 ecu cus they check to make sure it matches the motor. I dont think i can pass BAR with these pistons cus in order to run it without a tune i need to retard timing and the BAR checks timing to make sure its stock. So I think ill wait and BAR it stock and then pull it later and put CTR pistons and Toda cams port and polished head and make more power

92civiceg9gsr

It most likely will pass as long as everything emissions wise is in place and functioning properly.

m_shake

Did you read my post? Like the part where it passed smog on STOCK P72 ecu(stock timing...thats a no brainer though cause you only get a +-2deg)

Libertariat

Emissions/BAR is ridiculous. I'd totally move to another state.

BC_Garage

I just dont want to build the motor and then not be able to pass emissions. I dont see how you could get the higher compression to run correctly without having to retard the timing

Drive 4 fun

Trying to understand the thread and compression. In a Honda motor of similar years and similar emmssion standards, seems like a Type R and Gsr of the same compression would pass. IIRC the JDM-R has slightly more compression and changed emission equipment. I thought part of the reason for our lower USDM compression was US/California emissions. It seems that exceeding USDM-R compression will start to get iffy passing Emissions/BAR in California where you cannot otherwise tune.

spAdam

iTrader: (1)

It will run fine on stock timing.

m_shake

Well it did and i got my bar sticker, so i was happy 2 years later after beating the car every day, i passed again running neptune and a wideband(no stock o2 sensor, no ELD)

94eg!

iTrader: (2)

Modern cars get away with high compression (04+ TL = 11:1 and some BMWs are even higher) by using an EGR system to reduce emissions. At low load they funnel hot exhaust into the intake which reduces the NOx reading.

This is why you fail emissions if your EGR ports become blocked w/ buildup.

BC_Garage

So if my emissions equipment is okay then running 10.8:1 compression usdm ITR pistons in a GSR with stock timing no tune at all will pass emissions??

m_shake

Assuming the engine is in proper running condition and a good cat is used(oem is the best, my random tech cat went from passing OKAY, to gross polluter in used a few months) i dont see a issue. My compression was about 11.2to1

spAdam

iTrader: (1)

10.8:1 is nothing to worry about. If you were above 11.5:1 or so you might start running into issues.

I used to run a gsr w/ the p73-a0's in it and .040" off the head (about 12.4:1!!) with a stock p72 ecu. In the dead heat of the summer I had to mix 93 octane with about 25% 100 octane low-lead avgas to absolutely keep it from occasionally pinging but otherwise it ran like a champ. Current build is at 11.34:1 and I never have detonation issues, even with really aggressive timing maps.

Just make sure to read your plugs, you may need to go 1 heat range colder, like a bkr7e11.

Granted I'm speaking for whether or not the motor will be mechanically sound or not, but that emissions crap you guys deal with out there sounds annoying. Is BAR'ing just something you do so that you don't have to get annual inspection or something? Whats stopping you from pulling a fast one and doing the build after you get your sticker?

BC_Garage

Here in California if you get your hood popped and you dont have the stock motor and dont have a BAR sticker than they will fine you like $1000 and make you put the stock motor back in. Its bullshit here. I mean i could put the motor in stock and BAR it and then pull motor and run something like CTR pistons with toda cams and make more whp than i originally wanted. But if USDM ITR pistons dont mess with emissions at all and i can use stock timing then i think i might stay this route

rhymeshark916

BAR your car with the stock B18C1 and then modify it to your needs after. You won't regret it. You would buy a $700+ catalytic converter? Where you can put that money towards your build.

spAdam

iTrader: (1)

^ Thats was I was thinking. As long as you've got that sticker and the motor looks stock on the outside, who's to know?

I still think you'll be fine with the itr pistons in there, but don't run ctr pistons with a gs-r head... you'll be over 13:1!

BC_Garage

^^Actually no CTR pistons in a GSR is about 12.32:1 def not over 13:1!! But i think you guys are right, I think I will build the motor stock for now and have fun with it and then once i have the sticker ill add higher compression pistons for a higher hp build

spAdam

iTrader: (1)

You sure about that? They have around an 8cc dome and compression height is around 30.75mm iirc. Thats HUGE, especially when you figure in the quench pads on a gsr head.

00Red_SiR

About 12.9:1

https://honda-tech.com/forums/all-motor-naturally-aspirated-44/pct-ctr-piston-compression-ratio-717928/