I’m building a b18c right now, the head is done, it’s P&P with valve job with crower cams (402’s), now i’m thinking about the block. The more i think about it, the more I think I should raise the compression, BUT, i don’t know how it’s going to affect smog. I’m in california, and I still need it to pass on emmisions . Anyone in cali have experiences with higher than normal compression and smog?
I’m concerned about this as well. I raised my b20 to 10.5 over the 8.8 it use to be. I’m just crossing my fingers that it will pass smog without problems.
I asked my dad which is a mechanic, and he told me that I shouldn’t have much worry since the b20z engines have the 9.6cr pistons. He just told me that if you go pretty extreme from the stock ratio, then u will prob have a smog prob.
well, stock usdm itr compression is 10.6:1, so that should be safe. I’m hoping i can go higher though. I’m planning on running between 10.9-11.1 in my setup. And i’ve been trying to find out the same thing.
dan is running 11:1 in his engine and passed the relatively strict tailpipe tests up in oregon (they use the rolling dyno technique just like some areas in cali). And his engine is pretty much completley built. However it did take some de-tuning to get it to pass.
also, i’ve been trying to figure out if 11:1 is safe on 91 octane… anyone know?
Running 11.7:1 C/R, 16 degrees of timing, and 91 octane. No problema…
thank you leo! so its set, p30 pistons, and remove a layer of the headgasket. That should put me somewhere around 11.1:1! oh boy, its gonna be fun
i’m stuck at 9.7:1. 
Originally posted by 93B18
Running 11.7:1 C/R, 16 degrees of timing, and 91 octane. No problema…
ahh but u have tried smogging it yet Leo??? tailpipe wise i mean… will it pass teh sniffer… unless u went the lowdown route smogging like me
robbie: do you know if i’ll be able to pass emissions w/ my 11:1 setup?
hahahahhahhha in florida we dont have emission testing!!!sukas!!!
whats up with your sreen name? Are you running a 2.2 b series motor? If so whats the set up?
hey kiddies…
high compression is fun and all, but we in SoCal dont have the freakin gas for it. I put b16 Pistons in my ls-v and i can hear it knocking…no and its not just the valves.
Originally posted by 91IntegGS
robbie: do you know if i’ll be able to pass emissions w/ my 11:1 setup?
Colin u might… but only a sniffer will tell for sure… i know with my set up i won’t biut then i don;t care… 
well, i’m hoping that cali’s sniffer tests aren’t any harder than oregon’s. Cause if dan can run 11:1 in his car, and pass smog, so as long as our rules aren’t stricter i shoud be able to pass w/ my humble future setup. I guess i’ll cross my fingers (but if i don’t pass i’m gonna be pissed).
I’m gonna bump this up in hopes someone can answer this question. I’m planning my build and am wondering if I’m going to have any smog issues. I’m not looking to go crazy on it but am currently planning either usdm or jdm b16 pistons and type-r cams on an otherwise stock b17. Fresh rebuild but stock. Any insight?
Colin have you smogged your motor yet?
You want the long story or the short story? lol When I originally did my build I ended up getting my smogs illegally because I couldn’t pass the visual, I’m not sure what the tailpipe results were or if he fudged that as well. Then the car sat for a long long time. I rebuilt the engine again and here’s the current status. My first go-around for smog I had a stock p61 ecu, stock intake, carb legal DC header, and SMSP highflow cat. This setup would not pass smog, but it was fairly close. The only way it would run clean enough is with the ignition retarded ALL the way. After this experience I assumed my problem was the cat.
Fast forward to this year and I’m up for smog again. This time my plan of attack was to keep my aftermarket intake and 4-1 header like normal but swap out to an OEM ITR cat and use my chipped ECU. I thought that since the ECU was tuned it’d be efficient and thus burn cleaner than using my stock p61 which was mapped for an entirely different motor. Well, the results this time were even worse than 2yrs ago, it didn’t even get close to passing. I should probably gather some more info, but what I’m being told now is that I would have been better off with the stock ecu. Reason being that the chipped ecu is programmed to run a little rich as a safety precaution. I’m now past due on smog but haven’t had time to deal with it (car is not my daily). Within the next month or two I need to take it back and see if I can get it to pass. I’m going to try the following setup:
- stock p61 ecu
- aftermarket or stock intake (depending on if I need to pass visual or not)
- Toda replica header (I am changing to this header because my 4-1 is trashed, not because I think it’ll help with smog)
- OEM ITR cat
I’ve got my fingers crossed. If that doesn’t work then I’ll likely take the car back to Church Automotive to have it tuned again. It could use a little tuning since I’ve changed some parts and at that same time I’ll ask him if he can make a second map designed purely for smog. A friend asked him to do this once and the guy said it wasn’t needed but maybe if I show him what’s happening to me he can figure out a way to help.
On a side note, I have a friend w/ an ITR engine in his EF and he passes smog (AEM intake, DC header, some kind of aftermarket cat, not sure if it’s high flow. I’m also not 100% sure if it’s a 10.6 or 11:1 engine).
Thanks Colin! I don’t remember the exact specs you’ve posted of your build but I believe it was a more aggressive build then what I’m planning right? I would really like to avoid needing to go the tuning route and just use a stock p61 but I’m not sure if that can be done if I change the pistons and camshafts. I know in order to get any major power upgrade out of it I would want to but if it would run ok and pass smog I would prefer to just use the stock ecu. What do you think?
Tune it. I cannot stress this enough. Lack of tuning is why I had to rebuild my engine twice. The first time around I thought the stock ECU would be fine, ended up running rich, washing out my rings, and needing to put the stock engine back in. Tuning should be under $300, which is pennies compared to the money you’re likely gonna dump into the rebuild and other parts. Hell, I’d even buy less parts and have a more stock build plus tune it just to be safe (if the money is a problem). Then you can always add more stuff later. You’ll want to tune for those other mods later, but if they are basic mods then it’s not nearly as crucial as the initial tune. Another option would be to run a P30 ecu instead of a P61, that would at least be closer to correct, but still less than ideal.
My engine (first build):
b17a
P30 pistons (11:1)
Second build:
b17a
P30 pistons (11:1)
ITR IM
CTR intake cam, P61 exhaust cam
Thanks for your input Colin. I’ve got a lot of reading and research to do before taking this on. I appreciate you letting me pick your brain though.
Being tuned is definitely a big step in the right direction… a “chip” or stock ecu is simply not what you need if you’re wanting to pass state smog inspections.
My biggest reason for wanting to use a stock ecu instead of tuning is I simply don’t trust anyone in my area to do it. I know there’s lots of reputable tuners down south but I don’t know anyone from my area I would even let touch my car let alone tune it.