Yo California guys, As we all know, some of us live in areas with very strict smog testing, on the chassis dyno with the sniffer up the tailpipe. The question is, if you are subject to this extreme testing, how much can you get away with on the engine? OK, we all know that it has to pass visual, so *everything* has to be there, hooked up and working. That's EGR, AIR, cat, etc.... everything. And if it's not working you probably will fail the sniffer test.

So, how far can we go on displacement, compression, cam, ignition, injection, etc, and still pass the smog test, visual and sniffer, on the chassis dyno?

TIA.

 

Until it fails....

There's no hard-and-fast "this many degrees" or whatever. Alot, and I do mean ALOT, of the equation, is in the skill (or lack of it) of whoever is doing the tuning.

Ignition will basically never hurt. For that matter, because they test parts per million and not grams per second or whatever, even displacement won't.

 

Is that what is used in California? Colorado's enhanced testing uses grams/mile.

 

Last time I had a car tested at an "enhanced" California facility, the readingswere all in PPM.

But if they used grams per mile, then displacement would cause trouble; although you could help that with gear. Put a T-56 in it.

But that was a couple of years ago, maybe in about 2001 or so. I could be obsolete. (and my knowledge too)

 

T56 won't help at all in California. They don't test in high gear, they test at 15 and 25 mph, with a given min engine RPM at each speed. For example, last time my IROC was tested, they ran both the 15 and 25 mph tests with the T5 in second gear. And yes, it's in PPM. 25 mph in second on my car spins the motor over 2500 rpm. That's faster than it runs when I'm driving 60 on the freeway. I think they do that specifically to make sure the EGR is working. if it isn't you'll fail that test.

So, since displacement and ignition seems to be out of the question, that leaves cam and compression as the big variables. Along with tuning and prom burning.

So, California guys, how much cam and compression can you pass smog with?

 

I just passed with 10.5:1 compression. Will be upping that to 10.72. Like Sofakingdom said the tune will be the deciding factor. Friends in our car club have cams in the high 220 degree range at .050 and have passed with no problems.

On the visual they can't see inside your motor so they won't know the displacement, cam etc. So as long as everything looks proper and you have CARB approved parts or appear to be factory you are good to go. With a good tune that should take care of the sniffer.

 

EGR is only truly actuated on the decel of the engine. Too much EGR when in the throttle will cause a lean condition which will cause the engine to stall. The EGR's function is to redue the formation/transmission of Nitrates of Oxygen or NOx, which occurs when there are high temps in the combustion chamber, i.e. after a hard acceleration. Here in Pa esp near Phila where I am from we have the ASM test which is the dynomometer run which puts a load on the engine and tests the HC to 02 PPM (Parts Per Million). The reason why the 25 mph test is actually conducted is to check the proper function of the catalytic converter and the A.I.R. system if so equipped.

As, far as performance parts/ modifications to internal engine i am unsure of what will warrant a failure during the "sniffer" test. Hope that the above information may help with your understanding of the test. -Bob