I have a question for cammed folks, especially those of you in Cali. How hard is it to pass emissions with cams or ported heads. Normally I'm all for FI since you get more bang for the buck but lately I've been kinda obsessed with the idea of cams and juice. Cams and a direct port setup hidden under intake manifold would be pretty sleepy under the hood(but not at idle
). Whats the science?
Well, I don't know squat about how CA tests anymore, but over here in NE where we pray to the CARB altar (read: parrot everything CA does emissions-wise) - the "test" for cars after ~1996 is entirely electronic and visual... (ODB code scan and check for cats and other required components on the engine).
That said if they are using a sniffer - here's what you are likely to run into:
1. "porting" increases the engines ability to "breath" - more air. More air means more efficient combustion (i.e. cleaner output), but it also typically means more fuel as well which means more "particulate emissions" (crap coming out of the tailpipe). Its like installing a larger, but proportionally cleaner engine.
That said - since they won't be taking your car down the track with a sniffer in the tail - its easy enough to have a "street tune" that goes easy on the fuel and timing and in most cases will mean that a ported head can run cleaner (if you want it to).
2. "cams" are a different issue. With the exception of towing cams (we can assume you aren't building a towing mule out of your stang), most all cams are going to sacrifice idle/low end combustion efficiency for mid and top-end which means the engine will have less efficient combustion at idle/low RPMS and thus "sniff" dirtier. To some extent - provided your cam can cooperate with VVT (largely a function of lift and/or piston relief ensuring no valve collision), again you can compromise a little here and use a "street tune" which cleans things up...
So, first - find out if the test is just an ODBII test in which case all you need is the right parts on your exhaust pipe and you are good to go...
Second, if you are concerned about passing a "sniffer" - then do ported heads, but stick to the stock cam or something close and keep VVT functional.
