How does street porting affect emissions?
 

im planning on porting my 13b na motor, and am wondering if it will affect emissions enough to make it impossible to pass.

im using the pineapple large street port template

(I'm in Iowa, so I don't have to bother with emissions testing - take what I say with a grain of salt - though I have read up on it, because I used to live in Chicagoland)

For the emissions testing dyno, the load and RPM are low enough that the primary ports are the major factor.

If you hog out the primary ports, it may cause some issues with emissions. However, if you just clean up the primary ports some (but not dramatically changing their timing), you shouldn't affect emissions terribly much.

There have been a number of NA porting threads recently. Some of them IIRC have emissions information in them. General wisdom seems to be that leaving the primary ports alone (just cleaning them up) is a good idea, open up the secondaries a bit, and then do whatever you want with the aux ports.

-=Russ=-

let's just say that a mild streetport can make your car unsmoggable.


If you want to do engine porting and not worry about smog then I'd start looking into smog exempt cars or go start meeting people and make friends with smog techs. I'm waiting for 2009 to roll around so I can find a nice SA and to a Street Ported 13B-T.

A streetport will make emmissions worse, but not so much that you cant pass it. You will need a new cat with an air pump blowing into it, though.

Sorry, but thats just bullshit. I passed smog with a streetported 13bt with flying colors! You just need a fresh cat with air blowing into it. Its very easy.

wait, who has the most strict emissions? Does it vary by state?? AS far as I know my friend with his street ported NA did not pass and he had the air pump and CATS on there.

Just because your friend didn't pass doesn't mean its impossible to pass. I know people in many locations with strict emissions that have passed with a streetport. It is doable, but everything else must be in very good shape. That said, just don't go crazy with the ports. Introducing overlap can severely hurt emissions. Its pretty hard to add too much overlap with a regular street port, its usually the exhaust porting that gets you into trouble.

my friend not passing is what kept me from porting. I still won't until I get a smog exempt SA just to be on the safe side.

so only porting the AUX ports is probably the best choice and cleaning up the others.
but the pineapple template doest open up the aux ports much at all. So i need to search for some good aux port pictures.

if you have any pictures fell free to post them

yes, emissions tests vary by state. i believe CA is one of the worst (correct me if im wrong, people). i live in nc, and all pre 96 cars are all but completely exempt. i think they'll do the visual cat inspection, and kick the tires, but that's about it :)

well, we have the dyno test. CAr is tested at idle and then it's tested at 3000 or 3500 RPMs. SO porting would be a lil harder to pass but the guy above says it's ok. I still won't port my car though, I don't want to deal with it in case it doesn't pass.

The Pineapple template opens the primaries quite liberally and barely touches the secondaries, leaving the Aux completely untouched. Id say it makes the primaries 30%-40% larger. We dont have emissions in my area so thats why I chose the Pineapple template without hesitation.