Basically, I'm trying to decide what to do porting wise on my next engine. The main thing I'm worried about right now is passing emissions. We don't have emissions testing in Bell county yet, but I just noticed a clause that said if you are caught operating the car in a county that requires emissions testing and your car is registered in an adjacent county, you must get it tested. Williamson County, which is right south of Bell, has emissions testing and I have to drive through there to get to where I will probobly work soon.

So basically, there is a possibility that my car will have to pass emissions at some point.

That said, how far can you go with porting and still be able to pass a smog test? The car is already street ported, which I think already makes it iffy. I would like to get the exhaust ported is well. Will that kill any chances of passing the emissions test?

 

street port will not greatly affect the emmissions...much beyond that will mess with your numbers.

the rule of thumb is any increase in overlap will affect your emissions

 

In line with the above - You can open the exhaust earlier but not any later.

A bridge port is likely going to flunk emmissions.

My rotor bevel experiment may be passable, but It would need testing.

 

Yeah, that was kinda my thinking. Is it possible to make it flow better without changing the timing?
And yes, I kinda figured a bridge would kill emissions. I don't really have much interest in a bridge anyway.

 

There are some that have passed even califormia emmisions with bridge porting.

The key is tuning + cat with constant air supply. With a constant cat airflow and proper tuning to lean out the mix any port job can pass emmisions, I dunno about peripheral porting though. I would stick with the street port you got and maybe open the exhaust a tad.

I have a street ported 13bt that I will be trying to get thru emmissions in the next few months. I'll be probably running a restrictive 2.5 inch cat flanged in to temporarily replace my 3 inch RB presilencer. I will have an LS1 airpump constantly pumping to the cat. Also, a Steve Kan SAFC II tuning job. I think I shouldn't have much problem passing but I will post about it when I go.

There have been posts on here that show stock motors that had failed miserably.(due to old useless cats) Then passing with a fraction of the emmisions limit and all they had was a new cat + running airpump.

 

Make big aux ports. Those will not be detected. even the dyno tests. They never get the cars up into the top end.

 

Yeah, we only have the two-speed idle test in Austin (where I might have to pass emissions) so it shouldnt be too hard. I plan on having a megasquirt in the next year or so, so I can tune it with that.
As for the aux ports, I already have a port just done, and I don't know the specifics. I guess I'll found out soon enough, now that I'm done for the semester and finally have time to pull the damn engine.

 

You almost need absolute control over the fuel delivery and ignition timing to get the car to pass emissions.
It's not impossible, but it takes a few tricks to make it pass.

1) The cat has to be in absolute top shape - get a new replacement one if your original one is questionable.

2) Get the cat as hot as possible - it really helps to have an air pump here.
If you can rig it, get the air pump to blow into the cat at full blast all the time.

3) Lean the fuel mixture as much as possible - this drops the HC's.

4) Run as much split timing as possible - this cleans up the emissions.


-Ted

 

So, are you saying that I would have to have all that stuff to pass with an exhaust port, or just in general?
At the moment, I have no emissions, so I would have to get all of this other stuff if I have to pass emissions.