fast400

iTrader: (1)

I want to retain as much emissions as possible. I'm seeing that I'll probably wind up using hooker long tubes. If I put cats directly after the longtubes will they be effective at all? Has anyone done this...or been forced to do it due to regulations?
Where are you mounting your evap system (those that kept it)?
Thanks.

a10beav

The cats should be fine right behind the headers. I recommend using Random Technology cats as well.

bczee

iTrader: (12)

Yes you can do that, they will work, but not as effective as if left in the Stock configuration.
Also.. just putting them right behind the Headers will still not make them legal. What are your goals for using Cat's. ? You should really check your state or local SMOG laws if your trying to pass the test. (not saying that you will not pass or get checked if your setup is not compliant to the letter of the law, but technically, not legal).

What car are you working with and what state are you in?

For my EVAP on my Chevelle, I use the stock Chevelle venting system to the Chevelle Charcoal Canister. Did not use the Purge valve cause the PCM would not activated it anyway. It requires the fuel tank pressure and level sensor input into the PCM. So I setup up like the stock Chevelle setup with Vacuum to the Canister just to pull the flumes throught the Charcoal Canister.

fast400

iTrader: (1)

Germany. It's a 69 Firebird. I'm concerned about the effectiveness not the legality. Not sure they'll heat up enough to work well. I'm trying to have fun, but not be a total polluter at the same time
I'll probably try to make the evap work also..

bczee

iTrader: (12)

They will work, but it might take a bit more to get them to heat up and be effective until they do. The rear O2 sensors should assist with reading and inputting to the PCM.

If you can get the EVAP system to work (with fuel tank inputs to the PCM) or just using the Charcoal Canister.. either way will be good.

But, you can pertty much get a good tuner to get it to run almost as clean as without the cats.

Keep us posted on what you do and the results.. as this subject is not really talked about much. I am considering doing a swap that will have to be Smog Compliant, so.. I'll be watching..

a10beav

Right now you don't have to pass emissions with a SOFA registration, is someone telling you that's changing?

ssvolvo

Don't skimp on the quality. I usually use Random Technology bullets. VERY good air quality, but spendy. I also have a portable 5 gas analyzer to verify these cats.
My last project I used Dynomax cats from summit. They look identical to Randoms at less than half the price. My tune is dead on 14.65:1 at low load and these Dynomax cats are garbage. THEY DON'T WORK. They also smell like a car with a gutted cat, might as well not have any. Spend the money and use Randoms.

fast400

iTrader: (1)

Thanks guys! I'll take a closer look the the random cats.

A10--I wouldn't be surprised if they start check emissions in the next couple of years. First the dB meter, then the tint law....next.....