2 BBl Dual Exhaust

[MOPARJ]

I just recently acquired a 1975 Dodge Dart Swinger with a fairly fresh 318 anc 904. It is a 2 bbl car with a 3.21 geared 8 1/4 rear. The car has single exhaust with one cat, as its a California car. The car is fairly peppy as is, but just looking for a little more. I think I am going to keep it a two popper cruiser for now. Would removing the cat and intalling a 2 1/4 inch dual exhaust make a significant difference on this two barrel car? Do I need to keep the cat, even though its smog exempt?

If I have to keep it, can I add another one and still go with dual exhaust and get improved performance?

 

[340mopar]

It may be smog exempt in your state but it is not smog exempt as far as federal law is concerned. Legally you are not supposed to modify/remove any emission items. With that being said plenty of people do remove emission items and if you do decide to pitch the cat and go to duals you may need to go a little richer in the jetting.


Chuck

 

[MOPARJ]

It may be smog exempt in your state but it is not smog exempt as far as federal law is concerned. Legally you are not supposed to modify/remove any emission items. With that being said plenty of people do remove emission items and if you do decide to pitch the cat and go to duals you may need to go a little richer in the jetting.


Chuck

If it is absolutely illegal to remove the cat, can I add another cat to make it a true dual unit, or should I just put the muffler of my choice on the existing setup with a higher flowing cat and have a single inlet/dual exit design to get the look? Would that be the best way to go, legally, and would it still help performance?

 

[66dartgt]

You need someone that is familiar with the laws in CA to answer these questions - obviously.

I would imagine that if you were to install another cat then it should be okay in the eyes of the feds, but Im no expert on this topic. You will have problems getting a shop to install these, since it is technically against the law. Nothing to stop you from doing the work yourself I suppose.

 

[340mopar]

I am speaking in terms of federal law. Even putting two cats on a car that is supposed to have one is illegal. Being all states except one used the Federal standard this is what I am refering to and actually if a car has California emissions it still falls under Federal law. A state can make a law more strict than a Federal law but it cannot make a law more lenient that a Federal law. The Feds have juristiction over both 49 state and California emission standards. This is because the California emission standard vehicle may end up in another state. I have an '85 Cherokee with California emissions in Washington. Does this mean I am exempt because California can't do anything to me? No it doesn't because it is the Feds that have jursidiction over it.

Washington in some counties have emission testing for certain model year car. When a car gets to a certain age it is exempt from state testing but it doesn't mean that owners can do what they want because the state has no jurisdiction over federal law to allow modification.

Now because the state has no jurisdiction their law enforcement can't do anything about modifying, I know because I went down this path with a State Trooper some years back. It would take a Federal law enforcement officer to do anything about it.

Being you are only running a small 2 bbl I would just split to duals after the cat if you want the look and flow of duals. A single cat will flow much better with a bigger or more exit pipes because of lower or no back pressure on the backside. If you increase flow on the backside you will most likely increase flow on the front side.


Chuck

 

[Thrashard340]

If it is absolutely illegal to remove the cat, can I add another cat to make it a true dual unit,QUOTE]

In California, the answer is "no". The law says that if the vehicle came from the factory with a single cat then it must stay that way. The only way you can add another cat is if the vehicle came factory equipped/optioned with 2 cats. Which few vehicles in the 70's did.

The "emissions legal" option? Run 2 1/4 from the manifolds to the head pipe, then increase to 3". Run it into a 3-4" performance cat...tons of aftermarket companies make these. And then run a 3" all the way out the back. This is similar to what some aftermarket exhaust companies were offering for 93-97 LT1 Camaros and Firebirds when they first came out.

Or you can go with your 2nd option to upgrade the cat and split the tailpipes behind the muffler.

California doesn't require emissions testing on 1975 vehicles and earlier.

 

[rumblefish360]

I did a dual exhaust on a 360 in my first magnum (79). At the time, New York state was being squezzed buy the Fed Gov. on doing a upgrade on the testing via a Dyno machine that also reads MPH and tests the pipe at the same time.

So I did a dual exahust of the manifolds with twin cats and a H pipe (After the cats) and turbo mufflers.

It was still a nice improvment. Go for it with twin cats at 2-1/4 pipe size. Mount the cats as far foward as practical to the exhaust. You won't have to get crazy on how close it is.

 

[jaxle]

my buddy is a smog guy in California and as of now a 1975 is exempt from smog testing so do what ever the hell you want to it just as long as it dont blow smoke or cause you to get a ticket for noise. what matters in california "smog exempt" on not. however he did state that by the "letter of the law" if you get pulled over and a cop who really wants to mess with you he can but come on now, thats probably not going to happen.

 

[340mopar]

I install custom exhaust systems and have a Washington State emission certification and will say it again, it is against Federal EPA law to remove/modify an emission part on a vehicle for on road use. The exception would be for an off road use vehicle (race car). The individual states cannot overrule a Federal EPA law, period. I just read this morning that 17 states want to make their own CO2 emission standard (California is one of these states) and the EPA said no. The EPA is the one that makes the final determination on motor vehicle emission standards. A state may request higher standards than the Federal standards but it has to be approved by the EPA.

What Thrashard340 says is true, you cannot add a second cat legally on car that was supposed to have one.



Chuck

 

[player1up]

Now if "the guy Before" you did something strange to the car then....all bets are off .

I perfectly agree with Chuck, however, the likelihood that the feds are going to show up on your doorstep and haul you off in the middle of the night... not so much. That said, you probably wont find a "reputable" shop that will do it for you. SO

1. go with options mentioned by thrashhard340
2. hire a lawyer to make sense of the legalities
3. do the work yourself... go into self imposed witness protection program. JK

I have a /6 duster with no cat to speak of, not even a "test" pipe where the cat should be, so lets get back to performance increases like good, better, best , bring your options to a shop and let them decide on what they are willing to do.. after all they are in the business they should know..
Thanks Chuck for trying to keep us all law abiding citizens like I KNOW we all are.

Matt

 

[71Duster]

If its not being tested not sure why you'd even think twice, Hands up for how many guys pulled egr's off? Same thing.

Glad we have no testing here, my dad has stories about the late 70's when he'd pull the protective caps they put on idle mixture scres off fatten them up, can the egr, cat and thermactor pumps at the engine made more power and fuel mileage.

Emmissions stuff now a days works well with little impact on performane, in the 70's they just hurt more then they did good because the technology wasn't there.

 

[C130 Chief]

As has been already stated, the "Official" answer is no, if the letter of the federal law is being followed. Just like it is a Federal Offense to replace your engine with an engine that is earlier than the year of manufacture of your car. And any replacement engine must retain all emission control equipment for the year of manufacture of that replacement engine regardless of the year of vehicle. The Federal Regulations are a Toolbox for the states and local municipalities to use to meet Federal Clean Air Standards. The enforcement of any such reg your state choses to adopt is up to the state not the Feds. In any event, no exhaust shop is likely to remove a cat and not put one back "for hire" on a street driven car.

So, how do you work around this? I have a few suggestions. First, there was a 360 cid engine option in 75 that DID have dual cats and dual exhaust. So you could use factory style replacement 360 exhaust parts, with more modern "universal replacement" cats which flow far better than the original. (as original parts are possibly obsolete and out of production, you may be more free to have "suitable replacements" fabricated locally). You could also replace the original cat with a more modern "universal replacement" cat and a free flow muffler. If you plan to keep the 2 bbl, this would probably be adequate, so long as the original exhaust system is in decent shape and the original cat has 100,000 miles on it. You could and should contact the California Air Resources Board and find the location of the nearest "Referee Station". This is a place where you can get a mod certified or exempted by the CARB. By putting dual new cats on a dual system, you maintain the original functionality of the system, and in fact probably improve it's function. You will have to convince the rep and he will issue you an EO number to keep with the car (this is the CORRECT way to do it in California, other states will differ). You could drive to Reno or Vegas and look for a "don't ask/don't tell" exhaust shop. If you show up with a cat installed, the shop will be compelled to put one back, but some places will hand you a sawzall and turn a blind eye while the cat "magically disappears." You could take the car to a shop on a trailer without license plates and have duals put on your "racecar".

If it were me, I'd do a little research with the CARB and see if you can find an "approved" solution. They may tell you that being exempt due to age, they don't care. If not, you may have to get more "creative". If you end up doing something that isn't quite legal, keep the original exhaust system so you can dodge any fix-it ticket you may get down the road. Personally, I wouldn't sweat it too much. Put on some fairly quiet mufflers, don't drive like an idiot any you should be fine.

 

[340mopar]

Being I do what I do I have to by law advise against removing emission items, but being I only do work on custom and muscle cars I see lots of emission sytems gone. I could care less that these items are gone, as far as I am concerned I never saw a thing.

Everyone has the freedom of choice to do what ever they want and to decide if they want to deviate from the law. I am by no means any different than the next guy and have fractured a few motor vehicle laws myself in the past. It is all about choices.


Chuck

 

[MOPARJ]

Being I do what I do I have to by law advise against removing emission items, but being I only do work on custom and muscle cars I see lots of emission sytems gone. I could care less that these items are gone, as far as I am concerned I never saw a thing.

Everyone has the freedom of choice to do what ever they want and to decide if they want to deviate from the law. I am by no means any different than the next guy and have fractured a few motor vehicle laws myself in the past. It is all about choices.


Chuck

You are right in all aspects Chuck. I will just take it over to my exhaust guy down here and see what he says. At worst , I will just leave the cat alone, enlarge the piping up to 3" off the cat and run it into a single inlet dual outlet Flowmaster with 2.25 or 2.5" piping on each side with turn downs at the rear. It will look and sound better and may slightly help out performance.

 

[71Duster]

Drive it into an exhaust shop minus the whole system.. it was rotten.

Who's to say it ever had a cat?

When I had my 93' Dakota a big reputable exhaust shop cut it off for me when it was rattling and did single 3" pipe from the y back.

Lurk on some of the Dakota R/T boards there are companies that make and sell 02 sims for the downstream sensors so you can pull the car.

or you take the other route we did in the dealership I was at when the deisels plugged their cats up we'd take it off and bust out all the ceramic and put it back on hollowed out.

 

[Johnny Dart]

Put a set of 340 manifolds or headers on it,go with a dual 2.5 exhaust and be done with it.irat:

 

[rumblefish360]

340mopar;

I install custom exhaust systems and have a Washington State emission certification and will say it again, it is against Federal EPA law to remove/modify an emission part on a vehicle for on road use.

What if you get a car that has no exhaust...or, no engine/drive train and the owner goes from there, down to the shop, like yours, where do you stand leagally?

Looking at the vehicle as a everyday driver the owner will use. That should be noted.

I wondered about this from state to state. Not mention, leagally speaking, if I purchase a car like this and bring it into my state. Hummmmmmmm

 

[Thrashard340]

340mopar;

What if you get a car that has no exhaust...or, no engine/drive train and the owner goes from there, down to the shop, like yours, where do you stand leagally?

Looking at the vehicle as a everyday driver the owner will use. That should be noted.

I wondered about this from state to state. Not mention, leagally speaking, if I purchase a car like this and bring it into my state. Hummmmmmmm

If you are in California, the law is applied to the chassis of the vehicle and not the drivetrain. It would be the new owners responsibility to bring the vehicle in to compliance. So if you brought a car from out of state with no drivetrain or exhaust into California, then you would be obligated to return it to smog legal condition.

 

[Thrashard340]

You are right in all aspects Chuck. I will just take it over to my exhaust guy down here and see what he says. At worst , I will just leave the cat alone, enlarge the piping up to 3" off the cat and run it into a single inlet dual outlet Flowmaster with 2.25 or 2.5" piping on each side with turn downs at the rear. It will look and sound better and may slightly help out performance.

You should swap out the cat for a performance one. Early cats were the pellet type and very restrictive. The newer designs are more of a honeycomb design and are more free flowing. Also, the head pipes on most factory vehicles are inefficient, you should look into redoing the exhaust from the manifolds and back.

 

[jaxle]

and some places will tint your windows so dark you will get pulled over by the first cop who sees you.

 

[340mopar]

340mopar;

What if you get a car that has no exhaust...or, no engine/drive train and the owner goes from there, down to the shop, like yours, where do you stand leagally?

As an installer of exhaust I would have to make it compliant to the year of the auto. But, if the car was brought to me on a trailer with no license plates and I was told the car was going to be a race car and was not intended for "on-road" use I can legally put any exhaust system on the car and still be within the law.

Chuck

 

[MOPARJ]

As an installer of exhaust I would have to make it compliant to the year of the auto. But, if the car was brought to me on a trailer with no license plates and I was told the car was going to be a race car and was not intended for "on-road" use I can legally put any exhaust system on the car and still be within the law.

Chuck

Chuck, thats what we did. The cat was shot anyways and probably hurting emissions and performance more than without. Everything was cut off, the exhaust guys did their homework on smog equipment and asked me several times if it was smog exempt, just to be safe. 2 1/4 piping, from the manifold back was used with two turbo mufflers. It sounds great and gives that 2 bbl 318 some more torque. It runs great, probably burns cleaner too. Thanks for the guidance.

 

[GoFish]

This is another reason I like my pre-smog, '71 Scamp! :bootysha:

 

[adriver]

Now I'm sort of worried.


This just in.
With limited success in catching illegal immigrants, ICE officials now turn to raids at antique car shows looking for automotive Federal Emission scofflaws.