D1 Getting rid of Cats......

L

landy light

Guest
Has anyone ever thought of removing y-pipe on a D1 3.9, removing both of the cats and welding in straight pipe where the cats sat and reinstalling the y-pipe. Then remove the resonator and install a new high flow cat where the resonator sits. Just a question to see what kind of opinions this type of operation would cause. I know CA has strict smog laws, here in PA not quite a s strict, but I figure if you remove 2 cats and a resonator and just replace it with 1 high flow cat, there could be a PERFORMANCE gain????????
I have a 1995 D1 with @ 101K on it and absolutely love it. :cool:
 
H

Hokie_Rover

Guest
Adam,
I'm pretty sure that if your engine came with 2 cats, it has to retain 2 cats, as per EPA regulations. Anyone?
 
Eric N.

Eric N.

Well-known member
Apr 20, 2004
3,980
0
Falls Church, VA
Landy Light, if you search here and in the archive posts you will find that some one posted a good amount of info about replacing the whole exhaust system with headers, new high flow cats, muffler, and pipe.. Should be the same type of gain that you are looking at while still being smog legal (hopefully).
 
A

asurover

Well-known member
Jul 19, 2004
157
0
jonesville, nc
if you don't have emission test in pa then i would just gut the cats all together. thats what i'm getting ready to do. just don't get caught
 
S

syoung

Guest
Any modification to the cats that was not oem quality and type is technically illegal according to the EPA. It's really not enforced though. In the last year or so, they even passed a law making ANY mod to the entire exhaust system illegal all the way to the tailpipe- they essentially reclassified the entire exhaust system as an emissions device.
Then again- not enforced. This is all federal stuff- so it doesn't matter what state.

I wouldn't 'gut the cats' or anything because they serve a purpose, but what you are proposing sounds as if it would work. I did the same thing on an old Mercedes with a V8 and it improved performance quite a bit.
 
LuisC

LuisC

Well-known member
Jun 25, 2004
494
0
Austin, Texas
The cats are more effective and self cleaning the hotter they are. That is why they are located close to the exhaust manifold.
Several years ago, Oldsmobile came out with the Quad4 engine. The cats were practically attached to the header. They were so effective that Olds was able to do away with other emission devices on the engine.
If you move the cats further back, you will find that you will shorten their life, and have to replace them more frequently.
 
jcollett

jcollett

Well-known member
Jun 9, 2004
222
0
the bluegrass state
if you kill the cats all together, wouldn't that cause a check engine light?? i have seriously considered doing this. i am pretty close to having to replace my cats anyway... just don't want that annoying check engine light!!
 
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jcollett

jcollett

Well-known member
Jun 9, 2004
222
0
the bluegrass state
Joey said:
Yes you will get a check engine light if you remove the cats or gut them. The rear O2 sensors are looking for the changing effects of the Cats to sense if they are working properly... Cheap fix you ask, yes....

http://www.o2simulator.com/4436.html
Click to expand...


i figured the engine would "think" somthing was wrong if the cats jumped ship.

great link joey, do these things actually work?? that would be better than buying up a couple of 02 sensors for the engine to "eat" like philip said...

how do you think the little v8 would sound with no cats and just a resonator/muffler at the rear?
 
L

landy light

Guest
Joey the D1 only has the two O2 sensors both before the cats.
I do not want to gut the cats just remove the two and replace with one. The only other vehicle I had that i kept a hold of long enough in order to have exhaust work done on was a Ford Bronco II. Cant remember what was done but do remember that something was deleted from the system.
So what you guys are saying that "any tampering" to the exhaust is "illegal" even if you do put back on the emmision control parts????
Whats the deal with all of these rice burner imports that are screwing around with there systems????
DO the inspection stations have diagrams of all the exhaust and ECS for all vehicles???? How would they know....If it passes, whats the difference.
:confused:
 
S

syoung

Guest
well, like I said- it's not enforced.. for now. I'd like nothing more than for them to find a way to rid the streets near my house of all the little civics with fart pipes.

I think that eventually they (the man) wants to get to the point where all emissions devices on all cars regardless of age must be installed and functional. Right now, antiques are exempt from emissions inspection but eventually they plan to include them with at least a visual inspection.

Like the problems I'm having on my D1- it passes the sniffer test, but fails because the ECU is throwing a code that lights the 'check engine' light. Since the CEL is an indicator of an emissions problem, they fail my truck. If it isn't polluting any worse than the acceptable limit, why do they care what is on it and what does/doesn't work?
 
Joey

Joey

Well-known member
Apr 19, 2004
976
0
Liberty Township, Ohio
Sorry Adam, I didn't even notice the '95 D1 part of your post. Then it shouldn't cause an issue for you. As far as legal goes, (do not take my word as any legal advice or assume that I have a clue) it depends on how strick they are in your neck of the woods. but you would be better off gutting the two that are there or going High flow then trying to make it into one Cat. Most Inspection shops do know what came on most vehicles, but of course some my not know or care.

Collett, I can say that it sounds very nice with headers and a flowmaster and no cats.... or at least that is what I hear :cool: (this does not advocate breaking any laws and only should be done for off road only vehicles) :rolleyes:
 
J

James Fulcher

Active member
Sep 14, 2004
36
0
Cedar Island NC
guts

I gutted the cats on my 95 disco several years ago with no ill effects at all. The O2 sensors are before the cats on mine so I dont think they knew the difference. It did make that little 3.9 sound a lot tougher though and I saw a noticable improvement in gas mileage and pick up. I did end up replacing them with different cats later just so I could sleep at night. :D
 
H

Hokie_Rover

Guest
I'm going to say this, and then leave it be:

Please don't gut your cats. Anyone. The health benefits for us all far outweigh the 2hp you might gain, and the $20 you might save at the pump this year. This is from OSHA, regarding the effects of NOx, one of the gases removed by your cats:

"Effects on Humans: Nitrous oxide is an asphyxiant at high concentrations. At lower concentrations, exposure causes central nervous system, cardiovascular, hepatic, hematopoietic, and reproductive effects in humans [Hathaway et al. 1991]. At a concentration of 50 to 67 percent (500,000 to 670,000 ppm) nitrous oxide is used to induce anesthesia in humans [Rom 1992]. Patients exposed to a 50:50 mixture of nitrous oxide:eek:xygen for prolonged periods to induce continuous sedation developed bone marrow depression and granulocytopenia [Hathaway et al. 1991; ACGIH 1991]. Although most patients recover, several deaths from aplastic anemia have been reported [Hathaway et al. 1991]. Neurotoxic effects occur after acute exposure to concentrations of 80,000 to 200,000 ppm and above; effects include slowed reaction times and performance decrements [Hathaway et al. 1991]. Long-term occupational exposure (dentists, dental assistants) has been associated with numbness, difficulty in concentrating, paresthesias, and impairment of equilibrium [Hathaway et al. 1991; ACGIH 1991]. In one study, exposure to 50 ppm nitrous oxide was associated with a decrement in audiovisual performance, but this result has not been duplicated in other studies [ACGIH 1991]. Epidemiological studies, primarily of operating room personnel, have shown increased risks of spontaneous abortion, premature delivery, and involuntary infertility among these occupationally exposed populations [ACGIH 1991; Hathaway et al. 1991]."
 
nosivad_bor

nosivad_bor

Well-known member
Mar 27, 2004
6,060
63
Pittsburgh, PA
http://www.pacode.com/secure/data/067/chapter175/s175.80.html

(d) Visual inspection of emission control system. Vehicles registered in counties where there is not an emission inspection program under Chapter 177 (relating to emission inspection program), shall be checked visually for the presence of emission control components. These components may be original vehicle equipment or an equivalent aftermarket replacement component meeting the same standards. In addition to the exceptions under ? 175.4 (relating to vehicles required to be inspected), this subsection does not apply to vehicles registered as collectible or classic motor vehicles as defined in 75 Pa.C.S. ? 102 (relating to definitions).

(1) The visual inspection shall be performed through direct observation or through indirect observation, using a mirror or other visual aid.

(2) Provided that the make and model year of the vehicle would have originally been equipped with the device, reject if one or more of the following apply:

(i) The catalytic converter has been removed, disconnected or is the wrong type for the certified vehicle configuration.
ii) Exhaust gas recirculation (EGR) valve has been removed, disconnected or is the wrong type for the certified vehicle configuration.

(iii) Positive crankcase ventilation (PCV) valve has been removed, disconnected or is the wrong type for the certified vehicle configuration.

(iv) Fuel inlet restrictor has been removed, disconnected or is the wrong type for the certified vehicle configuration.

(v) Air pump has been removed, disconnected or is the wrong type for the certified vehicle configuration.

(vi) Evaporative control system components have been removed, disconnected or are the wrong type for the certified vehicle configuration
 
S

syoung

Guest
remember though- it's the EPA that is moving towards these more restrictive standards, that's them there Feds, not states. Reclassifying the whole exhaust system as an emissions device I *thought* would cause a huge outcry in the aftermarket world, but it didn't. These laws have no teeth for now, but it's as if they are stacking their deck one card at a time. **conspiracy theory**
 
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