Anybody added a cat?

[Johnnyb]

I was goofing off watching YouTube the other day and I saw a guy restoring an old Jeep having a metallic core catalytic converter added to reduce exhaust odors.
My EB is fuel injected but it has a soft top and in some situations the exhaust is noticeable. The more delicate might even call it objectionable. My AFR is about 13.0.
Since I'm in for a new exhaust system anyway I was wondering if one of these high flow metallic core cats might further improve odors?
https://privatelabelmfg.com/collect...flow-performance-metallic-catalytic-converter

https://www.summitracing.com/parts/...R2jZY091nuyGroN6qdQ4aKQo4SkADVjYaAgKDEALw_wcB

-JB

 

[fordguy]

What EFI? I have added a cat and Garry programmed the ecu for purge valve and canister. It is running pretty clean, but I am still building not driving.

 

[399strokerEB]

I've been thinking of throwing one on mine, even with the efi I still get a little smell rolling back in when I have a window down.

 

[1969]

I am going to add a generic cat from Summit to help cut down on the smell. Figure I’d find a universal one for a V8.

 

[Johnnyb]

What EFI? I have added a cat and Garry programmed the ecu for purge valve and canister. It is running pretty clean, but I am still building not driving.

ProFlo 4

 

[fordguy]

I am running stock explorer efi

 

[Bruners4]

Not quite the same but relevant. I put a Bassani full system on my '96 with a 5.8L, headers to tail pipe w/o the cat. Drove it for about 2 weeks and took it in to add a cat. I didn't notice any performance or fuel mileage difference. But the exhaust smell was so much more tolerable.

 

[904Bronco]

Yes, I have added a Cat to my Explorer builds. The Wife complained about the gas smell when the hardtop was off. It will clean up the exhaust and muffle down the exhaust sound some. I have a two into one exhaust system. (pictures are from my 69 Bronco)

I have been using the Cat model for 1996 Ford bronco with 5.0. The Walker Part # I have used has been discontinued at Summit. (WLK-80708) It was considered a CAL CAT, which means they would ship it to me in CA.
Summit advises that a MagnaFlow MPE-51206 ($194) or MPE-99206HM ($178) will fit the application, but they are 49 state replacements, so they will not ship either one to me in CA. Good thing I stopped by the Reno warehouse on a road trip to Idaho last month. The difference in the two is based on the webbing material inside.

Same hoops to jump through for my 79 Bronco, only 3 replacement cats are listed to be acceptable to the state of CA. One is discontinued, I was able to get one of the two remaining at Summit and picked it up at the Reno warehouse as well. This state doesn't make things easy...

 

[Johnnyb]

Yeah I have been considering options for exhaust systems and I appreciate the pictures @904Bronco . I think I'll probably stick with duals but I am definitely considering my options. I have some considerable space challenges over the rear axle and around the 23 gallon tank. My present system is limiting upward travel and pinching my shock absorbers.
My understanding for catalytic converters in aftermarket applications is that it's better to use a metallic core when you don't have a post cat oxygen sensor. Supposed to be more tolerant to temperature ranges.
It'd be great to clean out the smell as much as possible especially given how drafty a soft top is by very nature, not to mention when you're running with the top down.

THX,
JB

 

[Jakedog]

I've thought about using a cat as well. Right now I'm duals with side exits before the rear tires.
Before I do that I'm thinking of going to a single exhaust with a 2 in 1 out flowmaster. 3" on the exit.
I had that set up on my 75 and I didn't have excessive exhaust smell.
Worth the try.

 

[Broncobowsher]

Modern cats are nice and high flow. Not the restrictive monsters from the 70s.
I see no reason to not run one, even on old stuff that didn't have one before. With EFI the A/F will stay close enough to keep it functional.
You do have to watch heat, they get hot. 13:1 A/F might be an issue. If it can be a little leaner, get a little more oxygen into the exhaust to take care of that excessive fuel, that will really help. 13:1 is fine under load, try for closer to 14~15:1 off load. Best power is slightly rich, best economy is slightly lean, best emissions is in between.

Heads up, this will not fix a cold start smell. The cats only work when they are warmed up. It will take a little bit of running to get one warm enough to work. Modern cars shove the cat as close as possible to the engine so they will heat up faster. Look at 1 ton and greater trucks from about 30 years ago and the cats were after the muffler so they were not too hot (big work trucks are designed to pull at full throttle nearly continously). For your wants, put the cat where it fits. Don't be concerned about getting any specific distance from the engine. The Bronco is a short enough wheelbase you really can't place it too far back. Anything in front of the muffler will be a good location.

 

[nvrstuk]

Colorless and ODORLESS is the gas that kills ya. CO

Catalytic converters convert most but not all Carbon Monoxide to harmless gases... however, if you can smell CO now that means it's getting in the cab. When you put a CAT in line it's still letting exhaust fumes into the cab.

Route the exhaust properly so you aren't getting exhaust in the cab

 

[nvrstuk]

Yeah I have been considering options for exhaust systems and I appreciate the pictures @904Bronco . I think I'll probably stick with duals but I am definitely considering my options. I have some considerable space challenges over the rear axle and around the 23 gallon tank. My present system is limiting upward travel and pinching my shock absorbers.
My understanding for catalytic converters in aftermarket applications is that it's better to use a metallic core when you don't have a post cat oxygen sensor. Supposed to be more tolerant to temperature ranges.
It'd be great to clean out the smell as much as possible especially given how drafty a soft top is by very nature, not to mention when you're running with the top down.

THX,
JB

Where do your exhaust tips come out and point?

I run a half cab with just a windscreen instead of a rear window and don't get any fumes inside. I had to seal up my spare tire carrier which is my "tailgate." Before I sealed it up just driving 10 min to town and I'd feel woooozy with a headache coming on. Took me a while to seal it up but no issues now. My 108 duration cam (before I swapped it out) would almost shoot raw gas (exaggerating here) out the pipes.-obnoxious & so obvvious I had to keep that out of the cab.

 

[Johnnyb]

Colorless and ODORLESS is the gas that kills ya. CO

Catalytic converters convert most but not all Carbon Monoxide to harmless gases... however, if you can smell CO now that means it's getting in the cab. When you put a CAT in line it's still letting exhaust fumes into the cab.

Route the exhaust properly so you aren't getting exhaust in the cab

So I was concerned about this too and went out and bought: https://www.amazon.com/dp/B0D1BTC2P4/?tag=classicbroncos-20
I'm very pleased with this unit, it runs all the time when I'm driving and does not show any CO in the cab.

-JB

 

[Johnnyb]

Where do your exhaust tips come out and point?

I run a half cab with just a windscreen instead of a rear window and don't get any fumes inside. I had to seal up my spare tire carrier which is my "tailgate." Before I sealed it up just driving 10 min to town and I'd feel woooozy with a headache coming on. Took me a while to seal it up but no issues now. My 108 duration cam (before I swapped it out) would almost shoot raw gas (exaggerating here) out the pipes.-obnoxious & so obvvious I had to keep that out of the cab.

My exhaust comes out at about 60°, on both rear corners. It may not extend far enough beyond the body line, but I am going to do exhaust in the next week or two. I will probably include some of the new cats just because of the responses here and some of the other stuff that I've read. Doesn't seem like it could hurt and if I don't like them I can cut them out later.

I also have renewed interest in the James Duff kits, but I am indecisive regarding two to one or dual exhaust.
I also have pretty good space constraints up and over the rear axle. I have a 2 inch body lift and a 2.5 inch suspension lift with a 23 gallon tank and wild horses discs, so it's real tight back there.
I was considering coming out the sides in front of the rear tires though I'd prefer to come out the back if that's doable?
I'm also indecisive about whether to do it myself or take it to a shop. I found a shop here in town where an old guy (Manny) seems to know his stuff. Unfortunately Manny will probably delegate it to some of his staff who are more used to muffler replacements than custom exhaust.

-JB

 

[Johnnyb]

Modern cats are nice and high flow. Not the restrictive monsters from the 70s.
I see no reason to not run one, even on old stuff that didn't have one before. With EFI the A/F will stay close enough to keep it functional.
You do have to watch heat, they get hot. 13:1 A/F might be an issue. If it can be a little leaner, get a little more oxygen into the exhaust to take care of that excessive fuel, that will really help. 13:1 is fine under load, try for closer to 14~15:1 off load. Best power is slightly rich, best economy is slightly lean, best emissions is in between.

Heads up, this will not fix a cold start smell. The cats only work when they are warmed up. It will take a little bit of running to get one warm enough to work. Modern cars shove the cat as close as possible to the engine so they will heat up faster. Look at 1 ton and greater trucks from about 30 years ago and the cats were after the muffler so they were not too hot (big work trucks are designed to pull at full throttle nearly continously). For your wants, put the cat where it fits. Don't be concerned about getting any specific distance from the engine. The Bronco is a short enough wheelbase you really can't place it too far back. Anything in front of the muffler will be a good location.

I watched the AF ratio during a run yesterday and I am running close to 14 to 1:00 most of the time.

 

[nvrstuk]

If your rig is running right now, try putting a short pc of tailpipe or PVC or whatever to extend the pipes out a bit to copy the angle and placement of the stock exhaust exit out behind the rear tires and see if that takes care of your exhaust smell before the cats go on. Then you know you aren't getting any exhaust gasses at all. Just a thought.

Carbon monoxide has a cumulative affect on the neurological & cognitive systems in your body. Small exposures over time build up that's why I brought up the exhaust system design. Just trying to let people know.

I used to deal daily with exposure to toxic gasses and taking readings for them with my crews when entering confined spaces so that's why I never want to be exposed to any trace amount of any gasses if at all preventable.

Like Brakleen which is now a known link for Parkinsons, nothing (edit: small amounts) affects your body immediately but repeated exposure and your life has dramatically changed.

I bought one of those CO meters for checking enclosed areas I work in that are heated sometimes w'o adequate ventilation. Sometimes the levels say it's OK but I can smell that the air isn't right so I'll vent the space with cold outside air before working.

 

[ntsqd]

I ran a universal cats on Patch. Had to replace them every 5 years or so as the cores would rattle loose. Might have been due to how I drove that truck. Once made a "test pipe" and hated driving it like that after only a few miles. I saw no performance gain with the test pipe over a good cat, but the stink reminded me of the not so great old days. If, after following nvrstk's suggestions to get the smell out of the truck, you put a cat on (recommended!) keep in mind just how hot they can get. It will need heat-shielding to keep the heat from coming up thru the floor. A simple piece of 1/8" aluminum spaced down from the floor 1/2" or more, but not any closer to the cat than a 1/2", of a little larger size than the shape of the cat should do the job. Can attach it to the floor or to the exhaust, doesn't seem to matter. I've used hose clamps to attach to the exhaust.

Yeah, CA's rules about cats. My '96 is a 49 state truck, bought new in Florida and then bought to Sandy Eggo by its presumably serviceman owner. 49 state trucks that year had two cats in series, CA systems were different - don't recall how. The front cat's matrix eroded physically and it ran like they were plugged. Only CA won't allow a 49 state system to be shipped to CA. Yet to comply with the EPA I have to put a 49 state cat system on the truck because that is how it was certified for the EPA. Putting the CA system on it would not comply with EPA laws. Ergo we have a State rule over-ruling a Federal law. The CARB is currently the worst Autocracy in the country.
I put a Magnaflow 49 state head-pipe & cat assembly on the truck and could not be happier. Feels like it picked up 100HP!

 

[Broncobowsher]

The smell most get from the exhaust is HC. Raw hydrocarbons just passing through the engine. Can be from running lean, incomplete combustion. Can be from running very rich, so much fuel that it can't even break down into CO, just passes through.

 

[Johnnyb]

Yeah I think the heat shields will be a must, and I don't mind the idea of replacing them every few years if the cores rattle loose. I think the new metallic core ones are designed to better withstand but only time will tell.
Yes of course I'm going to do everything possible to get the exhaust system so that we aren't getting anything in the cab in the first place, but adding the cats is becoming part of the specification.
I live in Northern Arizona and we don't even have emissions tests, not to mention the 71 in Arizona didn't really have any emissions control stuff on it OEM. Maybe some evaporative cartridges, but no air pump and definitely no bad old days 1970s catalytic converter.

THX,
JB