1987 Coupe - To Cat or not to Cat (and how)

johnny21

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Jan 26, 2020
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Hello Everyone, first post here at Stangnet - what a great community!

I picked up an 87 coupe (5.0/5spd) and one of the first issue's I'd like to address is the exhaust (it smells and is a bit too loud). There are BBK shorty / BBK Offroad H / and 40 series mufflers. I don't see any O2 sensors in the Offroad H and under the hood there is a smog delete kit.

My initial thought was...okay easy enough install something like this midpipe to resolve the smell issue. But...after researching I think that without the smogpump / O2 sensors that might not be a good long term solution. Here are a couple initial questions:

When I install the cats do I need to reinstall a smog pump?
When I install the cats do I need to hook up O2 sensors?
If I need to hook up O2 sensors where can I look to see how to do that (I don't really know where to begin on this)

Any general advice/guidance/tips/etc is definitely appreciated, thanks!
 
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Mustang5L5

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If you are still efi you need the o2 sensors. Just installing those can probably solve most of your smell issue.

As for your other question, if you install s stock catted mid pipe, you will need the air pump. If you install a modern catted pipe, you won’t need it.
 
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johnny21

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Jan 26, 2020
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Okay thanks for the information!

I just verified that there are O2 sensors installed. In general should I replace those since I don't know how effective/old they are?

Also I haven't mentioned that the car has some aftermarket parts (70mm throttlebody, Trickflow upper/lower intake, BBK mass air flow, 24LB injectors, b303 cam) and has been tuned so that seems likely a contributing factor as well to the exhaust smell. Sounds like I am good to go for installing a midpipe with cats...
 

Mstng93SSP

You have a nice rear end there Dave.
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I personally would NEVER...EVER run a car with no cats. I HATE the smell and you really gain nothing by running no cats.
 

7991LXnSHO

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I replaced the BBK off road h pipe and Dronemasters with a BBK X pipe with cats and super turbo mufflers. Now I can stand it on the highway and the added weight was not enough for me to measure the performance difference of. Maybe with slicks, a stickier clutch and precise track timing and a clean track, then I could tell. But a stopwatch and to 55 shows no difference.
If you have no O2 sensors now, the computer cannot be running the motor at it’s best. I bet it is running rich to be safe.
 
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johnny21

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Jan 26, 2020
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Miami
If you are still efi you need the o2 sensors. Just installing those can probably solve most of your smell issue.

As for your other question, if you install s stock catted mid pipe, you will need the air pump. If you install a modern catted pipe, you won’t need it.
So the BBK catted H pipe showed up and I looking at the installation instructions here and they say if I don't connect an air pump then premature failure will occur...is this considered a modern cat? If so do people generally ignore this warning and have cat failures?
 

johnny21

Member
Jan 26, 2020
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Miami
I replaced the BBK off road h pipe and Dronemasters with a BBK X pipe with cats and super turbo mufflers. Now I can stand it on the highway and the added weight was not enough for me to measure the performance difference of. Maybe with slicks, a stickier clutch and precise track timing and a clean track, then I could tell. But a stopwatch and to 55 shows no difference.
If you have no O2 sensors now, the computer cannot be running the motor at it’s best. I bet it is running rich to be safe.
Do you still have the smog pump in place providing air to your cats? Curious about your experience with the BBK cats and your setup as the BBK instructions are saying premature failure will occur without hooking up the air pump.
 

Mustang5L5

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So the BBK catted H pipe showed up and I looking at the installation instructions here and they say if I don't connect an air pump then premature failure will occur...is this considered a modern cat? If so do people generally ignore this warning and have cat failures?

If BBK says to do it, then you should do it.

I bought a Bassani x-pipe with cats and asked their tech dept specifically and they said it did not require the air pump
 

johnny21

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Jan 26, 2020
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If BBK says to do it, then you should do it.

I bought a Bassani x-pipe with cats and asked their tech dept specifically and they said it did not require the air pump
Okay cool, thanks for the perspective...the smog pump has already been removed so I am just trying to understand what most people do since I'm guessing that there are quite a few people who have smog delete kits..sounds like your experience has been good without the air pump. Trying to decide if I "have" to buy/install the pump or if most people just get away without it...
 

02 281 GT

Agreed...My wife has great Boobs
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I would return the BBK catted pipe and either get the Bassani that was mentioned, get an off-road pipe and buy the cats separately, or just add cats to your existing system. All options allow you to shop around and ensure you get some cats that won’t need an external air pump.

Option #2 is my eventual plan for my ‘95. I need to replace the aluminized off-road h-pipe currently in my car. Like you, I’m very much over the gas smell and excessive noise. My smog pump and associate piping and solenoids are also long gone. I have no intention of sourcing new ones.
 

7991LXnSHO

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These are probably the appropriate to the application catalysts, only in a less restrictive form. So I followed the air pump inclusion instructions and hooked it back up with good take out valves and some new hose. The pump, the hoses, valves and some missing EGR stuff only weighed about eight pounds. Putting it back kept the computer happier, made the garage less smelly, the daisies fresher, the environmentalists happy, and getting the missing stuff off of eBay was less hassle than trying to get a tune or even find a competent tuner in the middle of the country. I did not have time to become the local/regional expert on chips and programming. So it was not a hard decision for me, even living away from the smog thugs. (They are busy chasing our cattle with plastic bags trying to emission test my future dinner.) My only PITA problem was someone had plugged the air injection ports in the heads, (with the same kind of plugs that are in the front), and they are stuck. I made a couple of tools from hardened, grade 8 fasteners, and they still would not move! So until I up grade these ported heads to aluminum with the smog holes, the air crossover pipe is hooked up to look stock and hold up the hoses. But the valve to send air to the cats gets a signal not only when warm, but also at warm up. That’s when the air is supposed to go to the heads for lower cold start emissions. For now, the computer is happy, and I do not have to worry about constipated or melted dual cats.
@General karthief is correct about two way or three way cats. The information in that link varies in quality from ok to total hooey, but yes, if the two way cats our cars came with do not get extra air, they can clog way too soon. At the price of the nice fitting pipe that just slipped in place of my off road one, I would not want to monkey around with fitting cheap-o universal ones in. Unlike the BBK MAF fiasco, I expect this BBK part to still be good when I go to the nursing home and one of my kids makes me sign it over to them. Off topic - The boy Wants it, but it’s probably too high strung for him. I bet he would just cruise and over heat the clutch with slipping smooth starts. The girl could use it closer to it’s limits and arrive home safely. But how many tickets will that get her?
Don’t think that this is an immediate plan, I hope to not go to stay in a nursing home for many years. But the will needs updated since child #2 can get a school learner’s permit next birthday, and he is not listed in the will by name, only as other offspring.

Do you still have the smog pump in place providing air to your cats? Curious about your experience with the BBK cats and your setup as the BBK instructions are saying premature failure will occur without hooking up the air pump.
 
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Mustang5L5

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Okay cool, thanks for the perspective...the smog pump has already been removed so I am just trying to understand what most people do since I'm guessing that there are quite a few people who have smog delete kits..sounds like your experience has been good without the air pump. Trying to decide if I "have" to buy/install the pump or if most people just get away without it...


I ran an off-road pipe and put the stock pipe back on my car. My air pump was gone so I had to track one down. This was 10 years ago so everyone was still chucking them.

Only recently did pull it off due to the bassani pipe. I’m still hanging onto it though
 
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7991LXnSHO

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I ran an off-road pipe and put the stock pipe back on my car. My air pump was gone so I had to track one down. This was 10 years ago so everyone was still chucking them.

Only recently did pull it off due to the bassani pipe. I’m still hanging onto it though
Did you notice any difference in performance? I wonder if the Bassani flows better than OEM and the off road pipe. I bet it is better looking than either.
 

General karthief

wonder how much it would cost to ship you a pair
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I am a google expert, I look stuff up when someone asks something that I don't know about then spend more time than I should comparing info to pick the best one. Most times it starts the conversation and gives the question more answers for comparison. Other times I prolly look like a fool.
Ok, most times I look like a fool :doh:
Any advice given is not based on actual mechanical experience and is for entertainment purposes only.
 

Mustang5L5

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Did you notice any difference in performance? I wonder if the Bassani flows better than OEM and the off road pipe. I bet it is better looking than either.

Can’t really answer that. It’s part of my latest round of mods in redoing my engine
 

Willybill32

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If you are still efi you need the o2 sensors. Just installing those can probably solve most of your smell issue.

As for your other question, if you install s stock catted mid pipe, you will need the air pump. If you install a modern catted pipe, you won’t need it.
I'm curious. The smog pump on my '86 5.0 seized years ago, and it was abandoned. The car still has the stock H-pipe and cats, and I can't tell of any problem. How do I know the cats have failed?