Catalytic converters : specs, refurbishment, etc


#1

I am interested in a high-quality catalytic converter - that is, one that is highly efficient at catalysis. I want to install a modern cat onto an older (1987) car. from browsing after-market parts which are claimed to fit my car, there is very little I have found besides glossy advertisement-style information as to what makes a catalytic converter good at its job. frequently they make a big deal about the warranty. also, the shape alone sometimes appears to be completely different from the one on my car.

so what parameters can buyers look at to judge what a good cat is?

how about refurbishment of an old cat? can not the old junk in there be blown or rinsed out at an appropriate shop?


#2

All cataytic converters are designed to be as effecient as possible.

The substrate has cells. These cells are the holes that pass thru the substrate. The more cells there are more surface area the substrate has. Then the substrate is then treated to a wash coat. This wash coat is what contains the noble metals. Platinum/Paladium. This is measured in grams that are to be applied to the substrate. Because these noble metals are very expensive so only enough is applied to the surface area of the substrate to cover the entire surface.

Catalytic converters can be cleaned out. This is called a burn-out. But it requires special equipment and contol when doing this. The subtrate is exposed to slowly rising heat and oxygen until the carbon in the substrate lights off and burns turning it into ash. Then the substrate is cleaned of the ash with compressed air. However, a runaway burn-out can occur. This where the carbon burns out of control too fast and hot to where it melts the substrate. I’ve done that a couple times. So because of the cost of the equipment and the possible chance of a runaway burn-out nobody provides this service.

So whatever catalytic converter is specified for your vehicle, it’s the most efficient for your vehicle.

Tester


#3

thanks Tester, that is an interesting writeup.

So whatever catalytic converter is specified for your vehicle, it's the most efficient for your vehicle.

Dr. Pangloss would agree. This explains my results calling around the area.


#4

@JuniorMint

You are asking an interesting question

Is something wrong with your cat?

Did you fail the emissions test?

Is it plugged?

Do you want a “free-flowing” cat?

Is the cat shell rusted out?


#5

@JuniorMint,

One option might be to go to your neighborhood muffler shop and ask for a custom exhaust system. They should have lots of options.


#6

I don’t understand what the end game is regarding converter nit-picking. As Tester said, the one specified is the best.

The car is an '87 model which has not been named and may even be an oil burning, carbureted car with a shaky state of tune. If so, nit-picking the converter is even less relevant.


#7

Plus 10 for OK…A 1987 anything, the converter is the LAST thing you need to be worrying about…


#8

Perhaps we can do better than Pangloss and suggest to you that you also coat your radiator with a catalytic material. That way, simply driving the car through the air around you can help to reduce hydrocarbons and carbon monoxide, thereby improving upon this best of all possible worlds.

Some carmaker, Volvo I believe, actually thought about this several years ago.


#9

Several people, including Houston radio talk show host Scott Kilmer says if you can get it off, toss it in a tub with soapy water overnight. and it will clean it out. I forget if he said laundry or dish soap, I am guessing laundry soap, but check it out if you want to try that.

There has been a lot of controversy on this topic. He also suggested lacquer thinner in the gas tank. Everyone who said he actually tried it said it worked and did not harm the car, except one on an old Honda. Everyone who has not tried it says it will not work, and will harm your car. Hee, hee.

Personally, I would not do any of these things until as a last resort when I felt the only other choice was to install a new cat. I have had several 0420 failures on my Sienna, and eventually they went away, and stayed off for a very long time. First thing is replace the sensors, since a lot of mechanics here have said the sensors always are the problem, unless you have an extreme oil burner.

Others have said the sensors are never the problem, that it is always the cat, and frankly I don’t believe that claim. I am betting those mechanics always tell the owner, “Wal, let’s just replace the sensors while we are at it.”

Someone on a thread posted a cat cleaner material available from car part places. Not sure what it has in it, but designed to, er, clean cats.


#10

"Others have said the sensors are never the problem, that it is always the cat, and frankly I don’t believe that claim. I am betting those mechanics always tell the owner, “Wal, let’s just replace the sensors while we are at it.”

An experienced mechanic with a decent scan tool can easily tell if the fault code is caused by a failing sensor or a degraded catalyst. There’s no need for guessing. Unfortunately, many guys with nothing more than a $100 code reader pass themselves off as “technicians.”


#11

thanks for all these interesting comments

db4690 wrote:

Is something wrong with your cat? Is it plugged?Is the cat shell rusted out? Did it fail?

not that I know of. the cat is original.

Do you want a "free-flowing" cat?

I don’t know.

coat your radiator with a catalytic material.

brilliant!

The car is an '87 model which has not been named and may even be an oil burning, carbureted car with a shaky state of tune.

not that it generalizes the discussion, nor are any symptoms apparent at this time, but the car is a normally aspirated Porsche 944 and it does not burn oil, is not carbureted, is not in a shaky state of tune, does not have oil in the coolant, does not shake when it runs, does not have old timing belts, does not have an old oxygen sensor, does not have old balance belts, does not have old front-end seals,… just tell me when should I stop, here… yeah sure the timing could be adjusted, etc.

Scott Kilmer

good for Scott Kilmer and his home-made superfund site.

… anyways, I guess some other terms I have heard out there are the number of cells and high-flow.

however, this information seems difficult to elicit from various vendors. in the end I might just get one that fits and is cost-effective.


#12

After learning all this pertinent information, I stick with my advice to go to a local muffler shop to see what kind of custom exhaust system they recommend.


#13
go to a local muffler shop

in my case, the cat is welded onto the headers and there is no way I am welding anything, so I am not doing this, yes someone else will.


#14

I don’t see why you’d have to do any welding. You could cut it off and use clamps on the new one.


#15
I don't see why you'd have to do any welding.

previous owner did it, or I can’t recall what side was welded on by my mechanic all those years ago.