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Miniox converter only and overall exhaust info
https://slantsix.org/forum/viewtopic.php?t=45415		 Page 2 of 2
Author:  SlantSixDan [ Wed Jul 06, 2011 4:50 pm ]
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Quote:
I think I might just remove the exhaust and have him fabricate the pieces for me to put on the car myself.
...without benefit of pipe jacks, pipe benders, or a proper lift? And this is supposed to make life easier for you…how? :shrug:
Author:  Reed [ Wed Jul 06, 2011 4:59 pm ]
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You know me, I am just a troublemaker. Heaven forbid people use critical thinking skills to solve problems.

I second Dan's recommendation to not do the work yourself without the right tools. I would just find a different shop. It sounds like the shop you are dealing with just doesn't want to do the job. If you have access to a welder, I recommend cutting the miniox out and either (a) replacing it with straight pipe or (b) hollowing the converter out and reinstalling it.
Author:  Wesola78 [ Thu Jul 07, 2011 8:11 am ]
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Quote:
You know me, I am just a troublemaker. Heaven forbid people use critical thinking skills to solve problems.

I second Dan's recommendation to not do the work yourself without the right tools. I would just find a different shop. It sounds like the shop you are dealing with just doesn't want to do the job. If you have access to a welder, I recommend cutting the miniox out and either (a) replacing it with straight pipe or (b) hollowing the converter out and reinstalling it.
I also agree. I have a 1980 Volare with a slant six, and I have a cat that will be hollowed out. I don't have to contend with emissions testing for a car this old, this is just in case some picky inspector looks underneath.
Of course, the aforementioned mod is for off-road purposes only. :wink: :twisted:
Author:  krytellan [ Thu Jul 07, 2011 9:22 am ]
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OK then guys, I'll bite. What's the process for hollowing out a miniox converter? If I can do that, all I need replace is a 2' piece of straight pipe, the muffler which I already have, and the tailpipe.
Author:  Reed [ Thu Jul 07, 2011 9:28 am ]
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(1) Cut cat out of pipe.
(2) Shove tire iron or long screwdriver into ends of cat, chipping away at catalyst until catalyst is completely removed from cat housing.
(3) Catch all the catalyst bits in a bucket and see if you can sell it to your local metal recycler (there are exotic metals and gold in catalytic converters. Where I live meth-heads have been cutting catalytic converters off of cars at night and selling them to metal recycling places for $50-$100 each).
(4) Once cat is hollow, weld back on or replace with straight pipe.

Done!
Author:  krytellan [ Sat Jul 09, 2011 6:50 am ]
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I'm confused now. In looking today, I see that the inlet to the miniox converter is only 2" outside diameter. Where would 2-1/4" exhaust be coming from if the exhaust manifold is only 2"?
Author:  SlantSixDan [ Sat Jul 09, 2011 8:07 am ]
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I'm confused now.
This is why there exist such things as exhaust shops equipped with pipefitters and special tools.
Author:  krytellan [ Sat Jul 09, 2011 10:08 am ]
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But that comment doesn't explain why a 2.25" pipe makes any sense considering the outlet is seemingly 2". You only get as much flow as your smallest pipe, yes?
Author:  SlantSixDan [ Sat Jul 09, 2011 2:23 pm ]
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Quote:
But that comment doesn't explain why a 2.25" pipe makes any sense considering the outlet is seemingly 2". You only get as much flow as your smallest pipe, yes?
No.

The manifold collector outlet is 2"ø by about 4 inches long. That 4-inch length of 2"ø creates less restriction than, say, a 14-inch or a 24-inch or a 16-foot length of 2"ø.

In other words, with any given muffler, a 2¼"ø headpipe will make a system with less flow restriction than a 2"ø headpipe, even though the manifold outlet is 2"ø.
Author:  krytellan [ Sat Jul 09, 2011 3:00 pm ]
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Now that makes sense. I much prefer to know the why rather than just the what. I had assumed that the outlet would have to be 2-1/4" but now I see.

A side note. I contacted a custom exhaust guy yesterday to do the job and he proceeded to tell me that it made no sense to make a 2-1/4" exhaust system because of the 2" outlet. If he and I are both wrong, how does someone work for so long doing exhaust and not understand this concept as it was explained to me?

I just get tired of contacting people to do a job the way I want it only to invariably be told that what I want makes no sense. It's not just this job but so many others. Why can't people just do the job you want to pay them for without trying to make you feel like you're a dumba$$?
Author:  SlantSixDan [ Sat Jul 09, 2011 4:03 pm ]
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Quote:
how does someone work for so long doing exhaust and not understand this concept
The world is full of ignorance and incompetence. There is no knowledge test required before you can hang out a shingle selling exhaust work. Even those mechanics whose field of speciality does have some kind of a (usually voluntary) knowledge test, such as the ASE test series, often have less-than-zero understanding of some aspects of what they're working on. They profess what they think they understand of what they think they see. Often they manage to fix problems despite not really understanding what they're looking at or doing. Often…but not always.
Quote:
I just get tired of contacting people to do a job the way I want it only to invariably be told that what I want makes no sense. It's not just this job but so many others. Why can't people just do the job you want to pay them for without trying to make you feel like you're a dumba$$?
That's a pet peeve of mine. It's one thing if you were asking for something dangerous (to the mechanic, to you, or to others) or something illegal, but the illegality of removing a catalytic converter isn't what your guy is objecting to. Nor does he appear to be taking the legitimate position that he doesn't want his name associated with work done to a sloppy or improper specification from an insistent customer. He's arguing a principle of gas flow that he thinks he understands, but doesn't. In other words, he won't do the work the way you want it done because he thinks he's right and you're wrong and/or because it's more difficult to work with 2¼"ø pipe than to work with 2" pipe.
Author:  coconuteater64 [ Sat Jul 09, 2011 7:53 pm ]
Post subject: 
Quote:
Quote:
how does someone work for so long doing exhaust and not understand this concept
The world is full of ignorance and incompetence. There is no knowledge test required before you can hang out a shingle selling exhaust work. Even those mechanics whose field of speciality does have some kind of a (usually voluntary) knowledge test, such as the ASE test series, often have less-than-zero understanding of some aspects of what they're working on. They profess what they think they understand of what they think they see. Often they manage to fix problems despite not really understanding what they're looking at or doing. Often…but not always.
Quote:
I just get tired of contacting people to do a job the way I want it only to invariably be told that what I want makes no sense. It's not just this job but so many others. Why can't people just do the job you want to pay them for without trying to make you feel like you're a dumba$$?
That's a pet peeve of mine. It's one thing if you were asking for something dangerous (to the mechanic, to you, or to others) or something illegal, but the illegality of removing a catalytic converter isn't what your guy is objecting to. Nor does he appear to be taking the legitimate position that he doesn't want his name associated with work done to a sloppy or improper specification from an insistent customer. He's arguing a principle of gas flow that he thinks he understands, but doesn't. In other words, he won't do the work the way you want it done because he thinks he's right and you're wrong and/or because it's more difficult to work with 2¼"ø pipe than to work with 2" pipe.
I believe the guy just doesn't want to do it. Find another shop that will. the guy welds pipe for a living; he is not an engineer.

P.S. I hollowed out the cat on my old man's Ranger for off road use only by drilling a 1" hole with a hole saw, ramming the guts out with a long screwdriver, and welding the metal back into the hole. Took maybe 30 minutes and was nearly free.
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