Catalytic Convert Replacement

Your concerns are scientifically unfounded, just make sure it is an EPA
approved replacement.
"Mike Dobony" <sword.RemoveThis@notasarian-host.net> wrote in message
news:1deva69xtgvcc.1w8ntiwgv5ffu.dlg@40tude.net...
> Somebody cut out one of my catalytic converters on my 99 4wd Suburban
> (also
> on my Toyota PU). My concern is that an aftermarket (affordable)
> replacement might have a significantly different resistance (backpressure)
> than the OEM that they didn't get and cause vibration due to uneven
> backpressure. How significant is this with 2 different catalytic
> converters?
>
> Mike D.
>




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 >> Stay informed about: Catalytic Convert Replacement 

On Thu, 14 Aug 2008 18:09:09 -0400, Bill wrote:

> Don't you have a cross over connect pipe on the exhaust?
>
> "Mike Dobony" <sword DeleteThis @notasarian-host.net> wrote in message
> news:1deva69xtgvcc.1w8ntiwgv5ffu.dlg@40tude.net...
>> Somebody cut out one of my catalytic converters on my 99 4wd Suburban
>> (also
>> on my Toyota PU). My concern is that an aftermarket (affordable)
>> replacement might have a significantly different resistance (backpressure)
>> than the OEM that they didn't get and cause vibration due to uneven
>> backpressure. How significant is this with 2 different catalytic
>> converters?
>>
>> Mike D.

The 2 catalytic converters go into the muffler so the muffler acts as a
crossover.
 >> Stay informed about: Catalytic Convert Replacement 

On Thu, 14 Aug 2008 19:43:25 -0400, Shep wrote:

> Your concerns are scientifically unfounded, just make sure it is an EPA
> approved replacement.

Kindergarten science? One bank with one measure of resistance and another
with a different measure of resistance causes uneven running. The
qwuestion is will it be enough to have a significant effect? Years ago
Bell Aerospace experimented with a partially ducted fan aircraft. The
vibration tore the engine apart due to unbalanced resistance.

> "Mike Dobony" <sword.RemoveThis@notasarian-host.net> wrote in message
> news:1deva69xtgvcc.1w8ntiwgv5ffu.dlg@40tude.net...
>> Somebody cut out one of my catalytic converters on my 99 4wd Suburban
>> (also
>> on my Toyota PU). My concern is that an aftermarket (affordable)
>> replacement might have a significantly different resistance (backpressure)
>> than the OEM that they didn't get and cause vibration due to uneven
>> backpressure. How significant is this with 2 different catalytic
>> converters?
>>
>> Mike D.
>>
>
>
>
>
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 >> Stay informed about: Catalytic Convert Replacement 

The difference is like running one cat on a dual exhaust engine and no cat
on the other, the slight difference in back pressure, will not cause a
vibration, if this is what you mean.
"Mike Dobony" <sword.TakeThisOut@notasarian-host.net> wrote in message
news:lpk3zkfwmxz5.xyoc199p70oz$.dlg@40tude.net...
> On Thu, 14 Aug 2008 19:43:25 -0400, Shep wrote:
>
>> Your concerns are scientifically unfounded, just make sure it is an EPA
>> approved replacement.
>
> Kindergarten science? One bank with one measure of resistance and another
> with a different measure of resistance causes uneven running. The
> qwuestion is will it be enough to have a significant effect? Years ago
> Bell Aerospace experimented with a partially ducted fan aircraft. The
> vibration tore the engine apart due to unbalanced resistance.
>
>> "Mike Dobony" <sword.TakeThisOut@notasarian-host.net> wrote in message
>> news:1deva69xtgvcc.1w8ntiwgv5ffu.dlg@40tude.net...
>>> Somebody cut out one of my catalytic converters on my 99 4wd Suburban
>>> (also
>>> on my Toyota PU). My concern is that an aftermarket (affordable)
>>> replacement might have a significantly different resistance
>>> (backpressure)
>>> than the OEM that they didn't get and cause vibration due to uneven
>>> backpressure. How significant is this with 2 different catalytic
>>> converters?
>>>
>>> Mike D.
>>>
>>
>>
>>
>>
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>




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 >> Stay informed about: Catalytic Convert Replacement 

On Fri, 15 Aug 2008 16:11:09 -0400, Shep wrote:

> The difference is like running one cat on a dual exhaust engine and no cat
> on the other, the slight difference in back pressure, will not cause a
> vibration, if this is what you mean.


Yes it will. One bank with significant resistance followed by another bank
with little resistance will cause vibration. With no cat there will
definitely be vibration. With mismatched cats there will be vibration.
That is simple fluid dynamics. The question is will the difference in
styles and sizes of cats make enough of a vibration to significantly affect
long term engine wear. Since you reject basic science your answer is
totally invalid. Go back to science class and study basic fluid dynamics.
Racers understand this and that is why they go to great lengths to balance
flow in intakes and exhaust, especially in those high revving grand prix
racers.
 >> Stay informed about: Catalytic Convert Replacement 

What vibration are you talking about sound wave pulses, exhaust pulses,
ridiculous. There is no way that doing this will cause something you can
feel in engine vibration ,performance may be slightly, after 45 years of
operating a shop, ASE master tech and former NHRA recorder holder with a 64
Hemi super Stock car, I have experimented and run into all types of issues
like this and never experienced this " "vibration"! Maybe your terminology
does not describe what you are focusing on?
"Mike Dobony" <sword DeleteThis @notasarian-host.net> wrote in message
news:18p49szpqsovm$.1w5eb8bg2fmii$.dlg@40tude.net...
> On Fri, 15 Aug 2008 16:11:09 -0400, Shep wrote:
>
>> The difference is like running one cat on a dual exhaust engine and no
>> cat
>> on the other, the slight difference in back pressure, will not cause a
>> vibration, if this is what you mean.
>
>
> Yes it will. One bank with significant resistance followed by another
> bank
> with little resistance will cause vibration. With no cat there will
> definitely be vibration. With mismatched cats there will be vibration.
> That is simple fluid dynamics. The question is will the difference in
> styles and sizes of cats make enough of a vibration to significantly
> affect
> long term engine wear. Since you reject basic science your answer is
> totally invalid. Go back to science class and study basic fluid dynamics.
> Racers understand this and that is why they go to great lengths to balance
> flow in intakes and exhaust, especially in those high revving grand prix
> racers.
>




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 >> Stay informed about: Catalytic Convert Replacement 

On Mon, 18 Aug 2008 10:35:43 -0500, Mike Dobony wrote:

> On Fri, 15 Aug 2008 16:11:09 -0400, Shep wrote:
>
>> The difference is like running one cat on a dual exhaust engine and no
>> cat on the other, the slight difference in back pressure, will not
>> cause a vibration, if this is what you mean.
>
>
> Yes it will. One bank with significant resistance followed by another
> bank with little resistance will cause vibration. With no cat there
> will definitely be vibration. With mismatched cats there will be
> vibration. That is simple fluid dynamics. The question is will the
> difference in styles and sizes of cats make enough of a vibration to
> significantly affect long term engine wear. Since you reject basic
> science your answer is totally invalid. Go back to science class and
> study basic fluid dynamics. Racers understand this and that is why they
> go to great lengths to balance flow in intakes and exhaust, especially
> in those high revving grand prix racers.

Well now, you have answered your own question haven't you?
 >> Stay informed about: Catalytic Convert Replacement 

On Thu, 21 Aug 2008 22:03:01 -0500, Gordie wrote:

> On Mon, 18 Aug 2008 10:35:43 -0500, Mike Dobony wrote:
>
>> On Fri, 15 Aug 2008 16:11:09 -0400, Shep wrote:
>>
>>> The difference is like running one cat on a dual exhaust engine and no
>>> cat on the other, the slight difference in back pressure, will not
>>> cause a vibration, if this is what you mean.
>>
>>
>> Yes it will. One bank with significant resistance followed by another
>> bank with little resistance will cause vibration. With no cat there
>> will definitely be vibration. With mismatched cats there will be
>> vibration. That is simple fluid dynamics. The question is will the
>> difference in styles and sizes of cats make enough of a vibration to
>> significantly affect long term engine wear. Since you reject basic
>> science your answer is totally invalid. Go back to science class and
>> study basic fluid dynamics. Racers understand this and that is why they
>> go to great lengths to balance flow in intakes and exhaust, especially
>> in those high revving grand prix racers.
>
> Well now, you have answered your own question haven't you?

Nope. I still do not have an answer about the significance of the
imbalance. The fact is any imbalance will affect longevity. The question
is will it cause a significant decrease to the life of the engine. And now
it is a mote question. I could not run around with the converter missing.
I had to get one to use the truck. Good thing I did as the 35 mpg pickup
was stolen. Now the suburban is both people hauler and construction
vehicle.
 >> Stay informed about: Catalytic Convert Replacement