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-   -   Straight pipe ? test pipe? (http://www.ramforumz.com/showthread.php?t=118332)

williecarrillo 07-31-2012 07:32 PM

Straight pipe ? test pipe?
 
i was wondering if you can just buy a straight pipe to get rid of the catalytic converter? without having to cut of weld anything? and besides making it loud and giving the truck a lil power is there anything else i should worry about ?

ArtNJr 08-01-2012 02:10 AM

Quote:

Originally Posted by williecarrillo (Post 854255)
i was wondering if you can just buy a straight pipe to get rid of the catalytic converter? without having to cut of weld anything?

I haven't seen a "test pipe" for sale for years & shops have told me they were "outlawed" by Gov't. regulations. Wouldn't be hard to make one though, you'd just need the flanges for either end, a piece of pipe the right length & maybe access to a pipe bender. Although you can buy pre-bent sections & piece together a pipe with bends in it.

Quote:

besides making it loud and giving the truck a lil power is there anything else i should worry about ?
Inspections, assuming you have them in your State. And a "test pipe" wouldn't increase the noise level much @ all -- but it would most assuredly improve flow. Also, if you can't get away running no converter @ all, the are aftermarket versions which flow a lot better than stock.

Warlock III 08-01-2012 12:49 PM

Ha, Art. Guess I'm not the only one that remember's the "test pipe". They were also outlawed here in NJ years ago because the loophole that allowed the "test pipe" was closed.

Some states probably allow them, or at least probably allow them to be produced. Having one and using one can be two completely different things.

Willie, most Advanced Auto's or Autozone have suitable pipes that strangely enough if you put two of them together usually come out perfect. Most have universal "flange clamps" or flanged ends that can be clamped or welded to the cat flange.

bigVtwin 08-01-2012 06:44 PM

Wouldn't removing the cat mess with the post cat O2 sensor? I'm not sure if the superchips or diablosport have a test pipe feature but it might be something to look into. Better flow = more power, but limp mode = no power.

williecarrillo 08-01-2012 06:45 PM

Quote:

Originally Posted by Warlock III (Post 854832)
Ha, Art. Guess I'm not the only one that remember's the "test pipe". They were also outlawed here in NJ years ago because the loophole that allowed the "test pipe" was closed.

Some states probably allow them, or at least probably allow them to be produced. Having one and using one can be two completely different things.

Willie, most Advanced Auto's or Autozone have suitable pipes that strangely enough if you put two of them together usually come out perfect. Most have universal "flange clamps" or flanged ends that can be clamped or welded to the cat flange.


Thanks guys I'm defiantly going to give this a try

ArtNJr 08-01-2012 09:27 PM

Quote:

Originally Posted by bigVtwin (Post 855073)
Wouldn't removing the cat mess with the post cat O2 sensor?

Yes it would -- a sensor after the cat that gives information to the ECM for adjusting the air/fuel ratio would give the wrong information with the cat removed.

Warlock III 08-02-2012 12:04 AM

The only way I know around it is to add an 02 simulator or delete.
http://www.bigdaddiesgarage.com/imag...el-cel-fix.gif

There are complete simulators out there but ^ is a spark plug non fouling tip with the center drilled out to accept the 02 sensor.

snrusnak 08-03-2012 10:45 AM

The post cat O2 sensors don't provide any input for A/F ratios to the pcm. Only the upstream O2 sensors do. The downstream O2 sensors are mainly just for evaluating catalytic efficiency(if the catalytic converter is good or faulty). Removing the cat will throw a CEL but won't effect performance(due to that code/light). You can do the spark plug non fouler trick to keep this code/light from showing up and it works most of the time.

The main reason for doing it is so if ANOTHER code is thrown(say random misfire, emmisions code, whatever....) you realize it and can correct it. If the CEL is always on(due to the O2 sensor and cat converter removed) then you won't know when another code is thrown.

redram2007 09-09-2012 03:42 AM

What if you were to straight pipe it do away with the cats drill hole and weld a nut and then reinstall the O2 sensors? Would you lose any performance due to back pressure. Im wanting to install headers and was thinking of going that route? Any suggestions would be awesome.

ArtNJr 09-09-2012 08:16 AM

1 Attachment(s)
Quote:

Originally Posted by redram2007 (Post 884517)
What if you were to straight pipe it do away with the cats drill hole and weld a nut and then reinstall the O2 sensors? Would you lose any performance due to back pressure.

Back pressure would not be the issue -- but the change in the content of the exhaust gasses would. If you remove the catalytic converter(s), the O2 sensor(s) would give the engine control module the wrong information since the factory ECM settings assume the converter is there, altering the content of the exhaust gasses (including oxygen). I'm not a chemical engineer so I can't tell you exactly how the content of exhaust gasses is changed by the converter(s), I just know that it is, and that in applications using different fuels an engineer friend of mine is working on, the sensors have to be changed or the engine won't run right.

Quote:

Im wanting to install headers and was thinking of going that route? Any suggestions would be awesome.
Several companies make headers / exhaust systems with bungs for exhaust sensors already welded in place, but you'd be better off using aftermarket free-flowing cat converters than eliminating them. Again, exhaust sensors (on a dyno we call them "sniffers") are set for a given range of exhaust gas content & if you do away with the converter(s) altogether, the exhaust gas content will be different & the sensors will be sending information to the ECM which indicates something's wrong -- then the ECM will alter the air/fuel ratio & the engine won't run right.

Oh the wonders of modern technology! Ain't like the "good ol' days" when you could tune a carburetor with a screwdriver, set the ignition timing by ear, etc. & you didn't have to worry about the content of the exhaust gasses! Also, my 1998 Dodge/Cummins diesel truck didn't come from the factory with a cat converter, so making my own free-flowing exhaust was no problem & I don't have to worry about not passing a State inspection because there's no converter!


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