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Old 09-09-2012, 08:16 AM
ArtNJr ArtNJr is offline
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Join Date: Jul 2012
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Vehicle: 1998.5 Dodge 2500HD 4x4
Trim Level: SLT Laramie
Color: Black
Engine: 1998-1998 359ci (5.9L) Cummins ISB 24-valve Diesel I6 235hp 420lb/ft (manual), 215hp 420lb/ft(auto)
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Quote:
Originally Posted by redram2007 View Post
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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