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The Bavarian
Join Date: Mar 2012
Location: Pfaffenhofen/Bavaria/Germany
Posts: 247
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By-pass pipe instead of cat?
While tearing down my '81 engine (930/16 US version) I discovered that I have what I think is a by-pass pipe instead of a cat in my exhaust. Right? I didn't pay much attention to the exhaust since I have bought the cat a year ago and always assumed the car would have a cat. All the CIS components are there including the O2 sensor, and the system is perfectly working in closed loop mode (term?).
As a European I'm not familiar with US regulations. I have always read about the strict US smog tests (visual and measurement) and I'm now wondering how the car may have passed these tests. The by-pass and the bolts are such rusted that it must have been there at least the last ten years. The car was last registered in Wisconsin, and I have a bill that shows the O2 sensor has been changed in 2011. Any thoughts??? Thanks, Manfred 
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03-28-2013, 10:49 AM
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Checked out
Join Date: Jun 2009
Location: On a beach
Posts: 10,127
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Smog tests are a state-by-state issue. The rules in each state are different.
Many/most states no longer smog test a car that old. |
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03-28-2013, 10:53 AM
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Registered
Join Date: Apr 2010
Location: New Orleans, LA
Posts: 1,493
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that is a bypass. in Europe they had a premuffler in that spot; it was a straight through design but had an outer tube and perforated inner tube and reduced the sound a little (probably tuned the sound more than reduced it). only some states have smog testing, like California. most in the South don't.
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1982 911SC, Mocal oil cooler, Bilsteins, Carrera tensioners, backdated heat, factory short shift, Seine gate shift, turbo tie rods, pop off. 2005 Mercedes-Benz C230 kompressor sport 6-speed (daily driver) |
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03-28-2013, 11:08 AM
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