Catalytic Converter Bypass Valve

[zjrog]

Catalytics are a FEDERAL requirement. Just because you don't have emissions testing locally doesn't negate the legal issues. Here in Utah, my county doesn't do emissions testing YET, but they do look to see if you have a cat. You will fail safety inspection without a cat.

[Christ]

Originally Posted by Domman56

Well not places that don't have emissions laws

Anywhere in the US, and most other countries have that have environmental laws, it's illegal to remove or otherwise alter emissions components. Just because you can get away with it doesn't mean it's not illegal.

This is why you check your local, state and federal laws before modifying your vehicle. Then, if you determine that there is not enough risk compared to reward for your intended modification, you go forth with it.

I know guys that run 75w head lights... they're not legal, b/c they're not DOT approved... who's going to know, though?

[Duffman]

Originally Posted by Frank Lee

Seems bass-ackwards on several levels.

For one, the cat doesn't work very well when it's cold. So you're going to run gases through it when it doesn't work, then when it's warm enough to work you bypass it??? I'd say with that logic just tear it out... but as noted, the cat isn't the biggest restriction and even if it was, tearing it out doesn't help fe.

[zman]

I really apreciate all the opinions generated by this thread, its a wonderful thing to get instant feedback on the crazy ideas going on in my head from people who's opinion I respect. Thanks

[bgd73]

bypassing hot convertor brings a dramatic change in homogeny (the way the fuel fires and when- inside each cylinder), then returning to its use is going be a risky one, with hot engine and cooled convertor, below it's functioning temps.
I experimented with this...and I am an idiot. The change is dramatic. simply...

[winkosmosis]

I don't think you realize how much the cat reduces pollution. A lawnmower, because it has no cat, pollutes as much as 10 cars (or was it 100?)

[Bicycle Bob]

Things that affect maximum horsepower are not usually much of an indication of increased efficiency under normal, part-throttle operation. This is one of those.

[Allch Chcar]

Originally Posted by Bicycle Bob

Things that affect maximum horsepower are not usually much of an indication of increased efficiency under normal, part-throttle operation. This is one of those.

And on the same note removing/bypassing the catalytic converter will affect your available torque badly at low RPM. If you were going to replace the entire exhaust to peashooter size it might help but your mileage may vary.

The entire emission systems used in your car saps something on the high side of 15% of your peak HP. It does reduce fuel economy but not nearly as much as it does HP. The biggest losses to FE are during warm up not after. Running the exhaust gases around the cat would be a waste of time and more polluting.

A Gasoline Engine without a cat is not street legal, emissions wise. I believe just Tampering with the emissions systems is considered in violation of Federal Ordinance, eg; bypassing or punching out the catalytic converter. I don't think you are forbidden from touching it but replacing the second Oxygen Sensor with a fixed voltage Bung would be a violation too.