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Old 06-21-2011, 11:16 AM   #388 (permalink)
Motordyne
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Quote:
Originally Posted by Arnold K. View Post
The test pipes tilt up and down with the motor, and if you have an exhaust with a flex section like the Gemini, it will tear.

I'm going to cut and weld the mount tabs from the OEM cats to the ART Pipes. I don't want to risk an exhaust leak, having to replace a flex section, headache, etc. - so I'd rather just do it right.
I certainly don't recommend it.

The tabs you refer to are bolted to the transmission, which is bolted to the engine, which is free floating on the engine mounts, so the entire assembly moves all the same. The bracket doesn't stop the engine movement. It only reduces flexure of the test pipes or stock cats between the engine and the bracket. But then all the flexure force or torque is then moved from the bracket on back.

In the case of the stock cats, they are heavy and large in diameter and have a high coefficient of rigidity. IE they have no tolerance for flexure because any flexure will be localized to the inlet flange weld point. This obviously is a bad place to have any flexing.

In the case of ART pipes or regular test pipes, the ENTIRE PIPE IS A FLEXURE. It is better to allow the whole pipe flex because there are no stress risers in it. The pipe can easily flex over its entire length and have no problem doing it for a long period of time with a high number of cycles.

Add a bracket to the mix and all that flexure force will be localized and focused right at the bracket weld joint... Stress risers are not a good thing.

If any exhaust has flex sections breaking, it is a result of weak flex sections.

Last edited by Motordyne; 06-21-2011 at 11:18 AM.
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