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Tech Maintenance

My exhaust is colored. What does it mean?

Often times, users can experience exhaust discoloration due to improper tuning, engine malfunction or after-market additions. It's important to keep in mind that steel exhibits different oxidation and incandescent colors depending its temperature. Below 800°F it will have oxidation coloration. Above 800°F and it will display incandescent (glowing) coloration.

Below is a chart that can be used as a general guide for determining how hot your engine or exhaust system is running. This is not an accurate way to determine header pipe or exhaust gas temperature. Use this as an indicator to check the temperature by a more accurate method.

My exhaust is colored.  What does it mean?

If your pipe is blue or bluish grey when it is cold (the hottest oxidation colors), it may actually be much hotter when running. After the pipe cools from glowing hot, the oxidation color will remain.

A good exhaust gas temperature at the exhaust port is 1250°F (blood to cherry red). In general, glowing is acceptable for the first 6-8 inches after the exhaust port. When cool, the head pipe shouldn't be blue more than 10 inches from the exhaust port.

No part of a slip on exhaust should ever be blue.

If your exhaust is displaying of the above conditions, your engine is running extremely lean. You most likely need to richen your jetting/fuel map. If this does not fix your problem, you should look for an air leak after the carburetor/throttle body.

If you need help with any of the information in this article, please contact our tech department at (866) HMF-PIPE.

Posted Saturday, July 26, 2014


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