Author Topic: Exhaust Pipe Heat Management: Ceramic Coatings vs. Heat Tape  (Read 8736 times)

Offline elvin315

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It's not often you get multiple benefits from one modification. Applying a ceramic coating to your bike's exhaust headers, or wrapping them with thermal tape, does just that. The rapid out-rush of expanding exhaust gases creates a slight vacuum in the cylinder. When the intake valves open a fresh shot of fuel/air mix rushes in to fill that vaccuum. The overlap where the exhaust and intake valves are all open create a path where both gases are flowing together (as the piston starts its intake stroke). Basically, the outgoing exhaust sucks in the incoming fuel/air mix. That's called scavenging. Poor scavenging leaves a higher percentage of exhaust gases in the cylinder. The second benefit is a reduction of under fairing temperature, meaning HOT AIR, that eventually makes it to your legs. A third benefit is a reduction of carbon build-up inside the header pipes. The increased internal temperatures burns a good portion of it away.

Ceramic materials have low heat transference. They act like an insulator keeping the heat in the exhaust gases from "heatsinking" to the steel exhaust pipes. The hotter the exhaust gas temperature the greater the pressure inside the pipes. The higher the pressure the faster the exhaust gas flows to the atmosphere. The faster the exhaust gases flow the greater the vaccuum created in the cylinder. The greater the vacuum the more fresh fuel/air charge enters the combustion chamber when the intake valve opens. The coating (internal and external) is thin so the temperature difference between coated and non-coated pipes is less than ten percent but that typically works out to a 110 to 140 degree drop in radiated heat. On top of all that, coated pipes are so damned pretty. Most coaters offer a variety of finishes and colors.

Exhaust Pipe Wrapping Tape has performed these same functions for decades on hot rods and race cars, and done it well. Decidedly low tech, there is nothing wrong with wrapping your bike's pipes. It will improve scavenging and reduce radiated heat same as the ceramic coatings. It's cheaper than ceramic coating and relatively easy to wrap. I'm not sure if the radiated temps are higher or lower than with the coatings but they should be comparable. On the aesthetic side the fiberglass tape soaks up road scum, that grimy oily film that floats on rain water not to mention mud, and bug bits. Whatever passes though the radiators is deposited on the wrappings.

NOTE: Heat Tape is rumored to crumble steel headers into dust after some years of use from hydrogen embrittlement. The high temperatures the steel endures when insulated by the heat tape causes hydrogen atoms to be driven into the steel changing its chemical bonds. It makes the steel more brittle and reduces its resistance to corrosion. However, though they don't look it, Concours header pipes are made from stainless steel and far less prone to hydrogen embrittlement and thus should be a non-issue.

RECAP
Ceramic Coating: Less radiated heat, more power, resists carbon build-up, better looks, expensive, requires shipping to coater and back, various colors and finishes.

Heat Tape: Less radiated heat, more power, resists carbon build-up, cheap, requires wrapping, various colors, collects road grime.

The choice is yours.

http://www.jet-hot.com/motorcycles.html
http://www.performancecoatings.com/headercoatings.html
http://www.heatshieldproducts.com/p_index.php