exhaust wrap?

Anyone have experience with wrapping their exhaust system the way the race car drivers do? Just curious. I've seen the material advertised but have not seen nor heard of anyone who's done it on an airplane. Any benefits?

Thanks!

Larry Vetterman says ABSOLUTELY DO NOT!

And Larry has built a few aircraft exhaust systems.

Thanks Mel. What material does Larry use and do you know why he says this?

RV8R999 said:

Thanks Mel. What material does Larry use and do you know why he says this?

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From Larry's website:

Can I wrap my exhaust with automotive type of wrap material and obtain more power?
Any material on the exhaust will shorten it's life and failure will occur. We are using air cooled engines and one the best heat sinks on the engine is the exhaust system. The mass air flow comes in and is forced down and around the cooling fins and then is directed over the exhaust system and then exited out the bottom. If the exhaust is covered it cannot aid in the cooling process. Our tests show that any type of wrap on the exhaust makes both the cylinder head and exhaust temperature run higher. The stainless steel used (type 321) will degrade if the surface temperature is over 1250 degrees F. We also did not find a power increase of any kind by wrapping the exhaust.

How about ceramic coatings?
The jury is still out on them as to whether there is any benefit, however as stated above, they have the same effect as wrapping the exhaust. We do know that once a ceramic coating is applied, the system can never be repaired as it gets into the pores and welding is not possible. How about cooler cowl temperatures with either of the above? Yes, the temperature in the cowl will probably be cooler, but the engine produces so many BTU's of heat so it either is kept cool by the mass air flow or it stays in the cylinder heads.

It is also impossible to inspect...

...you will know you have a problem after it completely blows a hole through. I had a complete wrap on my Bucker and the exhaust failed in about 400 hours.

Wraps trap moisture and will definitely shorten the life of of a bare exhaust.

Ceramic coating done correctly has a good track record and cuts the radiated heat by as much as 400 degrees ( one test I read). In theory you might be able to wrap a coated exhaust as it would be sealed and protected, but exhaust systems are pricey to test on.

Some ceramic coatings can be welded and some cannot, just need to check with the shop you may choose.

I have had my exhaust coated as I want to keep the temps under the cowl cooler. I have yet to see any evidence or compelling argument to not coat the exhaust on a Lycoming.

RV8RIVETER said:

I have had my exhaust coated as I want to keep the temps under the cowl cooler. I have yet to see any evidence or compelling argument to not coat the exhaust on a Lycoming.

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I have mine also coated and though only 300+ hours on them, but no issues so far has been noted.

RV8RIVETER said:

Wraps trap moisture and will definitely shorten the life of of a bare exhaust.

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I had my original exhaust wrapped since sometime during the first 25-hours of flight testing. The exhaust wrap does deteriorate and needs to be replaced as needed during oil changes.

I replaced the exhaust when I replaced the cylinders after 2,200+ hours. No leaks, holes in the stainless exhaust.

IMHO, the exhaust wrap is worth the heat reduction even if it shortens the exhaust system life. In my case the exhaust wrap did not shorten the exhaust life. Oil temp is LOWER with exhaust wrap and CHT is NOT higher with exhaust wrap.

The ONLY down side that I know of about exhaust wrap is a large oil leak and a fire at the same time could be made worse by the exhaust wrap holding the oil.

I have to agree with Larry Vetterman. My business involves the transfer of heat. And without doubt, the use of the exhaust system as part of the "heat sink"...... certainly is beneficial! In fact, numerous gas heating products use formed tubing as the primary heat exchanger. My oil temps and chts are right where I want them with the "un-altered" Vetterman exhaust.

L.Adamson --- RV6A

wraps

Some years ago, I wrapped my Vetterman crossover exhaust system, for what seemed like obvious reasons.....without any reasearch. Soon after, the crossover slip joints elongated and were leaking bad enough to need repair. I contacted Larry and sent the system back to him, which is no easy task in inself. Larry reworked the joints and also the head flanges and sent it back to me. Larry asked if I had wrapped the system? I confessed I had and asked how he could tell? Larry didn't exactly say the wrap had caused the egg shapeness of the slip joints, but maybe he could see some trace cross pattern the woven wrap may have been left on the Stainless Steel when it arrived to him. He cautioned me about wrapping the exhaust and said above a certain temperature that escapes me now, the metal starts to do funny things and moves around. Now that I have been enlightened, I don't wrap my exhaust and all seems normal. I like normal.
Just my experiance. YMMV.

We carry several nifty items to keep exhaust heat away from other components and the cowling, but we don't carry any exhaust wraps! 'nuf said!

Flyboy Accessories heat products

I know there aren't any 912 powered RV-8s out there (at least I hope not), but FWIW, several LSAs using the 912 employ exhaust header wrap to keep temps in the cowling down. There is little blast air going through much of the cowling in those installations.

TODR