Carbon fiber gas pipe

[john v]

I heard for the longest time that the epoxy did not hold up to the exhaust temperature that the gas motors were generating, then I saw that someone had a carbon fiber pipe for a gas ob tunnel for sale?, do we have a epoxy now that will handle high temps?

 

[RaceMechaniX]

I believe it is a phenolic resin that is quite nasty to work with and was banned in the US.

 

[john v]

Oh, I would think when carbon pipes hit the market for gas boats it's going to be big

 

[Mark O'Malley]

I ride standup jetskis and in "freestyle" built jetskis that do flatwater backflips, and other aerial tricks, there are carbon expansion chambers being used. They do have water injected into them to keep the temps down but also, they do not run wide open for more than a few seconds at a time. The oil doesn't affect the resin as much as the heat. They definitely can't handle a clogged cooling line and melt fairly quickly. The water injection helps the engine make more low end torque but reduces rpm up top so I'm not sure how well that would run in a rc boat.

 

[Timbo Whalen]

The ultra temp phenolic resins are good to around 660°F. Cotronics makes an epoxy ultra temp resin advertised as stable to 650°F, but in practice withstands even higher temps.

The supposed issue with phenolics is the use of formaldehyde in their composition, which is not stated as a known carcinogen, but possibly so.
They are not banned for purchase or use in the US, but certain precautions should be prudent when working with the resins. Tyvex wearables and proper air filtration?....seems about right, considering the same recommendations for catalyzed urethanes we use to clear coat the boats to fuelproof.

Normally, in a gasoline fueled 2 stroke EGT's leave the port at about 1100°-1200°F....push much beyond that and pistons will get holed.

Tuned pipes drop EGT's quite rapidly once gases enter the diverging cone when wave form amplitude rises, and slows down, but when hitting the converging (baffle) cone the wave form is compressed and heat rises....so there's a thermal cycling effect occuring.

It would seem that maybe a water cooled header would form a friendly relationship with a pipe constructed of CF and resin.

The latest technology in phenolic resins is compounding with boron particulates. Boron nitride is a component of hi temp ceramic coatings.

All just food for thought.

 

[Scott Tonak]

Many moons ago, Salisbury offered a carbon pipe for gas engines. It was all the hype at the time but as I recall, had very little success.

 

[Mark O'Malley]

One issue with carbon in an exhaust application like that is that the carbon doesn't retain heat very well and a hot expansion chamber will.make more horsepower in the upper rpms the hotter it gets. A cooler exhaust will make better low end torque at the expense of rpms and horsepower up top and a hotter expansion chamber will make more rpm and peak horsepower at the expense of low end torque.

 

[Timbo Whalen]

One issue with carbon in an exhaust application like that is that the carbon doesn't retain heat very well and a hot expansion chamber will.make more horsepower in the upper rpms the hotter it gets. A cooler exhaust will make better low end torque at the expense of rpms and horsepower up top and a hotter expansion chamber will make more rpm and peak horsepower at the expense of low end torque.

Yes, the temperature ambient in the pipe affects wave velocity- hotter=faster, cooler=slower.
On our drag race sleds (snowmobiles) we used hot and cold pipes, depending on track conditions. We controlled the wave velocity/pipe temp using different pipe volumes.

Have heard from some who've used the Salisbury carbon pipes that they don't hold up well under high nitro use. I don't know, never tried them.

Aluminum isn't the best material for pipe construction, either, from a performance perspective....unless they're ceramic coated inside and outside...same goes for headers.

 

[David Ashcroft]

Many moons ago, Salisbury offered a carbon pipe for gas engines. It was all the hype at the time but as I recall, had very little success.

Fellow boater had one on his gas rigger ,long time ago ,,needed to be nice and hot before it turned on..

 

[john v]

Fellow boater had one on his gas rigger ,long time ago ,,needed to be nice and hot before it turned on..

The guys who have a carbon pipe on there nitro motors tell me the same thing

 

[LohringMiller]

A long time ago I built a carbon gas pipe with high temp epoxy as an experiment. It lasted a few seconds before the inner wall pealed off and plugged the stinger. I decided thin stainless was a better material for limited use experimental pipes.

Lohring Miller


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[LawlessMan]

Quite a few years ago, I bought a carbon fiber pipe made in Australia. Unfortunately, I was never able to put it on a gas outboard (my intended use), because the header was over 1 pound of cast aluminum that did not mount well on the exhaust port of the motor, and it seemed to me that the super heavy header totally negated the light weight of the pipe, 6.5 ounces. If anyone is interested in seeing it, I can post a picture. I think the maker was Colin Bushmaster, or something like that. I think he stopped making them due to a lack of raw material at the time.