Carbon Fiber Fresh Air Exhaust System - Need Help !

[Mz3bo]

Hi Folks,

This is something we want to ''try'' and we are equipped to mold, print and desing a fresh air exhaust system based on modified Carbon fiber compound. We have done many engineering parts so far for race cars but nothing for boat. I am not expert with marine tech and I was wondering if anyone know what is the exhaust outlet air/water temperature once it get out of the back of the boat. To my understanding, water is cooling a part of the manifold, but to what point ? Car exhaust car reach thousands of degree, but I've seen boat exhaust running as low as 110 !!! Thanks for your input !

[MikeC]

The exhaust outlet is sitting in a water bath, a few feet from the exhaust manifold - I'd think the temperatures are negligible. The exhaust runs through a rubber hose on it's way to the outlet and I can put my hand on any part of the exhaust except for the manifold while the engine is running.
My only question, other than the novelty and the challenge of making one, why try to lighten an already fairly light part? On a race car we want as light as possible, especially any unsprung weight, so CF is the go to, or if metal is needed then some exotic light metals. On a boat, however, we're pumping water in so we can have more weight, losing 3 or 4 pounds off the stern won't make much difference - it will certainly look cool though. If I had the tech to mold and print an exhaust I'd probably do it too, just for the novelty.

[Mz3bo]

MikeC, you are absolutely right as it is simply a new challeging project we would like to do But as you said, there are no real benefit of doing it like that Is all the air coming to the oulet ''cooled'' by the water ? I am unsure what would be the air temperature that comes out when you are at WOT.

[srock]

It's not only in a water bath, water exists through them as well. Under the worst-case scenario, a failure of the cooling system on a trailer, I bet you would struggle to get temps over 225 degrees. As noted, it is negligible and nowhere near the thousands of degrees, you note for automobile temps.

[hal2814]

I don’t have a specific number for you but I know who does. Part of the exhaust system is reinforced rubber hose. I would contact the manufacturer of exhaust hose and see the max temp it’s rated for. It’s the weakest link as far as heat tolerance goes in the exhaust system.

[Mz3bo]

That's a good idea ! I checked Greenline hose and Fittings and they stated : 4'' Marine wet exaust

• Temp. Range-40 Degrees to 100 Degrees C

[g_force]

Also, higher temp resin is readily available. We built a carbon fiber muffler for our FSAE car using 400 deg C resin.