Modifying the TG-10 heat box for redirecting dumped air

[Lycosaurus]

I am in the process of re-installing my engine after a 17 year run, in so doing I am applying a few improvements and modifications.

I have an aftermarket TG-10 heat box that is constructed of stainless-steel, but this applies for the TG-10 that most people have installed on their RV. The excess hot air not used by the cabin is dumped off to the left side of the airplane. This dumped hot air gets directed in the general area of the fuel pump and in my case the fuel flow sensor, which I surmise is not great thing to do. My special case is that I have dual mufflers with integral heat muffs that are Y-ed to the heat box and produce a lot (*A LOT*) of hot air. Not ideal for the engine compartment during summer hot days.

I decided to fabricate a dumped hot air deflector that would channel that air flow down via that area of the cowl opening near the nose gear leg. I have not flow it yet.

I just used some cereal box cardboard to generate my 'CAD template", and then used my human analog CNC capabilities along with metal snips to cut it out of thin aluminum. One pop rivet, one screw at the top placed to minimize the interference on the deflector flap), high temp RTV, and finally sharing the oil breather tube support screw as shown in the photos. I did do a some cleanup of the coked oil and such on the TG-10 after taking these photos.

If I would do anything different, I would attempt to enlarge the opening at the bottom. I think this should work just fine.

 

[BillL]

Great idea - I did one when building to keep hot air from blowing on sensitive oil hoses. My exit temperature is 350F - likely yours is too with all that heat recovery.

Also, a good note for others, this heat under the cowl increases lower cowl pressure and thereby increases CHT and Oil temperatures. I lost maybe 7F ambient with addition of a second hear muff. That means 400F CHT now at ambient of 92F instead of 99F under repetitive TO and Climb. A Young Eagle Test.

 

[Carl Froehlich]

For both RV-10s I did two things to reduce the heat getting blasted back toward the engine when the cabin heat valves are shut:
- Inserted a 3/4” orifice in the 2” SCAT hose coming off the rear baffle, one on each side. The RV-10 has great heat muffs so the extra air is not needed. The side gain is you get more engine cooling air (less air stolen off the top of the engine) and less air is dumped to the lower cowl further enhancing engine cooling.
- I used a piece of KoolMat between the valves and the firewall. The KoolMat is then draped over the valves so dumped air is directed down toward the cowl exit instead of the engine driven fuel pump. The KoolMat also provide a barrier for heat transfer to the tunnel from these valves that are always hot.

Carl