Hobbico exhaust deflector

I have not seen many of these in use and
was wonerding if using one would affect
the engine run.
Engine over heating.
Excessive back pressure.
Power loss.
These deflectors are made of silicone
and approx. 31/2 inches long with 45
degree bend.

> I have not seen many of these in use and
> was wonerding if using one would affect
> the engine run.
> Engine over heating.
> Excessive back pressure.
> Power loss.
> These deflectors are made of silicone
> and approx. 31/2 inches long with 45
> degree bend.

Works pretty good on my airplane.

See them or similar ones all the time on piped engines with no effect. On my overweight plane my engine sagged with the deflector on, probably wouldn't be a problem on a light stunter.

Although there are many in use, it very definitely does affect the power output of the engine. There are a lot in use on pipe ships just to get the exhaust out of the tunnel. But it affects the power. Some newer pipes have the stinger coming out of the cone angled down. These will give more power than the pipe with the exhaust deflector. Some mufflers also have the stinger coming out angled down. Same thing here. If you put the exhaust deflector on your muffler, it will choke off some of the power.

Now, if you aren't running your engine to its absolute fullest, (using a smaller prop, for instance, than the engine is capable of turning) it may work fine for you. Or you may be able to open up the venturi a size or two (or three) to enable more power output to overcome the power loss. Brett is probably in both camps (using a smaller prop and a larger venturi) and for him it works fine. For you it may work fine as well. But for Matt's 97 Stuka, the muffler was angled back and the outlet was quite close to the wing leading edge. We tried an exhaust deflector and it absolutely destroyed the power. Well, I suppose we could have gone back a prop size, but we chose to take the deflector off and let the exhaust blast the wing. It never hurt the dope finish. No harm, no foul.

Just remember, the longer the garden hose, the lower the pressure at the other end. Any additional plumbing, piping, tubing you put at the end of your exhaust outlet will affect the power in a negative way.

>Just remember, the longer the garden hose, the lower the
>pressure at the other end. Any additional plumbing, piping,
>tubing you put at the end of your exhaust outlet will affect
>the power in a negative way.

There's not doubt that the smaller or longer it is, the more back-pressure it creates. Sometimes, it helps the power, and probably more of the time, it hurts the power. To be fussy, varying the length and ID of the deflector is another tuning feature that you can use to get it the way you want it. Of course, we are using the engines at 25% of their capability anyway, so if you have a restriction in one place, you can get rid of it somewhere else and get the power back.

I do know that if you run the exhaust through an arrowshaft from the pipe outlet 18" through to the tail of the airplane, it hurts the power.

Mine works and the plane has less oil on it. the two gngines i use it on have Big Arts Tube Mufflers. See Ya NEAL

Thanks everyone for the info.