Ram air set up rotax 912 ul

[foxkit3]

Hello. Trying to obtain alittle more power out my 912 ul. My thoughts were a ram air set up would be ideal for alittle more power or efficency. anybody played around with a ram air set up? wondering if it would be worth my efforts.

[Av8r3400]

They say that adding the intake plenum behind the carbs adds a couple of HP.

If you have an older 'Fox like mine (IV), this isn't possible to use because of the reversed manifolds and oil tank position. I have toyed with the idea of an intake plenum to aid holding the carbs in position and add some power, but haven't done it.

The down side to a cold air induction system is the possibility of carb ice becomes more likely than the warm air induction of the normal setup. As they are now, carb ice is very rare.

To me the very moderate power increase - 1-2 hp? - would not be worth it.


What is your objective for more HP? Climb? Takeoff?

[SkySteve]

Av8r3400,
We played with the ram air induction idea on my 912 80hp. Here is what we ended up with (and works, by the way). We removed the regular carb air filters. Replaced them with one large K&N cone shaped air filter on the front top of the engine. Fabricated a rear cap for the filter that captures and splits the air flow thru the coned filter. Then ran 2 scat tubes to the carbs (1 to each carb). I've flown with this for 4-5 years now. I like it.

[Av8r3400]

That sounds very similar to the carb-heat box that came on my plane.

When I took it off, I gained 200 static rpm. It was very restrictive with the long scat tubes.

I was thinking of a variation of something like this. Link Also with the added benefit of eliminating the crappy dual carb setup and all of it's weirdness.

[foxkit3]

Thanks for the info gentleman.