912 EFI System

[Av8r3400]

http://www.sdsefi.com/rotax2.htm

Scroll down the page a bit to see…




This is awfully interesting…

[Pilot4Life]

Indeed...although, I like the picture and layout you have posted better than the layout on the twin and test stand. Much cleaner and less cluttered if it's produced as you have pictured.

[HighWing]

I have asked trusted friends their thoughts about fuel injection and consistently get the question back - what are the real benefits? I can only imagine the cost of the system, but 3-5 HP increase and level EGTs? I need more info.

[Danzer1]

Generally speaking and efi system is used because they are supposed to be more efficient. Fuel injection should provide better atomization and computer control should be able to more efficiently determine best ratio of air/fuel.

If this only provides 3 - 5 hp, the only efficiency gain would be if you didn't use that additional hp - it should then equate to some degree of fuel savings.

As they say fuel flow does not change, I would suspect, the computer and/or programing is not optimized well enough to gain anything. The injectors and or throttle body may also not be optimized.

I do see some significant inefficiency in the intake canister arrangement. Air out of the can to the intake tubes has to make a 90 turn with nothing "encouraging it" other than pressure. A smooth (ported) transition or inlet scoops would greatly help here.

The other advantages (usually) are, no choke, no carb heat (on this type of injection) and usually no mixture control. I'm kind of baffled with this one - as in their 7th picture down, they show and describe a "mixture knob". What for? On any efi system the primary advantage is the computer is supposed to be selecting mixture automatically - it's how the efficiency is usually gained. SO I don't know what the knob would be for or what the computer really does, if you still manually adjust mixture?

As a WAG, I'd bet this system will cost at least 3 grand. Would be hard to justify for 3 - 5 hp, no choke and no carb heat and no efficiency gain. Besides having to redo the panel and fit the (rather ugly and large) programmer into it.

Looks like a costly experiment to me.

Greg

[SkyPirate]

going to guess, here the computer only controls injection/per rpm, not air mixture,,one could put vortex generators from the main can into each tube but that might allow too much air per cylinder creating a vortex inside of a tube will also add pressure

[Danzer1]

going to guess, here the computer only controls injection/per rpm, not air mixture,,one could put vortex generators from the main can into each tube but that might allow too much air per cylinder creating a vortex inside of a tube will also add pressure

Could be, but why? If the computer adjusts fuel, then you still have to use the computer in your head to adjust mixture (and actually remember to do it). Kind of defeats part of the purpose. And is likely (partly) why there is no efficiency gain. Not sure if thats how it works because they also include a MAP sensor and the "mixture knob" is electric (not a cable) so it seems it would connect to the computer. Odd arrangement?

The intake should be designed like a high performance exhaust manifold backwards. 1 round throttle body exit split (inline) into 4 equal tubes.

[SkyPirate]

the throttle body controls air intake ,,you control the throttle body

[SkyPirate]

I don't see and oxygen sensor in the photo,..so you do the fine tuning at altitude per EGT CHT temp

[Danzer1]

7th picture down shows and or describes a MAP sensor and mixture knob (electric). And yes you would also have to pay attention to EGT/CHT. As mentioned, defeats part of the purpose of computer controlled EFI.

[mr bill]

This looks really interesting. I will be watching for their production release with more details, such as cost. I have already ordered the big bore kit for my 912 ULS, but I am months away from first flight. I am also looking at the Silent Hek-tik 37 amp alternator.