Rotax 912 ULS carburetion?

[Mayfield]

This is simply a question.

Has anyone successfully built a single carburetor manifold system for a 912 ULS?

I can think of pros and cons for such an installation.

The biggest challenge would be to design and fabricate a manifold with decent flow and balance.

I know there are many carburetors that would have adequate CFM for the little 1352 CC engine.

Jim

 

[Aerofoam]

This is simply a question.

Has anyone successfully built a single carburetor manifold system for a 912 ULS?

I can think of pros and cons for such an installation.

The biggest challenge would be to design and fabricate a manifold with decent flow and balance.

I know there are many carburetors that would have adequate CFM for the little 1352 CC engine.

Jim

Flow and balance would be less of an issue with a turbo in the mix.....

 

[MilesW]

This is simply a question.

Has anyone successfully built a single carburetor manifold system for a 912 ULS?

I can think of pros and cons for such an installation.

The biggest challenge would be to design and fabricate a manifold with decent flow and balance.

I know there are many carburetors that would have adequate CFM for the little 1352 CC engine.

Jim

Simple answer, I don't believe so Jim. This has been canvassed for years on builder forums, but as far as I know, no one has ever successfully built one. I am sure had they done so, we would have never heard the end of it. People have successfully implemented modding the intake manifolds for a larger balance tube, but I have never found anything more advanced than that.
The conversion from multi carb to single has been tried extensively across cars and bikes for years and it is pretty hard to find much love for it. The idea really appealed to me, but ended up dabbling with building intake manifolds of equal runner length while retaining the twin carbs, but never got past fabbing up the first one before I realized i much prefer flying to fiddling. With the the ready availability of fuel injection now, the conversion to single carb is probably an idea well past its use by date.
The design and fabrication of a single manifold is much simplified these days with CAD and 3D printing. It is already pretty common in the go fast world.
Jabiru used a single Bing on their engines. 64 for 80hp and 94 for the 120. The choice of CV's flowing around 100HP is a bit limited.


Miles

 

[Mayfield]

With the the ready availability of fuel injection now, the conversion to single carb is probably an idea well past its use by date.

Thanks Miles,

Being somewhat past the "Best by date" myself it's not surprising that I would be thinking of carburetors instead of FI.

Since many gyros don't have tight cowls, I am somewhat surprised it has not been tried just to get rid of the syncing requirement. The 912 ULS on my airplane and my TAG have been trouble free so no overriding reason to change. Just curious.

Jim

 

[Doug Riley]

Having the carb(s) below the engine somewhat lessens the chance of fire (as long as the muffler isn't placed so that leaking fuel lands on IT).

I've not heard of any "balls o' fire" originating in a 900-series installation, but it's always possible.

 

[WaspAir]

For a while before the best by date, there was a fairly popular conversion for Norton Commando 850 motorcycles to go from twin Amal to a larger single Mikuni carb, avoiding any balancing efforts.

 

[Libelledoug]

The Rotec 40-4 TBI is marketed as being suitable for a single carb 912 application, but Rotec does not make a manifold to implement it.

The engine pictured on this page has the single Rotec TBI setup, so they at least built up one. https://store.rotecaerosport.com/alternator-conversion-kit-for-2200~235