> >Fly Bum wrote:
        > >>
        > >>  Figured you folks would be the best to answer this? I
        > >>  have the opportunity to buy an affordable plane but it
        > >>  has a two-stroke Rotax 582 with carbs.  I would like
        > >>  to add a fuel injection so that I can control the
        > >>  mixture (I will be operating at a variety of
        > >>  altitudes) and also so that I can hopefully improve
        > >>  the fuel economy.
        > >>
        > >>  I was reading about semi-direct injection and came
        > >>  across the following? ?This bring us to Ski-Doo SDI -
        > >>  a quite different and more economical route [vs DI or
        > >>  HPDI] to low two-stroke emissions and fuel
        > >>  consumption. SDI stands for Semi-Direct Injection, and
        > >>  it describes a system by which fuel is injected, not
        > >>  into the combustion chamber, but into the fast-moving
        > >>  air streams in the rear transfer ports. Because
        > >>  injection into the transfer streams more than doubles
        > >>  the amount of time available for evaporation of the
        > >>  fuel droplets?.. Cylinder head and piston crown do not
        > >>  have to be redesigned to work with SDI (they do with
        > >>  bi-modal DI), and ordinary automotive-type fuel
        > >>  injectors, working on a normal 60-psi injection
        > >>  pressure make no call on high technology.?
        > >>
        > >>  So is it possible to use this technology (or at least
        > >>  some fundamental principles from it) in conjunction
        > >>  with Tracy?s controller to get better fuel economy
        > >>  from the 582?
        > >>
        > >>  Where is the best place to inject- straight into the
        > >>  port or just downstream of the throttle body?  Also,
        > >>  better to use a single throttle body and split the
        > >>  flow (how evenly?) or use smaller dual throttle
        > >>  bodies.
        > >>
        > >>  Thanks folks.
        > >>
        > >  > Joa

        >   I am into snowmobiles and I use an adjustable needle kit that

screws

        > into the drain plug of the carb, it is operated by a speedometer
        > cable, it works great and a hell of a lot simpler that going to
        > injection and less to go wrong.
        >   Also there is a kit that adjusts the pressure on the air

correction

        > jets that works good and the late model snowmobiles use a

automatic

        > alt adjusting carb that is computer controlled.
        >   They tried injection on snowmobiles and it didn't work out.
        >
        >   Ken Welter

Ramón Fonseca wrote:

I also fly 582's (4 of them) . I understand that Bombardier/Rotax very

soon will announce a fuel inyection option for this engines. Ramon

I built a 582 powered Rans Chaos. Great fun, wish I still had it.
I never got around to changing the stock carbs (it always started so easily
when I stopped it with neg. G :-). It operated up to 10,000' on a regular
basis without any trouble, how high will you be going?

It probably wasn't as efficient as it should have been and I would have
preferred injection but if Rotax are about to do it I'd just fly it as is
until they do. As for fuel economy, pulling the throttle when you feel poor
has an even more dramatic effect than with a four stroke.

As an aside. I now pay more in one year for insurance on my Pitts than the
Chaos cost me in fuel, maintenance and depreciation over 200 hrs.

Regards

Martin
Pitts S1-S

 
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