REFLECTOR: Alternative Engines

[Al Gietzen]

I have never heard anyone say that the certified engines are so unreliable
that they were installing an auto engine.

Actually my primary reason for chosing to go with an alternative engine was
reliablility. After some friends with certified aircraft engines (CAE) had
experienced a broken crankshaft, dropped valves that blew cylinders, and
expensive overhauls that had to be overhauled again in less than 500 hours;
I knew there had to be a better way. Other priorities were better power to
weight ratio, smooth operation, lower maintainance costs. 

After extensive research of the alternatives I chose to go with a 3-rotor
(20B) rotary. 

My conclusion was that I would probably not chose an automotive piston
engine over a CAE on the basis of long -term reliability; but I'll leave
that as an open question. I agree with you that doing an alternative engine
installation is more difficult and time consuming than installling a CAE.  I
likely would not have done it if I had not had a scientific and engineering
background as well as hands-on mechanics experience. Bad design and
installation can obviously lead to bad results. I also agree that an
alternate engine installation done optimally may not save you any money.
De-bugging issues during the initial test phase was also more than typical
of a CAE.

The results of my efforts was an engine that was always easy starting; was
smoother, quieter, more powerful, considerably lower operating costs
(mogas), and simple easy maintainance. If it ever gets to overhaul time it
will cost less than 1/10 that of a CAE.  Performance actually improved
slightly over the first 100+ hours, and it was very reliable for the 215
hors that I flew it.

Any time I fly in another Velocity, or other small aircraft with a CAE; I
come away with the assurance that what I had was a considerable improvement.

Long-term reliability is still to be proven.

 

Al

 

With auto engines many times that is the case. They give up and install a
certified engine. Auto engines aren't designed for extended high power
output and don't do well with the power pulses driving a prop. A typical car
engine loafes along at less then 20% power most of it's life. I've known
people who have had RX7 auto's. The engines just don't seem to have the
durability of a recip. One friend of mine was driving his home with 60,000
miles when the engine just quit. A rotor seal failed with no prior symptoms.
W!  ith a 4 cyl engine, 1 bad cyl will not make the engine quit. Again
without experimentation, we wouldn't be as far as we are with homebuilts. Be
careful with an auto conversion, there are many people who have had bad
experiences with them. Just my 2 cents from a crusty old A&P.
---- Chris Barber <cbarber at texasattorney.net> wrote:
> With today's first flight using an alternative engine and then another
> chiming in that he too is using an alternative engine, I was wondering how
prevalent alternative engines are in the Velocity community. I have always
assumed Lyc and Connie's were so well established that I was pretty much the
only one using an alternative. I know Al Getzen, like me is using a
rotary....uh, but Al is actually flying.  I guess I have always figured
everyone but me has the money to just cut a check for a new certified fire
breather.
>
> I guess my head is so far in the alt eng community it seems more are
> attempting.....and with better product and the blessing of the Internet,
succeeding.
>
> Just curious
>
> Chris Barber
> Houston
> Velo SE
> Rotary 13b 2 rotor turbo
> Dynon Skyview EFIS/monitor
> RWS PSRU & electronics
>
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