REFLECTOR: Engine Selection

[Al Gietzen]

Subject: REFLECTOR: Engine Selection

 

I am quickly approaching a point where I have to make a decision on engine
selection.  My current leaning is towards a Rotary, 20B.  To those who have
taken the auto conversion route, I ask if you had it to do over again would
you have made the same decision?  Would you opt for a firewall forward
package or build the engine accessories yourself?  On a 20B does anyone have
a good idea of what the total cost will run to build and install?  Atkins
Rotary is the only one I have found so far that will supply a firewall
forward package (less mount, radiators, prop) his price for a 20B is 20K,
sounds high to me but how does that compare with all the incidentals that
come with building your own?

 

All opinions are appreciated.

Joe

 

Engine selection can be a tough decision, mostly because aircraft engines
have not evolved much in performance or reliability, and a good firewall
back installation of more advanced engine technology with good performance
and reliability isn't yet available (in my opinion).  As you may know, I am
in the final stages of a 20B installation on a Velocity SE RG.  I have
answered these questions before, so this may be repetitive; and if you wish
to contact me directly, I'd be happy to discuss further with you.

 

Would I do it again?  There have been moments when I may have said no,
usually in moments of frustration.  But deeper down, I know I would have to
make the same decision again for the same reasons.

I agree with Kurt's comments about it taking innovation, engineering,
patience; etc.  My background as a "knuckle buster" on my own vehicles since
a teenager, and in engineering and physics were factors in my decision.

 

There is no firewall forward (backward) package for a 20B.  I got my rebuilt
engine from Atkins, and a few custom parts.  Anything beyond the basic
engine was a nightmare.  He is a good mechanic and knows all about the mazda
rotaries and the parts they use, but that's it.  I'm satisfied with his work
on the engine; however he used the lower compression turbo rotors in a
normally aspirated engine (which is fine if you want to run over 6000 rpm),
put on a front pulley with incorrect timing marks, a few other things that
may be good for a dragster, but not necessarily advantageous to an aircraft.
Either get your own engine to rebuild, or get one from Bruce Turrentine.
Or, consider a 220 hp Powersport - the closest thing to a complete package.
And you can also consider the new renesis engine with a 2.85 reduction which
will give you at least 230 hp and about 100# less weight than a 20B.  If I
were starting over, that's probably what I would do.

 

I have done a fairly high level of customization on my installation in order
to get good performance without turbocharging, minimize the weight, and make
a clean installation.  I've spent about $22K, including $1100 on dynometer
testing.  I'm sure it could be done for about $15K if you don't mind some
extra weight, maybe less compact or a little more drag.  And, of course,
service and overall later will be dirt cheap compared to a certified
aircraft engine.

 

My engine runs smooth and delivers a solid 265 hp at the max design prop
speed of 2900 (6300 engine shaft, 2100 rotors).  The dyno report is at
<http://members.cox.net/alg3/Dynamometer%20test%20report.htm>
http://members.cox.net/alg3/Dynamometer%20test%20report.htm, and engine
installation photos at  <http://members.cox.net/alg3/ROTARY%20ENGINE.htm>
http://members.cox.net/alg3/ROTARY%20ENGINE.htm. The complete package weighs
425#, including coolant (no prop) - probably pretty close to an all-up
Franklin installation.  It is a simple, reliable engine with complete
redundancy in the electronic ignition and fuel injection.  If I have done a
good job on the ancillary systems, it should be a reliable package. 

 

Best of luck,

 

Al

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