"Building On A Budget" and Choosing the Right Engine for Your Plane

The April 2011 issue of Kitplanes magazine has an excellent article on "budget building."  Written by the former editor of EAA Sport Aviation magazine Scott Spangler and featuring Wayne Clagg and his now famous Zenith STOL CH 701 airplane, which was built from plans (scratch-built) and powered by a geared VW engine conversion.

Wayne Clagg, of West Virginia, embodies the spirit of the true homebuilder, constructing not only the entire airframe from scratch, but also putting together the firewall-forward installation for his aircraft with a custom VW engine with a belt reduction unit and fabricating his own fiberglass cowls.  As with any custom engine installation, Wayne had to test and troubleshoot the auto conversion.

Building the airframe (from scratch) took Wayne 14 months to complete, but it took another 9 months to complete the airplane (with the engine installation and IFR instrument panel).  The entire project was completed "for less than $23,000. A thousand of that was freight, $7,000 was engine, and the rest of it was airframe.  He started construction in October 2006 and made the first flight on November 3, 2008."  (Wayne also built his own home as well as a hangar for his CH701).

Just as building from a factory kit makes a lot of sense for most builders (many builders would never consider scratch-building their own aircraft), so too does installing a "firewall-forward package" of a proven aircraft engine make the most sense for most builders.  However, scratch-building does make good sense for some builders, as does installing a custom engine (and is the only way for some to be able to afford their own aircraft).  That's the reason we continue to offer the drawings (blueprints) for Zeniths, allowing builders to pursue their dream of building and flying their own aircraft (regardless of the size of their pocket books). There are many success stories of beautiful plans-built Zeniths (and I must also point out that many scratch builders do not embark on a plans-built project to save money, but instead to savor and learn from the entire process of building an entire airplane from blueprints.)

For builders on a budget (and aren't we all?) the cost of the engine easily becomes the single most expensive item on the aircraft.  While we all want to minimize this cost, we also want and need a reliable engine that will give us good performance, and we want to minimize the amount of "troubleshooting" that will be required to get the engine installed and operating properly.  Finally, we also want a powerplant that will be economical to operate (especially important in these days of increasing fuel costs), and that will last a long time (with a proven high TBO) and that's simple to maintain with readily available spare and replacement parts.

Designer Chris Heintz did not engineer any of his aircraft "around" a specific engine, maximizing the builder's choice and options of installed powerplant, whether conventional aircraft engines, new lightweight engines or auto conversions, and stimulating new powerplant developments for light aircraft (Chris was one of the first airframe designers to install a pre-production Rotax 912 engine).  Over the years we have seen new engines come (and go), and we continue to see needed new developments with lightweight engines, such as the UL Power with full FADEC, as well as new auto conversions such as the Viking Honda Fit conversion.

The May 2011 issue of Kitplanes magazine provides a good summary of available auto engine conversions.  In the feature story "The State of Auto Conversions" (pages 24 - 32), writer Pat Panzera concludes that "the state of affairs in the automobile conversion arena is better than ever..." but cautiones that, like Wayne Clagg's VW conversion, "none of these is truly for the faint of heart. It takes a hardcore experimenter to nurse the successful installation and operation of an auto conversion..."  In a bright yellow sidebar to the article, Marc Cook, Kitplanes magazine's editor (who is himself an experienced kit builder), has this to recommend to builders about auto conversions: "If what you really want is to build, complete and as simply as possible bring your homebuilt aircraft to its first flight, you must avoid them."  While this may sound like a challenge to experienced builders and mechanics, they are also words of wisdom that need to be heeded by first-time builders.

To help builders complete their aircraft, at Zenith Aircraft Company we offer (directly ourselves or together with the engine manufacturer or distributor) firewall-forward packages for a number of popular engines, including the 100-hp Rotax 912 ULS, Continental O-200, and Jabiru.  We're also excited to be working on new UL Power firewall-forward packages.  By design, both the STOL CH 750 and the CH 650 share the same firewall to make it possible for them to also share firewall-forward components.

Engine questions are by far the most common questions we receive from both prospective and current builders, and we often don't have the answers to many of the questions.  While we do want to continue to encourage builders to install the engine of their choice and to promote and foster innovation in the light aircraft engine industry, we simply do not have the time, skills, or resources to thoroughly test (let alone install) all possible engine choices.  I invite builders and owners to share their experiences below (both good and and not so good) with their engine installations so that others may learn and make informed decisions.  I also invite plans-builders to share their experience of building from blueprints.


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Comment by Beppe Bottacin on May 8, 2011 at 5:47pm

I'm thinking of a middle way between building and adapting to aviation use an engine myself, and buying a quite expensive Rotax, about which I also have some doubts due to the relatively small diameter of the propellers we can install on our Zodiacs because of ground clearance.

My current favourite is the Sauer engine, a VW derivative, with crankshaft, cylinders, flywheel...almost everything redesigned. It's made in Germany since more than 20 years, and it's also built in a certified version which is standard on several German planes.

This is the 4 stroke engines page of their website:


The company owner told me that the big weight difference between the 2100 and the 2400 is due to the different crankcase which was used on the 2400 that they weightd, which was aluminum instead than the standard magnesium.

I think I'll mount the 2400 on my Zodiac UL:


Here is a video, not from the factory, unfortunately with subtitles only in German, but the images are pretty interesting:


Ideas? Comments?

Comment by Wayne Clagg on April 29, 2011 at 9:40pm

Since the article came out I have had many contacts about the service of the engine. I have written a follow up article and submitted it to Kitplanes for consideration for publication. Mr. Cook said it will definitely be published on the kitplanes webpage and a condensed version printed in an up coming issue. The airplane and engine has been great since I worked out the bugs and added the cooling fins to the engine. After the interview it took ten months to get it in print and much happened in that amount of time, I presently  have a much more positive about the choice I made. Let me tell you, it was a hard row to hoe but the plane is an really gets the attention at the airport which makes the effort a little more worthwhile.

 I have made contacts and friends all around the world and if it were not for the requests from these folks to not give up I would have been flying behind a rotax right now. It does my heart good to hear that I have given others hope for a reliable, affordable powerplant. A few others are currently working on their own fat fin heads for the vw, the most recent comment from a guy with a Sonex said the difference was "AWESOME" and "unbelievable". We just need to get a few more fat fin engines in the air building time as his is the only way to prove the design.  

 Anyone interested should email Kitplanes and watch their website for the followup story. My email address is rclaggf4u@aol.com for those who would like more info or check out my blog at http://waynesexperiments.blogspot.com/2011/01/welcome.html

Thanks for the recognition. 


Comment by Andre Levesque on April 29, 2011 at 4:36pm

 I think this topic will generate lots of interesting points of views -:) 

For myself (my opinion), I'm building half from plans and half from kit. The spars and many complicated bends I buy and the simpler and less demanding parts, I build. That model of building suits me just fine. 

When it comes to engines, I  agree it's the most expensive component of our aircraft if we don't over do it on the instruments -:)

The Rotax 912 is by far the most popular choice but then again it may not be the choice of others...like me for instance. I am building my 750 to be on floats and the thought of using a Rotec Radial is still in the back of my mind. I fully understand it may be off the beaten path, the cowl could be a challenge , TBO is 1000 hrs, not 1000's of them flying, etc... but I love building and the challenges that comes with it. Having said that, safety, reliability and price are my main concerns when I think of my engine of choice. To me TBO is directly dependend on how you take care  and maintain your engine.

I dont look at the 1000,1500 or 2000 hrs TBO necessarly as the only criteria. Yes it is important but not the only important criteria.  LSA, AULA are probably best suited for middle of the road and well accepted engines like the Jabiru's, Rotax, O-200 etc.  Experimental builders are more inclined to experiment !!  

So right now I am I still thinking Radial 2800 ( yes I know...I'm nuts) but the ULpower 350is is a close second.

The deciding factor will be FWF technical issues left to be ironed out. I'm up for the challenge. Idf that fails....I'll be all over the UL power 350is. That 130hp, Fadec, fuel injection engine is something extremely interesting.


Looking forward to other builder's opinions and experiences.That's how we learn and formulate opinions and finally make decisions.  

My opinion.

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