Engine Inquiry and request for advice

[N418SX]

Now that we have selected the Sonex platform for our latest youth aviation education project, several areas of discussion and interest have come up in our meetings. I hope the questions we have are not too sophomoric for membership here.
We are looking to build an 80 to 90 HP EFI/Dual EI normally aspirated aero VW engine to power the Sonex we have bugan to build. To this end, any advice is appreciated and if there is any ambiguity in any of the following questions, feel free to let me know.

1. Due to the need to teach, we want to assemble the engine on site, and as donated funding/parts become available. If viable, is there a best/brand/route/way to do achieve our teaching objectives while moving forward on budget?

2. With a possibility of local part donations, are there parts that we can source locally and use say in a GP or similar engine build? And, maybe more importantly are there parts that absolutely should not be sourced locally.

3. Are there any Aero VW construction manuals available that can be used to teach young people while building a safe, adequately powered, aero VW engine?

4. As we plan to use the SDS EI/EFI systems on our engine, is anyone out there flying this set up that would be willing, some day to be a resource for us?

5. Any advice, assistance and recommendations are appreciated.

[Bryan Cotton]

An Aerovee kit is not a bad deal. Alternatively you could buy a used one a lot cheaper, and take it apart for educational purposes.

Is EFI a real requirement? If it is for education rebuild a Saturn or something.

[N418SX]

Bryan,

To answer your questions, a full Aerovee kit is not in our current plan, as I outlined above. Yes on EFI and other than my quick visit to Spring Hill, TN last week, I have no idea how a Saturn works into our aviation education program.

Thanks for responding though. Good luck with your build.

[sonex1374]

Robby,

If you are interested in EFI on an AeroVee VW you may find some useful information contained in SonexFlight Episode 35. Our Australian Friends have converted several of their AeroVees to EFI and that episode discusses some of the factors involved.

SonexFlight.com/35

I have been working on this myself and hope to install an EFI system on an AeroVee in the future - it's an intriguing project and I'm very curious to learn more. However, it's a lot of work to sort everything out, fabricate the parts, and then ultimately tune the system to work well. It would be a mistake to underestimate the scope and effort required in such a project.

I'd encourage you to think about your goals for the EFI project. If the goal is for the mentors to learn about converting an existing VW conversion to use EFI, then that might be best done separate from the youth project, then brought back to them after it's fully developed to teach the kids everything you've learned. If the goal is to develop a superior VW engine that uses EFI, that also might best be done separate from a youth project and/or a new airframe construction project. If the goal is to concurrently build an airframe, create a new VW conversion using a hybridized design from existing conversions, develop an EFI/EI adaptation for the new engine, and do this in front of youth as a teaching opportunity, you may be launching an overly ambitious project.

To answer your original questions, see my comments below.

1. Due to the need to teach, we want to assemble the engine on site, and as donated funding/parts become available. If viable, is there a best/brand/route/way to do achieve our teaching objectives while moving forward on budget?

I don't think there is a *best* brand of VW conversion. All the current offerings have proven fairly reliable. They each have differing approaches to the conversion, and that drives the parts they source or produce themselves. One thing they all have in common is that the current version is NOT the version they started with - each engine has evolved over time. Should you decide to design your own conversion, or hybridize existing designs, you'll need to have a plan for developing, refining, and evolving your new engine.

Depending on the exact nature of your teaching objectives, it may be better to teach the kids using a proven, exiting model of engine, and stick to the roadmap already laid down. Effectively, this will limit the ability to use substitute parts (such as what you may find locally, or those donated that are *similar, but not exact*. The most cost effective way to move forward on a budget is to find a good deal on an AeroVee/GP/Revmaster/Hummel, then rebuild it with the kids.

2. With a possibility of local part donations, are there parts that we can source locally and use say in a GP or similar engine build? And, maybe more importantly are there parts that absolutely should not be sourced locally.

I would only use parts called for by the conversion manual or company producing your engine. Substituting parts is tricky, and can have unintended consequences. These are often not obvious until the parts are in service and building hours - only then do we fully understand that those parts were not up to the task, and were not good substitutes (MoFoCo heads, for example). Great Plains, Revmaster, Hummel, Valley Engineering and AeroConversions could probably provide you with a list of all the parts they bought, tested, and ultimately rejected for one reason or another, but that's part of their intellectual property, and I don't think they'll want to share that.

3. Are there any Aero VW construction manuals available that can be used to teach young people while building a safe, adequately powered, aero VW engine?

I'm not aware of a conversion manual available for the VW. There are some old Sport Aviation articles (from the 60's) that talk about conversions, there are assembly manuals by GP, AeroVee and others, and there are conversion manuals for 1/2 VWs. Those resources might be of use to you in developing your own conversion.

4. As we plan to use the SDS EI/EFI systems on our engine, is anyone out there flying this set up that would be willing, some day to be a resource for us?

None that I can readily think of. Perhaps SDS can assist.

I think what your team is trying to accomplish is absolutely wonderful. Using a Sonex to introduce kids to aviation is a fantastic fit! But just like it may be better to leverage the design work and refinement already done by the airframe designer, it may also be better to leverage an existing engine. Find one used and that will be the cheapest, easiest, and most reliable way to build a great airplane, teach kids about aviation, and ensure you have a safe, fun airplane when you're done. Even if you purchase a running VW that performs like a Swiss watch, you can always tear it apart and put it back together again to accomplish your teaching objective, and the kids will love it all the same!

I look forward to hearing more about your youth project, and maybe we can use your successes to help start more of these projects around the country.

Jeff

[Bryan Cotton]

I think a Sonex is a great project to build with kids. My oldest is my build partner. I got him started at 12 years old and we should be flying before he turns 18. I have done a lot with my younger son too. He just finished his UH6F hovercraft and we were both involved in a local Explorer post called Youth Exploring Aviation. Just this last Saturday we had the ceremony to recognize the completion and first flight of the 1946 Aeronca Chief the kids restored. Almost made it to Oshkosh except the FAA didn't like all the paperwork and it took time to work through that.

I only mentioned the Saturn as I rebuilt one with my kid. We had to take a break from the Waiex for 5 months. It has EFI.

I am with Jeff on this one. I see an EFI VW as great therapy for a middle aged guy but for the run of the mill kid it seems like a lot of work vs the perceived progress. That was what I didn't articulate very well before. Unfortunately I have no experience I can share so I'll bow out after this post.

Once both my kids are off to college I am going to see if our community will sponsor a Sonex or Waiex youth project. I love to teach.

Best wishes for your project!

[N418SX]

Brian and Jeff,

Thank you for responding. As a former youth league sports coach, an assistant scout master, father of two grown sons and two daughters under age 6, one thing I've learned is I don't have all the answers. The other is to ask before spending money. Frank advice and opinion is deeply appreciated.

SDS EFI owner Ross Farnham has been very forthright on Lycoming projects and offered options when I decided to formalize Build2Fly into a 501c3 using the Sonex project(s). So as the leader, I feel comfortable with his support, but not to the point of reinventing the wheel. The door is open, but In every build I've undertaken, carburetors were not allowed, only FI.

Another thing I've found is that we are more likely to achieve long term retention if we have a plan to complete the project. Straying from the proven path prolongs or threatens completion and derails the plan. Part of the planning includes this type of advice. Part of the planning includes building relationships that we hope to share with our young people. This includes vendors and fellow builders. That is why you input is valuable to me, us and to the start of this project.

With little experience in the Aero VW area, recommendations pointing us to a vendor that does't mind stupid questions are deeply appreciated.

While in the planning stage, I've been fortunate to find a tail kit for $100 and ER tanks at a bargain price. We've had an entire legacy kit promised, then sold out from under us for $3K and are currently talking to several about other kits and subkits. We've had a VW engine offered, but it was only 47HP. We will keep looking for used items, kits at bargains and donations,but this long term endeavour will ultimately not be about an airplane, but about touching young lives. When you offer advice, you will be touching them too.

Thanks guys.

[vigilant104]

Robbie,
Just some comments on your post:

We are looking to build an 80 to 90 HP EFI/Dual EI normally aspirated aero VW engine to power the Sonex we have bugan to build.

80 HP is about the maximum for a reliable normally aspirated air cooled Type 1 VW aircraft engine. The limiting factor is the ability of the cylinder heads to shed heat, and if we burn enough fuel to produce more than 80 HP, the head gets hot enough to produce several problems that reduce engine reliability and longevity.

4. As we plan to use the SDS EI/EFI systems on our engine, is anyone out there flying this set up that would be willing, some day to be a resource for us?

SDS makes very good equipment and their systems have performed well for several Sonex builders (who may chime in here). But, from what I've heard from others, the support provided by SDS is very good, and you should be able to count on them for any assistance you need. If your goal is to help students understand the workings of EFI/EI systems in general (e.g. automotive use as well as on aircraft), using the SDS system has pros and cons. Because you can get involved with the programming of the system, students will earn about how this works. As a "con," one of the things that makes the SDS setup good for aircraft use is that it is an "open" system (i.e. no feedback from O2 sensors, etc). This allows 100LL to be burned, it simplifies the system and provides better reliability which is critical for aircraft use. The "con" is that this is very different from any automotive EFI architecture, so your students may not be learning things directly applicable the hardware/software used in cars.

[epvans]

I have built two Sonex types both with SDS EFI. They can be seen on the SDS page http://www.sdsefi.com/vw.htm

I have about 600 hours on the two systems. I have helped two other builders and they are extremely happy. I shared my experience with Jeremy Monnett but unfortunately his untimely passing may have prevented them pursuing a kit.

I would be glad to help anyone interested and can be reached at shaypete@gmail.com

N38YX and N773 SX

Peter

[MichaelFarley56]

I have built two Sonex types both with SDS EFI. They can be seen on the SDS page http://www.sdsefi.com/vw.htm

I have about 600 hours on the two systems. I have helped two other builders and they are extremely happy. I shared my experience with Jeremy Monnett but unfortunately his untimely passing may have prevented them pursuing a kit.

I would be glad to help anyone interested and can be reached at shaypete@gmail.com

N38YX and N773 SX

Peter

That looks like a very nice and well engineered setup Peter. I love your airplanes!

I don’t suppose you’d be willing to offer a brief summary or overview of the benefits of installing this system, would you? Does it provide a better running engine, more balanced temperatures, more power, etc.? Thank you!