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Proof of concept Honda R18Z9 engine conversion kit for DIYers

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KeithO

Well-Known Member
Joined
Nov 29, 2009
Messages
1,608
Location
Jackson, MI
So companies like Viking have done a lot to promote the use of "off the shelf" Honda car engines being converted to airplane power plants. I would say that the engine conversions that they produce have definite value compared to buying equivalent Lycoming or Rotax engines brand new.

However, there is a different option to arriving at the same goal and that is allowing builders to acquire their own junkyard engine (I use that term because that is what people will say who are flying behind "real" airplane engines). One then needs to provide said builders with a package of parts needed to successfully assemble the engine package. Right now there is no-one providing this service. Many of the engine build companies have withdrawn support for DIY engine build by refusing to sell any of the parts they have developed for their own engine builds. Obviously DIY engine builds have the capacity to decrease sales of complete engines, assuming that the builder had the funds for the engine in the first place. As an example, the Viking 150 sells today for $15 500. One is able to obtain the base engine on ebay for a price from $460 to $1500. The reduction drive (gearbox) costs approximately $2500 and would then need an adapter to fit on the back of the engine. Its going to need an engine mount to fit the specific airframe with suitable weight and balance. Its going to need a fuel system to feed the EFI system. Its going to need a engine controller to set the ignition timing and fuel rate to operate properly.

So lets make a few assumptions:
Junkyard motor $1000
PSRU $2500
Engine mount $800
PSRU adapter $1000
Engine controller $850
New engine harness (Honda part) $330
Custom wiring harness from engine to Cockpit $500
So far we are at under $7000 with all new parts except the engine itself

The part of this scope that I am personally looking at developing is the controller, the tuning of the controller and possibly some parts of the fuel system (beyond what comes on the engine) so that the pilot has as much redundancy as is possible based on the engine configuration. The controller itself and its associated software and tuning is a non trivial project and so long as the builder uses the correct engine for the application, there would not be any need to re-tune the controller by the builder. Modern controllers allow data logging and the builder can get support for his installation by looking at the datalog files. But to stay solvent this would have to be a paid service.

Furthermore, if putting together a complete engine package the expectation would be that every engine would be run either with a dynamometer or with a prop for a certain number of hours to burn in the system and demonstrate the expected performance. Data from the run would be given to the customer for reference when he started his ground testing of the system. There would certainly be some set up time involved but confidence that the entire system had been validated prior to the customer receiving it.

My activity right now is to build up a proof of concept system. I have acquired a junkyard engine, and I say that without any shame...
Honda R18Z9 engine-1.jpg
The engine cost $461 and with shipping and tax it came to $648 it is a 2020 Model Honda HR-V engine with 9000 miles on the odo
HR-V PCM.jpg
I then bought the PCM that came out the same vehicle for development purposes, it was $124 + tax, free shipping I figure that the tune for the car would be a very good starting point for further development and this is the cheapest and simplest way to get it since I dont currently own a Dyno.

HR-V harness.JPG
As mentioned before, since I'm not a bulk engine buyer, I have to accept the donor engine "as is" after the wrecker has removed it from the vehicle and usually that means that they have removed the wiring harness from the engine. For $330 I am able to buy a brand new engine harness and there is no way I could make up such a harness with all the connectors, pins, wiring wrap and harness supports included in the factory product. I think the security of knowing that one is working with a brand new harness and connectors that have not been subject to potentially years of heat, dirt, salt spray and connect/disconnect cycles is well worth the cost, without even considering the labor involved in making all those connections. In my opinion, if one was to leave the making of such a component to the end user, it would be inviting trouble. But we dont need to since we can buy a brand new component, one of the joys of using automotive stuff...

For the proof of concept system, this harness has 2 of the 3 x44 pin sealed connectors needed to mate to the PCM. The 3rd connector is on a different harness that enters the cabin and given that I will have to defeat the immobilizer and various other vehicle interlocks (transmission selector, brake switch and possibly a few additional devices) this part of the harness would anyway need to be significantly modified. But remember, in the final application the 3rd connector would probably be eliminated anyway, along with the automotive PCM. It is just needed to get the engine running and acquire the base tune data. I originally thought of doing this with a microsquirt controller which is a little over $300+ a wiring harness, but then I determined that it wasn't capable of sequential spark and injection on a 4 cylinder engine and that is what the final controller will do. Switching to a Megasquirt 2 controller, with modifications to allow for sequential injection and spark would have pushed the price up to $800 and over and then I am starting from a blank slate with the tune.

OK, so again for the POC system, I need peripherals that the PCM wants to see. The sensors are mostly on the engine, with the exception of the MAF which is integrated into the air filter housing and the gas pedal with its double potentiometer feedback to the PCM. No big deal, I found an airbox on ebay for a little over $60 and the accelerator pedal is available new for $61. Neither of these parts will be used in the final system, but are needed to make the PCM be happy and not go into limp mode. The final part is the catalytic converter that attaches to the exhaust manifold. The junkyards appear to recycle these parts immediately for their PGM value (and I assume there is little call for them because they last a very long time). So I bought an aftermarket unit for under $100 that has the pre and midbed O2 sensors and will have to buy 2 more O2 sensors to plug into the bosses and connect to the engine harness. In the final application there will be an option for a wideband O2 sensor with an independent gauge to provide feedback on the operation of the engine management system. However the utility of such a system will depend strongly on whether something changes with the current state of leaded fuel for aviation. Several member have pointed out that a system designed fr unleaded fuel will be totally impractical when doing a cross country trip because of the very limited availability of unleaded fuel at airports across the country. For people doing local flying, the use of mogas is entirely plausible and could by itself offer a substantial operating cost reduction if our fuel prices ever were to return to "normal" levels.

For the reduction drive, we have seen a significant reduction in our options. The SPG reduction drives are basically gone until the suppliers find alternate sources for the housings and gears in a country that is not under sanctions and who knows how long that will take or if it will even happen. It impacts a lot of companies who had been using a version of the SPG system, including Mohawk Aero who had to switch to the Rotax E box. The E box is still for sale but is not the greatest fit since it includes a starter on the gearbox that I would not use. So one has to buy a brand new gearbox and then potentially invalidate your warranty by immediately removing parts from it. There are multiple suppliers where one can buy the E box, one of which is Leading Edge Airfoils, who gave me a quote for $2364.

A second option at this stage is Aeromomentum. I have corresponded with Mr Kettering and he has confirmed that they are still selling the gearbox and will sell the gearbox to competitors with an OEM discount. They too have had their own problems developing the supplier to make the gears, which had severely impacted the development of their smallest engine during the covid period, but they were not coming from Russia and thus he is still in business and will be sticking with his current supplier. The website is not necessarily intuitive, but he did clarify that parts were sold from an independent company called Aeromomentum Parts Inc. Then you find individual parts ordered by the parent engine that they belong to. Since I am looking at a 140hp engine, that aligns with the AM 13 AM15 engine line.
AM Parts inc.jpg

So in my personal opinion, the Aeromomentum reduction drive is likely stronger than the Rotax E box, slightly cheaper and there is a good possibility that with enough demand, AM could make the adapters to install the gearbox to a Honda engine (sacrilege if one knows his opinion on the Honda engines !!). So it is likely that I will pick the AM gearbox for my POC system with the hope that they will remain in business in the years to come. He certainly is not hostile to the DIY segment or even selling to someone competing directly with his engine packages. With the Rotax gearbox there is clearly no customization scope possible, for instance one could not even order it without the starter and would be on your own to find a supplier to make you the adapter from gearbox to the engine.

My engine is due to be delivered tomorrow and most of the remaining parts throughout the next week, then I will be deep in to getting the wiring harness built and trying to work around all of the systems Honda put in their system to prevent such unauthorized use. Even such a harness is marketable to the boating industry where they would not have any concerns about running an engine off an automotive ECU, because in a worst case scenario they would need a tow.... There are very successful companies in New Zealand producing jet boats using GM Ecotec engines and saving a fortune compared to buying a 140hp marine engine package.

I will report back when I have made progress on getting the engine running.
 
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