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**jaredyates** · 03-15-2015, 10:34 AM

I'm certainly not an expert, or even knowledgeable at all about auto engine conversions, so keep that in mind as you read my reply. It seems like most of the folks that I've heard from doing auto conversions count on using less horsepower than the engine produced in the car, in part because the airplane runs at high RPM for such a long time. In that sense I wonder if the 150hp engine is too small, since even a 150hp aero engine is on the small side for the Bearhawk. marcusofcotton is working on a very lightweight Bearhawk with an engine in that size range, but I don't recall having met anyone else who has actually flown with one yet.

Can you get local access to the Subaru engine parts? I've heard of four Bearhawks that have flown with various auto engines, and as of today, the only one that I know of that could be called a continued success is Dan's Subaru-powered Bearhawk in Alaska. This is something I'd love to be wrong about, and if I am, hopefully we'll hear about it!

**Chris In Milwaukee** · 03-15-2015, 10:47 AM

There is one Bearhawk using a Chevy LS3 conversion from AutoPSRUs (http://autopsrus.com/bearhawk). It's a heavy thing, but it appears to be working. We haven't really heard from the builder since he started flying with it, but I haven't heard anything negative about the conversion. It's a spendy conversion, but appears well executed.

Your other option is perhaps a Subaru EG33 (235hp@5400) out of the late 90s Subaru SVX with an Autoflight PSRU out of New Zealand. That's the combination that Dan Shilling is using in Alaska that Jared was talking about. That will be the most economical of the Subaru options.

There is another with a Chevy V-6 conversion, and that one's in the 160hp range. Belted Air Power.

**jaredyates** · 03-15-2015, 11:24 AM

The LS3 Bearhawk sold on eBay. We never know for sure if the ending price was actually the price that the buyer paid, but if it was, then I'd approximate that the original builder lost at least half of his investment, not counting labor. That's depressing!

**Luna** · 03-16-2015, 05:02 AM

Originally posted by jaredyates View Post

It seems like most of the folks that I've heard from doing auto conversions count on using less horsepower than the engine produced in the car, in part because the airplane runs at high RPM for such a long time. In that sense I wonder if the 150hp engine is too small, since even a 150hp aero engine is on the small side for the Bearhawk. marcusofcotton is working on a very lightweight Bearhawk with an engine in that size range, but I don't recall having met anyone else who has actually flown with one yet.

Yes, I also rather have more and derate it, after all that's exactly what Lycoming, Continental and all full certified engine manufacturers do. Derating big engines. Thing is the 150hp is listed by Mr. Barrows on it's web site (http://www.randbaircraft.com/#!engines/casz). I do know i'm on the low side, and I do know it's not recommended, or desirable since auto engines are very close to max output.

Originally posted by jaredyates View Post

Can you get local access to the Subaru engine parts? I've heard of four Bearhawks that have flown with various auto engines, and as of today, the only one that I know of that could be called a continued success is Dan's Subaru-powered Bearhawk in Alaska. This is something I'd love to be wrong about, and if I am, hopefully we'll hear about it!

Subaru engines are not so easy to find, and so harder to find options to choose from.

Originally posted by Chris In Marshfield View Post

There is one Bearhawk using a Chevy LS3 conversion from AutoPSRUs (http://autopsrus.com/bearhawk).

I appreciate the info, but that engine will cost more than my house once all taxes and fees are applied. It's very hard right now to get parts, materials from abroad into Argentina. Specially for personal projects as this one.

Originally posted by Chris In Marshfield View Post

Your other option is perhaps a Subaru EG33 (235hp@5400) out of the late 90s Subaru SVX with an Autoflight PSRU out of New Zealand. That's the combination that Dan Shilling is using in Alaska that Jared was talking about. That will be the most economical of the Subaru options. There is another with a Chevy V-6 conversion, and that one's in the 160hp range. Belted Air Power.

Subaru EG33 is on my list. Have not yet found one here. I do not know any V6 GM cars I can pull engines from!

**N942VT** · 03-16-2015, 05:34 AM

Sergio, you're a long way off from needing to make that decision, don't fret about it now. For what it's worth we were able to import two Lycoming powered GPU's into Columbia as equipment rather than aircraft saving a bunch of money, not sure how that would apply to your country. Argentina has a light aircraft history, would an aircraft engine be all that difficult to find?

**Chris In Milwaukee** · 03-16-2015, 05:49 AM

I have an EG33 sitting on my workbench that I'm slowly building a Bearhawk around :-). But as N942VT points out, I'm a long way from needing it, so anything can change!

**Luna** · 03-16-2015, 07:32 AM

Originally posted by N942VT View Post

Sergio, you're a long way off from needing to make that decision, don't fret about it now. For what it's worth we were able to import two Lycoming powered GPU's into Columbia as equipment rather than aircraft saving a bunch of money, not sure how that would apply to your country. Argentina has a light aircraft history, would an aircraft engine be all that difficult to find?

I know I'll find an engine sooner or later. But, engine set up is a MAJOR issue to be taken into account.But as I said before it's not nearly as easy as getting an engine in the US. Is not that i'm cheap and want to build on auto engine conversion to save when buying the engine. Is just an option to buy an aeroengine.

Originally posted by Chris In Marshfield View Post

I have an EG33 sitting on my workbench that I'm slowly building a Bearhawk around :-). But as N942VT points out, I'm a long way from needing it, so anything can change!

Yes, I rather change it if I get something better than having to drop the project.

**kestrel** · 03-16-2015, 07:13 PM

While it is true that it will be a long time before an engine is needed, entire designs have failed in part do to the intended engine failing to materialize and no suitable substitute being available. I think that some of the BD designs might have had this problem. So long as one is certain that Bearhawk 4 place engines are available, go ahead and build. ...but if there is risk of no suitable engine being available, a different design may need to be considered. ...some have used honda engines. Can you get one of those in the 170+ hp range? Suzuki is an other one people have used.

**marcusofcotton** · 03-16-2015, 08:30 PM

One of the most successful auto conversions is the Roverhawk Bearhawk by Ken Wardstrom in Surrey BC Canada. GM/Land Rover 4.6L V8.

Keep in mind that auto engines are designed to typically run ~15% of their rated horsepower. I wouldn't consider less than a 200hp auto engine for a Bearhawk, preferably much more.

**Glenn Patterson** · 03-17-2015, 11:28 AM

Just a couple thoughts on an auto engine. I researched that in detail because aircraft engines are flying antiques. Engine ignition technology from 1903. It really is hard to find a good engine. I would recommend that you follow tightly in someones footsteps that has a lot of hours on an auto engine if you are set on that direction. Ken Wardstroms Rover engine has been flying for about 10 years. There is Shillings Subaru in Alaska.

You can spend more trying to save money with an auto conversion. We have a friend with a Murphy rebel whose airplane has more hanger hours than apron hours. He bought a reputable redrive that gave out, bought a second, has been fighting cooling issues and rad configurations. Now he is putting the P51 style cooling shown in the March 2015 Kitplanes. He has spent money on a couple rad configurations, 2 redrives, headaches with cooling, custom engine mount and building a custom exhaust. At the end of it if he gets it flying this spring with the new cooling he is flying with his fingers crossed worrying about what bites next. He built that plane years ago and we have watched it spend more time in his shop that the air. He is technically smart but has been snake bitten taking this route. He will be the first to tell you that he would have save money buying & been happier buying a Lycoming 320 with a myriad of prop options.

The issue with auto engines is that eventually they pass into history meanwhile parts are still available for 50 year old Lycs and Conti's. Secondly most are geared 2:1 so that engine is turning 4400 RPM to cruise at 2200. So that engine will wear out 2x faster. Normally an engine with an overdrive transmission is running about 1800rpm and that is why a person can get years out of a car engine in a car. The one advantage is that liquid cooled engines consume less fuel than air cooled engines because of efficiencies of design, electronic ignition, fuel injection and ability to run leaner with less expensive fuel.

We bought an aircraft engine with 800 hours on it that came from a power upgrade. We bought a first run McCauley CS prop for 3500 and had it rebuilt for $2900 that needed basically nothing but a detailed inspect, labour and seals. Our engine is a Continental IO-360 that came with its challenges. We had the skills & support to be able to step off the path a little bit. If you go with the lycoming everything is available and there should be lots in S.America. There is so much support for Lycomings as you can get the mount from Bearhawk Aircraft, wide selection of props, electronic ignitions, Vetterman exhaust and the list is endless. If you can find a part time engine that is solid for $8500 & overhaul a prop or buy a rebuilt for $6500 that is a solid set up for $15000. You may even do better.

So again I recommend that you copy someone else's auto engine set up with a lot of successful hours because inventing your own set up could become a trail of tears. Here is a nice 6 cylinder auto conversion for the Supermarine Spitfire kits that is not a V8. It uses an Izuzu V6 which is pretty universal. It makes 250 hp without the weight of a Chev 350 engine. Lots of V6's are in the 250 - 300 hp range so should be able to stay away from a V8.

http://www.supermarineaircraft.com/options-v6-engine

If you are starting your build then build it with the 5 point engine mounts on the fuselage that you can mount anything to it. That will give you time to do your research and maybe find a good auto drive to copy or a good aircraft engine.

Check out props for engine auto conversions and what they require as well. May be limited choices there. I have read where a homebuilder can go through 2 or 3 props to find one that is successful. That is the headache our Murphy owner friend has with his Subaru. He has it pitched finer s that it can take off and if he coarses it out then he needs to long a run to get up to speed. We used a common engine and prop that are used for Cessnas of comparable size & commonly available. The blade lengths are adjustable, the CS prop has stops that are adjustable and a wide range of governors. Our set up was taken from an STC to up grade a Cessna to a Continental IO-360 that 172's use for floats.

All the best in you quest,
Glenn
BH727

**Luna** · 03-18-2015, 09:00 AM

Great feedback from all of you. All are really appreciated.

kestrel My friend, you are right on the spot. That is why I'm asking all those questions. I saw Honda SUV (CRV model here) 185hp engines, but I'm not sure which model is available as to evaluate it. Which Susuki engines are suitable for BH?

marcusofcotton : thanks for the input.

Glenn Patterson : we share the same vision on this: