What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Eggenfellner H6

Fuzzyflyer

I'm New Here
Friend
Anybody flying the Eggenfellner h6 engine. I have read a lot of negative reviews. Looked at a nice RV9 with the h6...thanks:)
 
Welcome to VAF!

Those engines didn't live up to the hype and I don't believe they are still supported.

There were a lot of issues with the engines in terms of life expectancy, both the engine and yours once the engine failed. Try using the Advance search feature and put in "Egg" or "Eggenfellner".

When I was tracking such things, airplanes with these installed typically weighed 100+ pounds more than a comparable RV with a Lycoming up front.

Honestly, I'm surprised there are any still flying.

Now, Ross will be around with his input. He is VERY knowledgably and will slap my hand for the above. He has been flying behind one of his own design, but that is what does for a living.

As a good friend of mine said about his auto engine conversion, "If you like to tinker, put an auto engine in your plane. If you like to fly, put a Lycoming in it." BTW, he has more RV glider time than anyone else I know. His core engine has never failed but all the support systems that keep it running have.
 
Last edited:
What Bill said.
I was there in the beginning, and Jan even had a few of my dollars for a bit (hard to admit, past life). RUN.
 
Anybody flying the Eggenfellner h6 engine. I have read a lot of negative reviews. Looked at a nice RV9 with the h6...thanks:)

If you're an engine/ mechanical type guy and the plane is cheap, it might be worth a look. If you're not, I'd steer clear unless it really is cheap and you'd be prepared to swap the Sube out for a Lycoming.

The engines themselves have been pretty reliable if the EFI is tuned properly but expect to go 10-20 knots slower and burn 1 to 1.5 GPH more than an injected Lycoming 360. Most of the problems were in the Egg designed stuff bolted to the basic engines.

The gearboxes have had their issues. Don't buy a plane with a Gen 1 or Gen 2 GB. The Gen 3 also had issues fairly often although some have had no issues and accumulated several hundred reliable hours each.
New gearboxes are being produced by Mike Talmadge with all the problems addressed.

There have been hub issues with the Quinti 3 blade props and those are no longer supported either to my knowledge.

The H6 installations are usually at least 100 pounds heavier than your average Lycoming RV.

Depending on vintage and equipment, some of these don't cool well in the climb on hot days.

On the plus side, when running right, these are much smoother than a Lycoming and don't suffer from some of the same problems that afflict those engines. They do have some of their own unique issues though. They are generally not fond of a continuous diet of 100LL long term. There have been some issues with improperly mounted crank trigger magnets, misaligned sensors, slipping balancer rings, starter kickbacks, VVT issues.

The Egg support Yahoo Group SubeNews has migrated over to a new place recently so there is support there but no factory support for parts.

Some people hate 'em and some people love 'em, depends what your cup of tea is.
 
Last edited:
Anybody flying the Eggenfellner h6 engine. I have read a lot of negative reviews. Looked at a nice RV9 with the h6...thanks:)
A RV (any model) with a Lyc sells for much more than an RV with an auto engine. To build an RV with auto engine, especially an Egg kit, is not cheaper than a Lyc which is relatively cheap and easier to build and complete.

If you want to fly, not spend time tinkering, have a good performing RV, lighter and with higher resale, go with a Lycoming. Weight matters if you want to stay within Van's limits. A heavy engine will limit payload, fuel.... etc. Most people just ignore Van's limit and arbitrarily add to Van's recommend gross weights. You can do that with experimental. There are debates on the wisdom of that. In general a light RV is much more of a delight to fly.

I am a die-hard fan of Lycoming or I ain't going. I love the idea of auto engine conversions and admire people who pursue and get those alternate power plants and get them flying in their airplane. I just don't think (my opinion) they work as well as an air cooled, direct drive, Horz opposed Lyc. It has not been for the lack of trying. People who are really talented, have skill and resources, and really commit to an auto engine conversion, come out with fairly good results. However these are very custom planes, not bolt on Egg H6 kits. It is just not for me.

Go to rv6ejguy web page and see his RV-6 build with a Subie, amazing. His is not an Egg, but his own setup. Could you do that? I can't. I have built two RV's and the Lyc is fair easier to build and get flying from what I have seen. I have not built a plane with an auto engine but been around builders who did. He also sells the best electronic ignition and electronic FI in my opinion. Keep that in mind for an upgrade on any RV you buy.
 
Last edited:
i do

I fly an H6 powered RV7. You can message me if you want my full experience.

You will hear mostly negative comments here (and maybe rightfully so), and a lot of those will come from those who don't have experience with them. This forum is most definitely biased against auto conversions and especially Subaru conversion from eggenfellner.


Rv6ejguy gives great advice... it really comes down to you and price.

Ross, did you mean Gen3? or Gen2? Def don't use a gen 1 or 2. the Gen 3 (gen3 v4 red anodized PRSU) have been pretty reliable with a few defective ones out there (Although there is still controversy about how the main shaft was made). There is another gearbox out there that had initial problems resolved. The new version from Mike T looks promising, but again, is new so....
The Marcotti gearbox Ross has seems to be be really nice but is made of unobtainium.
 
If you like to tinker...

I know someone who does, and things seem to be working pretty well. The carbon fiber intake manifold he fabricated is pretty cool, too ;)

Have to admit, his experience has softened my stance. Sound great (subjective, I know) too.
 
Subaru H6 Still Running

Chiming in 2 1/2 years late just to say, there are still some Eggenfellner H6's still flying. I bought an RV8 with the H6 conversion in February of 2021. The plane had over 800hrs at purchase so I was comfortable enough that it was tested thoroughly. I have put over 100 hours on it since and it has always completed the mission.

All points made in this thread are accurate. It's heavy, drinks a lot of fuel, and you're at the mercy of the Subaru engineers and Jan's tinkering to hope that the fuel air mixture works at altitude.

Performance is not good... It drinks 10.5 at a best of 143kts. I typically use it to go from DC to Alabama. That means a stop mid way.

My takeaways from being an Eggenfellner owner is, for this plane, it was done correctly. I contribute that to the builder and not to the setup. It also filled a need to be the cheapest IFR capable plane I could use to go from DC to Alabama. That said, I will likely swap it out for a Lycoming IO-360 in the very near future. But for now, I'll fly out to DC in two days and trust the H6 will get me there safe as it has done in the past.
 
If done properly, it can be done and it will work.

Having said that - I'm an engineer by trade, a tinkerer and gearhead by choice, and I love turning wrenches on my plane almost as much as I love flying it. I installed a Lycoming.
 
Brian, what seems to the cause (or causes) of the performance loss?

Thermodynamics and sub-optimal engineering Dan.

Liquid cooling has advantages and disadvantages.

The disadvantages are clear - added complexity, added failure points, possibly added weight.

The advantages include better temperature control and thus the possibility of running closer engine tolerances. So less oil consumption, less blow-by and thus longer lasting oil. Furthermore no shock cooling, and - and here’s the kicker - the possibility to transport heat to have it removed from the system to a more suitable place than the up-front-in-the-nose location that you are forced to with air cooling.

Turns out that right behind the prop is not the best place for cooling. No good flow due to disturbances from the prop, no room to create a smooth path for air to flow without having to navigate all sorts of turns and around objects. As a result, with our air-cooled engines, cooling drag can form a significant part of the total drag of the airplane. As high as 40%.

The P51 Mustang is also known for its “Meredith effect” of its cooling system, which according to many actually produces a little thrust. While this is debatable, what its cooling doesn’t do is create 40% of the total drag of the Mustang. 

The Spitfire and BF-109 with their wing-mounted radiators don’t do so bad either.

The secret is the smooth ducting that they can have, slowing down the air to hit the radiators at a significantly reduced speed, and then once through the radiator, the air can be accelerated again to exit at roughly the same speed as it entered. Thus posing very little drag. And enabled by liquid cooling, which transfers the heat from the engine to that place in the rear fuselage or wing.

One thing that air cooling has going for it is that you need less air over an engine than you need through a radiator. Simple thermodynamics - heat transfer is proportional to the difference in temperature between the media. And the cylinder heads of an air cooled engine get hotter than the coolant in a radiator. And so you need more air through that radiator than you would over an equally powerful air-cooled engine.

Now for the Eggenfellner.

Presumably for reasons of simplified installation, Eggenfellner chose to not take advantage of the option of moving the heat to a more suitable place for cooling. In stead, he stuffed the radiators in the nose. Worst of both worlds - bad cooling location, no way to create a smooth airflow with an engine sitting right behind the radiators, and to add insult to injury you need more air through them than you would have needed with an air cooled engine.

Result - massive air resistance and mediocre cooling.

And there’s your answer…

As an aside - an excellent read on this subject are the (now ancient but still valid) Hans Mayer articles:



http://www.glasairproject.com/GlasairI/AirSig/CoolingSystems/cooling1/CoolingSystems1.htm
http://www.glasairproject.com/GlasairI/AirSig/CoolingSystems/cooling2/CoolingSystems2.htm
http://www.glasairproject.com/GlasairI/AirSig/CoolingSystems/cooling3/CoolingSystems3.htm
http://www.glasairproject.com/GlasairI/AirSig/CoolingSystems/cooling4/CoolingSystems4.htm
 
Last edited:
800 Hr. Subie!

Robercom: From watching the Egg in RV fiasco play out from the beginning, one of the biggest issues was always the "factory" PSRU, as seen by the requirement to keep coming out with new "Generations" (1, 2, 3, etc.). Great to see a Subie out there with 800 hrs. on it, but sadly more than one RV ended up "off airport" when their PSRU failed, safe flying with yours.

Doug

RV-9A Mazda 13B/FWF
 
Last edited:
How did the Gen3 fare? Did it finally have a good torsional vibration analysis done on it?
 
How did the Gen3 fare? Did it finally have a good torsional vibration analysis done on it?

It seems like it really depended on how lucky you were. Some units were doing perfectly fine, others ran very hot.

I've seen a Gen 3 taken apart. It had some questionable engineering practices inside. Gears WELDED onto an axis. Ball bearings doubled up and slid up against the weld. That kind.

Seemed like there was plenty of room for unit-to-unit differences.

Some people have reported issues with severe fretting on the splined output shaft.

Having said that - For a friend, I've built a Robin with a 6-cylinder Egg engine and gen 3 gearbox coupled to a 3-bladed MT prop. The unit has over 500 hours with no issues.

I seriously doubt if a torsional analysis has ever been performed..
 
Last edited:
Back
Top