Aeromomentum AM20T 260HP

[whee]

I always enjoy a good engine discussion. I think Schu hit the biggest points.

The one reason there isn't a LS v8 on my BH is the lack of a properly engineered PSRU. There's a few TLAR engineered PRSUs that have the features I want but they have mediocre track records. Plus a PSRU costs in the neighborhood of $15k so that eliminates any potential savings over an aircraft engine. I have zero concerns about the reliability of an auto engine itself, it is everything else necessary to use it on an airplane that introduces a multitude of failure modes.

Anecdotally; My boat has a Ford v8; 351 Windsor with a carburetor and mechanical advance distributor ignition. Solidly 1950s technology, light years ahead of a Continental or Lycoming. It has over 3000hrs on it and is hardily abused. 3200rpm cruise, 4400rpm WOT for extended periods, lots of throttle jockeying, and when climbing whitewater it will experience over revs into the mid 5000s. Marine use is a pretty good proving ground for engine toughness IMO.

[schu]

I think the reliability of the auto engine has come along way. I have multiple chevy trucks with 250,000 miles and only thing ever done is oil changes. Here is another option http://www.autopsrus.com/bearhawk

I know what that airplane weighs, do you?

[JimParker256]

Schu, can you share the airplane's weight? I think it might make your point better... Is it super-light, or super-heavy?

[schu]

I'm not sure the owner told me for the purposes of making it public, and you know how these forums are, nobody is allowed to say ill of anybody else, but just the same, I thought I would post a bit of information to inform people, as new airplane owners are sometimes kit plane owners, and many times these same people get caught up in how cool auto conversions are before they understand the real pros/cons.

Anyway, I've made my point plenty well without posting the weight. Besides, it's not hard to figure out. If that page says "Wet weight with all accessories 580 lbs" then you can be sure it's not in the super light category, and you can also be sure that if it was in the normal 540 bearhawk weight, I wouldn't be saying "and your airplane will almost certainly be 100-200 lbs heavier or it won't be 260HP"

[JimParker256]

Sorry, Schu. I wasn't trying to be snarky - I missed those points in your earlier post. You're right – it was a good enough answer to validate your points.

[schu]

I think the advantages and disadvantages are somewhat equal for both auto and aircraft engines. Aircraft engines lagging because of all the red tape the manufacturer has to deal with. Running drag racing engines for years, if you balance all components, use high end parts, time ignition and fuel for each cylinder with a good ecu, an auto engine can live at moderate RPM for a long time. My race motor is a SBC 427 @ 8200 making 820hp built in 2007 was reringed and bearing twice but had little wear. I just think the technology of auto engines are far beyond aircraft engines. They're just not certified and that's what keeps these aircraft engine companies alive. But not just anyone can deal with some of the complications of Installing an auto conversion.

Agreed, the actual engine isn't the problem. You can for sure build a SBC to produce 300hp at 5000rpm and have it last for 2000 hours. I'm not arguing the engine part, I'm arguing everything else.

If you go look at the statistics of auto conversions in experimental aircraft, it's rarely the engine that fails, it's everything else.

Now, if you are sure of your mechanical and engineering ability and can make the rest of it reliable, then great, you will probably end up with one of the few successful auto conversions, but I can guarantee you that what you saved in cost will be lost in resale value, it will add a year to your build time, and your airplane will almost certainly be 100-200 lbs heavier or it won't be 260HP.

If you really want to pursue the auto conversion, I would talk to Dan Shilling and copy what he has done with the EG33 engine. It's the right size, right weight, fits well, and Dan absolutely knows what he is doing.

[schu]

I think anyone thinking about an auto conversion needs to read this: http://www.epi-eng.com/propeller_red...y_contents.htm That's the engineering behind a properly designed psru.

[Burgerilla]

I want to emphasize what "schu" is saying here. I totally agree!! Just about every EAB website (Van's Air Force, etc.) has gone through the lengthy debate about auto engine conversions, some several times over. This debate is healthy in that it leads to education and learning. But in a world that lives with increasing amounts of "fake news" and oodles of misinformation, it is people like Jack Kane (the genius behind EPi, Inc.) who hold the actual facts and who we should seek guidance from. Some of you may be aware that Jack is also a "Contributing Editor" to "RACE ENGINE TECHNOLOGY" magazine (published monthly out of London, England and easily considered the world's authoritative publication on Formula One racing) in addition to his aviation engineering prowess. May I suggest that those of you who question "schu's" PSRU information, visit the website he has identified above and read the detailed information about engine torsional vibration and PSRU harmonic problems. "schu", I salute you!

[fairchild]

Im scared just reading that description ! I would sooner try a rotax than this rig. Or a rotary even. This engine sounds like a good match for a small lightweight flat track race car-- like
a re-power for a miata track car. You could use a 4 cylinder Acura TSX engine and get more horses for about 1000$ --- but like yall said--- there is a reason why people 75 years ago liked the slow reving radials or yesteryear. The lycoamings and contenentals may not "seem" modern or high- tec---- but we would all have to agree that they run reliabily most of the time with proper routine preventative maintenance. Even as "old" and well worn in those designs are-- even they have an occasional surprise pop up. Who wants to sit behind a design that is 95%
unknown failure modes. ????? The whole reduction system adds another whole universe of failure modes even if the engine is running fine. No thanks...… pass...….

Not to mention the people who advocate and sell these things--- how many have we seen go down that road---- get a bunch out in the field--- they start blowing up for unknown causes-
and the maker sees that the research for finding the solutions and the fixes are not worth his trouble--- easier to go belly up and screw all the customers who paid good $. It LOOKS like Rotec
might be having that problem-- but I hope they have the will and expertise to stay ahead of the problems. But time will tell. Just ask anyone who has bought a ford powerstroke 6 liter
diesel ???? They pumped those things out like they were the gold standard--- and then when they had them start blowing up every 10K miles---- at some point they just turned their back on
all the owners who paid 50-60K$ --- and now you cant give one away. ( I bought one without the engine and put in a mechanicaly injected first gen cummins--- that's my finger in the air to ford :-)

I figure if I stick with the big 2 MFG.---- and I don't make a big mistake mechanically-- I cant go too far into the weeds. Known quantity-- understood fixes - lots of knowledge base.....

My 2C

[yateselden]

I would be surprised if that 4 cyl makes 160 hp. When someone talks about a tuned exhaust on a turbo engine, snake oil comes to mind. If I have problems with my PSRU, I'm not sure where I'll get parts. It has a good track record but I may end up with an 0-360 or similar down the road.

[svyolo]

http://www.seqair.com/Other/PFM/PorschePFM.html

I found this a week or so ago when I read the original thread on the Aeromomentum engine.
I always thought you could turn a good car engine ito a good airplane engine.

I am going to go out on a limb, and say I don't have the engineering talent of the entire Porsche R&D department. They spent 10's of millions of dollars trying to take one of their very state of the art flat 6 engines, and make it an airplane engine.

It was all the rage, until it wasn't.

I still like the idea, I just doubt I could do better than Porsche.

[WylieECoyote]

Porsche got it to work just fine. The problem was in volume of engines for the liability. That is what the problem is with aircraft engines - low volume and huge liability, which explains why certified engines cost so much.

[Chris In Milwaukee]

I wonder if that’s the same tech that went into Mooney’s planes for a while.

[svyolo]

Yeah it was the Mooney PFM. A 201 with a converted 911 flat 6.

[Bdflies]

I tried to get some information about Gershwinder conversions, but found very little. I was just getting involved with aviation at the time, but remember some Gershwinder powered Ag planes. I don’t know if he held some specific type certificates for the airframes, but I remember they were well regarded. I think they were 351 Fords with belted chain reduction drives. I wonder why his conversions never went further?
Could be that the old Lycoming and Continental dinosaurs are just hard to beat, for this application.

Bill

[zkelley2]

If you could triple the fuel capacity, it'd be fun to see the 420HP Allison on a bearhawk like the Maule M7-420.

[way_up_north]

viking engines(Honda)...has taken over the zenith line of aircraft...I think there is a Viking engine in the factory demo plane.....

Viking offers an inflight adjustable prop....

the engine can run without the battery connected ....

1000s of hours on the fleet...the psru resonance problem is tamed with thier engine prop combination

the sun has not set on auto conversions....

https://m.youtube.com/watch?v=VI2xJolBwF8

[yateselden]

This power plant is also flying in the T51. I was checking it out on U tube. It's certainly interesting to see. I beleave they also use a Toyota 4 cyl also, not as much power tho

[svyolo]

Thousands of hours on how many engines? I want to see many engines with thousands of hours.

I think everybody would like to see it work. The cost of engines is one of the worst things about aviation. A new IO-540 shouldn't cost the same as a BMW.

[yateselden]

Tracy Crook had nearly 2000 hrs on his 13B. He came up a little short because of the Ross PSRU issue. He decided to build his own PSRU. On inspection there was no measurable ware on the 13B. His PSRU had been working well and inspections were looking very good. Unfortunately I don't know what the deal is now. I had gone to his seminars at Sun & Fun and was excited to dive into this combination for my BH

[way_up_north]

I’m just the messenger... and you don’t believe me...so please feel free to investigate my claims

[jaredyates]

viking engines(Honda)...has taken over the zenith line of aircraft...I think there is a Viking engine in the factory demo plane.....

Viking offers an inflight adjustable prop....

the engine can run without the battery connected ....

1000s of hours on the fleet...the psru resonance problem is tamed with thier engine prop combination

the sun has not set on auto conversions....

https://m.youtube.com/watch?v=VI2xJolBwF8

Another success story is the Corvair, and these have some things in common. Both are approximately half of the output of an engine for a 4-place Bearhawk, and both have been engineered by lots of other builders. It is crucial to think about the whole propulsion system and not just the crank and cylinders part. In the Zenith example, enough folks have been down the road to make the installation easier and better supported.the Corvair gets an extra leg up because it is already air cooled and horizontally opposed.