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Auto engine conversions

Posted By:
James Whitaker
Homebuilder or Craftsman
29
Posts
1
#1 Posted: 4/28/2011 23:57:47

I was in conversation with my DAR-A&P/IA about the experimental aircraft movement and it's continued growth. The DAR mentioned to me that in his opinion the experimentals  and auto conversions as well would probably see tremendous growth when the economy turns around simply because people will have alot less cash to work with and the cost of certified aircraft is out of the question for so many. I thought this was a very strong statement coming from an A&p/IA as most don't want anything to do with an auto conversion.

 I know many of us are using the auto conversions for our own reasons and are confident in our decision. Personaly, I am using the Belted Airpower PSRU which is a belt driven redrive with ratio of 1.43:1. The v6 that supplies power has an output of 192hp@ 3500 rpm for a prop speed of 2447. One of the popular wood prop manufacturers told me that I would probably find that I was using a cruise power setting of 3000 on the engine. All this for a wide body cub type aircraft similar to the 2+2.

Belted Airpower has had great success with their redrive and it has been mounted on a variety of aircraft.

What are some of the other conversions you guys are using and what aircraft are you putting them on?

I'm making this inquiree because it came to me in conversation with one of the auto conversion builders that Lycoming and Continental approached one of the EAA magazines with a threat to remove their ads if the magazine endorsed any auto conversions. As always, I know there's more to the story,BUT, if the EAA would buckle to the certified corporate structure, why bother with AirVenture. After all, it's for the EAA!

In the name of what the EAA was started for, please, tell us ( experimental aircraft builders) what power plant your using and how you came to your decision to use it.

 

Jim



Michael Gerard
9
Posts
3
#2 Posted: 4/29/2011 13:43:05

I'll be using a Corvair conversion built following William Wynne's plans and using a Dan Weseman 5th bearing.  I'm going to build a Zenith CH 750 (already did the rudder at the factory workshop), which is designed for 80-100 horsepower.  A 164-cid Corvair conversion puts out right at 100hp and has the benefits of being easily found and rebuilt using off-the-shelf parts and a little elbow grease.

I'll admit that cost was the initial factor that got me looking into the Corvair, but the combination of the solid nature of the engine and the philosophy and people of the Corvair movement solidified the choice.  "Movement" isn't a flippant word choice, either -- everyone at the Corvair College I attended was passionate about homebuilders and homebuilt aircraft.  It was an amazing experience, and I can't wait for the day when I get to fly to one in my own Corvair-powered 750.

And if Lycoming and Continental are threatening to yank advertising from EAA over auto conversions, they'll only have guaranteed that I'll buy a Rotax if I'm ever in the market for an off-the-shelf engine.  I don't think the relatively small number of auto conversions is likely to do enough damage to those two companies' bottom lines to justify such a heavy-handed approach, which in any case would only alienate people who join an organization like EAA -- the kind of people who participate out of passion, not consumerism.



James Whitaker
Homebuilder or Craftsman
29
Posts
1
#3 Posted: 4/29/2011 15:26:35

Brandon,

I have been a fan of th corvair engine for a long time. It's a great choice as long as you don't ask too much from it. Besides the smaller stols, it works well with the exp cubs as well as some others. Great choice Brandon, you're going to have so much fun.

 

 

Jim



Ron Wanttaja
246
Posts
98
#4 Posted: 4/30/2011 02:22:28
James Whitaker wrote:

 

I'm making this inquiree because it came to me in conversation with one of the auto conversion builders that Lycoming and Continental approached one of the EAA magazines with a threat to remove their ads if the magazine endorsed any auto conversions.

Ummmm...when has the EAA "endorsed" any aviation product?

Reviewed, yes.  Printed articles about, yes.  But "endorsed" means that the EAA would officially approve a product, and that almost never happens.  I know of only one case.  It wasn't an engine, it happened almost 50 years ago, and they've never done it again.

I bet EAA has refused to print self-serving articles written by marketers of auto-engine conversions, though....




Ron Wanttaja
Matthew Long
Homebuilder or Craftsman
122
Posts
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#5 Posted: 4/30/2011 16:49:06

On the subject of auto conversions generally, it will be interesting to see if the advances in modern auto engine technology actually make it to the flight line in any significant quantities.  There are a number of companies in Europe working on small aero engine conversions, such as the little Smart turbo diesel built by Mercedes.  There is also the Honda Fit/Jazz conversion being marketed by longtime Subaru engine builder Jan Eggenfeller.  Personally, I'd like to see some of the simple, rugged little engines used in the Japanese minitrucks converted to aircraft use, which would be just right for low-cost, lightweight American LSAs or European microlights.



******* Matthew Long www.cluttonfred.info
James Whitaker
Homebuilder or Craftsman
29
Posts
1
#6 Posted: 5/1/2011 13:25:30

Ron,

You are absolutely right. I believe that the EAA makes no practice of endorcing any engine or other product for that matter. I think the point that the product manufacturer that I was speaking with was making was that the certified guys were flexing their muscle. In the same conversation I was told about a writer for one of the experimental aircraft publications that made the comment regarding auto conversions "don't use them". That's qiute a statement to make considering the rag he writes for being for EXPERIMENTAL AIRCRAFT. Look, the auto conversion isn't for everyone and I would never tell anyone to go with an alternative engine. It reqiures alot of research prior to making that decision. That fact of the matter is that are alot auto conversions powering a wide variety of homebuilts and they work. It goes to the very core of what the experimental aircraft movement is. I'm not going to argue the point with anyone. If you don't like the concept of the auto engine, don't use it. But, for many of us, it does work. 



Frank Giger
Homebuilder or Craftsman
117
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33
#7 Posted: 5/1/2011 20:41:51

I'll be putting a VW bug engine on my 7/8ths scale Nieuport 11...



Dave Prizio
Young Eagles Pilot or VolunteerHomebuilder or Craftsman
118
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29
#8 Posted: 5/2/2011 11:44:55

I saw the "don't use them" comment, too, but in all fariness there was a lot of important context that went with that remark. The point being made was that if you want to maximize reliability and minimize installation and maintenance problems, then an auto conversion is probably not for you. Also, if you do a lot of flying over places where a forced landing may be challenging, then, again, you might want to think twice about an auto conversion.

The truth is that auto engines such as the Volkswagen, Corvair, or Subaru are all good auto engines. However, the efforts to convert them to reliable airplane engines have been, shall we say uneven at best. Many conversions have not worked out well, others have worked reasonably well if the builder has a full appreciation of the special needs that these conversions have, and lastly only a very few have worked really well.

I would never suggest that experimental airplanes never use auto conversion engines, but I would suggest that enyone who goes that way do so with a well-informed understanding of what they are getting themselves into. There are no auto conversions to my knowledge that have been able to match the service record in airplanes of Lycoming and Continental. Each builder will need to decide how important that information is to him or her.



Ron Wanttaja
246
Posts
98
#9 Posted: 5/2/2011 20:35:24

Doggone it, Dave, how did you reach into my brain and end up saying the same things I was going to post?
pilot_beer4.gif

What is the most important feature of an aircraft engine?  Some will jump up and say, "Power to weight ratio," others will point towards low specific fuel consumption, and many will center on low cost.

But the most important feature of an airplane engine is reliability.   Without reliability, any other virtue of an engine is meaningless.  It might be capable of producing ten horsepower per pound, burning half a gallon of ethanol-laced gas per hour, and cost only $500 to build, but all this is to no avail if the plane ends up embedded in the trees off the departure end of the runway.

Is it possible to build a reliable auto-engine conversion.  Heck yes!  Talk to William Wynne, Ben Haas, and others with long-flying aircraft.

But...but...the track record for auto-engine conversions is not that good.  In the studies I've made, I estimated that auto-engined homebuilts have a 23% higher accident rate than those powered by traditional engines.

The problem is not the suitability of the engines themselves, but the abilities of the folks converting them.  People experienced with engines may not have much trouble, but someone who doesn't understand engines that well can get into trouble.  They don't have the right background for how things should be done, and they don't have decades of experience to detect when a problem might be brewing.

Here's a chart from a presentation I gave at my EAA chapter.  This compares the number of hours on the aircraft at the time of accident, for traditional engines and auto-engine conversions.  Note that over 20% of all auto-engine homebuilt accidents occur in the first ten hours...about three times the rate of conventional engines.  This indicates that too many homebuilders can't get their engines running reliably.

 
auto.jpg

The main areas where auto engines suffer is because of those systems that Lycoming/Continental users don't have to contend with:  Reduction drives, radiators/water pumps, and electronic ignition.  Yes, electronic ignition is more reliable than the old-fashioned magneto.  But it is NOT more reliable than TWO old-fashioned magnetos, especially when a single electrical-system failure can kill the engine..

The best auto-engine solution, for a typical homebuilder, is to buy a "firewall forward" conversion from a reputable company. This...surprise, surprise... usually ends up being sold at a significant percentage of the cost of a rebuilt Lycoming/Continental.

I'm all for folks experimenting with alternate engines.  However, folks have to understand they ARE experimenting, and that experiments do fail.  If you are building to have an aircraft that you can enjoy with the least worries, you're better off with a traditional engine.  A very respected local homebuilder installed a Ford V-6 conversion in his BD-4.  He was an engineer, with extensive engine-rebuilding experience, using a commercially-available reduction drive system.

What, you're expecting some disastrous  finale highlighting the folly of auto-engines in aircraft?  Not from me.  He installed the Ford after the BD-4's original Lycoming failed on takeoff and he crashed.   He flew that airplane with the Ford engine for a number of years, all across the country, even to Oshkosh a couple of times.

But he bought a used Bonanza to use whenever he was taking his family anywhere.  He recognized there would always be uncertainty regarding the with the auto conversion's reliability.  He was willing to take the risk himself, but wasn't willing to risk his family.

 

 



Ron Wanttaja
James Whitaker
Homebuilder or Craftsman
29
Posts
1
#10 Posted: 5/3/2011 21:49:57

It's the same for the engine as with the rest of the amateur built aircraft," know your limitations". As for the long time flyers. I was in contact with Ben Haas when I decided to go with the Belted Airpower reduction drive and called him when I fired the engine up. Ben uses the BAP drive unit that has been modified to bolt up to a Ford instead of the Chevy. That being said, I called Ben when we were passing through after leaving Yellowstone and took a ride in his 801. No complaints here. I am using the BAP drive and had the machine shop build the engine with only mild mods (ie; vortec heads for an additional 25  bolt on hp). Belted Airpower has been flying this drive and engine for some 20 years now with great success. I made this decision after researching the Eggenfellner subaru conversion. I just liked what BAP did and how they did it. BAP's success spoke very loud to me in terms of safety. There are several choices for conversions of different engines so this is not to be taken lightly. Again serious research needs to be done before a sound decision can be made. Personally, I studied the engine and drive unit for over a year before I commited to the project. As for 23% higher accident rate, it looks like 14% at best to me. But I may be reading your chart incorrectly.

 I think the auto conversions are here to stay and will grow in popularity as the economic picture turns around as many people are going to less money to work with and the alternative engine will be the only choice available if they want to fly their own aircraft. I just hope the market doesn't become flooded with bottom feeders that are out to make a quick buck then disappdsear. Does anyone remember NSI.

Hey guys, we could go on like this forever. The only point I want to make is that there some very successful conversion out there that deserve to be taken seriously. Instead some writer makes a blanket statement and says "don't use them". Well at least he doesn't have an open mind as to let garbage fall in, instead he lets stupidity fall out of his mouth.

BTW, are there any scale mustangs that use anything other than an auto conversion?

 

Jim



Ron Wanttaja
246
Posts
98
#11 Posted: 5/3/2011 23:34:00
James Whitaker wrote:

 

... Personally, I studied the engine and drive unit for over a year before I commited to the project. As for 23% higher accident rate, it looks like 14% at best to me. But I may be reading your chart incorrectly.

Yes, the chart is completely different from the overall accident rate data.  The chart compares the number of aircraft hours when an accident occurs, NOT the overall accident rate.   The number of total accidents is not a factor, just what percentage of the total fell within a given range.   I computed the accident rate (number of accidents vs. the total number of aircraft in the homebuilt fleet) differently.  See the February 2011 issue of KITPLANES magazine to see the process.

This does highlight the difficulty when discussing accident rates.  Few people are statisticians (heck, I'm not a statistician!), and it can be easy to mis-interpret the results.  I'm not sure which case you're referring to, when you mention a writer who said "don't use them," but I know my data was interpreted incorrectly by a writer of my acquaintance.

When I take accidents over a ten-year time period, I find that 12% of the accidents involving traditional-engined aircraft were caused by the engine, and about 37% of the auto-engined homebuilt accidents were caused by the engine.  It's easy to interpret this as "The accident rate is three times higher," BUT THAT'S NOT THE CASE.   Remember, that 12% and 37% rate is of homebuilts that had accidents, and only about 0.85% of homebuilts have an accident in a given year.  When you consider that most accidents are due to pilot error, the higher failure rate of auto-engine conversions gets diluted quite a bit.

For instance, assume there are 10,000 traditional-engined homebuilts.  In a given year, assume there are 100 crashes (accident rate of 1%), of which 55 were due to pilot error and 10 were due to the engine failing.  35 were thus other causes.

OK, assume there are 10,000 homebuilts that are otherwise identical, but with auto-engines.  You'll have the three times the accidents due to engine failures (30), but you'll have the same 55 crashes due to pilot error and 35 due to other causes.  This gives a total of 120 crashes.... a total accident rate of 1.2%.  Which is 20% higher, not three times higher.

 



Ron Wanttaja
James Whitaker
Homebuilder or Craftsman
29
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1
#12 Posted: 5/4/2011 14:59:24

RON,

This is exactly what I didn't want to do. ARGUE! My point was and is that there are some conversions out there who have proven safety records that have been flying for a long time. Do we agree on that? Not all products that have hit the market are as good as others. Do we agree on that? Again, if the altenative engine is what someone wants do, please for everyones sake research the product to make an educated decision. Don't be the only one to try to fly a product with only marginal testing. But, for it to be said "don't use them". That's a blanket statement that makes about as much sense as any other blanket statement that has ever been said. I think we all can come up with some of them.

I have personally seen some award winning examples of beautiful aircraft with auto conversions (the corvette  powered lancair, stewart mustang and let's not forget the thunder mustang who's engine is an extended small block chevy) as I'm sure most of us have.

I believe the corvair engine was originally designed as an aviation engine wasn't it. The VW based engines are enjoying great success.  Which brings me back to the original point. Research the product, know your limitations and procede armed with the knowledge neccesary to fly your aircraft safely in all aspects. Never make such an important decision based solely on cost. I have always said that I'm not trying to build the worlds cheapest airplane.

Soooo, what engine are you guys using for you aircraft? Any other chevy V6's out there?

 

 

Jim



Robert Dingley
Homebuilder or Craftsman
161
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#13 Posted: 5/4/2011 19:39:57

Ron, good job on your research, I spent many hours reading and re-reading it when it was first published. There is another type of engine that is not being discussed in our thread and one that gives me fits. It is the two cycle aircraft engine.

Designed from the get-go to power aircraft. However, I have heard passing remarks about seizures and stoppages that are expected to happen as a matter of routine. The engine failures don't seem to be recorded or investigated if no one is hurt. It seems that the owners simply haul it home and fix it without further ado. I have heard 250 hours as an average time between failure.

I have never left the ground behind a two cycle engine, don't have any first hand experience and just listen to the "buzz". I do know that a certified piston engine is seven times more likely to have an inflight failure than a turbine engine. Ron's work indicates that an auto conversion is far more likely than a certified engine to pack it in. But the drift that I get is that the two cycle aircraft engine is the all time champ.

I appologize if I have bad data and got my facts wrong. I am just currious as to what the facts realy are as to two cycle engines.

Bob

 



Gary Skeens
6
Posts
0
#14 Posted: 5/4/2011 22:26:33

Hi,

I just wanted to jump in here since I am also considering the possible use of an auto engine. I noticed the chart shown lumped all auto engines together. Since there are many different configurations, i.e. some with reduction drives, some direct, rotary, air or liquid cooled, some well thought out, and some cobbled together with whatever the builder could find. So it seems to me the data is a little incomplete at best.

Gary



James Whitaker
Homebuilder or Craftsman
29
Posts
1
#15 Posted: 5/4/2011 23:30:14

Gary,

Thanks for that post. I too have seen some set ups that just looked too good to be true and let's leave it there. It's hard to tell in my avatar that I am using the Belted Airpower redrive. I built the test stand to get the engine set up and running and it sounds great. I did the coffee cup thing on the air cleaner and it just sat there. I chose the BAP redrive because IT IS ENGINEERED for aircraft use. The biggest issue I can see is the correct prop. I have talked to a few of the prop manufacturers and am going with Catto. Not because he's cheaper, he isn't, but because his props are engineered and he can cut one that will do what he says it will do with no embellishments.

The engineered redrive and an engineered prop to go with it. Research is the key. I'm confident in my choices and am sure I will have many hours of safe flying.

 

Jim



Dennis Cote
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#16 Posted: 5/5/2011 23:13:09

I have been studying use of a VW based turbo engine for a CH 750.

Seems like a good way to improve high density altitude performance for mountain flying.

The sierras are fairly tall!

An engine with 135 hp for takeoff (5 minutes) then fly at 80hp for cruise should work out well.

Any suggestions?

 

Dennis in central California



James Whitaker
Homebuilder or Craftsman
29
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#17 Posted: 5/5/2011 23:39:41

Dennis,

I'm the wrong guy to answer that question as I don't have any details on the VW based engines. I have seen them pushed to extreme limits though and have heard of one guy that put a small ray jay turbo on a VW to power his KR2 so I know it can be done. Just for fun try this. Do a search on ebay for vw engines and take a look at some of the claimed hp on them. I think you'll be surprised. This is one of the projects that people will watch. Good Luck with it and keep us informed!

 

Jim



Dennis Cote
Homebuilder or Craftsman
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#18 Posted: 5/6/2011 15:24:32 Modified: 5/6/2011 15:27:33

Thanks Jim:

I was thinking of an engine with quench chambers and aluminum heads to allow a bit more compression and an EFI with a turbo dodge ecu or a Megasquirt 'n spark unit.

The system by these folks looks close to what I had roughed out.

www.bushkingperformance.com

 An other alternate may be an NA 3.5 liter based on the Pauter Machine "VW" block, but there would be more system integration for me to do than the BushKing FWF "kit". It may be capable of direct drive, eliminating the weight and complexity of a reduction drive. It would not have the turbo normalization, however.

 Dennis

 



Jay Jacobs
Homebuilder or Craftsman
16
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#19 Posted: 5/6/2011 18:39:51

Mazda 20B rotary completely rebuilt.  Currently it's on a test stand.  It has a 76mm turbo two fuel pumps duel oil coolers, dual radiators and dual intercoolers. I'm using Tracy Crooks engine computer and expect a power to weight ratio of about 1:1 with moderate boost and an RPM of 6500.





Dennis Cote
Homebuilder or Craftsman
3
Posts
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#20 Posted: 5/6/2011 20:38:58
Jay Jacobs wrote:

 

Mazda 20B rotary completely rebuilt.  Currently it's on a test stand.  It has a 76mm turbo two fuel pumps duel oil coolers, dual radiators and dual intercoolers. I'm using Tracy Crooks engine computer and expect a power to weight ratio of about 1:1 with moderate boost and an RPM of 6500.



Jay:

What is your expected HP and full weight including all cooling strategies and the PSRU and propeller?

What are you using for injection and ecu?

Dennis

 



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