# EJ 22 in Zenith 750 STOL

Discussion in 'Subaru' started by littlejon, May 5, 2016.

1. May 5, 2016

### littlejon

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I am currently building a Zenith 750 STOL and am looking at engines. I understand that a certified engine would work well, but am leaning towards an EJ 22. If I go this route I will go with the SDS wiring harness for ease of application and tuning, also looking at a Garrett turbo but have not decided on if I will run a turbo or not? I am wondering if anyone has pictures of engine mounts and any input. Thanks for the advice.

2. May 5, 2016

### cluttonfred

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Welcome, littlejon, I can't help with your questions but we don't hear as much about Subarus today as in days gone by and I'll be looking for news of your project with interest.

3. May 5, 2016

### Victor Bravo

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PLEASE make sure to do a valid, fair, accurate comparison on engine weight between the Subaru and other choices. The Zenair CH-750 was specifically designed to allow the use of a stock as-removed Continental O-200 engine, or a lightweight version of the Lycoming O-320 (using the smaller and lighter accessories).

So if cost and reliability are major factors in your decision, then I humbly suggest you compare the price of a used, mid-time O-200 or O-320 to the costs of your other options. I'm fairly sure you will be pleasantly surprised. Not to mention flying 6 months or a year sooner.

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4. May 5, 2016

### Direct C51

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OP, don't let this guy discourage you. Experimental aviation is about experimenting and learning. If your goals include learning to adapt an alternative engine for airplane use, experimenting, and the advantages of non certified engines, then go ahead and learn, build, and fly your EXPERIMENTAL airplane. If your goals are to get flying as soon as possible with the least amount of experimentation, then an O-200 or Rotax might be the better choice.

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5. May 5, 2016

### Victor Bravo

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Absolutely not trying to discourage. Please accept my apology if it seemed that way.

C51 is correct... if part of your experimental airplane desires is to adapt a car engine or alternative engine as an alternative to "airplane" engines, then by all means godspeed and bonne chance.

6. May 5, 2016

### BoKu

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Also consider that experimentation with turbos introduces a whole new dimension in demolishing pricy bits. If you're following a recipe for a known good configuration of engine, turbo, wastegate, FI setup, etc, you stand a good chance of getting the power you need on the first try. Otherwise, you'll likely want an extra motor on hand for when things go wrong.

7. May 5, 2016

### rv6ejguy

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If you're going to turbo, get an actual EJ22 turbo block. There are many differences internally which make it a far better choice than slapping a turbo on a standard block. Redrive wise, look at an SPG-3 if you're below 160hp or so, Autoflight if above that. Use a flywheel of at least 12 pounds to minimize torsional vibration typical just above the idle rpm range.

These engines don't take kindly to 100LL so if you plan to use a lot of that, skip this engine and go with a traditional aircraft engine.

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8. May 5, 2016

### littlejon

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Thank you all for your comments and concerns. Price is a major factor, I will look at a mid time 0-200/0-320. From everything I have seen even these engines are a little pricey. I am putting extra tanks in my wings, the thought being that I do not want to use 100LL, so if I take a long trip I will be able to fuel up with auto gas and not have to worry about 100LL. I have done some research and these engines will take 6 psi boost and will not hurt them, I might try and go turbo normalized, I am not looking for a power house, but I live about 5500 elevation, so will want a little extra help on a high density day. There is some information on the Simple Digital Solutions web site about using the Garrett turbo, it being better for a contunious duty operation.
I am hoping someone has some pictures or diagram of an engine mount to go off of. I will have a local machine shop fabricate up the mount, but if I can provide pictures or diagrams that will help them a lot. I plan to use the 12 pound fly wheel as I have read that the lighter ones do not address the torsional vibration issue. I will look into the SPG-3 redrive, I have looked at some, many say that the belt redrives work well, others like the gear redrives. I do not have a preference at this time, other then something that will work.

9. May 5, 2016

### BoKu

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You might also consider looking at an O-290D or converted O-290G. The parts are a bit pricy, but in the recent past there seems to have been a good handful of these motors available at reasonable prices. The O-290Ds were standard on a lot of Piper Pacers and Tri-pacers and similar airplanes that have been converted to O-320, and some have been turned loose by folks similarly converting 1960s and 1970s homebuilts. If you get one and it works, it will probably keep working for a while yet, and it will probably give you fair warning (reduced power, fouling plugs, blowing oil, metal in the screen) before crapping out entirely.

Thanks, Bob K.

10. May 6, 2016

### PW_Plack

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Part of the experiment with a Subaru conversion is the budgeting. I know a few people who have ended up spending more getting an EJ22 or EJ25 running reliably and successfully in their aircraft than they would have spent on an O-320. I have a good friend who upgraded his converted O-290G to an O-320 for under $6K, so it doesn't have to be super expensive if you look for deals and are patient. 11. May 6, 2016 ### Eagle ### Eagle #### Well-Known Member Joined: Aug 31, 2015 Messages: 83 Likes Received: 22 Location: Good ole Usa As the Subes seem to be fading in popularity the Corvair seems to have a solid following. Lots of information available, newer and stronger components. When complete you have an engine comparable in weight and power to an O-200. Don't have to deal with a cooling system and extra weight of both the Subes engine or cooling components which gives a lighter airplane overall. If you want to turbo it, you can. Bill Clapp Dan Weseman. William Wynne. all have development info and two of them conduct classes on engine assembly. 12. May 6, 2016 ### rv6ejguy ### rv6ejguy #### Well-Known Member Joined: Jun 26, 2012 Messages: 3,749 Likes Received: 2,814 Location: Calgary, Alberta, Canada There are way, way more Subes flying than Corvairs. The Corvair is a good 120hp engine if that's what you need. If you're looking for 150+, the Sube is a good choice with the right drive. You need to be able to stand about 300 lbs. ready to run though. If that's not in your weight budget, forget the Sube. I've worked extensively with both engines. There are pros and cons to both. 13. May 6, 2016 ### littlejon ### littlejon #### Member Joined: May 3, 2016 Messages: 14 Likes Received: 2 Location: Rogerson, ID The Zenith is designed for a 300 pound engine weight, so it will take a Sube. The engine should be about 120 hp, but I am looking to have it dyno'ed, that way I will know what my max rpm will be and can run at a lower rpm to achieve the 120 hp, which will help with engine wear. I have looked some at the Corvair, it looks like a good engine but finding parts is the thing that concerns me. I know there are still a lot of parts out there, but the Sube has many more parts available, as Ross points out there are plenty more Subes flying and I do not mind having liquid cooling. As I stated above, my elevation is 5500 ft, so a little extra power will not hurt on hot days. As for pros and cons, there are pros and cons with any engine I go with, even 'certified' engines fail, have issues and sometimes just do not run right. I have a few months before I will need to look at an engine, so am hoping to get some ideas, if something better comes along then I will go with it, but I am not going to be discouraged because some are not in favor of an auto conversion. I work on a ranch and have some experience turning a wrench, and when all is said and done an aircraft engine is pretty much like a car engine, just an air pump that uses fuel to drive it. As for a turbo, I have a turbo diesel truck and it is no more complex, in my opinion, then the non turbo, so long as things are laid out in a good manner. I might be wrong, but my truck has over 400,000 miles on it and still pulls as strong now as it ever did and I have not had a single issue with the turbo. 14. May 6, 2016 ### rv6ejguy ### rv6ejguy #### Well-Known Member Joined: Jun 26, 2012 Messages: 3,749 Likes Received: 2,814 Location: Calgary, Alberta, Canada The Sube can be pretty cheap if you know what you're doing since it doesn't need a bunch of parts changed out like the Corvair. You do need the drive but the SPG-3/4 is pretty cheap from Air Trikes as well. My entire FF setup cost$9500, including engine, prop, drive, turbo etc. My drive was a lot more than the SPG. I did all my own fabrication and overhaul though.

I have several friends who did their conversions for a lot less and they work well- some turbo too.

15. May 6, 2016

### Direct C51

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I just completed building my Corvair and will be test running it this weekend at the Corvair College in Cloverdale, CA. I can tell you without a doubt there is no shortage of parts for a Corvair. Finding a usable core took me 3 days and \$250. All parts that get reused can be found cheap on eBay or several Corvair parts websites if your core parts are damaged. The new parts you need are in production and for sale at Clarks Corvair among several other places. Cylinders and Pistons for the 3L 120HP conversion are modern VW racing products. Seriously this is a non-issue. If you are looking for 120HP there is no simpler, cheaper, and lighter way to get it. There have been several Corvairs installed on CH-750s and all of the needed conversion parts including engine mount are available at Flycorvair and flywithspa.

16. May 6, 2016

### cheapracer

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**** 4 times in 11 posts.

The OP didn't ask for comparison opinions or alternate options, he asked for information about SUBARU engines, in the SUBARU sub forum where, surprise surprise, people talk about SUBARU engines.

OP, welcome and rv6ejguy is a highly respected experienced guy in fly Sube area.

He has the decency not to spam, but I can do it for him ..

Simple Digital System EM-5

SDS EM-4: Aircraft

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17. May 6, 2016

### cluttonfred

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Off-topic, so sorry littlejon, but Direct C51, I hope you will tell us more about your Corvair build and experience at the Corvair College in another thread.

18. May 6, 2016

### Eagle

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He said he was "considering " a Subaru, so its not out of line to talk about both the Subarus pros and cons and mention an engine that might also be worthy of consideration.
Using your logic it would therefore never be correct to mention a Lycoming in any thread that wasn't about Lycomings.
HBA is supposed to be about the free exchange of information to help all builders. Its the final result that is important, not brand loyalty.

It's wise to at least consider what the Sube does and doesn't do well.

It is a given that the Sube conversion will be at the max allowed engine weight or maybe a little more as most conversions exceed expectations on weight.
Does the additional advertised 30 hp provide more of a benefit than being 100 lbs lighter on the nose of the airplane ?
Given that the whole idea of a 701 is STOL capability, light weight is an important consideration, especially on the nose of an airplane.
There is no way to compensate for weight in an existing design. Weight is weight, and when trying to land short it is the direct enemy of stall speed.
The main question then becomes whether in this particular type (STOL), will the benefits of 30 hp overcome the weight penalty during landing ?
Will the benefit of 30 hp overcome and aid take off when compared to a lesser powered but lighter engine. For sure it will not provide the full
benefit of 30 hp difference because of having to overcome the weight, so additional takeoff benefits will not fully realize the benefit of the 30 hp.

If you compare parts count, the Subaru conversion will be more complex and will consist of more parts.

The Sube will require a radiator,coolant,computer,wiring,sensors,and a reduction drive. All things that cost money and can potentially fail.
The Corvair will require a 5th Bearing of some kind. If it doesn't have a component it doesn't cost anything and it can't fail.
Operating speeds of a Subaru will place higher stresses on engine components, and the higher number of cycles the engine completes will
reduce the engines service life compared to the lower operating speed of a Corvair.
Maintenance on the Sube is more difficult due to a more complex overall system where a Corvair is pretty simple.
The last thing to consider is whether the cruise speed of the two engines is comparable. Since the 750 is not a high speed aircraft, there
is a certain speed that becomes a barrier to increased speeds. At that point due to the design of the airplane it takes lots more hp and lots
more fuel to get only a few mph more speed. If engine C can obtain normal cruise speed and only gain 3 mph when pushed hard, and engine
S can attain normal cruise speed and gain 6 mph with its higher hp, is it worth it? How often will you use that option ? If the OP does decide
to turbo charge a Corvair, he can get comparable hp and still be at least 50 lbs lighter than the Sube.

In the situation of this particular build, the Sube is a viable option but does not appear to be the best option. In a different situation where
higher speeds and cross country travel are the goal, the Sube would probably be a better choice because the additional 30 hp could provide
significantly higher cruise speeds in a more streamlined aircraft.

Not saying the Sube isn't a fine conversion, just don't feel the pluses outweigh the minuses in a STOL airplane.

Both the Sube and the Corvair (or Lycoming) all have good reliability when properly built.

Note: If you want to get an idea of what an additional 100 lbs is like, set an 80 lb sandbag on two sawhorses. Then take an
eight foot 2x4 and try to lift the sandbag. Grip the 2x4 at the end and maybe 2 feet from the end and begin lifting.

Last edited: May 6, 2016
19. May 6, 2016

### rv6ejguy

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There is no maintenance on the Sube to speak of and its reliability and longevity is better than the Corvair IMO. The Subaru happily operates at 4500 rpm for many hundreds of hours and internal parts counts does not relate to reduced reliability on a well engineered engine since most modern car engines today follow the same recipe- OHC, 4 valve/cylinder. The high time EJ engine I know of in had 3800 flight hours on it without being touched. No Corvair has even 1/3rd of that time on it that I am aware of.

30 hp will make a massive difference in TO/climb capability- even with the extra weight.

With the turbo at his high density altitude, the HP difference will be even more pronounced.

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20. May 6, 2016

### Eagle

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Not referring to just internal parts count. If you don't have a radiator or a hose or a water pump, they cannot fail. If you don't have a computer
or wiring or a sensor , they cannot fail. None are internal parts. If you subscribe to Contact magazine, the newest issue (110) has a story by
Keith Spreuer about his Subaru powered Cozy. It is an excellent story of the tribulations he went thru because of a small head gasket leak that
he was unaware of. It subsequently brought his airplane down. After managing to land safely, he performed repairs thinking he had fixed his
problem. Again he had to immediately land his airplane. He replaced the engine with another one only to have the brand new water pump fail.
Also read about the complexity of dealing with "all those wires" while trying to make repairs away from home base. Its a good read for anyone
with a Subaru because he had accumulated hundreds of hours and thought his airplane was fine.

As for the weight vs horsepower comparison, I noticed you only mentioned take off, which is always optional . Landings however are not always
optional or by choice as the story in Contact magazine describes. Weight is weight.

Last edited: May 6, 2016
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