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Zenoah 20cc Electronic Ignition Gas Engine Review

Rich Noon has a great time exploring this 60-120 sized model's newest power choice -- an ignition gasoline engine from Zenoah.

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Introduction


ADVERTISED SPECS:
Type:Gas Electronic Ignition
Displacement:20cc
Bore:32mm
Stroke:25mm
Cylinders:Single
Total Weight:41.6oz with muffler, ignition, and mount
Engine (Only) Weight:33 oz
Crankshaft Threads:8x1.25mm Benchmark
Prop:APC 15 X 6 9500rpm
Prop Range:14 x 6 through 16 x 6
RPM Range:1400 - 10,000
Fuel:Gas Oil mix 32:1
Muffler Type:Compact Welded can (included)
HP:1.7HP @ 8500rpm
Cylinder Type:Nikasil, ring
DIMENSIONS:
Crankshaft thread size:8x1.25mm
Distance Between Mounting Holes Same Side:1.96" (50mm)
Distance Between Mounting Holes Opposite Side:3.0" (77mm)
Distance Rear Engine Backplate Mount to End of Crankshaft:6.3" (161mm)
Distance Rear Engine Backplate Mount to Drive Hub:4.72" (120mm)
Height Bottom of Crankcase to Sparkplug Connector Top:6.29" (160mm)
Width Center of Crankcase to End of Velocity Stack on Carb:4.17" (106mm)
Width Center of Crankcase to Outside of Muffler:3.0" (77mm)
Engine Total Width (From Outside Muffler to Velocity Stack Inlet):7.2” (183mm)
AVAILABLE:
Approximate Price:$339.99
Manufacturer:Zenoah Engines
Distributor:Horizon Hobby
Instruction Manual:Zenoah 20EI

For as long as I can remember, Zenoah has been synonymous with reliable, high quality gasoline engines for airplanes, cars and boats. The image it brings to mind in airplanes is 1/4 scale or larger.

The advantages of gas engines have always made sense for larger planes: reliability, excellent power, fuel economy, less expensive fuel, easy operation, simple maintenance, less mess, bigger props, etc.

When a big gas plane was fired up at the field, you often heard the lament: "I wish someone would make a gasoline engine for the .60 - 1.20 size planes." Zenoah has filled that gap in a spectacular way with their new 20EI!

From the manufacturer

Zenoah's website rightfully brags:"Zenoah’s groundbreaking G20Ei isn’t just Zenoah’s first engine with electronic ignition, it’s the first gas engine from any manufacturer that can fit .60-size planes that, until now, were limited to glow or electric power choices. Its dimensions are especially well suited for round cowl models like Hangar 9’s popular Corsair 60 and P-47D 60 ARFs. It has plenty of power for many .90 to 1.20-size sport applications as well. Much of this incredible versatility can be attributed to its lightweight magnesium-aluminum alloy crankcase that gives it an impressive thrust to weight ratio compared to most gas engines.

Let's take a look

The Zenoah 20Ei came well packed in the colorful Zenoah box. All components were individually packaged and no damage noted. Included with the engine were: Instructions, decals, warranty card and wrench for both the prop nut and sparkplug.

About the Engine:

  • Displacement 20 cc
  • Bore x stroke ø32mm x 25mm
  • Weight 990g (not including DC Ignition Unit)
  • Model Application: .90 to 1.20-size sport applications
  • Mounting Application: Integral rear mounting plate
  • Internal Construction: Steel piston ring and liner, aluminum piston
  • Muffler: Compact Welded Can
  • Carburetor: Carburetor type WT-811
  • Ignition Battery ignition; digital control
  • Sparkplug Champion Y82
  • Revolution direction Counterclockwise (from PTO side)
  • Starting method External motor
  • Sensor spacing 0.8 ~ 1.2mm (1.0mm ± 0.2mm)
  • Fuel consumption 1-LPH / 9000rpm (at full throttle)
  • Noise (at 2-meter points) 98dBA (APC 15x10)
  • Battery capacity 4.8V / 1500 ~ 2700mA
  • Warranty: Three-year limited

Crankcase

The new magnesium-aluminum alloy die-cast crankcase is incredibly light. The crankshaft is mounted in three ball races with double counterweights. This combined with roller bearings on both ends of the connecting rod makes for a very smooth, long life engine.

Ignition System

Note!

The temperature of the ignition module may rise to as high as 158 to 176 degrees (70~80°C) depending on the operating environment and conditions, but this is not abnormal. However, make sure not to touch this part or you could risk being burned.

The ignition system is designed for 4.8V / 1500 ~ 2700mA operation. Use of anything other than 4.8 volt batteries could damage the module! Don't try to substitute higher voltage batteries!

Carb

Note:

The engine kit didn't include a throttle arm. I used a front wheel steering arm from a tricycle landing gear setup.

Exhaust

The compact welded can type muffler really does a great job. The 20EI was surprisingly quiet for a gasoline engine.

Sound Levels
IdleWOT
66.5db.96.0db.
Readings taken at app. 6 feet with an APC 15X6 prop installed.

Assembly

Note:

I did have to remove the carb, carb mounting block, and muffler assemblies to access the top two holes on the engine mount plate.

Assembly steps:

  • Installed the carb base gasket to the mounting block,
  • Attached then the carb and velocity stack with two Allen head bolts,
  • Installed the muffler, utilizing one gasket and two mounting bolts.
  • That's it!

The cylinder may be rotated 180 degrees to move the carb to the other side of the engine. This would require also rotating the piston 180 degrees.

Actual Weights:
Engine Block Assembly:25.32 .oz (718g)
Carb Assembly:5.6oz (158g)
Ignition System (Less battery):5.7oz (161g)
Muffler with Screws and Gasket:4.7oz (133g)
Total Assembled Weight:41.32oz (1171g)

Quick comparison

I had a couple engines sitting on the bench. So I decided to to set them next to the Zenoah just to compare size.

Quick Comparison
Engine:Zenoah 23Zenoah 20EI1.20 Size Four Stroke
Weight:51.00 oz (no muffler)41.6oz with muffler, ignition, and mount31.08 oz with muffler
Length Backplate to Drive Washer:5.47" (139mm)4.72" (120mm)4.01" (102mm)
Width:*4.13" (105mm)7.2” (183mm)*2.64" (67mm)
Prop:15X814x6-16x615x6-16x8
RPM:2000-100001400-10,0002000-11000
HP:2.0 BHP1.7 BHP1.9 BHP
*Without Muffler
All data taken from the engine's manuals

Bench Run Session

I charged the ignition battery, mixed up a fresh batch of 32:1 two stroke fuel and headed to the test stand. The temperature was running in the mid 90's with 88% humidity. It was warm out there!

I mounted the engine to the stand, filled the fuel tank, closed the choke and spun the engine over with my trusty Sullivan starter till fuel reached the carb. Then I opened the choke, turned on the ignition and spun the engine with the starter. In about one and a half revolutions the engine came to life and just set there purring. After allowing a minute or two to let the engine warm up, I slowly advanced the throttle. The engine accelerated smoothly to wide open. I felt the top end was a little slow so I stopped the engine and turned the high speed screw in 1/8 turn. This was the last adjustment I had to make for the entire test run. And the last time I had to use the starter. Just a flip with a chicken stick was all it took to start the rest of the day.

I felt the top end was a little slow so I stopped the engine and turned the high speed screw in 1/8 turn. This was the last adjustment I had to make for the entire test run. And the last time I had to use the starter.

Much as I like to tinker with mixture screws between prop changes, it just stayed consistent. I'm sure a bit more RPM could be squeezed out the engine by fine tuning between prop changes. Even though Zenoah states no "break-in period" is actually required, I hate to push a brand new engine to its limits. I usually try to run at least a gallon of fuel through a new gas engine before adjusting for peak RPM.

The manual provided detailed instructions on setting both the high speed and low speed needles, along with the factory settings for initial start up.

I used the JR Sport 4.8V 2700mAh Ni-MH battery battery for the bench runs. It lasted through all the initial test runs and prop changes with power to spare.

RPM & Static Thrust
PROPWOT RPMIDLE RPMSTATIC THRUST (calculated)
APC 15X69360200013.34 lbs
APC 16X68530200014.3411 lbs.
APC 16X107350200010.65 lbs.
Zinger 15X6-108690200010.85 lbs
Zinger 16X87430200010.27 lbs
MA 16X68130200012.29 lbs.
Idle speed was adjusted to the recommended 2000 rpm on each prop run.
I used a static thrust program that computes thrust based on prop size, air density and RPM.

Downloads

Test Flight

Coming soon!

The Zenoah 20 will be installed in the new Hangar 9 F6F Hellcat 60 for an upcoming review! Should make a perfect combination. I'll keep you posted.

Conclusion

Zenoah has filled a massive void in the .60 to 1.20 size engine class. They've produced a gasoline engine that is: Simple to set up and operate, small and light weight, reliable, inexpensive to run and efficient. It's hard to ask for much more in any engine, let alone a gasoline engine, in this compact size!

Is the Zenoah 20EI perfect for every 60-1.20 size plane out there? Just as there is NO glow engine out there that's ideal for every model in this size range, I have to admit no, there are aerobatic performance models that cannot accept the added weight, no matter how nice the fuel price savings and reliability may be. Is this the right engine for your model? You'll have to make that decision based on the particular aircraft and type of flying you plan to do.

This engine is a little wider and a bit heavier than your typical two or four stroke engine. However, since most planes I’ve built have required bit of extra weight in the nose anyway, this can actually be a plus. I'd much rather add engine weight for balance than useless lead weight. Plus, the simplicity of managing a gas engine over glow, the decreased ounces of fuel carried per run time, and more... This is definitely the ideal engine for those sport and particularly scale projects that need to emulate the real engines used -- big, honking, stump-pulling, gas burners! A scale warbird just doesn't sound right burning glow fuel. Plus, why add dead weight to the nose to make that glow engine come up to the model's CG needs, with the inherent risk of losing weight in flight and suddenly be horrifyingly tail-heavy, when you can instead burn gasoline, carry a smaller tank farther back from the nose, look great, sound great, and be as reliable as the day is long???

So if you have the room under the cowl and the model isn't an ultra-weight-conscious aerobat, I’d say go for it! It's an amazing engine that I will be using in a variety of scale projects in the very near future.

Plusses...

  • Reliable
  • Strong running
  • Electronic Ignition
  • Easy to setup
  • Light weight
  • Fuel Efficient
  • Cheaper fuel
  • Larger props
  • Excellent power to weight ratio
  • Almost no exhaust mess
  • Needle bearings on crank and connecting rod

Hmmm points...

  • Larger size and weight than comparable glow engines (which is a benefit in many installs!)
Last edited by AMCross; Dec 06, 2006 at 11:14 AM..

Discussion

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Old Aug 18, 2006, 08:42 PM
Just-Fly-It
Augusta, Ga
Joined Sep 2004
432 Posts
I was very interested in trying this engine, however one of the big disappointments to me and one of the big "Hmmm points..." you failed to list is the large battery required to power the EI.
It seem the designers pooled all the expertise to build a nice, light weight gas engine and then fell asleep on the EI. Why did this motor end up requiring a small brick for power??
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Old Aug 19, 2006, 09:55 AM
Registered User
Joined Mar 2004
51 Posts
As an after-thought I wish I had put a meter on the ignition to get some exact readings.

I used the JR Sport 4.8V 2700mAh Ni-MH battery for all the test runs. After over an hour of taking readings and prop changes, it was still powering the system well. But it is a pretty good sized battery.

And you're right, it is a heavier battery. I'm installing the engine in a H9 Hellcat and mounting the battery just behind the CG to help with balance. I'll try to get some readings on current draw then.
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Old Aug 19, 2006, 05:02 PM
Just-Fly-It
Augusta, Ga
Joined Sep 2004
432 Posts
Quote:
Originally Posted by RichN
As an after-thought I wish I had put a meter on the ignition to get some exact readings.

I used the JR Sport 4.8V 2700mAh Ni-MH battery for all the test runs. After over an hour of taking readings and prop changes, it was still powering the system well. But it is a pretty good sized battery.

And you're right, it is a heavier battery. I'm installing the engine in a H9 Hellcat and mounting the battery just behind the CG to help with balance. I'll try to get some readings on current draw then.
Not meaning to step on your great review. My LHS has this motor in stock, and I probably will buy one. I like the everything-in-one box, and the complete package is quite light. I was just disappointed the EI appeared to be so inefficient.
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Old Aug 19, 2006, 06:04 PM
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GassPasser's Avatar
BoonVegas, Indiana
Joined Dec 2005
674 Posts
pleez ...brick. no,this is not a 3D engine.
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Old Aug 19, 2006, 07:23 PM
Registered User
Joined Mar 2004
51 Posts
Quote:
Originally Posted by Michael Ga
Not meaning to step on your great review. My LHS has this motor in stock, and I probably will buy one. I like the everything-in-one box, and the complete package is quite light. I was just disappointed the EI appeared to be so inefficient.
No problem! I did think to myself "I should have put a meter on it and checked current draw". But I already had it off the test stand and more or less mounted in the Hellcat. Fits great in the Hellcat.

I'll check it when I finish the Hellcat and let you know.

Rich
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Old Aug 21, 2006, 05:14 PM
Registered User
Billund, Denmark
Joined Nov 2003
10 Posts
Toni Clark, the european importer of the Zenoah line, recommends using a single 3,7V lipo cell of about 2000mah capacity. That should be enough for about one hour´s running.
www.toni-clark.com
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Old Aug 22, 2006, 08:05 AM
Just-Fly-It
Augusta, Ga
Joined Sep 2004
432 Posts
Quote:
Originally Posted by Pelle Gris
Toni Clark, the european importer of the Zenoah line, recommends using a single 3,7V lipo cell of about 2000mah capacity. That should be enough for about one hour´s running.
www.toni-clark.com
Now that opens up some nice possibilities. I quickly read threw their ZG20 manual and was even more excited about this engine. I plan to by one and I will definitely try the lipo. I have at least 2 three cells that I can take apart. Glad I did not throw them away.
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Old Sep 03, 2006, 03:22 PM
Just-Fly-It
Augusta, Ga
Joined Sep 2004
432 Posts
Zenoah 20 on lipo

Maidened this engine today. Ran the EI on a single cell 1900mh lipo. After 50 minutes voltage was only down to 3.6 with no power problems at all. I can live with this.
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Last edited by Michael Ga; Sep 03, 2006 at 08:50 PM.
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Old Sep 04, 2006, 10:55 PM
Registered User
Malaysia
Joined Jun 2001
1,009 Posts
that good to hear michael. What plane you maidened on? Pls share more spec ie AUW, loading, prop size, rpm. etc.

Thanks!
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Old Sep 05, 2006, 03:50 AM
Just-Fly-It
Augusta, Ga
Joined Sep 2004
432 Posts
Quote:
Originally Posted by Magna
that good to hear michael. What plane you maidened on? Pls share more spec ie AUW, loading, prop size, rpm. etc.

Thanks!
Mainened on Hanger 9 Funtanta X100. Plane has over 1000 sq in and comes in at around 9.25lb. My scale only goes to 5lb and I didn't want to take the engine off to weigh it. I'll weigh it later this week on a bigger scale. Prop is APC 16x6. I have about two hours on the motor using only single cell 1900 lipo. Motor starts with around 8 turns on the prop and keeps getting better. Pulls the dog out of this Funtana. Full rolling verticals with maybe 75 to 80% throttle. Only checked rpm's once and they were very much in line with with those posted above. I have not touched the factory settings yet, but will experiment soon. No smoke, no mess, and very low engine noise in flight.
I found the included manual to be very lacking. I probably would not have bought this engine if not for the great information obtained from the Toni Clark site linked above.
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Last edited by Michael Ga; Sep 05, 2006 at 04:13 PM.
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Old Sep 05, 2006, 09:50 AM
Registered User
Billund, Denmark
Joined Nov 2003
10 Posts
Toni Clark quotes an APC 17x8N at 7700rpm, and my experience has been that if you do what he tells you, you will get the best from the engine. So I would recommend that you try this prop..:-)
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Old Sep 05, 2006, 12:58 PM
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Joined Aug 2006
5 Posts
Hanger 9 Corsair

Did anyone put the Zenoah 20cc EI in a Hanger 9 Corsair? I am thinking about it!
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Old Sep 05, 2006, 03:35 PM
Just-Fly-It
Augusta, Ga
Joined Sep 2004
432 Posts
Quote:
Originally Posted by toponewjersey
Did anyone put the Zenoah 20cc EI in a Hanger 9 Corsair? I am thinking about it!
Horizon markets this engine as a good choice for round cowl warbirds. I think you would like it.
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Old Sep 06, 2006, 09:50 AM
Registered User
Long Island
Joined Nov 2003
588 Posts
If you use a LIPO for the ignition don't you also have to use a cutoff so the voltage doesn't drop too low?
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