|Type:||Gas Electronic Ignition|
|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|
|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)|
|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!
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.
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.
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.
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!
The engine kit didn't include a throttle arm. I used a front wheel steering arm from a tricycle landing gear setup.
The compact welded can type muffler really does a great job. The 20EI was surprisingly quiet for a gasoline engine.
|Readings taken at app. 6 feet with an APC 15X6 prop installed.|
I did have to remove the carb, carb mounting block, and muffler assemblies to access the top two holes on the engine mount plate.
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.
|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)|
I had a couple engines sitting on the bench. So I decided to to set them next to the Zenoah just to compare size.
|Engine:||Zenoah 23||Zenoah 20EI||1.20 Size Four Stroke|
|Weight:||51.00 oz (no muffler)||41.6oz with muffler, ignition, and mount||31.08 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)|
|HP:||2.0 BHP||1.7 BHP||1.9 BHP|
|All data taken from the engine's manuals|
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.
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|
|PROP||WOT RPM||IDLE RPM||STATIC THRUST (calculated)|
|APC 15X6||9360||2000||13.34 lbs|
|APC 16X6||8530||2000||14.3411 lbs.|
|APC 16X10||7350||2000||10.65 lbs.|
|Zinger 15X6-10||8690||2000||10.85 lbs|
|Zinger 16X8||7430||2000||10.27 lbs|
|MA 16X6||8130||2000||12.29 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.|
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.
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.
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??
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.
I'll check it when I finish the Hellcat and let you know.
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.
Last edited by Michael Ga; Sep 05, 2006 at 05:13 PM.
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