Stinger Engines by RCGF – 20cc Rear Exhaust Gasoline Engine Review

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Introduction

So what exactly are Stinger Engines? That’s a great question – one I found myself asking just a few months ago, when I received an email from RCGFusa.com. Here’s what they had to say:

Our New Direction!!

Hello RCGF Engine Friends and Family. This is your RCGF Engine design and marketing team. As some of you may be aware, our RCGF Engine brand will be celebrating its 12th birthday this year.

Over the past 12 years, we have offered more hobby engine sizes than any of our competition to better supply our customers with that perfect engine size.

Because of our aging engine molds, we have been forced to make a decision.

Do we invest in making new molds of our older model engines, or do we invest in new more innovative engine models? Being our aging engines have been pushed as far as possible to make the best power, this decision could not be taken lightly.

We are here to tell you, our engineering and marketing teams have all voted. We have unanimously come to the decision to take our engine brand in a whole “New Direction”!

Our “New Direction” is to move away from the old and outdated. We want to move our engine line into the future with all new designs.

These new designed engines will put RCGF back on top with fresh innovations to bring our engine family a much higher quality, more powerful lineup!

From our much-loved 10cc purpose built gas engine to our big powerful 120cc twin engine, we are bringing them into the future to deliver our customers a powerplant for the 21st century modeler.

Some of our older 18 engine sizes will be retired to make room at the table for some new rear exhaust engines, as well as wen sized singles and twins too!

We are so excited to announce that we will be re-branding these new engine designs in order to make sure that you are getting the “real deal” and not some cheap, poorly made knock off! Our “New Series” name is “Stinger Engines” by RCGF. The “Stinger Engines” are made with stronger materials. They’re more stable, more precise, and more powerful.

To verify if your engine was produced by RCGF Model, please type in the serial number of your engine at www.rcgfservice.com. You will find information there.

Thank you,

YOUR RCGF TEAM!!

RCGF USA LLC

www.rcgfusa.com

ZHEJIANG RCGF MODEL CO., LTD

www.rcgfservice.com

 

Wow! That’s a lot of information! So what are Stinger Engines? It boils down to this: Stinger Engines are a redesigned, new engine series from RCGF. ‘Nuff Said! Let’s take a look at one of their first engines off the line and see how it stacks up!

First Look

The Stinger Engines 20cc Rear Exhaust engine arrived in a colorful, glossy cardboard box. The RCGF logo is still present, along with a new logo featuring a scorpion. Inside, I found a very well packed engine, laid out and protected well in closed cell foam padding. A manual, a copy of the letter above, and an RCGF decal are all included as well!

Every thing you see in the above photo are included – and it’s a lot! One of the newest features you should take note of is the Rcexl high voltage ignition module!

One of the other things that caught my eye immediately was the luster of the aluminum parts. They’re SHINY! The casting and quality of the metal is as good or better than the previous versions as well!

 A rearward canted CM-6 sized spark plug hole is new, along with an included throttle arm adapter for RC use. While not a new feature, the Stinger Engines will still use the Walbro brand carburetors that were standard on the older RCGF engines.

 Back to that Rcexl ignition module, you’ll notice that it’s a high voltage unit – it will operate on Voltages from 6.0-14.4, giving the modeler a wide variety of battery packs to use! The Muffler is cast from the same metallurgy as the case, and has the same shiny appearance. It is a rear exhaust engine, meaning it’ll fit into narrow cowls! The included composite engine mount is designed to wrap around the crankcase  of the engine. All of the needed  hardware is included, which is good for most applications.

The new Stinger Engines also include the protective wire wrap, battery wire extension, and safety clips for the engine connectors.

Specifications

Name:   Stinger Engines 20cc Rear Exhaust Gasoline Engine

Where to Purchase in US:   RCGF Store

Price:   $229.99 USD

Type:   2 cycle reed-valve type gasoline engine for RC airplane

Piston Displacement Cylinder (cc):   20cc (1.22 cu in)

Bore x Stroke (mm):   1.3 in(32mm) x 9.5 in (24mm)

Carburetor:   Walbro

Ignition:   Rcexl DC-CDI (Computer Controlled auto advance, electronic ignition system)

Power supply:   6-14.4V

Maximum Output:   2.8HP /2.1KW

Requires:   Gasoline, 2-cycle oil, ignition battery & propeller

Max Speed Range:   1500-10500rpm

Gasoline-Version:   Pre-mixed Gas, Recommend:   30:1

(90% high otcane unleaded (Non-Ethanol recommended for carburetor longevity) gasoline)

Lubrication Oil:   2 cycle air-cooled engine oil (Not marine engine oil)

Recommended RPM:   1800 – 8900 (Standard two blade prop)

Suggested Propellers:   14×10, 15×8, 16×6, 16×8, 17×6

Spark plug:   NGK CM6 Type

Cooling System:   Air Cooled

NEW Stinger Engines package Includes: Rcexl CDI ignition, muffler, spark plug, gaskets, bolts, throttle arm extension & manual.

Weight :

Engine:   1.37 lb (620 g)

Muffler:   2.08 oz (59 g)

Ignition Module:   4.4 oz (125 g)

Total: Weight:   1.75 lb (795 g)

Technical Data:

Ignition Battery:   6-14.4 NiCd or NiMH, 6.6V LiFe or 2S LiPo pack

Gasoline/Oil Mix:   30:1

Replacement Spark Plug:   NGK CM6 or equivalent

Idle Speed:   1800 rpm/min

Static Thrust:

14.2 lb (6.4kg) @ 328 ft (100 m) altitude

12.8 lb (5.8kg) @ 5,900 ft (1800 m) altitude

Photo Shoot

Engine Installation

There’s one thing to do before installation. The 20cc RE comes with a very non-RC type throttle arm that is standard on most Walbro carburetors. Thankfully, Stinger Engines (and RCGF) has included an nice RC throttle arm! The stock arm needs to be removed – it’s just a Philips head machine screw, and it’s small. Reviewer’s Note: DO NOT use a lot of force on this screw! I have twisted these screws off on other engines, and it is a real problem…

With the original removed, the new RC throttle arm is installed – it is keyed, so it will only fit in two directions. Plan out your install, and you can figure out which direction is best. I added a drop of ZAP Z-42 Blue Thread Locker to the machine screw and carefully installed it without over torquing it. Now, we are ready to install the engine!

The Stinger Engines 20cc RE is being installed in my new Seagull Models 90″ L-4 Grasshopper ARF (See the assembly review here: Seagull Models L-4 Assembly Review). The firewall to prop hub measurement required was approximately 5mm longer than what the included engine mounts were able to provide, so I went to my scrap box and found some ply engine spacers that I had saved from another project. The two 3mm ply spacers were the perfect amount of offset for the L-4 firewall, and required just a little modification on the top to match the L-4 Firewall and new holes drilled. My wife thinks I’m crazy for saving all this stuff, but it’s nice to have the scraps! I attached the engine mounts and spacers to the firewall, clamped the engine in place, and marked the four holes to mount the engine. After removing the engine, I drilled the four holes.

The engine was temporarily mounted so I could determine the throttle pushrod hole location. The hole ended up needing to be drilled through the engine mount – there’s plenty of material and strength in the mount that I felt confident that this was not an issue. I drilled the hole without another thought.

Before permanently installing the engine, the muffler had to be attached. A couple of drops of ZAP Z-42 Blue Thread Locker were applied to the exhaust bolts before torquing them to the exhaust flange on the cylinder.

Using my trusty Z-bend pliers made connecting the throttle pushrod to the arm a snap. the pushrod was guided through the hole in the firewall/engine mount, and through the quick connect swivel on the throttle servo. Seagull includes this swivel in their ARF models, and it is great!

The fuel line was cut to length (a nice short run from the tank to the carburetor makes for easy starting) and pushed onto the barbed fuel inlet. There was enough room beside the fuel tank to install the ignition module, which I wrapped in DuBro  1/4″ protective foam rubber. The security clip was installed on the ignition pickup connection to the module.

 

I installed the cowl, which needed the prop hub hole opened up a bit, and installed a choke rod and the propeller. The choke rod exits the front of the cowl though one of the eight cooling slots I added to allow airflow over the engine’s cylinder head cooling fins. I felt that there wasn’t quite enough airflow through the original opening in the lower cowl, so the eight slots were cut.

The Stinger Engines 20cc RE was a great fit in the Seagull Models L-4! Only the tips of the muffler and a little bit of the spark plug cap protruded from the cowl, and it looked really nice!

Flight Report

After what seemed like weeks of waiting for a good day to fly with my good friend and video pilot, Jim Buzzeo, we were finally both able to make it out to the field on a Saturday afternoon in October. The weather cooperated for the most part, with a high temp around 65° F, and the sun was shining. There was a 10-15 MPH wind from the west, which was straight down the runway. We started the Stinger Engines 20cc RE by hand, as I had run it the night before. But, before I talk more about how well the engine ran on Saturday, I have to tell you about the night before…..

Before I put any of my engines into the air, I like to run them on the ground. The L-4 Grasshopper was complete, and I needed to get a little running time on the 20cc RE, so I tied it down and started the engine. With the choke on, it popped quickly. I opened the choke, and it started and ran pretty well at idle. I let the engine warm up for a few minutes, and then set the idle to about 2500 RPM with the needles turned to the rich side. After several more minutes, I started pushing the throttle stick forward, and trying to lean out the needles a bit, but I couldn’t get the engine to run consistently. I tried a few more times before going back to the garage. Ultimately, I ended up pulling the cowl and engine to remove the carburetor. With the carb completely disassembled, I cleaned all the orifices with carb cleaner and compressed air. I didn’t see any real debris inside the carburetor, before or after cleaning, but reassembled it and reinstalled the carb on the engine. The engine was then reattached to the engine mounts, and I was ready to try again. This time, the engine fired up immediately, and ran very well! It transitioned easily, and didn’t hesitate at all. By this time, it was after 9:00 pm, and it was time to be done for the night.

OK – Back to Saturday! At the field, the Stinger Engines 20cc RE was started and was given a few minutes to warm up to operating temps. This time, she was ready to get into the air!

The engine performed well at all throttle levels, and had no bad tendencies – it sounded great in the air, and pulled the Seagull Models 90″ L-4 Grasshopper around effortlessly!

Flight Video

Check out the video below to see the Stinger Engines 20cc Rear Exhaust gasoline engine in action:

Summary

I think RCGF made a great call by redesigning and making new molds. If the new 20cc RE is any indication of what I can expect from the new Stinger Engines lineup, I think we will all be very happy with these new engines. Their pricing is reasonable, and the quality of the Stinger Engines seems to be excellent. As nice as this engine looks, it’s almost a shame to hide it inside a cowl! Even considering the carburetor teardown, I’m very happy with the 20cc RE’s performance. I usually crack open the carburetor on new engines – had I done that with this one, it would have saved a little time later. with that said, this is a great little engine, and it has great power and performance! If you’re looking for a slim 20cc gas engine, look no further than the new Stinger Engines 20cc Rear Exhaust gasoline engine – you’re gonna love this one! That’s all for now. From my shop to yours, Happy Landings! -GB

Contact Information

Seagull Models –    seagullmodels.com

VQ Warbirds –   vqwarbirds.com

Stinger Engines –    rcgfusa.com

Graupner –   graupnerusa.com

Hitec Servos –   hitecrcd.com

Falcon Propellers –   justmodelprops.com

Bob’s Hobby Center at Steve’s Hangar –   shopbobshobbycenter.com

Zap Adhesives –   franktiano.com/zap-adhesive

Du-Bro Products –   dubro.com

Turnigy Batteries –   hobbyking.com

Geoff Barber email –   gbarber726@gmail.com

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