SEMTO ST-FL2 vs ST-NF2 (Toyan FS-L200AC): Which Inline Twin Engine Kit Should You Buy?
If you are trying to choose between two SEMTO inline twin engine kits that look almost the same on paper, you are not alone. The SEMTO ST-NF2 and ST-FL2 are both four-stroke, both have push-button electric start, and both can go into an RC car. So which one should you buy?
It is one of the questions we get asked most, so we put the SEMTO ST-NF2 (also sold as the Toyan FS-L200AC) and the new SEMTO ST-FL2 side by side. Here is how the ST-NF2 and ST-FL2 differ, and which engine fits your plans.
Our Quick Verdict
SEMTO ST-NF2
Also known as Toyan FS-L200AC
Simple, affordable and air-cooled. Choose nitro or gasoline, connect fuel and power, and it runs. Want to go further? A ready-to-print Supra RC car design is made just for it.
Shop ST-NF2SEMTO ST-FL2
About twice the power, a higher top speed and a water-cooling system like a real car engine. Made with 1/8-scale RC projects in mind.
Shop ST-FL2Hear the ST-NF2 and ST-FL2 Run
The ST-NF2 and ST-FL2 both start at the push of a button. Turn up the sound and hear the difference between an air-cooled and a water-cooled twin.
SEMTO ST-NF2 (Toyan FS-L200AC) · Air-Cooled
SEMTO ST-FL2 · Water-Cooled
SEMTO ST-NF2 vs ST-FL2 at a Glance
| SEMTO ST-NF2 (Toyan FS-L200AC) |
SEMTO ST-FL2 | What this means for you | |
|---|---|---|---|
| Best for | Your first running engine | RC builds and longer runs | Pick by what you plan to do once it runs. |
| Engine size | 7.0cc | 8.6cc | The ST-FL2 is the bigger engine, which is where its extra power comes from. |
| Power | 0.6 PS | 1.2 HP | The ST-FL2 has about twice the power, enough to move a heavier RC car. |
| Speed range | 4,000–16,000 rpm | 3,000–20,000 rpm | The ST-FL2 can run faster at the top and idle slower at the bottom. |
| Cooling | Air-cooled (fan) | Water-cooled (pump + radiator) | Air cooling: nothing to fill, quicker setup. Water cooling: steadier temperature on long runs. |
| Fuel options | Nitro or gasoline | Nitro | With the ST-NF2, you can choose the fuel that is easier to buy where you live. |
| Weight | approx. 535 g | approx. 900 g | The lighter ST-NF2 is easier to fit into a build; the heavier ST-FL2 brings more power for bigger cars. |
| Size | approx. 112 × 90 × 92 mm | approx. 113 × 92 × 103 mm | Almost the same footprint. The ST-FL2 is about 1 cm taller. |
| Engine Only | from $199.99 | $399.99 | The ST-NF2 costs about half as much. |
| Starter Kit | $79.99 | $109.99 | Required to run the ST-NF2 or ST-FL2. Each model has its own kit. |
Orange highlights show where each engine has the advantage. Regular prices at the time of writing; prices may change during promotions, so please check each product page.
What the ST-NF2 and ST-FL2 Have in Common
The ST-NF2 and ST-FL2 are both four-stroke inline twin engines, so whichever one you choose, the build will feel familiar:
- Two cylinders in a row, four-stroke, like a small car engine
- Overhead camshaft (SOHC) driven by a timing belt, the same basic design used in many real cars
- One carburetor, so there is only one fuel mixture to adjust
- Push-button electric start, with no pull cord to learn
- CNC-machined aluminum parts with an anodized finish
- Supplied as a kit that you assemble yourself
ST-NF2 vs ST-FL2: Key Differences Explained Simply
Power and speed
The ST-FL2 has wider cylinders, so it burns more fuel on every turn. The result is about twice the power of the ST-NF2 and a higher top speed of 20,000 rpm. If you want your engine to move a bigger RC car, the ST-FL2 has the extra muscle.
Cooling: air vs water
ST-NF2: a fan on the front blows air over the engine. There is nothing to fill or connect, which keeps setup quick and simple.
ST-FL2: a pump moves water through a radiator and back to the engine, just like a car. It takes a few more steps to set up, but it keeps the engine temperature steadier during longer runs and at higher speeds.
Fuel options
The ST-NF2 comes in two versions: nitro (glow plug ignition) or gasoline (spark plug ignition). You can choose whichever fuel is easier to buy where you live. The ST-FL2 is currently available as a nitro engine.
Size and weight
From the outside, the ST-NF2 and ST-FL2 are almost the same size. The ST-FL2 is about 1 cm taller and about 365 g heavier because of its water-cooling system. The lighter ST-NF2 is easy to fit into RC cars and boats, and already powers a 1/8-scale Supra RC project. The ST-FL2 adds more power for heavier 1/8-scale builds.
Upgrade parts
The ST-NF2 has been around for several years, so many add-ons are ready now: car clutch kits, a marine clutch, a 12V generator set and even a ready-to-run 1/10 nitro RC car. Browse the full range in the ST-NF2 parts collection.
Want to put it in a car, but don't want to design one yourself? Building an RC car around a model engine usually means designing your own chassis, mounts and drivetrain layout, which takes a lot of time and experience. To make this much easier, we offer the 1/8 Scale Supra RC Car Project, a ready-made design package created by Scale Addiction specifically for the ST-NF2.
The design work is already done. You get the 3D-printable chassis files and step-by-step assembly instructions. Just print the parts, assemble the chassis and install the ST-NF2 to make your own running Supra RC car. A 3D printer with a 320 × 320 mm print bed is required. Stirlingkit is the only officially authorized seller.
Here is a finished build:
The ST-FL2 was designed with room for a clutch and transmission, and a dedicated ST-FL2 clutch is in development. Select "Notify Me" on the ST-FL2 product page to hear when it is ready.
Good to know: the ST-NF2 and ST-FL2 use different parts, including different belts. Starter kits, clutches and spare parts do not swap between the two models.
SEMTO ST-NF2 (Toyan FS-L200AC): Best First Engine
What we like
- Lowest cost to get a twin running
- Quick, simple air-cooled setup
- Choice of nitro or gasoline
- Lots of ready-made upgrade parts
- Ready-made 1/8-scale Supra RC car design: no need to design your own chassis
Keep in mind
- About half the power of the ST-FL2
- Lower top speed (16,000 rpm)
- Less power for heavier RC cars
Buy it if: this is your first running engine, you want to run it on your desk or use it for teaching, you are buying it as a gift, or you want to build the 1/8-scale Supra RC car.
SEMTO ST-FL2: Best for RC Builds
What we like
- About twice the power of the ST-NF2
- Higher top speed (20,000 rpm)
- Water cooling for steadier temperatures
- Made with 1/8-scale RC projects in mind
- Same easy single carburetor and push-button start
- Built-in belt tensioner: if the timing belt loosens over time, just adjust the tensioner to tighten it
Keep in mind
- Higher price
- A few extra setup steps for water cooling
- Heavier (about 900 g)
- Nitro version only for now
- Dedicated clutch still in development
Buy it if: you want more power, plan to put the engine into a larger RC car, or like the idea of a car-style water-cooling system.
What You Need to Run the ST-NF2 or ST-FL2
The ST-NF2 and ST-FL2 are both engine kits, and neither will run straight out of the box. Here is what to add:
| SEMTO ST-NF2 | SEMTO ST-FL2 | |
|---|---|---|
| Starter kit | ST-NF2 Starter Kit (nitro version) | ST-FL2 Starter Kit |
| Battery | 7.4V 2S LiPo battery | 11.1V 3S LiPo battery with T-plug |
| Fuel | 20–25% nitro fuel, or gasoline for the gasoline version | 25% nitro fuel |
Tip for ST-FL2 owners: in the ST-FL2 starter kit, the pink tube is the fuel line and the clear tube is the water line.
See the Build Before You Buy
Not sure if you can build and run it? Watch the videos and look through the instruction manuals first. You will follow the same steps with your own kit.
SEMTO ST-FL2: How to Build It
Assembly steps, water-cooling setup and first start
View ST-FL2 ManualThe bottom line
Buying your first running engine? Get the ST-NF2. This air-cooled twin is affordable, simple to set up and available in nitro or gasoline.
Building an RC car and want more power? Get the ST-FL2. This water-cooled twin has about twice the power and a water-cooling system made for longer runs.
SEMTO ST-FL2 vs ST-NF2: FAQ
Is the SEMTO ST-FL2 an upgraded version of the SEMTO ST-NF2?
No. The SEMTO ST-FL2 is a separate engine, not a modified ST-NF2. The ST-NF2 and ST-FL2 are both SEMTO inline twin four-stroke engines, but they differ in size, power, cooling and parts.
Are the SEMTO ST-NF2 and Toyan FS-L200AC the same engine?
Yes. The SEMTO ST-NF2 and the Toyan FS-L200AC are the same engine. Earlier units carried an OTTO MOTOR logo on the top cover; current units ship with the SEMTO ENGINE logo.
Are the SEMTO ST-NF2 and ST-FL2 two-stroke or four-stroke engines?
Both are four-stroke engines. Like a full-size car engine, each cylinder goes through intake, compression, power and exhaust, with valves opened by an overhead camshaft. Building one is a great way to see how a real four-stroke engine works.
Is there a gasoline version of the SEMTO ST-NF2 or ST-FL2?
The SEMTO ST-NF2 is available in both nitro and gasoline versions. The gasoline version uses spark plugs instead of glow plugs. The SEMTO ST-FL2 is currently available as a nitro engine.
Which is easier to build, the SEMTO ST-NF2 or ST-FL2?
Building the ST-NF2 and ST-FL2 is similar: one carburetor, push-button start and the same basic layout. The SEMTO ST-NF2 is quicker to get running because it is air-cooled. The SEMTO ST-FL2 adds a few steps to set up the radiator, water tank and water lines.
Can I use SEMTO ST-NF2 parts or its starter kit on the SEMTO ST-FL2?
No. The SEMTO ST-NF2 and ST-FL2 use different parts, including different timing and starter belts, so starter kits, clutches and spare parts are not interchangeable. Please choose parts made for your model.
Can the SEMTO ST-FL2 and ST-NF2 go into an RC car?
Yes, both engines can. The SEMTO ST-NF2 already has clutch kits, a ready-to-run 1/10 RC car, and a ready-made 1/8-scale Supra RC car design package, so you can print the chassis instead of designing your own. The SEMTO ST-FL2 was made with 1/8-scale RC projects in mind, and a dedicated ST-FL2 clutch is in development. How it fits will always depend on your chassis, drivetrain and mounting.
Does the water-cooled SEMTO ST-FL2 need extra care?
A little. Before running the SEMTO ST-FL2, fill the cooling system and check the water lines for leaks or air bubbles. Check the water level from time to time, and drain the system before long-term storage or freezing weather. The ST-FL2 also has a built-in belt tensioner, so if the timing belt feels loose after a few runs, simply adjust the tensioner to make it snug again.
Still not sure which one fits your plans? Tell us what you would like to build at service@stirlingkit.com, and we will be happy to help you choose. You can also browse more options in our beginner-friendly engine collection.
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