Thank you for your interest in RETROL engines. If you love old stationary engines, you probably know the feeling: the heavy flywheel turning over, the first cough, then that steady, unhurried beat that fills the workshop. The RETROL G16 and RETROL D16 both bring that experience to your bench as a classic horizontal mill engine model, fully assembled and ready to run. They share the same layout, the same 225 mm cast iron flywheel and the same wooden base. What sets them apart is how they come to life: the red G16 fires on a spark, while the green D16 fires on compression alone, like a real working diesel engine. Here's how to choose the one that belongs in your collection.
The short answer
The RETROL G16 is the engine you'll run most. It starts readily, idles slow and steady, and blows smoke rings from its chimney. It's the one you fire up on a quiet afternoon or when friends and family stop by to watch.
The RETROL D16 is the engine you'll be proudest of. A working miniature diesel is something very few model engineers have ever pulled off. The first time it fires on compression alone, with no spark and no battery, is a moment you won't forget.
RETROL G16 vs D16: Gasoline vs Diesel Engine Model at a Glance
| RETROL G16 (Gasoline) | RETROL D16 (Diesel) | |
|---|---|---|
| Ignition | Spark plug + CDI igniter | Compression ignition |
| Fuel | 92 octane or higher gasoline | Diesel or kerosene |
| Oil in fuel | 2T oil, 1:50 | 2% mineral 2-stroke oil |
| Battery needed | Yes, 6–10V for the CDI | No |
| Starting | Drill + starter adapter (included) | Drill + starter adapter (included); optional preheating |
| Bore × stroke | 22 mm × 24 mm | 22 mm × 48 mm |
| Flywheel | Cast iron, 225 mm | Cast iron, 225 mm |
| Cooling | Water-cooled | Water-cooled |
| Color | Classic red | Classic green |
| Product weight | 4.5 kg | 5.5 kg |
| Product dimensions | 41 × 18 × 25 cm | 41 × 18 × 25 cm |
| Best for | First-time engine owners, display and regular running | Experienced builders, diesel enthusiasts |
What It's Like to Own Each Stationary Engine Model
How it comes to life
The RETROL G16 works the way most of us learned engines work: fuel, air and a spark. A small CDI igniter on a 6–10V battery fires the spark plug, and the engine settles into a smooth rhythm. It's easy to understand and easy to get running.
The RETROL D16 works the way Rudolf Diesel intended: the piston squeezes the air until it's hot enough to light the fuel the instant it's injected. No spark plug, no igniter, no battery. Making a diesel injector small enough to work in a model engine is a real feat, which is why a running model diesel engine like the D16 is so rarely seen.
Starting it up
Both start with an electric drill and the included starter adapter. The G16, a 4-stroke gasoline engine model with CDI ignition, usually catches quickly once the fuel line is primed. The D16 takes a little ritual, just like a full-size diesel on a cold morning: warm the cylinder with a hair dryer, open the decompression lever, and give it 20–30 turns. When it catches, you'll know.
Watching it run
The G16 is a pleasure to watch. It can tick over slowly, and at around 800–1,000 RPM it puffs smoke rings from the chimney, always a favorite with visitors. The D16, with a stroke twice as long (48 mm vs 24 mm), has the deep, purposeful beat of a working diesel.
Living with it
Both arrive ready to run and allow simple adjustments such as gear clearance. The G16 asks for little more than fuel, oil and a fresh battery. The D16 rewards a builder's touch: keeping the piston well oiled, using clean fuel, and fine-tuning valves and timing over time. If you enjoy a project that you keep improving, the D16 will keep you happily busy.
On the shelf
Both share the same mill engine silhouette, with polished brass and copper details against a deep wooden base. The G16 wears a classic red, and the D16 a classic green with its own "Diesel 16" nameplate. Side by side, they make a handsome pair and a true vintage engine display piece.
Which RETROL Stationary Engine Model Is Right for You?
The RETROL G16 is for you if…
- You want an engine you can start and enjoy any afternoon
- You'd love to show friends and family a running engine, smoke rings and all
- This is your first running stationary engine
- You'd rather spend your time watching it run than tuning it
- The classic red mill engine look speaks to you
The RETROL D16 is for you if…
- You've always wanted to own a real diesel, in miniature
- You enjoy the craft of tuning an engine and learning how it works
- You already have a model engine or two on the shelf
- You value rarity: few working miniature diesels exist
- The deep green and brass of an early diesel speaks to you
RETROL G16 vs D16 FAQ
Is the RETROL G16 or D16 better for beginners?
The RETROL G16 is the easier choice for beginners. It starts quickly and is simple to diagnose. The RETROL D16 is best enjoyed by builders with some basic model engine experience.
Do the RETROL G16 and D16 come with a hand crank?
From February 2026, both the RETROL G16 and D16 ship with an electric drill starter adapter instead of a hand crank. The hand crank has been discontinued for both models.
Does the RETROL D16 need a battery?
No. The RETROL D16 ignites by compression, so it doesn't need a battery, spark plug or igniter. The RETROL G16 needs a 6–10V battery (or USB power) for its CDI ignition.
Can I run the RETROL G16 on diesel, or the D16 on gasoline?
No. The RETROL G16 is designed for gasoline with a spark ignition system, and the RETROL D16 for diesel or kerosene with compression ignition. Please use the fuel each engine is designed for.
Are the RETROL G16 and D16 the same size?
Yes. Both measure 41 × 18 × 25 cm on a 410 × 180 mm wooden base, with the same 225 mm cast iron flywheel. The D16 is about 1 kg heavier.
Are the RETROL G16 and D16 kits or ready-to-run engine models?
Both are ready-to-run engine models. The RETROL G16 and D16 arrive fully assembled, so there's no build required. Just add fuel, oil and coolant, and start them with a drill and the included starter adapter.
Which makes a better gift for a vintage engine enthusiast, the RETROL G16 or D16?
For someone who loves to watch an engine run and show it off, the RETROL G16 is a wonderful gift: easy to start, with smoke rings to impress. For an experienced model engineer or a diesel fan who has "seen it all," the RETROL D16 is the rare working miniature diesel they probably don't have yet.
Own a RETROL G16 or D16? Tell us which you chose 🗳️
Why you picked gasoline or diesel, what surprised you on the first run, a photo of your engine on the shelf: if you own a RETROL G16 or D16, your experience helps the next buyer decide. Send it in and we'll add the best stories to this guide under your name.
🎁 If we feature your story, we'll send you a thank-you gift from Stirlingkit.
Email service@stirlingkit.com or join our Engine Tips Challenge.
More About RETROL G16 and D16
- RETROL G16 User GuideSetup, drill starting, CDI spark test and simple adjustments for the gasoline G16.
- RETROL D16 User GuideFueling, starting and care for the diesel D16.
- Retrol: Our Journey to the First Real Diesel EngineThe story behind building a working miniature diesel.
- Explore All RETROL EnginesSee the full RETROL range of engine models.
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