Radial Motion's 3-Cylinder Compact Radial Engine

Radial Motion’s 3-Cylinder Compact Radial Engine

Radial Motion's three-cylinder compact radial engine is a four-stroke gas engine in a 120° radial configuration. Lightweight and compact, the 2.0L and 2.1L engines deliver both performance and reliability with unique visual appeal and an emotive exhaust note. The engine is capable of withstanding high cylinder pressures, making it well suited for turbocharging and supercharging. Check it out!

Engine of the Week is presented by

In a world of copycats, Radial Motion’s three-cylinder compact radial engine stands apart from the crowd. Radial Motion and Bespoke Engineering have been undertaking development of its three-cylinder radial engine since 2017, and what they’ve learned in that time shines through. Initially developed for aviation use, the Radial Motion engine is just as comfortable performing at ground level in a number of motorsport applications as well. In fact, today the company has both water and air-cooled variants of the three-cylinder radial engine and is working on a number of future plans based on this engine platform.

Located in Lonsdale, South Australia, Australia, Radial Motion is a concept-to-product engine house specializing in innovative designs for aviation and specialist automotive applications. Radial Motion was formed in collaboration with Bespoke Engineering, which is an innovative engineering company that provides solutions to varied industries and specializes in prototype design and manufacturing. Radial Motion has extensive capability in industrial design, rapid prototyping, product testing and development, and manufacturing at scale.

The company is directed by Nick Mebberson, Loui Burke and Scott Pearce, and the radial engine was conceptualized in-house by designers and engineers with the end user in mind, making it simple, modular and with interchangeable parts.

Inspired by the dawn of aviation and built with the technology of today, the radial engine features both reliability and performance due to its simple, robust design that can be modified and tuned for ample power.

Radial Motion’s three-cylinder compact radial engine is a four-stroke gas engine in a 120° radial configuration. Lightweight and compact, the 2.0L and 2.1L engines deliver both performance and reliability with unique visual appeal and an emotive exhaust note. The engine features a common journal crank and gear-driven triple camshafts actuating the overhead valvetrain via pushrods. Each head contains two valves, a 2˝ intake and 1.5˝ exhaust. The engine is capable of withstanding high cylinder pressures, making it well suited for turbocharging and supercharging.

For motorsport applications, the radial engine’s high output, lightweight and slim profile offer instant benefits. The use of readily available, off-the-shelf components such as pistons, connecting rods and valves makes repair and maintenance simple and affordable.

While Radial Motion’s radial engine takes inspiration from the glory days of early aviation, it incorporates significant improvements. Unlike aircraft engines from the 1920s onward, the Radial Motion engine does not use the complex master/slave rod layout favored back then.

Instead, a common journal like those used in V-twin engines delivers a compact design. The engine’s footprint is inside that of a VW Type 1 (Beetle) engine and maintains the ground clearance of that engine while offering improved weight distribution.

Access to camshafts and internals is easy without stripping the engine down, and other internal parts are available worldwide. Radial Motion worked closely with Kelford to design a custom valvetrain to help get the engine up to 10,000 rpm. The engine features a bore and stroke of 99mm x 86.5mm (2.0L) and 101.6mm x 86.5mm (2.1L). Total displacement is 1,998cc for the 2.0L and 2,104cc for the 2.1L.

The radial engine is sleeved with cast iron sleeves, has a twin coil/twin spark electronically controlled ignition system, has a single throttle body induction system that can be injected or carbureted, features a dry sump oiling system with separate cylinder head scavenge pumps, and has water-cooled cylinder heads and barrels, but also available in an air/oil cooled variant.

The first air-cooled customer engine was fitted to an Outlaw Porsche 356 built by well-known Porsche afficionado Ron Goodman. However, Radial Motion has also put their engine in a restored 1972 superbug nicknamed “zombug”, a 1973 restored “post office” combi van, a three-wheeled motorcycle, and another running on their water-break engine dyno.

Naturally aspirated, Radial Motion engines can produce 100 hp per liter, and the engines can sustain high levels of boost. The company has these engines available as turn-key units that have undergone pre-delivery dyno testing. These are available in several customizable configurations.

They can supply the engine in carbureted form with three individual Mikuni carburetors and a single throttle cable linkage kit. This setup is perfect for analog vehicles and those seeking simplicity and period authenticity. Ignition in this case is programmed into an ignition control module that operates the multi-coil ignition system.

If you’re looking for fuel injection, Radial Motion has that option as well. In fact, direct port injection paired with either individual throttle bodies or a common plenum is the most common setup Radial Motion offers. Each throttle body is equipped with drive-by-wire hardware and is controlled by a MoTec engine management system, which also controls ignition.

The three-cylinder engine can come equipped with an integral slimline alternator mounted on the front of the crankshaft or a conventional high-output alternator that is belt driven and mounted alongside the crank pulley. This comes with a billet belt guard for aircraft and off-road racing applications. Water pump systems use an external electric water pump. Power Take Offs are also available via clutched or direct-drive couplings.

In automotive applications, the Radial Motion engine offers some distinct advantages over common existing engines. With a compact footprint and low overall weight, weight distribution can be improved in most applications, without sacrificing ground clearance, and individual cylinder barrels mean the cooling system can be smaller.

In addition, these radial engines are ideal for a variety of ground-based and aviation applications in a defense setting. The modular design and component availability allow for ease of maintenance anywhere in the world while its robust reliability assures product uptime. The engine lends itself to hybrid applications as well as heavy fuel and biofuel applications too.

Looking to the future, Radial Motion and Bespoke Engineering are currently developing a 4.0L six-cylinder version. The modular design of the product lends itself to nine and 12-cylinder engines for various applications as well. Radial Motion is also exploring engine solutions for defense, industrial, marine and civil applications, including engines in V2, V4 and V6 configurations, using fuels including diesel, gas, jet fuel, and hybrid options.

While Radial Motion engines are inspired by the past, the company’s focus is definitely on the future. They plan to be a globally recognized engine house producing 1,000 engines a year, and their three-cylinder compact radial engine is an excellent jumping off point.

Engine of the Week is sponsored by PennGrade Motor OilElring – Das Original and Scat Crankshafts. If you have an engine you’d like to highlight in this series, please email Engine Builder Editor, Greg Jones at [email protected].

You May Also Like

408 cid Nitrous LS Engine

During a tour of SAM Tech, we also got a chance to speak to a few students. One in particular, Jaylon Victorian, was nearing completion of a 408 cid nitrous LS engine. He applied his new engine building knowledge and skill set to the build, and it shines through in our latest Engine of the Week.

408 cid nitrous LS engine

One of the spots we were excited to check out while we were in Houston, TX last fall was the School of Automotive Machinists & Technology, also known as SAM Tech. We’ve been able to showcase the automotive technical school, which has a focus on engine building and machining, in prior features and articles, but we hadn’t been to the facility in person – until now.

760 cid Billet Big Block Chevy Nitrous Engine

Despite what you may think about nitrous engines, and those that are stock big block Chevy bore spacing, these 4.840″ bore space big block Chevy engines have some significant R&D in them. Just check out this 760 cubic inch billet version done at TRE Racing Engines.

Naturally Aspirated 440 cid LT1 Engine

The folks at Late Model Engines in Houston, TX run a top-notch engine and machine shop. You don’t have to look much further than this naturally aspirated 440 cid LT1 engine build to see what we mean. It’s our Engine of the Week!

All-Billet 903 cid Pro Mod Engine

Pat Musi of Musi Racing Engines has been meticulously developing and tweaking his 903 cid Pro Mod engine combo since 2010. We got to see the latest and greatest version of this nitrous-powered billet beauty. Check out our first Engine of the Week of 2024!

Pat Musi Racing Engines 903 cid Pro Mod engine
Naturally Aspirated 540 cid Big Block Chevy Engine

After having issues with an engine built elsewhere, a customer came to H Squared Racing Engines to build him a streetcar combo. Utilizing an existing block and crank, H Squared was given the freedom to spec the rest of the engine. Check out the result!

Other Posts

Stuffing a Supercharged 572 cid SMX Engine in a Porsche 928

For Danny Humphreys, drag racing is a progressive disease. Ever since he watched Tom Cruise outrun a pimp in a 928 Porsche, he’s wanted the car for himself. As soon as he got one, he pulled the engine and the horsepower has gone up from there. Today, Danny has a supercharged 572 cid SMX engine

Indy Cylinder Head’s Supercharged 588 cid Hemi Engine

We’ve been following Indy Cylinder Head and the engine work Ken Lazzeri for quite some time. We got a chance to speak with Ken on the final day of the PRI show when he was kind enough to walk us through the details of several of the engines they had on display, including this bracket

Ken Lazzeri Hemi Engine
Kaiju Motorsports’ All-Billet Subaru EJ 2.5L Engine

Hands down, this was one of the more eye-popping engine bays we saw during the 2023 PRI Show. The Kaiju Motorsports-built STi Subaru is a cool car in and of itself, but with an all-billet 2.5L EJ engine featuring titanium piping, this thing stopped you in your tracks and forced your head to turn. We

Noonan’s New Billet K24 Honda Engine

We aren’t trying to hide the fact that we’re impressed by what Noonan Race Engineering is capable of. That’s why we will always jump at the chance to highlight what NoonanRaceEngineering has coming down the pipeline, and the shop’s latest endeavor is a billet K24 Honda engine, which was showcased at the 2023 PRI Show. We caught

Noonan Race Engineering Honda engine