This engine promises to be the future of combustion engines. It burns practically anything.

When hearing the words "two-stroke engine," many still think of a Trabant or a lawnmower. Although these engines were once widely used, especially in post-war automotive applications, their drawbacks—high fuel consumption and exhaust emissions caused by burning a fuel-oil mixture—led to their near-complete disappearance in the passenger car segment. Meanwhile, the concept may be making a comeback in a new, much more modern form. Alpha-Otto Technologies, based in Detroit, founded in 2022, is developing an innovative two-stroke engine called REV-Force, which , according to the announcement, will be capable of running on a wide range of fuels—from gasoline and diesel, through kerosene, to low- and zero-emission fuels such as ethanol, hydrogen, and ammonia.

The technology of the future in a compact version

The REV-Force engine was tested in a two-cylinder, supercharged, liquid-cooled version. It weighs just 48 kg and measures 38 cm long, 35 cm wide, and 30 cm high. Despite its compact design, it generates 175 hp, and according to the manufacturer, it can achieve up to 223 hp and 176 Nm of torque. Most impressive, however, is the claimed thermal efficiency of 50 percent. This figure exceeds the performance of conventional combustion engines—even in high-efficiency automotive applications.

The REV-Force engine utilizes a dry sump, eliminating the need to burn oil in the mixture, as was the case with traditional two-strokes. Instead of drawing the mixture through the crankcase, the compressor controls the air intake, and fuel is precisely injected only after a special rotary exhaust valve closes, significantly reducing unburned fuel emissions. Alpha-Otto has equipped the engine with advanced control, allowing for the instant adjustment of parameters such as compression ratio, displacement, ignition timing, and fuel injection strategy—depending on the type of fuel used.

Engine project close to commercialization

The engine's creators claim it will be possible to run lean-burn, further reducing fuel consumption. Exhaust emissions are expected to reach "unprecedented low levels," although detailed specifications have not yet been released. Alpha-Otto announces the use of advanced exhaust aftertreatment systems to meet the most stringent standards—current and future. The REV-Force also offers advantages in terms of cost and maintenance. As a two-stroke engine, it does not require a complex valve train or camshafts. This makes it not only lighter and more compact, but also cheaper to produce and easier to maintain than a traditional four-stroke engine. According to company representatives, the project is currently nearing commercialization and has patent applications.