The defining attribute of a two-stroke engine is to fireplace (combust) each time the piston is at prime lifeless middle. This makes them extremely energy dense, but additionally notoriously makes two-stroke engines soiled, inefficient, and never liable to lengthy lifespans.
Alpha-Otto has a design that goals to eradicate all of these drawbacks. The RevForce engine introduces a single, transformative change to the standard two-stroke format that preserves its advantages whereas eradicating its main flaws.
The key is the addition of a rotary valve.
Yep, that’s it. Generally the best adjustments are essentially the most profound. Like including microtextures to plastics, the rotary valve thought within the RevForce design might doubtlessly be an trade game-changer.
Conventional Two-Stroke Engine Points
A standard two-stroke engine has the piston pushing down after firing, transferring previous an exhaust port and permitting the exhaust gases to go away the chamber. Concurrently, because the piston travels downward, injected air and gasoline are being compressed and are then launched right into a diversion port into the chamber. Because the piston rises once more, compression of the gasoline and air occurs because the vacuum created beneath the cylinder pulls in one other batch of gasoline and air.
The issue with that design is that it means lubrication can’t be added beneath the cylinder, as that’s now a pre-combustion consumption chamber. And to ensure that the compression stroke to work because the cylinder strikes upward, the diversion port and exhaust ports have to be open on the similar time for a part of the cycle to make sure that all the exhaust gases are out of the chamber. In any other case, a vacuum would happen and stop the gasoline/air from coming into the chamber. This inherently signifies that among the gasoline/air combination can also be exhausted earlier than combustion. That’s inefficient.
Fashionable designs utilizing exhaust resonance to “push” a few of that gasoline/air overflow again into the chamber have combined outcomes. Worse, lubrication nonetheless depends on mixing oil with the gasoline, which sees a few of it burned within the course of, creating extra emissions and lowering gasoline financial system.
Alpha-Otto
How Alpha-Otto Solves These Points
Alpha-Otto’s rotary valve is added to the standard exhaust port barely behind the opening. This eliminates the necessity for a bypass port and permits the decrease chamber to as soon as once more be used for lubrication, similar to in four-stroke engines. That alone reduces emissions and will increase engine longevity.
The rotary valve additionally signifies that the blockages brought on by standard poppet valves will not be a difficulty as poppet valves will not be wanted in Alpha-Otto’s design. Because the cylinder drops throughout combustion, the rotary valve opens on the proper second to permit exhaust gases to exit. Simply close to the top of that, because the piston passes the center of its stroke and vacuum begins to carry exhaust within the cylinder, the consumption valve is handed and compressed air from a easy supercharger comes into the chamber, persevering with to push the exhaust out. In the intervening time the rotary valve nears closure for the exhaust, gasoline is injected into the cylinder. The piston ends its downstroke and begins transferring upward, compressing the air/gasoline combine till combustion occurs and the entire cycle begins anew.
Which means the excessive torque effectivity of the two-stroke engine is stored, whereas the cleanliness and longevity of the four-stroke engine is gained. A win-win situation. What’s extra, the exhaust rotary valve, air compression, and gasoline injection are electronically managed, which means they are often adjusted on the fly to alter timing as wanted.
That on-the-fly adjustment is why demonstrations of the RevForce engine present it operating on compressed pure fuel, switching on the fly to burning hydrogen, and on to different fuels. Alpha-Otto has examined its two-stroke design with pure fuel, hydrogen, gasoline, and non-diesel biofuels.
The RevForce engine is a working prototype scaled to 200 horsepower (149 kW) in a straight-twin configuration. Alpha-Otto is launching a WeFunder marketing campaign in mid-July of 2025 to maneuver the RevForce previous the prototype stage and into restricted manufacturing. The corporate is focusing on fastened energy technology programs to start out, as that trade is a far simpler nut to crack than is automotive. However the final aim is to have the engine discovering use in a wide range of purposes, together with transportation.
Aaron Turpen / Alpha-Otto / New Atlas
It’s solely a matter of time earlier than one will get shoved right into a Miata.
Here is a video of the Alpha-Otto RevForce in operation:
Engineered for Immediately’s and Tomorrow’s Fuels | REV Pressure in Motion
Supply: Alpha-Otto
