This innovation addresses a key limitation in Opposed Piston Internal Combustion Engines (OP-ICE) by introducing a compact architecture where two pistons operate in a shared cylinder with facing heads. The design offers substantial improvements in size, performance, and volumetric self-sufficiency compared to existing OP engines.

Compact size:

This architecture reduces the engine block width by 30%, enabling installation in a horizontal position, even in compact vehicles. This allows for a low center of gravity, optimized weight distribution, and proper lubrication—essential advantages for light-duty platforms traditionally considered incompatible with OP layouts.

Improved performance:

The optimized angular positioning of the crankpin journal relative to the cylinder axis during peak compression increases mechanical advantage during combustion, resulting in higher torque and improved fuel efficiency. The reduced angular stress on the rod also helps prevent engine knock damage.

Volumetric self-sufficiency:

Unlike many OP engines requiring external compressors, this design incorporates an embedded compression chamber via a novel piston-cylinder combination. This enables the engine to perform the full thermodynamic cycle—intake, compression, combustion, and exhaust—with enough sweep and boost pressure for clean exhaust and effective power delivery on each revolution.

Regarding manufacturability, industry leaders have validated the OP-ICE approach. According to Achates Power:

“Because the Opposed-Piston Engine uses standard materials and processes, it can leverage the existing manufacturing methods, tools, and facilities used by OEMs globally. With modest re-tooling, OP engines can be produced in existing plants. A recent FEV study found OP engines to be 11% less expensive than traditional engines of similar performance.”

Saudi Aramco, the world’s largest energy supplier, presents opposed-piston architecture as a leading solution to maximize fuel efficiency, torque, and power, while reducing emissions and manufacturing costs. Since joining HORSE Powertrain with Renault and Geely, Aramco is contributing expertise in advanced combustion and low-carbon fuels, reinforcing industry momentum behind next-generation ICE.

The U.S. Army has also embraced this architecture. Cummins Defense will begin production in 2027 of the 1000-hp Advanced Combat Engine (ACE)—an OP platform designed for battlefield conditions. Its development confirms that OP-ICE is viable and superior for high-performance, heavy-duty applications, validating its strategic relevance across both military and commercial markets.

Climate change demands urgent decarbonization. Experts agree the path forward requires electrification, next-generation ICE, advanced aftertreatment, and cleaner fuels. OP-ICE technologies address all four.

Despite its advantages, OP-ICE has been considered “too bulky” for light-duty vehicles. This engine overcomes that, bringing efficiency, compactness, low emissions, and low cost to small vehicle platforms—making scalable, sustainable transport a reality where electrification alone is not enough.

This compact OP configuration finally enables integration into passenger cars and light-duty vehicles—markets previously out of reach—unlocking new opportunities for cost-effective decarbonization in dense urban and developing regions.

When a new engine platform delivers clear gains in efficiency, performance, and manufacturability, adoption follows. The compact OP-ICE introduced here is technically feasible and globally aligned. We welcome interest from OEMs, Tier 1 suppliers, R&D institutions, and fleet operators to evaluate, license, or co-develop this technology for real-world deployment.