Horse unveiled the B20 engine for underwater operation — Autocar

In the United Kingdom, Horse Powertrain unveiled the B20 petrol engine, capable of operating underwater at depths of up to 1.1 metres. The unit is suitable for use in hybrid vehicles and is designed for prolonged operation under high loads in challenging off-road conditions, including when climbing slopes with a 100% gradient.

As Autocar reports, the two-litre inline four-cylinder B20 produces between 189 and 280 hp and between 221 and 280 lb-ft of torque, depending on conditions. The engine has IPX8 protection, ensured by a fully sealed design and a special seal between the engine and transmission.

Protection against hydrolock

The entry of a significant amount of water into a cylinder can cause hydrolock: liquid is incompressible, so the piston cannot complete the compression stroke, which risks serious engine damage. For off-road vehicles, snorkel air intakes partly address the problem, but submerging a vehicle in water also requires protection for electronics and other components.

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The B20's electrical components and sensors also have an IPX8 protection rating. The sensors detect engine submersion, after which the control system can, among other things, limit power or change the response to pressing the accelerator pedal.

Design and efficiency

The B20 operates on the Miller cycle. According to Horse, 48% of the fuel burned by the engine is converted into mechanical energy. High injection pressure and intake ports with significant flow swirl are intended to promote the mixing of air and fuel and more efficient combustion.

The engine received an aluminium cylinder block with a rigid portal design and an integrated exhaust manifold, a simplified balance shaft system and a variable-displacement oil pump. The pistons are designed to enhance the squish effect, in which the air-fuel mixture at the top of the piston stroke is directed toward the centre of the combustion chamber, increasing mixture turbulence.