Technology >Horizontal rotating valve

Horizontal Rotating Valve

Sectioned Engine

Technical Description

  • The Horizontal Valve RCV (HRCV) is the lower performance/lower cost version of the RCV engine.
  • The HRCV engine employs a separate rotary valve and a fixed cylinder. This improves the thermal characteristics of the engine and reduces cost.
  • In this version the valve is parallel to the crankshaft and at 90 degrees to the cylinder. This slightly compromises the flow paths into the cylinder reducing maximum performance. The combustion chamber shape is also less compact.
  • However because the valve is now rotating in line with the crank it can be driven by a much simplified drive mechanism. Typically a standard toothed belt is employed.
  • Typical power densities for the HRCV are between 60-80bhp litre.
  • The primary application areas for the HRCV are utility engines where cost is critical. This is particularly key for the Forest and Garden application areas. For these applications the performance of the HRCV is still superior to any other 4-stroke engine. It effectively provides 2-stroke performance with 4-stroke emissions.


  • Low cost (compared to 4-strokes)
  • Low emissions and fuel efficient (compared to 2-strokes)
  • High performance and high speed (compared to 4-strokes)