STEYR MOTORS Vehicle Engines

M12 UI - 2-cylinder unit injection engine

The 2-cylinder unit injector diesel engine (M12 UI) of STEYR MOTORS is characterized by a horizontal parallel twin piston configuration resulting in one of the most compact products on the market regarding the power output. The M12 UI was created to work perfectly even under extreme conditions. It is proven and tested according to several civilian and military standards including high altitude requirements, varying fuel qualities, tough environmental conditions and other challenging requirements. Due to our vast experience in tailored engineering, the M12 UI can also be customized to fit specific requirements.

Small and lightweight, but also robust and powerful are the key characteristics of STEYR MOTORS' engines and, thus, also of the M12 UI. The 2-cylinder diesel engine is based on STEYR MOTORS' Monoblock design and features direct injection with a mass balancing system for smooth operation. The engine is fuel efficient, turbocharged (singlestage, wastegate) and intercooled as well as being multifuel capable (including military fuels). A long lifetime as well as the longest possible service intervals are further benefits of this product.

The main difference of the M12 UI compared to the 2-cylinder common rail engine (M12 CR) is the ability to run under toughest ambient conditions as for instance sand, dust, low fuel quality, temperature, shock/rough terrain. The operational temperature comprises a range from -32 °C to +49 °C, but can be extended to -46 °C with a preheater. In short, the 2-cylinder unit injector is the first choice for demanding environmental conditions and military applications.



The 2-cylinder diesel engine can be used for various applications. However, the perfect solution is applying it as an auxiliary power unit. The M12 UI is particularly suited for combination with small-sized permanent magnet synchronous motors (PMSM), but it can also be used for continuously variable transmissions, hydraulic pumps etc.



  • - Direct injection Diesel engine
  • - 4-stroke, turbocharged, intercooled
  • - 1.06 lt displacement
  • - 85 mm bore, 94 mm stroke
  • - Rated power: 26 kW @ 3050 rpm
  • - Torque: up to 95 Nm @ 2550 rpm
  • - Dry weight: 104 kg
  • - Perfectly suited for the use as auxiliary power unit (APU)



  • - Monoblock design with excellent water cooling
  • - Turbocharged, intercooled
  • - Mass balancing system for smooth operation
  • - Operational temperature range from -32 °C to +49 °C
  • - Multifuel capable: F-34/F-35/F-54/F-63/F-65/JP-8/JET A1/EN 590
  • - High ICE efficiency for higher range and/or lower fuel consumption
  • - High robustness and durability
  • - Outstanding performance
  • - Tested according to several civilian and military standards
M12 UI (2-Cylinder Diesel Engine) Leaflet by STEYR MOTORS
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