Funded Projects

Libralato Ltd. has benefited from four international research and development projects to investigate and determine the advantages of this new engine design:

1) Libralato Engine Prototype project (266059) supported by the FP7 Green Cars Initiative, 2011-2014. (£146,610)

2) The Proving Factory project supported by UK AMSCI, 2013-2015. (£167,996)

3) Libralato Rotary Engine project (672077) supported by H2020 SME Instrument phase 1, 2015. (£35,330)

4) 48V Town & Country Hybrid Powertrain project (101575) supported by Innovate UK, 2014-2016. (£291,000)

Libralato Mk4 Graphic smls

      The fifth generation R6 eco-engine is the result of 10 years of painstaking analysis, grounded in established engineering knowledge of thermodynamic principles, but presenting a completely new embodiment of ICE design. The Libralato team considers that the major design challenges have now been solved. These were secondary issues compared to the initial concept of the bi-axial inter-locking rotors, but these improvements were essential for maximised efficiency, minimised emissions, low cost, low maintenance, durability and reliability. Compared to previous generations of the design, the following advances have been made:

      1) A simplification of the thermodynamic cycle from 9 phases to 6 phases, increasing the amount of internal EGR

      2) Repositioning and reconfiguration of the linear bearing which connects the two rotors

      3) Introduction of a counterweight to independently balance the following rotor

      4) Removal of intake ports from the side plates

      5) Removal of rotating exhaust valves from the exhaust ports

      6) Conversion of the second exhaust port into the intake port

      7) Replacement of mechanical side seals with non-contact labyrinth seals, adopting aerospace turbine technology

      8) Change of material of power rotor core and following rotor to stainless steel (matching thermal expansion)

      9) Introduction of stainless steel side plates (for stiffness & matching thermal expansion)

      10) Introduction of glass-metal (ferrous bonding) thermal barrier coatings

      11) Repositioning of direct injection from the combustion chamber to the compression chamber

      12) Replacement of spark plug by glow plug for cold starts

      13) Introduction of homogenous charge compression ignition, utilising heat from the following rotor for ignition

      14) Introduction of a simple and robust variable compression ratio mechanism

      15) Introduction of water injection into residual EGR

      R6 architecture sml


      The main advantages of these changes are:

      • Instead of two intake phases and two exhaust phases, the residual exhaust is drawn into the intake chamber for ~15% exhaust gas recirculation (~20% in total including sealing losses). This also removes the requirement for internal surface sealing between the following rotor and the power rotor.

      • Instead of two exhaust ports, the second exhaust port is converted into the intake port and the rotary valves are eliminated. Both ports are made open and the engine breathing is governed solely by the ports being uncovered by the rotors and the internal gas pressures.

      • The removal of the two rotary exhaust valves and associated gear mechanisms is a major mechanical simplification and avoids any issues associated with thermal loading of these rotary valves.

      • The removal of the side intake port enables multiple units to be easily stacked together in series like piston-engine cylinders.

      Since indicated torque is given by

      Indicated Torque

      It can be seen that the R6 eco-engine architecture offers a significant advantage of greater leverage and therefore greater torque for the same displacement compared to a piston-engine.

      R6 Leverage

      Since power is given by

      Power formula

      Compared to the Ricardo Magma xEV engine (specifically designed as a high efficiency gasoline range extender); for the same max gas pressure (110 bar), the same displacement (0.5l) and the same speed (4,000 rpm), the R6 eco-engine delivers 2.74 x greater indicated power (70.2kW vs 25.7kW) due to:

      • 1.37 x greater indicated torque (max at 24o vs 34o ATDC)

      • power phase in every rotation of the output shaft

      R6 Mechanical Advantage

      ICE emissions are strongly dependant on the richness of the fuel-air mixture and the temperature of combustion. Minimization of HC, CO and NOx emissions occurs at equivalence ratios below 1 and combustion temperatures between 1500-2000K. The figure below shows the HCCI combustion zone, combining the following features:

      • Spontaneous and complete combustion of homogenous fuel-air charge

      • Avoidance of high temperature propagating flames (SI) for low NOx emissions

      • Avoidance of rich diffusion flames (CI) for low PM emissions

      • Sufficient temperature for complete oxidation of fuel-air mixture for low HC and CO emissions

      HCCI zone



      Libralato engines is supported by:



           Seventh Framework Programme   European Commission   Innovate