The revolutionary Libralato 9-phase Cycle

The Libralato engine design combines two rotors, with separate centres, joined by a link head and slider bars. The rotors do not have narrow apex seals like the Wankel engine and therefore have much superior sealing. The orbits of the rotors overlap, dynamically forming intake, compression and expansion volumes. The different diameters of the rotors create a highly efficient over-expansion compared to compression. The engine does not need to convert the linear motion of pistons into the rotational motion of the output shaft, therefore the torque from the gas expansion acts directly on the output shaft from 5o beyond Top Dead Centre (TDC). The Libralato engine dispenses with the need for conventional cylinders, pistons, con-rods, crankshafts, valvetrains and camshafts. It is tuned for direct injection and internal EGR, with high and more consistent levels of torque, very low vibration and very low exhaust temperature and noise.

Libralato Mk3 labels Libralato Cycle 360

The Libralato engine has a revolutionary new 9-phase cycle, with all 9 phases completed in each rotation of the engine. The cycle is difficult to explain and sequence due to the dynamic formation and exchange between three distinct chambers working in parallel (intake, compression and expansion). The combustion chamber is around TDC, within the water-cooled housing. Each 'power unit' has two intake ports and two exhaust valves. Intake port 1 is on the face of the engine close to the main shaft (cannot be seen in the illustration). Intake valve 2 uses exhaust valve 1 (on the left) but takes a different path which is separate from the exhaust path.

Rotating counter-clockwise, the Libralato 9-phase cycle is:

  • Phase 1: 0° - 163° - combustion takes place in a discrete combustion chamber around TDC; an expansion volume delivers power on the left side.
  • Phase 2: 40° - 184° - a first stage compression volume (low CR) is formed on the right side.
  • Phase 3: 139° - 290° - air enters intake port 1 into an expanding central intake volume.
  • Phase 4: 163° - 184° - exhaust valve 1 allows the exhaust gas to exit under its own pressure.
  • Phase 5: 184° - 210° - the first stage compression volume on the right connects with the combustion chamber at the top and through this with the expansion volume on the left. The first stage compression scavenges both the combustion chamber and the expansion volume. Gas exits via exhaust valve 2.
  • Phase 6: 210° - 222° - the expansion volume connects with the compression volume at the bottom, allowing exhaust gas recirculation at atmospheric pressure.
  • Phase 7: 222° - 360° - a second stage compression volume (high CR) is formed on the right side and forces air and EGR into the combustion chamber, where the fuel is injected and the spark ignites the mixture.
  • Phase 8: 222° - 290° - scavenge of the expansion volume continues via exhaust valve 2.
  • Phase 9: 290° - 5° - the expansion volume merges with the intake volume, allowing EGR into the intake and air continues to enter via intake valve 2.


The following diagrams illustrate the key points in the Libralato engine cycle.

Libralato Cycle 00 TDC image

Fig.1 - Libralato Cycle 00 TDC image

Libralato Cycle 010 image

Fig.2 - Libralato Cycle 010 image

Libralato Cycle 030 image

Fig.3 - Libralato Cycle 030 image

Libralato Cycle 040 image

Fig.4 - Libralato Cycle 040 image

Libralato Cycle 085 image

Fig.5 - Libralato Cycle 085 image

Libralato Cycle 139 image

Fig.6 - Libralato Cycle 139 image

Libralato Cycle 163 image

Fig.7 - Libralato Cycle 163 image

Libralato Cycle 184 image

Fig.8 - Libralato Cycle 184 image

Libralato Cycle 210 image

Fig.9 - Libralato Cycle 210 image

Libralato Cycle 222 image

Fig.10 - Libralato Cycle 222 image

Libralato Cycle 255 image

Fig.11 - Libralato Cycle 255 image

Libralato Cycle 290 image

Fig.12 - Libralato Cycle 290 image

Libralato Cycle 325 image

Fig.13 - Libralato Cycle 325 image

Libralato Cycle 355 image

Fig.14 - Libralato Cycle 355 image

The graph below illustrates the Libralato cycle chamber volumes across 360o of rotation. The red line describes the expansion volume on the left side. The blue line describes the compression volume on the right side. The green line indicates the intake volume in the centre.

Libralato cycle volumes with valve timings