Engineering Critique of the Bourke Engine

1) Seal friction from the seal between the air compressor chamber and the crankcase, against the conrod, will reduce the efficiency.

2) Pumping losses, the air charge is compressed and expanded twice but energy is only extracted for power in one of the expansions.

3) Engine weight is likely to be high as it will have to be very strongly built to cope with the high peak pressures seen as a result of the rapid high temperature combustion, and the scotch yoke/triple slipper bearing are heavier than a conventional crankshaft.

4) Each piston pair is highly imbalanced. This will limit the speed range and hence the power of the engine, and increase its weight due to the strong construction necessary to react the high forces in the components. (videos of running engines do not appear to show imbalance)

5) High speed two-stroke engines tend to be inefficient compared with four-strokes because some of the intake charge escapes unburnt with the exhaust.

6) When the charge is transferred from the compressor chamber to the combustion chamber it will cool down, reducing the efficiency of the engine.

7) Use of excess air will reduce the torque available for a given engine size.

8) Forcing the exhaust out through small ports will incur a further efficiency loss.

9) Operating an internal combustion engine in detonation reduces efficiency due to heat lost from the combustion gases being scrubbed against the combustion chamber walls by the shock waves.

10) Emissions - although some tests have shown low emissions in some circumstances, these were not necessarily at full power. As the scavenge ratio (ie engine torque) is increased more HC and CO will be emitted. See HCCI engine.

Home | Contact | Link To Us | Resources | Articles | My Other Sites | Sitemap

Bourke engine - Bourke engine critique - Bourke engine design features - Bourke engine operation - Bourke engine performance