A 4-cylinder in-line engine that was designed by Don Harkness and built by Harkness & Hillier Ltd. in Sydney, NSW towards the year 1929. (Written at times Harkness & Miller)

“Harkness Hornet engine”

-It had two magnetos and a Claudel Hobson carburetor from RR. The power was 115 hp at 2,000 rpm. It weighed about 300 lbs and was painted green.

From Appendix 7: We found an ad with the 115 hp Hornet. The cylinder block is from a Hispano-Suiza V8. Year 1929-30.

“Ad for the Hornet aero engine”

From Appendix 9: We have a photograph of a Harkness-Hornet engine that used a cylinder block from a Hispano-Suiza engine. The crankshaft bench was of his own design as well as the oil sump.

-We can clearly see that the block is from the well-known brand and that it is precisely the left one since we have the intake manifold and the carburetor in view.

-The design is from 1929 and the pistons had a bore of 120 and a stroke of 130, giving 115 hp at 2,000 rpm.

-Prototype Nr 101 is at the Powerhouse Museum in Australia. The design is owned to Donald Harkness and he obtained the Type Certificate for Aero-navigability in 1930.

-Nevertheless it was not commercialized due to competition from other engines that already existed in the market.