E.D. Super Hunter
The E.D. Super Hunter 3.46 cc diesel was one of the updated E.D. models developed by Alan Greenfield during the 1970's while working for Ken Day's reorganized E.D. company in Surbiton, Surrey. It was in essence a significantly upgraded version of the old E.D. 3.46 cc Mk. IV "Hunter" which had been introduced way back in 1949 by the "original" E.D. company of Kingston-on-Thames.
Like its predecessor, the Super Hunter was a rear disc valve unit, albeit featuring a moulded plastic backplate and rotor in place of the former cast alloy components. It also incorporated three bypass/transfer flutes along with a single rear exhaust port of generous size. Although this represented a move towards Schnuerle porting, the shape of the ports was not in fact appropriate for full achievement of the Schnuerle scavenging cycle. However, it was a significant improvement over the twin bypass system used previously. The crankshaft was now supported in two ball races as opposed to the single rear race of the original design.
The engine used an exhaust throttle, which did much to overcome the tendency of R/C diesels to cool down excessively during periods of idling and hence fail to pick back up to full speed when the throttle was opened. However, the price paid for this was very poor low-speed suction due to the fact that the intake remained fully open at all times.
The Super Hunter was originally manufactured solely as a marine engine, complete with water-cooled jacket. A very few air-cooled conversions were made in the 1980's by Brian Etheridge during the period when he was involved with E.D. prior to Alan Greenfield assuming full ownership. However, Alan has recently (2017) introduced his own very well-executed aero conversion of original 1970 examples of the engine. This unit is available from Alan's Weston UK outlet, along with the marine Super Hunter and Super Otter models as well as Mini-Pipes for these units. Alan's modern West engines are also well worth a look.
A review by Maris Dislers of the aero Super Hunter appeared in the June 2018 isse of "AeroModeller" magazine (issue no. 973). Maris found an output of around 0.40 BHP @ 13,500 RPM. With a few simple modifications, this can be substantially improved upon. A further analysis of this fine engine will appear in due course on this website.