Speedway Workshop

Denco Engines

Bob Denson of Christchurch built a variety of engines - singles for speedway solos, fours for speedway cars, and V-twin engines used in sidecars. It was a Denco V-twin which powered the first of the machines which soon achieved international fame as the Britten.

The Denco

Mitch Shirra was confident of further progress in the 1978 World Championships after trials on the new DENCO racing engine which was manufactured by Denco Engineering in New Zealand.

Pictured Left is new Zealand Engineer Bob Denson with the new Denco engine that made such a big impression and it was hoped that the machine could have been marketed in the UK.

The Denco was seen as a revolution with its brand new outlook regarding mechanical features and Shirra, the then Australian Champion, stated there were many reasons as to why the Denco would be the machine to beat during the World Championships that year.


1. The Big end could be changed in five minutes
2. Variable Compression ratios require just a small adjustment.
3. Dry sump and less friction - oil change every five meetings.
4. Parts available at ant Motor accessory shop.
6. Uses Shell Motor oil as used in cars.
7. Full slipper piston means less friction and higher revs.
8. All metals are machined to perfection and of very high quality.
9. Valve gear is driven externally by rubber belt as in Fiat, Ford, Datsun and all formula cars.
10. All cam gear is at five degrees which means that valve lining can
be changed at will during a meeting.

Shirra also added that he found it to be the best engine he had ever worked on.


Bennie Ludolphy kindly sent in this coloured photograph of the Denco together with the following information regarding the types of Denco Engines.

As far as it is known, there were three Types of Denco Motor:
Prototype - As detailed above
Second Type - As depicted in the coloured photograph. Note the belt driven oil pump fitted under the magneto and has the oil filter behind the cylinder.
Type Three - No picture of this one as yet. All we can tell you is that the belt drive for the Camshafts is on the left hand side, as opposed to the Prototype and Second type which had the belt on the right hand side.
Any pictures or information regarding the later two types would be greatly appreciated.


N.B. Information has been added which was not included in the original archive.

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