Thursday, June 29, 2023

Edward Turner Hemi

 I was reading this Jalopnik article recently on the smallest displacement production V8's made. Of particular interest to me was the Daimler 2.5 liter hemi V8 that came in the Daimler SP250 (not to be confused with Daimler Benz).

I had never seen a Daimler SP250, that I recall, before seeing a single family owned one at a Pacific Raceways vintage racing event a few years ago. I recall just being smitten once I looked under the hood. What a perfectly beautiful little British engine.

The really interesting aspect was legendary Triumph motorcycles designer Edward Turner's involvement. From the Jaguar Heritage Trust Foundation:

Shortly after being appointed Managing Director (Chief Executive) of BSA’s Automotive Division in 1956, Edward Turner was asked to design a saloon car powered by a V8 engine.  Turner and his design engineer Jack Wickes began considering the initial concept of their new engine by examining the manual and spare parts list of a Cadillac V8 engine.  Using a pushrod overhead valve system kept down design, development and production costs and allowed Turner to base the design of the cylinder head on those he had developed for Triumph motorcycles – including the use of hemispherical combustion chambers.  Adapting the Triumph head design for use in a saloon car engine required much work in reducing friction and improving timing.

Much of the development of the prototype engine was carried out by Dr. J.N.H. Tait.  Tait had been involved with Donald Healey in the early post war years, working successfully on modified Riley 2½-litre Big Four engines, the final incarnation of which was used in 1953 Zethrin Rennsport prototype, delivering close to 200 bhp with surprising tractability.

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