Jaguar Daimler Heritage Trust

Daimler V8 Engine 1959 – 1969

Sectioned Daimler V8 Engine

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.

The two sizes of the Daimler V8 engines share similar, but not identical, external dimensions and design, the 4.5 litre being longer, deeper and wider. Although it is possible to substitute one for the other, it requires a good deal of alteration of mountings, exhaust piping, etc.

The 90 degree V8 engine has part-hemispherical combustion chambers with two overhead valves per cylinder operated by push-rods from a single chain-driven camshaft positioned centrally high up in the vee. Aluminium alloy pistons with steel connecting rods run in a cast chrome-iron block with sand-cast, high-tensile, light alloy, heads and crankcase housing and a short, stiff, dynamically balanced, crankshaft carried on five bearings. The nose of the crankshaft carries a torsional vibration damper, a four-bladed fan, and the pulley for the triangulated thin belt drive for the dynamo and water pump. The dynamo is located between the cylinder blocks. At the rear the drive is taken from the back of the camshaft for the distributor positioned high above the unit, behind the two semi-downdraught SU carburettors. There is a separate exhaust system for each bank of cylinders. Light aluminium alloy is used for the valve covers, tappet blocks, sump and inlet manifolds. Cooling is by pump and fan with a thermostatic by-pass control.

Daimler SP250 at Compton Verney 1959

The V8 engine first publicly appeared in the Daimler Dart at the New York Motor Show in April 1959. Chrysler objected to the use of the name as they had already registered it for their Dodge Dart which had been shown in 1957 and was announced for the 1960 model year. Daimler changed the name of the car to its project name – SP250. This fibreglass bodied, V8 engined, sports car had been designed specifically with the American market in mind.

The 2.5-litre engine, only 30 inches (760 mm) in length and developing 140 bhp (100 kW) @ 5,800 rpm, gave better performance and smoother running than Jaguar’s own 2.4-litre DOHC in-line six, and after the 1960 merger the opportunity was taken to create an up-market Daimler V8 version of the Jaguar Mark 2.

Between the years 1962 and 1969 17,620 Daimler/Jaguar V8 saloons were built. Initially called the Daimler 2.5 V8, it was later called the Daimler V8-250.

Limited investment in tooling for the 2.5-litre engine led to limited production capacity, with a maximum weekly output of 140 engines, and the 4.5 litre was only ever made in small quantities. This prescribed maximum output was never achieved during the production of the engine.

In December 1961 Daimler announced a marine version of their 2.5-litre V8.

Daimler Majestic Major

Approximately 20,000 of the 2.5-litre version of the engine were made for use in the SP250 and the 250 saloon, while approximately 2,000 of the 4.5-litre version were made for use in the Majestic Major saloon, and its limousine variant, which remained in production until 1968.

The 4.5-litre engine was used in the Daimler Majestic Major DQ450, which is now rare, but was a respected high performance saloon in its day. The engine was also used in the Majestic Major’s limousine derivative, the DR450. The 4.5-litre was tested in a Jaguar Mark X and there are some unauthenticated reports that this car lapped the Motor Industry Research Association’s high-speed test track at 133 mph (214 km/h) but was reportedly not put into production precisely because its performance was better than the original Jaguar 3.8 Mark X’s. However, the more likely explanation is that there was not the production capacity for the engine, and in any event the 4.2 litre Mark X gave superior acceleration. All 4.5-litre V8 models sold were automatic, which makes connection to a manual transmission difficult.

Jaguar became part of the British Leyland Motor Corporation (BLMC) in 1968. BLMC chairman Sir Donald Stokes decided that the production costs of the Daimler V8 engine were too high and ordered its discontinuation. The Majestic Major was replaced by the DS420 Limousine in 1968 powered by the 4.2 litre Jaguar XK engine and the V8-250 saloon was discontinued in 1969. By 1970, the Daimler range was reduced to the Jaguar XJ6-based Daimler Sovereign saloon and the Jaguar Mark X-based Daimler DS420 limousine, both powered by Jaguar XK6 engines.

Author: François Prins