Daimler Straight-Eight engines
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Daimler Straight-Eight engines were eight-cylinder in-line petrol engines made by the
Daimler Company The Daimler Company Limited ( ), prior to 1910 The Daimler Motor Company Limited, was an independent British motor vehicle manufacturer founded in London by H. J. Lawson in 1896, which set up its manufacturing base in Coventry. The compan ...
to power the largest and most expensive cars in their range. The Straight-Eight engines replaced Daimler's earlier Double-Six
V12 engine A V12 engine is a twelve-cylinder piston engine where two banks of six cylinders are arranged in a V configuration around a common crankshaft. V12 engines are more common than V10 engines. However, they are less common than V8 engines. The fi ...
s. Unlike the Double-Six engines, which used
sleeve valve The sleeve valve is a type of valve mechanism for piston engines, distinct from the usual poppet valve. Sleeve valve engines saw use in a number of pre-World War II luxury cars and in the United States in the Willys-Knight car and light truck. ...
s based on the
Knight A knight is a person granted an honorary title of knighthood by a head of state (including the Pope) or representative for service to the monarch, the church or the country, especially in a military capacity. Knighthood finds origins in the Gr ...
patents, the Straight-Eights used conventional
poppet valve A poppet valve (also called mushroom valve) is a valve typically used to control the timing and quantity of gas or vapor flow into an engine. It consists of a hole or open-ended chamber, usually round or oval in cross-section, and a plug, usual ...
s in the
overhead valve An overhead valve (OHV) engine, sometimes called a ''pushrod engine'', is a piston engine whose valves are located in the cylinder head above the combustion chamber. This contrasts with earlier flathead engines, where the valves were located be ...
configuration. Three series of Straight-Eight engines were built between 1934 and the outbreak of the Second World War in 1939; another series, the DE36, was built after the war from 1946 to 1953.


Origin

The Straight-Eight engine was announced by The Daimler Company Limited on 1 May 1934 with its first vehicle, Daimler's new Twenty-Five saloon and limousine. The new engine was the first of a series intended to replace Daimler's outmoded large
sleeve-valve The sleeve valve is a type of valve mechanism for piston engines, distinct from the usual poppet valve. Sleeve valve engines saw use in a number of pre-World War II luxury cars and in the United States in the Willys-Knight car and light truck. T ...
six-cylinder and twelve-cylinder engines. The sleeve-valve engines with silence and great low-speed torque were unable to spin fast enough to make full use of new combustion technology and remain reliable.New Eight-Cylinder Daimler.''The Times'', Thursday, May 17, 1934; pg. 13; Issue 46756 These new engines were intended to run comfortably at 4,000 rpm. The general aim with the engine was "to give the greatest luxury in travel as expressed by quietness, smoothness, flexibility, and general ease and safety of control rather than great speed". While a great deal of useful experience had been acquired by Daimler from Lanchester, who were still building their overhead camshaft straight-eight when they were purchased in 1931, the Daimler Straight-Eight is not a copy.


Twenty-Five V 26

The crankshaft was fully counterbalanced, mounted in nine main bearings, and fitted with a vibration damper. The valves, like other poppet valve Daimlers, had wide clearances, in some cases more than . They were overhead and driven by pushrods from a chain driven camshaft taking power from the rear end of the crankshaft.


Increased engine size

In September 1935 it was announced that the cylinder bore was now increased to 80 mm increasing the engine's capacity from 3.746 to 4.624 litres following the 25% reduction in horsepower tax which took effect on 1 January 1935. intended to provide improved performance but more important lighter running for the engines and a consequent extension of silent and comfortable service. The tax horsepower rating is now 31.74.


Thirty-Two V 4½

In most respects, the Thirty-Two V 4½ was a bored out version of the V26, which it replaced. The compression ratio was increased to 6 to 1. These engines were also fitted to a number of chassis made after 1936 which were fitted with a Lanchester radiator and nameplates. Daimler Straight 8 Salmons Tickford Cabriolet 1936.jpg, Tickford cabriolet 1936 Daimler Straight 8 Salmons Tickford Cabriolet 1936 9138854426.jpg Daimler 32hp Straight Eight 1936 5918265486 f8c8394b6d o.jpg, limousine 1936
Sandringham royal livery Lanchester 2dr dhc c 1935i.jpg, Lanchester grilled
drophead coupé for
the Maharajah
Jam Sahib of Nawanagar


Light Straight-Eight E 3½ and E 4

Introduced in 1936, the E 3½ was an entirely new engine to power a livelier car for the owner driver. During 1935 a 3½-litre Straight-Eight open car achieved a maximum timed speed at Brooklands of slightly in excess of 90 mph.


Increased engine size

In August 1938 the engine bore was increased to and the engine was renamed E 4. The increase in bore increased the following: *Cubic capacity to *Power output to @3,600 rpm, and *Tax rating to 29.77 hp


Thirty-Six DE 36

The DE 36 was the last Daimler Straight-Eight. Developed from the Thirty-Two V 4½, the DE 36's bore and stroke were, at , identical to those of the
six-cylinder The straight-six engine (also referred to as an inline-six engine; abbreviated I6 or L6) is a piston engine with six cylinders arranged in a straight line along the crankshaft. A straight-six engine has perfect primary and secondary engine balan ...
27 hp (RAC) engine being used in the DE 27 limousine and DC 27 ambulance.


Notes


References

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External links


DE36, the biggest car in the world, 1947

Body of V 26

DE 36 swansong
{{Inter-war Daimler cars
Straight-Eight The straight-eight engine (also referred to as an inline-eight engine; abbreviated I8 or L8) is a piston engine with eight cylinders arranged in a straight line along the crankshaft. The number of cylinders and perfect primary and secondary engi ...
Vehicles introduced in 1934 Gasoline engines by model