sábado, 5 de mayo de 2012


Text and Photos: José Manuel Serrano Esparza

The Napier-Railton Special is one of the most powerful and beautiful classic cars ever made, featuring a tremendous 24-litre 12-cylinder Napier-Lion XIA aero engine, with an output of 530 bhp at 2350 rpm.

This British super classic car is able to reach 168 mph (278 km/h), a great top speed for the time in which it was built.
Not in vain, this unique work of art still holds the speed record of the banked Brooklands circuit in Surrey with 143.44 mph.
It became internationally famous when in 1935 and 1936 it beat twice the endurance world record of the salt flats of Bonneville (USA), with a then amazing average speed of more than 150 mph.
The Napier-Railton 24-litre W12 Special 1933 at full-blast 168 mph (278 km/h) on the track of Farnborough (Hampshire, U.K). July 22, 2004 

The sound produced at top speed by the astounding aviation industry power plant of the Napier-Railton Special 1933 has to be heard to be believed. Farnborough track (Hampshire, U.K). July 22, 2004

The Napier-Railton Special 1933 was incepted with a very clear aim in mind: the attaining of the maximum feasible speed, together with an unheard-of endurance in long races.
John Cobb had a previous significant background in sporting competitions all over Great Britain during twenties, driving different fast cars, including models such as a 10.5 litre V12 Delage, a 10-litre Fiat and a 27-litre Parry Thomas Special with which he had already achieved a lap record at the Brooklands circuit with a speed of 129 mph.
But in early thirties, Tim Birkin, Cobb´s great rival, was defeating him with his supercharged Bentley Special, and Cobb realized that he needed a new much more powerful and fast car to have chances.
Therefore, he made contact with Raid A. Railton, chief engineer of Thomson & Taylor firm, painstakingly explaining him what he needed: a car featuring a framework able to hold both the large size and the great weight and brutal power of an aircraft engine.
It was also necessary to manufacture a special three-speed gearbox to manage the immense strength and torque of the prospective new ´special´ racing car, and in order to avoid an excessive weight, it was mandatory a one seat aluminium made body.
On the other hand, the choice of appropriate tires was also a challenge, because they had to trustfully support the approximately weight of 2 tons of the vehicle, which was one of the key factors of the project.
Finally, regarding the gearbox, John Cobb could have the invaluable cooperation of  Moss, who created a remarkably very sturdy and realiable three-speed one.
The aluminium chassis was made by Gurney Nutting & Co. Limited (a highly reputed English concern of coachbuilders founded in 1918, who manufactured great bodies according to its customers specifications -among which were such pretigious firms like Bentley, Daimler, Rolls Royce and Duesenberg- and whose first designs had appeared in October 1920 at the London Motor Show) in its facilities of Lacland Place SW10.
And as for tires, the difficult to solve conundrum of finding the suitable tires to manage the heavy weight of the car, after a research stint Dunlop was able to provide them.
Following John Cobb´s  instructions, other specs developed by Raid A. Railton along with Thomson & Taylor for the new superpowerful and massive car were on drum brakes located on the rear wheel and a combo semi-elliptic leaf springs and live axle making up a ladder frame on which the whole car would lay.
But above all, the two most important goals to achieve were a top speed of around 168 mph (278 km/h) - a really impressive one for the time- and of course what would have to make up the core of the new racing super car: a very special engine featuring the superlative power, stamina and endurance to enable the 2-ton machine to flawlessly work throughout long competitions at every moment and win them, without forgetting the getting of new speed records, something to which John Cobb would devote all of his lifetime.

The power plant chosen for the new concept car was the Napier-Lion XIA aero engine, featuring 24-litres, with a W configuration of twelve cylinders arranged in an unconventional way, with three banks of four offset at 60º from one another and delivering 530 bhp at 2350 rpm, which is its nominal strength, though John Cobb had it specially tuned to reach 600 bhp. 



The exceedingly powerful liquid-cooled engine with a remarkable broad arrow layout of 12 cylinders, belongs to the Aviation Industry scope


and was made by the D. Napier & Son Ltd at his factory of  Acton, London, between 1918 and 1933, being fitted to 153 different types of aircraft, Marine Speed boats and World Record Cars.

Its transmission sports double overhead camshafts per bank and four valves per cylinder, with a three-speed Moss constant-mesh gearbox driving the rear wheels.

The manufacture of this outstanding aero engine - who was tackled from scratch with stacked aluminum billets to be used during production - was greatly handcrafted, with very high quality standards in all of its components, and a comprehensive range of skilful and experienced workers accomplishing different tasks and stages to build each of its parts, which included the handling of drilling machines, ovens and baths used for heat treatment of metal pieces, lathes to machine crankshafts, production of aero engine valves, pouring of molten aluminum from crucibles into cylinder cover casting moulds, vertical Cincinatti milling machines to cut splines, belt-driven lathes, boring machine tools, cylinder barrels, milling machines to manufacture the cylinder heads, caspstand lathes, vertical milling machines on crankcases, belt-powered Lang & Sons lathes to machine valves, removing of aluminum cylinder head covers from sand casting moulds, and even the taking of micrographs of steel.

On the other hand, in the Napier-Lion XIA aero engine, each four cylinder DOHC block is linked to the common crankshaft and each crankshaft main bearing has got three connecting rods.
Napier-Lion aero engine view of Distribution Gears, clearly showing the wise and often unique solutions found by D. Napier & Son Ltd in its factory at Acton, London.

Napier-Lion XIA aero engine impressive Crankshaft with Extension or Auxiliary Drive Shaft, a wonder of mechanical thoroughness.