BMW 328. Click image to enlarge
Article and photo by Bill Vance
BMW can trace its roots back to 1916 when Bayerische Flugzeug-Werke was established in Munich, Germany, to produce aircraft engines. The name was changed to Bayerische Motoren-Werke (Bavarian Motor Works) in 1922 and the company branched out into marine and truck engines. It soon added motorcycles.
In 1928 BMW decided to enter automobile production and acquired Fahrzeugfabrik Eisenach in Eisenach which was building English Austin Sevens under licence. They were called Dixis, and with its purchase BMW obtained the rights to the Dixi and continued producing these popular small cars under that name.
BMW soon evolved into designing is own cars and by 1933 it had developed the model that would strongly influence the company’s direction. This was the 303 which introduced BMW’s “kidney-shaped” grille. It had a 1.1-litre, overhead valve inline six-cylinder engine designed by BMW engineer Rudolf Schleicher.
Within a year the 303 was replaced by the 315 and the limited production 315/1, a two-passenger roadster that was BMW’s first sports car. With 40 horsepower the 315/1 was successful in sports car competition, so for 1935 BMW improved its successor, the 319, with the engine enlarged to 1.9 litres (1,911 cc), now producing 55 horsepower. These cars laid the foundation for the emergence of BMW’s most famous pre-Second World War car, the 328.
Design work began on the 328 in 1934 and prototypes made their debut in 1936 at the German Nurburgring race course where they vanquished all opposition. The displacement had been enlarged slightly to 1,971 cc via a 1-mm bore increase, but that made only a small contribution to its success.
Its really important improvement was its unusual valve operation. The 328 six’s chain-driven camshaft was located low in the block and operated the overhead valves via pushrods. BMW engineers wanted the efficiency of hemispherical combustion chambers without the expense of overhead camshafts.
A cheaper alternative was sought and it was inspired by a Talbot engine. A new cylinder head was designed with inclined valves. The intakes continued to be actuated in the conventional manner, but the exhaust valves located on the opposite side of the aluminum cylinder head were opened by a secondary set of horizontal, cross-over pushrods remotely operated off the same camshaft.
It was an ingenious, complicated sounding system but it proved to be sound, and would survive for many years. The external appearance of the engine meant that is was often mistaken for a twin overhead cam design.
With the improved efficiency of the hemispherical combustion chambers which allowed larger valves, the 328 engine developed 80 horsepower, an impressive output for a two-litre engine of that era. Engine durability was enhanced by an oil cooler.
Three vertical intake ports and three carburetors atop the engine fed two cylinders each. This produced an engine that was quite tall and would ultimately create challenges to lowering the hood line of cars. A four-speed manual transmission sent power to the rear wheels.
The frame was tubular steel and front suspension was via a transverse leaf spring with lower control arms, with the shock absorbers cleverly integrated into the pivots of the control arms. At the rear was a sold axle on leaf springs.
Steering was by rack-and-pinion and the hydraulic brakes had generous 279-mm drums. The disk wheels carrying 5.50 X 16 tires were secured by four pins located where conventional studs would be and locked in place by a central knock-off hub, a system used to avoid infringement of the English Rudge-Whitworth centre-lock patent.
The 328’s body was of aluminum and steel over a wood frame. Its lines were elegant and aerodynamic, the most striking feature being headlamps that were nicely faired into the area between the fenders and grille.
The 794 kg (1,750 lb) 328 was capable of almost 161 km/h (100 mph). In competition it was the cream of the two-litre class and could also acquit itself very well against cars of larger displacement. Among the many accomplishments, four 328s won their class in the 1938 Italian Mille Miglia finishing 7th, 9th, 10th and 11th. It won the Spa (Belgium) 24-hour race and came in 5th overall in the 1939 LeMans (France) 24-hour race.
The 328 would dominate the two-litre sports racing class for four years until the Second World War ended competition. It has been called the first modern sports car, and although less than 500 were produced it was truly BMW’s “coming of age” car.
And that unusual engine would prove to be extremely durable, undergoing a tripling of its power during its lifetime and being used by Britain’s A.C., Frazer-Nash and Bristol and the American produced Arnolt-Bristol, plus several competition cars. It survived into the 1960s.