Sunbeam 350HP
| Sunbeam 350HP | |
|---|---|
 |
|
| Overview | |
| Manufacturer | Sunbeam of Wolverhampton |
| Production | one |
| Designer | Louis Coatalen |
| Body and chassis | |
| Body style | Open wheel racing car |
| Powertrain | |
| Engine | 18.3-litre V12 Sunbeam Manitou of 350 hp (260 kW) |
| Transmission | 4-speed pre-selector, final drive ratio 1.5:1 |
| Dimensions | |
| Wheelbase | 10 ft 7 in (3.2 m), track 4 ft 6 in (1.4 m) |
| Length | 16 ft (4.9 m) |
| Curb weight | 1,550 kg (3,417 lb) |
The Sunbeam 350HP is an aero-engined car built by the Sunbeam company in 1920, the first of several land speed record breaking cars with aircraft engines.
The car was fitted with a purpose built 18.3-litre V12 engine based on a hybrid of the Sunbeam Manitou and Sunbeam Arab aero engines. This engine had four blocks of three cylinders arranged in two banks set at 60 degrees (unlike the Arab which were set at 90 degrees). Each cylinder had one inlet and two exhaust valves actuated by a single overhead camshaft. The two camshafts were driven by a complex set of 16 gears from the front of the crankshaft - a very similar arrangement to that used on the Maori engine which had two OHC per bank of cylinders. A 4-speed transmission initially drove a back axle with differential with a shaft drive rather than the hazardous chains of other cars. Harry Hawker drove the car in 1920 at Brooklands but suffered a burst tyre, spinning off the circuit. The differential was replaced with a simple crown wheel and pinion so that the rear wheels were locked together and it was more successful in the hands of Kenelm Lee Guinness. Brakes were crude, as was usual in the period, with a foot brake acting on the transmission and a hand brake on the rear drums. Suspension was also typical, with half-elliptic springs all round damped by Andre Hartford friction shock absorbers.
The 350HP was first raced at Brooklands in 1920 by Harry Hawker. In October Rene Thomas set a new record at the Gaillon hill climb.
On April 17 Jean Chassagne lapping at 114 mph won the Brooklands Easter Meeting 13th Lighting Short handicap. In May 1922 Kenelm Lee Guinness set three records with it: the Brooklands lap record at 123.30 mph (198.43 km/h), then the land speed record over a mile at 129.17 mph (207.88 km/h) and over a kilometre at 133.75 mph (215.25 km/h) – this was the last land speed record to be set on the Brooklands track.
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