Saturday, 5 March 2016

The BRM H16 engine – part 1: Concept

New rules for Formula 1 engines were introduced for 1966 which stipulated that normal pump petrol was to be utilised in either 3 litre naturally aspirated or 1.5 litre supercharged engines. This blog post details some aspects about BRM’s choice for this new formula.

BRM had much experience with supercharging due to their development of the 1.5 litre V16 unit in the late 1940’s and early 50’s. The new engine formula specified using pump petrol, which meant that intercoolers would be necessary. A 1.5 litre supercharged engine was therefore dismissed as it was believed that the powertrain would be complex, awkward in shape and heavy.

With a 3.0 litre naturally aspirated decided on, the next call for BRM would be the number of cylinders to utilise; 8, 12, 16 or even 24. BRM considered the V8 layout to be very attractive for packaging reasons in a racing car. BRM concluded that whilst the V8 engine would produce excellent torque and be relatively light, engine speeds of over 10,00rpm would be required to produce a power to make a car competitive. BRM therefore decided to dismiss the V8 layout due to mechanical limitations of operating such an engine at these speeds.

The 24 cylinder engine was also dismissed, as it would allow only a very small engine speed increase over a 16 cylinder unit. BRM then decided to let two separate teams carry out design studies on a 12 cylinder and 16 cylinder engine.
Prototype BRM H16 engine

The 12 cylinder unit would be arranged in a V formation and was based on the successful BRM 1.5 litre V8 engine, but using 4 valves per cylinder with a very narrow valve angle. It was estimated that the V12 could produce 475 HP from an engine 30 inches long and weighing 360lbs.

The 16 cylinder unit was based on a H-16 layout. A flat 16 was dismissed on engine length, whilst a W16 was dismissed on engine width. It was deemed that a H16 layout would give a very compact engine with a low centre of gravity, which would fit well into a racing car chassis. The cylinder head joint faces would run vertically fore and aft and could be used to carry the car’s rear suspension. The H16 was estimated to produce 500 HP from an engine 24 inches long and weighing 380lb. Another interesting aspect of the H16 layout was that initially it was planned to use only 2 valves per cylinder. This meant that the cylinder size and number of valves were as BRM’s already very successful V8 1.5 litre unit.

BRM believed that the increased length of the V12 unit would mean that the fuel tanks had to be placed alongside the crankcase, which would mean that engine could not be used as part of the car’s structure, as was intended with the H16 unit. This would therefore negate some of the weight advantages of the V12 unit. BRM therefore settled on the H16 unit.

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