During the 2020 edition of the Challenge & GT Days, which is a track day for Ferrari/Maserati historic and modern GT/Challenge cars and open also to historic F1s, I had the plasure to see a 1966 BRM P83 warming up its unorthodox H16 engine and doing a couple of ‘parade’ laps on track. I’m really sorry for the lack of action (generally typical of my videos) but it seemed to me it was the first time they started the P83 up after many years so it has already been a huge success to hear it turned on.
The BRM P83 was a Formula 1 car designed by Tony Rudd and built by BRM/British Racing Motors for the new engine regulations of 1966. It used a relatively rare H-layout, 16-cylinder engine which were mainly use in aircrafts during the 1930s and 1940s.
After winning the 1962 Drivers’ and Constructors’ championships BRM had finished second each year, coming close to the championship in 1964 and having a promising 1965 season with the excellent P261. In 1966 the Formula One regulations with regards to engines were changed from a maximum 1.5 litres normally aspirated to either 3 litres normally aspirated or 1.5 litres supercharged following complaints that the smaller engines used from 1961 to 1965 weren’t powerful enough for the premier category of motorsport. As a result, many teams were left looking for a new engine supply while BRM, who built their own very successful V8 engines, had to decide on what manner of new engine to develop to meet the new formula.
BRM decided to develop their existing 16 valve 1.5 litre V8 into a 32 valve 3 litre H16 (effectively two flat 8s one on top of the other and geared together) while also developing a new 48 valve 3 litre V12 and opt for whichever turned out to be the better powerplant. After much debate Sir Alfred Owen decided BRM would go with the H16. But what does a H engine consist of? It’s a piston engine comprising two separate flat engines (complete with separate crankshafts), most often geared to a common output shaft. The name “H engine” is due to the engine blocks resembling a letter “H” when viewed from the front. The most successful “H” engine in this form was the Napier Dagger. The benefits of an H engine are the ability to share common parts with the flat engine upon which it is based, and the good engine balance which results in less vibration.
However, H engines are relatively heavy and have a high centre of gravity. The latter is not only due to the second crankshaft being located near the top of the engine, but also the engine must be high enough off the ground to allow clearance underneath for the exhaust pipes.
Back to the BRM P83, its H16’s development was complicated by BRM’s involvement in two further V12 designs and a 4.2 litre version of the H16 for Lotus to use at Indianapolis
Various crankshaft vibration problems dogged the engine from the start. Each side of the engine had to have its own water radiator, fuel metering unit, distributor and water pump, with a common oil radiator. The sheer complexity of the engine led to a truly terrible record of unreliability; engine, transmission and related problems caused 27 of the powerplant’s 30 retirements from 40 entries. Sir Jackie Stewart said of the engine “it was unnecessarily large, used more fuel, carried more oil and needed more water – all of which added weight and diminished the vehicle’s agility”.
The initial 32 valve engine produced 395 hp at 10,250 rpm, with a later 64 valve variant raising this to 420 hp at 10,500 rpm. While these constituted reasonable figures compared to the Ferrari, Honda and Weslake V12s and the Cosworth V8 of 1967, the H16 had an extremely narrow power band and was by some distance the heaviest engine on the grid, starting out weighing 250kg when introduced in 1966 with the final lightweight version lowering this to 180kg. The engine was also used by Team Lotus in the Lotus 43 as a stopgap while the Cosworth DFV was developed.
The H16 was mated to a 6-speed gearbox, with the gear lever unusually situated to the left of the driver.