Repco V8 engine
In 1964 the Australian/New Zealand Tasman Series was created with a 2,500 cc capacity limit applied to engines. Jack Brabham approached Repco to develop a suitable engine, and together they decided to base the SOHC design on Oldsmobile Jetfire 215 ci block with six cylinder-head studs per cylinder. Combined with a short stroke flat-plane crankshaft, Repco designed cylinder heads, camshafts and two-stage chain/gear cam drive, a 2.5 L engine was built in 1965 with its cylinder head cast by Commonwealth Aircraft.
In 1963 the international motor racing body, the FIA, announced that the maximum engine capacity for the Formula One category would be doubled to three litres to start from the 1966 season. Despite calls for a "return to power" having been made, few teams were prepared as the main engine supplier in the UK, Coventry Climax, decided to get out of race engine building (under licence from Coventry Climax, Repco actually manufactured the 2.5L, Coventry Climax FPF straight-4 motor for the Australian and New Zealand racing markets).[14]
Jack Brabham used his friendship with engineer Phil Irving at Repco. He proposed they design and build a 3 L version of the 2.5 L engine by using a longer stroke flat-plane crankshaft.
The Repco board agreed to his proposal in light of the expected rival 2.75 L Coventry Climax FPF DOHC engine being of four-cylinder configuration deemed to be near-obsolete, and the plan to build the Cosworth DFV (revealed at the end of 1965 by Ford, its sponsor) was not known yet. A small team at Repco under Phil Irving developed the F1 engine, fitted with two valves per cylinder SOHC heads from the 2.5L version.
The first advantage of this Repco 620 V8 was its compact size and lightness, which allowed it to be bolted into an existing 1.5-litre Formula One chassis. With no more than 310 bhp, the Repco was by far the least powerful of the new 3-litre engines, but unlike the others it was frugal, light and compact.[15] Also unlike the others, it was reliable and due to low weight and power, the strain on chassis, suspension, brakes and tyres was low.[16]
This engine being based on British/American Rover V8/Buick 215 block[17] is a common misconception. The Oldsmobile version of this engine, although sharing the same basic architecture, had cylinder heads and angled valve covers designed by Oldsmobile engineers to look like a traditional Olds V8 and was produced on a separate assembly line. Oldsmobile's intention to produce a higher-powered, turbo-charged Jetfire version led to significant differences from the Buick 215, primarily in cylinder head design: Buick used a 5-bolt pattern around each cylinder where Oldsmobile used a 6-bolt pattern. The sixth bolt was added to the intake manifold side of the head, one extra bolt for each cylinder, meant to alleviate a head-warping problem on high-compression versions. This meant that Buick heads would fit on Oldsmobile blocks, but not vice versa. Changing the compression ratio on an Oldsmobile 215 required changing the heads, but on a Buick 215, only the pistons, which was less expensive and simpler. General Motors later use of parts diagrams drawn for Oldsmobile in Buick parts catalogue showing a six-stud cylinder block sowed further confusion. Later Rover versions of the aluminum block and subsequent Buick iron small blocks went to a 4-bolt-per-cylinder pattern.
