The Repco-Brabham V8 engines are a series of V8 piston engines for racing in 2.5L to 5.0L displacement. This engine family features a flat-plane crankshaft with an aluminium or magnesium alloy engine block, as well as dry-sump lubrication. These engines were produced by Repco-Brabham Engines in Australia from 1965 to 1970.
Background The Formula One regulation on maximum engine capacity was changed from 2.5 litres to 1.5 litres by the Commission Sportive Internationale (CSI) of FIA starting with the 1961 season, despite protests from the British entrants, constructors and engine suppliers. As a result, these British interests supported a new, alternative Intercontinental Formula, which had an upper capacity limit of 3 litres.Doug Nye, 1st February 2017, The InterContinental Formula - when regulation changes bred failure, www.goodwood.com The Intercontinental Formula was abandoned at the end of 1961 after the British failed to convince the Americans and others to join the revolt. Intercontinental Formula style racing continued In Australia and New Zealand where Formula Libre rules applied until the introduction of a 2.5 litre limit for the newly instituted Tasman Championship in 1964.
Repco is an Australian engineering company with a wide array of products and services in the automotive industry. Jack Brabham (knighted OBE in 1966) was friends with Phil Irving, a senior engineer at Repco. Together with another Repco engineer, Michael Gasking, this relationship grew into Repco's importing and servicing the Climax engines in 1962, and later producing Climax FPF engines in Australia. When they decided to build a racing engine of their own design with some input from Ron Tauranac, Repco-Brabham Engines Pty. Ltd. (RBE) was established by Repco in April 1964 at 81 Burnley Street (corner of Burnley and Doonside Streets), Richmond, and moved to 87 Mitchell Street, Maidstone, Victoria in December 1964.
In 1964, CSI agreed on increasing the Formula One engine capacity from 1.5 to 3.0L beginning with the 1966 season.
The people responsible included Bob Brown (Repco director in charge of RBE), Frank Hallam (RBE manager), Phil Irving (Chief engineer), Peter Hollinger (Production engineer), Stan Johnson (Commercial manager), Kevin Davies (Factory/production manager), Michael Gasking (Chief of assembly and testing), Howard Ring (Engineer), David Nash (Senior machinist), John Mepstead (Senior machinist), Geoff Walker (Machinist), Graeme Bartils (Assembly engineer/mechanic), Nigel Tait (Machinist), and Rodway Wolfe (Machinist).
Prototypes The initial six cylinder-heads for three engines were cast in England by Sterling Metals and machined by HRG. These were used for 2.5L E1 and E2 as well as 3.0L E3 prototype engines. The entire series of engines, including prototypes and production, was serially stamped starting with 'E1'. The E1 was fired up on 21 March 1965, 51 weeks after Phil Irving commenced its design. Initially tested with Weber 32IDM, the E1 produced at 8,200rpm on Heenan and Froude GB4 dynamometer in Cell 4 at the Repco Engine Laboratory facility in Russell, Richmond. The E3 made at 8,000rpm with longitudinally-mounted four Weber 40IDA down-draft double-choke carburettors, borrowed from Bib Stillwell, on vertically-faced intake ports, with the initial valve timing of 53/77/70/63°. The prototypes used a Coventry Climax FWB flywheel.
The E2 and E3 were re-assembled with '20' series production fuel injection heads and became RB620. RB620-E2 was used at Sandown and Longford, 27 February - 7 March 1966. E3 became RB620-E3C and was raced at East London, 1 - 2 January 1966.
RB620 Background As a result of discussions between Phil Irving and Jack Brabham, who was impressed by Dan Gurney's Indy 500 debut performance (qualified 8th as a rookie) with a GM alloy stock block on 12 May 1962, the initial RB620 was mostly designed by Irving at an apartment close to the Brabham Racing Organisation facility in Clapham, London. This version had the displacement of 2.5, 3.0, or 4.4L. The cylinder block was from Oldsmobile F85 with 18 head studs per bank, not the similar Buick 215 block with 14.
The Oldsmobile block was cast in aluminium alloy (GM 4097-M, 11-13% Silicon, 1% Copper) with 4.240" bore centres and eight 3.500" centrifugal-cast iron cylinder liners of 0.1875" thickness (with 0.010" deep serrations on the outside for a better bonding) cast-in during the pouring process. (Picture of the bare block used on this source page is of Oldsmobile F85 with 18 head stud holes per bank, not of Buick 215.) Twenty-six partially assembled Oldsmobile blocks with cast production crossplane crankshaft were purchased from GM via Holden.
Engine
The crankshaft was an EN40 nitrided forged steel unit custom-made by Laystall Engineering Co. Ltd. in England according to Irving's specifications, always in flatplane configuration but with different strokes depending on the displacement. Main journal diameter was 2.30" and the big-end journal was 2.00". The 6.30" centre-to-centre connecting rods were from 2.5L Daimler V8 lightened and balanced, and later were made in-house for the 700 and 800 series. Pistons (A143 aluminium silicon alloy, made by Russell Manufacturing Co. Pty. Ltd., a Repco subsidiary), piston rings, main and conrod bearings (by Repco Bearing Co.) were manufactured by Repco.
The crankshaft drives an intermediary shaft (jackshaft) with a single-row chain, that drives a water pump at the axis location of the original Oldsmobile OHV camshaft, which in turn drives the two camshafts with another single-row chain made by Morse in the US. The sprockets, including one for another jackshaft at the top centre position (that drives the distributor inside the 'V' angle) pressing down the chain in the middle of the left and the right camshafts, and one for a chain tensioner (SCD built, standard BMC unit), and another for the crankshaft, were all made at Repco.
The intake (1.625", Silicon-Chromium steel) and exhaust valves (1.375", austenite steel), both with the stem diameter of 5/16", were manufactured by an Australian company, Dreadnaught, and are positioned in-line, canted 10-degrees inward from the 45-degrees canted cylinder axis. Duplex coil valve springs were used at 82 Lbs on the seat installed, and 220 Lbs at the full lift of 0.40" for the combined spring rate of 345 Lbs/in.(WP:CALC) The cam-follower bucket was an Alfa Romeo part.
A stiffener steel plate of 3/16" thickness in ladder form was added to the bottom of the block, being sandwiched by a Repco-made ribbed cast aluminium oil sump of 3-1/2" height. The oil sump incorporated pressure and scavenge oil pumps with oil draining at the front-end and rear-end of the sump. An inertia valve opened the rear drain port and closed the front port during acceleration, then opened the front port and closed the rear port during braking, ensuring effective scavenging under either condition.
The fuel supply management was a Lucas mechanical fuel injection with throttle slide plates for production. The '20' series head had a throttle slide-plate with four bores mounted directly on the intake ports of the head, which incorporated four slider rollers for each plate within the head, with inward-canted trumpets mounted on top. The ignition system (two contact point distributor with single spark plug, except RB850 with twin-plug) was sourced by Brabham from Bosch GmbH.
The 2.5L engines had 85mm bore x 55mm stroke for a displacement of 2,496.78cc. For these engines, the cast-in iron cylinder liners of the Oldsmobile block were bored out, and metric Repco cast iron cylinder liners of 2.5mm wall thickness were inserted. The 3.0L (for F1) and 4.4L (for Group A Sports Cars) versions used the original liners in the block with their 3.500" bore until a race in 1966 when one liner failed. The broken liner was bored out, and casting cavities were found where the block meets the liner. Repco dry liners were used after the imperfections welded and fixed from that point on. The dry sleeves caused blow-by issues on the 4.4L version due to distortion, until they were replaced with wet liners on '700' and '800' series blocks.
Results The fuel-injected 2.5L version was run by Jack Brabham on Brabham BT19 at the 1966 Tasman Series event at Sandown on 27 February, then finished 3rd at Longford a week later on 7 March 1966.
The 3.0L engines, also with fuel injection, had 3.5" bore x 2.375" stroke, and was debuted by Jack Brabham on Brabham BT19 at the 1966 South African Grand Prix on 1 January 1966 gaining pole position, and set the fastest lap before retiring from the race on the next day due to fuel injection failure, and then at 1966 Monaco Grand Prix on 22 May 1966. This engine was used on Brabham BT19 and Brabham BT20 for the rest of 1966 Formula One season, making Jack Brabham the world champion, as well as making Brabham-Repco the winner of International Cup for F1 Manufacturers. The 3.0L RB620 was also used in the 1967 Formula One season on BT19 and BT20.
The 4.4L sports car engines (400bhp @7,000rpm) were run by Bob Jane and Frank Matich on Elfin 400 in 1967 and 1968. Frank Matich also used this engine on Matich SR3 for the 1967 Can-Am season in the US and Canada, and then won the 1968 Australian Tourist Trophy.
RB640 Background Phil Irving had experiences with the 'Heron' type combustion chamber, notably on Bob Chamberlain's boat engine, which utilized a 132.5ci version (nicknamed "The Grey Motor") of the Holden 48/215 (introduced in 1948 as a 215ci, inline six-cylinder engine producing 60bhp at 3,800rpm). This engine, in turn, was based on the GM Project 195-Y15, designed in 1938 and produced in Fisherman's Bend, Melbourne. Chamberlain was using the Grey Motor, which produced about 90bhp, but it was unable to pull skiers at the desired speeds. Phil Irving worked with him to design an improvement with increased displacement of 186ci and Heron combustion chamber, utilizing the original two siamesed and two independent intake ports, and three siamesed exhaust ports for a total of seven ports, all on the left side. Repco produced the result (6 with cast iron head and 25 with cast alloy head) from 1966 to 1970, with three SU carburettors and the Heron head dubbed "Cyclone Cylinder Head", which produced 150bhp.
Engine Incorporating this development work, the '40' series cylinderhead had the Heron arrangement, where the bottoms of valves and head are flat, against which pistons with a combustion chamber recess carved into the top are used. The head had SOHC 2 valves per cylinder with vertical valve angle (canted 45-degrees on the 90-degree V engine) for the Heron design. The 10-degrees valve angle difference made the width of the engine larger than the BT19 limit of 21 inches, at the same time provided more space on the inside of the V angle. This increased space was used to relocate exhaust ports from outside the V angle to inside, reducing the frontal area of the Brabham BT22.
Because Ron Tauranac and Jack Brabham preferred to have the exhaust on the inside of the V angle, the '40' series heads were used in races before the '30' series heads, until it was established that the '30' series heads produced more power.
Results This engine, in 2.5L format, was used by Jack Brabham and Denny Hulme on Brabham BT22 and Brabham BT23A during the 1967 Tasman Series races (and at non-championship Levin International in New Zealand), placing Brabham 2nd, and Hulme 8th for the season. Also, Leo Geoghegan used this engine on Lotus 39 and won Australian Gold Star Race at Sandown Park on 17 September 1967. Brabham's BT23A was used by Greg Cusack to win the Australian Gold Star Race at Symmons Plains on 12 November 1967.
RB730