It was installed at an 18° layover angle to the horizontal and the car so fitted could be identified by the bulge in the bonnet needed to accommodate the greater bulk of the stand-in Offy engine. So to address this, the 3-litre Offenhauser engine that had been used once in the sports cars was fitted into one of the new GP chassis and testing started in this configuration at Riverside Raceway in mid-July 1959. The Offy was about 45kg (100lb) heavier than the anticipated weight of the GP engine and developed about 240bhp (about what was expected from the GP engine). Somewhat long primary pipes from cylinders 1 and 4 and cylinders 2 and 3 were merged together just outside of the bodywork into two long secondary pipes that ran parallel to one another before merging near the engine bulkhead into a similar length big-bore tail-pipe that ended alongside the cockpit. The Scarab GP engine was a bespoke design, not based on the 220 Offenhauser four, although incorporating some similar design concepts because of the same designer. Reventlow was hoping to have his GP car ready to enter in the Monaco GP in May 1959. The successful sports cars had only taken six months to design and build and this may have lulled RAI into underestimating the time it would take to complete the more complex GP car, the biggest difference being they were now designing a race engine from scratch rather than modifying a production engine.
The design centred about the use of Hilborn fuel injection into the inlet manifolds. While there, Reventlow and Kessler visited the European racing car manufacturers Ferrari, Maserati and OSCA (at Maserati, Reventlow purchased one of their FIAT transporters for his own use). Reventlow at first wouldn’t allow the use of British disc brakes and much time was wasted attempting to develop drum brakes with aircraft-type expanding bladders actuating the shoes at the front and a single water-cooled disc-type brake on one of the half-shafts at the rear. Foundries failed to produce castings on time and constant delays were encountered with forging companies, some even returning the drawings and specifications and refusing to complete the job .Difficulties were also experienced with machine shops, in particular Meyer & Drake, who were building the engine, fell behind schedule as they were busy committed to their Indianapolis projects. While all of this was happening, the GP engine’s development was plagued with delays. The three intermediate bearing caps were also cross-bolted by cap screws through the crankcase walls, while the two end bearing caps were supported laterally by the crankcase ends. The intention was to enter the cars in the World Sports Car Championship in 1958, but in September the FIA unexpectedly announced that the current unlimited engine capacity that was allowed was to be replaced with a maximum capacity of 3 litres starting in 1958. This ruled the Scarabs out but Reventlow decided to continue developing the Chevrolet V8 and forgo European racing for the time being while he considered his options.
The extreme off-set of the final drive caused angularity problems with the short left-hand driveshaft and this was finally addressed towards the end of the year (with the 1960 season looming) by a redesign of the rear suspension and the final drive, which involved moving the primary gearbox to just behind the engine (and doing away with the starting and reverse intermediate gearbox), allowing the Halibrand final drive to be mounted separately and moved closer to the car’s centre-line. Around this flange, a circular slot was milled in the block face to receive hollow gas-filled copper O-rings that expanded at engine temperature and provided a fire seal between the block and the cylinder head. Fuel flowed from the metering valve to the junction block from which separate flexible fuel lines were connected to each of the injector nozzles. Because of the extreme cant of the engine’s mounting, oil collecting in the lower camshaft housing in the cylinder head was drained back to the sump, by separate rigid metal tubes extending from the bottom of the valve chest down to the sump casting.
There were two valves per cylinder, made from stainless steel, which were angled symmetrically at a valve included angle of 84° with inserted seats in hemispherical combustion chambers. They had detailed drawings of the features made, particularly of the desmodromic valve gear and then provided Ford with their findings. The Mercedes was in the Henry Ford Museum and staff only allowed Travers and Coon to take it on the condition that they would restore the car to running condition after they had finished studying it. Inopportunely, 1960 also saw the delayed entry of the American Scarab GP team with their front-engined car which would prove to be totally outclassed by the new rear-engined cars that it now had to compete against. Reventlow had intended to purchase a Lister chassis and fit a Chevrolet V8 for the following years World Championship Sports Car season, but he was not impressed with what he saw and felt that he could have a better car produced in America, so he resolved to set up a factory to produce a team of his own sports racing cars. The Scarab was manufactured by Reventlow Automobiles Inc., a company set up by young American, Lance Reventlow, to fulfil his desire to produce American racing cars to compete on the world stage.
