Mk.4 bore (72.40 mm) and Mk.II stroke (60.00 mm) and was used by Lotus in 1966 as a stopgap until 3 litre BRM H-16 engines became available but with little success. However, Jim Clark won the 1967 Tasman Series with this engine in his Lotus 33. Overall, FWMV powered Cooper, Lotus and Brabham Formula One cars won 22 World Championship Grand Prix races. FWMW By the middle of the 1962 season, Peter Windsor Smith and Walter Hassan were convinced that the only viable route to more power was through higher revs, and the decision was made, partly in light of Harry Mundy's experiences on the 1.5-Litre supercharged BRM V16, to develop a 1.5-Litre flat-16 designated the FWMW. Design work started in 1963, and a prototype was running on the bench in late 1964 with two flatplane flat-8 cranks end-to-end, shrunk-fit to a central spur gear at 90 degrees phase shift to each other (not a true boxer arrangement, but rather with opposing pistons sharing a crankpin). Work on this project continued through the later years of the 1.5 Litre formula with Lotus and Brabham the likely recipients. The engine was fairly compact at 30.9" long (only 1" longer than FWMV Mk.4) and 22.6" wide, but there were a number of design issues still to solve before the formula ran out. Not only had the engine shown no power advantage over the V8 despite its much higher rev limit, but it had mechanical problems that would have required either a major rework to solve properly or, at the least, the need for complete engine rebuilds after 3 hours of running. From the outset, the largest problem was torsional vibration of the crankshaft, which at one time necessitated a ban on using below 4000rpm on the bench. The vibration often caused one or other of the cranks to shear itself off the central spur gear, resulting in the engine becoming two aphasic flat-8s, or the parallel quill shaft (driven at 0.8 times the crank speed, located below crank, and in turn driving the flywheel and ancillaries) overheated and disintegrated. The central power-take-off system using the parallel shaft was intended to reduce torsional vibration of the long crankshaft, but destructive vibration appeared no matter what was changed in firing order, crank counter-weight configuration or crankshaft weight distribution. As a result, Coventry Climax could not derive revenues from the project, and was further forced