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by Christopher A. Sawyer > Contributing Editor Dan Gurney isn't just a legendary race driver, but a man who has developed some remarkable vehicles—and engines. Like his latest project, the Moment Canceling 4 Stroke (MC4S) engine. After reading the patent, slogging through its legalese, and ignoring the straight-cut gears shown in the patent drawings, it's pretty obvious the 84-year- old Gurney is on to something. The MC4S is not only a perfect ft for motorcycles (and light aircraft), but for an increas- ing number of cars and light truck applications as well. Its natural balance and impressive estimated power fgures point to a design that is just as at home under the hood of a sports or luxury car as it is next to the battery pack of a range-extended electric vehicle. However, Gurney isn't about to get caught up in speculation. Though excited about the engine's prospects, he admits it's too early to make any defnitive claims about the engine. "Naturally, we'd like to look at [the engine's] long- and short-term viability, both materially and fnancially," says Gurney. "All ofers to help are very much appreciated and will be considered. At the moment, however, our target is to prove that the simulation data is correct. We plan to be running by the end of this year on our test rig, and we expect to get confrmation in a reasonably short period of time after running." He says that the development "will take patience." If all goes well, a further four engines will be built, though it's not clear whether all will be built to the same exact specifcation, or be used to test other variants. The MC4S as envisioned in the patent is a high-performance, dual overhead cam, liquid-cooled, oversquare (bore greater than stroke) motor with a one-piece cast aluminum sump. Seven through bolts attach the crankcase and sump through the engine block, much like Rover's 1989-2005 K-Series four-cylinder engine. Unlike the Rover, which cost-reduced the engine to the point of failure, Gurney's engine has Nikasil-coated bores instead of liners and is ftted with a multi- layered steel head gasket. As the cutaway of the engine shows, however, this is as far as conventionality goes. From here on, it gets a little weird. Though it looks like a U engine with geared counter-rotating cranks at frst glance, the crankshafts are perpendicular to a line running through the pistons and camshafts. Odd-numbered pistons are located on one shaft (up to four for each, according to the patent), while even- numbered pistons are located on the other. The crankshaft gears determine the timing of the pistons to each other, and cancel the horizontal imbalance found in inline engines by reducing the transverse motion sent through the vehicle. This eliminates the forward/backward rocking Dan Gurney is no stranger to creating his own engine. In the 1960s he teamed up with Harry Weslake to create the Gurney-Weslake V12 for the Eagle TG1 Formula 1 car, with which he became the frst American driver to win a grand prix in a car of his own construction (the 1967 Belgian Grand Prix). (Photo courtesy AAR Archives.) Dan Gurney may be 84 years old, but his Moment Canceling 4 Stroke engine design shows his mind is as sharp as ever. motion common in inline designs, and signifcantly reduces vibration. Among the side benefts are improved bearing life, a reduction in the stresses sent through the vehicle's structure, and the elimination of expensive vibration dampers. In addition, less vibration is sent to the short dual overhead camshafts, which are operated by gears connected to the crankshafts and a chain. A variable valve timing system controlled by the ECU is part of the package. Each crankshaft is about half the length of a single crankshaft, and this contributes to the bottom end's rigidity. The idealized MC4S seen in the patent uses ball bearings in place of shell bearings, though those could be used in a less exotic variant. Further, with the odd and even cylinders located on diferent crankshafts, there is no need to ofset the cylinders. This reduces engine size, and makes for simpler, more uniform water coolant passages. Bore diameters range from 1.5 to 7.0 in. (38 to 178 mm) and strokes from 1.5 AD&P; > November 2015 > FEATURE > Dan Gurney Creates a New Engine > Christopher A. Sawyer 34