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Four-cylinder in-line automobile engines are inexpensive to build and economical to operate. However, they produce high crankshaft torsional vibration and high engine block vibration. Traditional ways to reduce this vibration may harm driveability and fuel economy, and may increase the cost of construction. Crankshaft-mounted pendulums have the potential to simultaneously reduce crankshaft torsional vibration and block shake at a reasonable cost without affecting driveability and fuel economy. Described in this paper is a study of the feasibility of applying pendulums to modern four-cylinder engines. The study involved the design, construction and testing of hardware, and an extensive analysis effort. Explored by analysis were optimal trajectories for pendulum motion, strategies for tuning sets of pendulums, the stability of pendulum motion and the shaking behavior of engines equipped with pendulums.