Chrysler engineered one of history's most unconventional powerplants during World War II. The A57 Multibank took five inline-six engines and bolted them together to create a massive 30-cylinder behemoth designed specifically for the M4 Sherman tank.
The configuration emerged from wartime necessity. American tank production demanded enormous horsepower for heavily armored vehicles, but manufacturing individual large-displacement engines proved impractical under combat pressures. Chrysler's solution took five standard automotive inline-six engines, each producing modest power individually, and combined them into a single unit that multiplied output dramatically.
This mechanical audacity reflected the engineering pragmatism of the era. Rather than redesign engines from scratch, Chrysler leveraged existing tooling and production capacity. The five cylinders ran in series, with a complex system of shafts and gearing to synchronize operation. The resulting power justified the engineering complexity. The A57 Multibank generated approximately 500 horsepower, a substantial figure for a World War II combat vehicle, allowing the Sherman to achieve competitive battlefield performance against heavier German tanks.
The downsides were substantial. Cooling five integrated engine blocks required exceptional radiator capacity. Maintenance became a logistical nightmare for field mechanics. The engine consumed fuel voraciously and generated considerable heat in confined tank compartments. Reliability suffered compared to single-block designs, and crews reported vibration issues that plagued longevity.
Despite these shortcomings, the A57 Multibank equipped thousands of Sherman tanks that saw action in Europe and the Pacific. Its existence demonstrates how wartime constraints forced creative engineering solutions. Modern powertrain designers would never consider such an approach, yet Chrysler's five-inline-six configuration achieved its objective. The A57 remains a peculiar footnote in automotive and military history, proof that sometimes combining multiple