Which of the following turbocharger arrangements has the best efficiency?

The turbocharger arrangement known for having the best efficiency is the pulse turbocharger arrangement. This efficiency is primarily because pulse turbochargers utilize the exhaust impulses generated from the engine's cylinders to drive the turbine, leading to optimal energy recovery from the exhaust gases.

In a pulse turbocharger, the design captures these pressure pulses, which helps in improving the acceleration response and reducing turbo lag. The arrangement of the exhaust manifold and the orientation of the piping are also specifically tailored to maximize the effectiveness of this pulse effect, thereby enhancing the overall efficiency of the turbocharger system.

In contrast, other arrangements such as radial, axial, and screw turbochargers operate differently. Radial and axial turbochargers have their own efficiencies based on their design and operational principles, but they do not optimize exhaust gas recovery in the same way that pulse turbochargers do. The screw arrangement, although effective in specific applications, generally is not designed for the same level of performance as pulse in terms of turbocharging efficiency in marine engines.