A tuned intake induction system using a Helmholtz resonator was applied to an in-line six cylinder, four cycle heavy duty diesel engine. The system adopted was designed to maximize the engine breathing performance at the peak torque engine speed. Significant advantages noted were improvements in volumentric efficiency by 12 percent, improved cylinder-to-cylinder air distribution and faster turbocharger response. The increased trapped air-fuel ratio also results in improved combustion efficiency and reduction of smoke emissions. Additional improvements appeared feasible by compressor redesign and optimization of valve timing. The primary disadvantage was the space claim the system required; however, compact designs can be achieved without great difficulty.