The series sequential turbocharging system, involving two differently sized turbochargers, effectively provides a small turbocharger for low air flow requirements and a large turbo for high air flow. The small turbo delivers good transient response due to its low inertia, while the large turbo maintains power at higher engine speeds. This helps eliminates turbo lag, providing a continuous delivery of peak torque through the RPM range.

In order to control the air flow between the two turbochargers, the new M² system from Cummins Turbo Technologies uses a patented rotary valve to open ports that perform the bypass or waste-gate functionality and provide exhaust after-treatment thermal management.