Dual Manifold as Exhaust Emission Control in Volvo Cars

The Volvo Exhaust Emission Control System is an engine modification system employing the dual manifold principle, lean mixtures, idle spark retard, deceleration bypass valves, and increased idle speed. The design and performance of the system are described, including the influence on the Federal cycle results of various factors such as idle speed and idle mixture adjustment. Fuel economy, octane requirement, etc, is also discussed. Results of durability test are reported.