SAAB WIS ONLINE

System overview (B235R, B205R/L)

System overview (B235R, B205R/L)


Brief description

Unlike a conventional induction engine, a supercharged engine is supplied with extra air mass during the induction stroke, which gives more efficient combustion, increased power and greater torque. Engine performance is consequently in comparison with that of larger engines, while retaining the advantages of a smaller engine such as fuel economy, space, weight, etc.

Supercharging

Supercharging is performed by a turbocharger. The turbocharger is driven by some of the engine exhaust gas, which passes through an exhaust turbine and drives the turbine impeller. The turbine impeller is mounted on the same shaft as the compressor wheel and rotates at the same speed. The compressor wheel is located in the induction system and creates a pressure rise that improves the rate of air passing into the combustion chamber. In order to regulate the additional air mass being supplied by the turbocharger, the exhaust gas bypasses the turbine section of the wastegate when the engine is producing more exhaust gas than is required to drive the turbocharger. The wastegate position is controlled by Trionic.

The turbocharger is designed to start operating at relatively low engine speeds to give high engine torque at speeds that apply during normal driving condition. The B235R and B205R engines are fitted with the Mitsubishi TD 04 turbocharger and the B205L with the Garrett GT 17–turbocharger.