Our Group B story on page 88 features Lancia’s Delta S4 which boasted ‘twincharging’. Its big turbo only came on strong at high revs leaving a low-speed torque void so, lacking today’s electronic anti-lag systems, Lancia plugged this gap with a supercharger and complex pneumatic valving. Air from the turbo went through an intercooler, then the supercharger, into a second cooler and finally the intake. Once the turbo took over, a bypass let the blower idle, cutting its power use by 90%.
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