Hast recht G60Ing. Der Delta S4 hatte das- untenrum Kompressor und obenrum eien höchstwahrscheinlich riesigen Turbolader - aber wurde dr Kompressor vielleicht ab ner bestimmten Drezahl abgeschaltet - der war meines wissens nur dazu da um das Turboloch zu kompensieren.
"The S4 engine, displacing 1759 cc, is based on proven Abarth hardware and mounted longitudinally behind the front seats. In the 'production' cars its
KKK turbocharger and Abarth Volumex supercharger boost output to a maximum of 250 bhp at 6750rpm and 2141bft of torque. That sounds a lot from less than 1.8 litres, but the similar-sized motor of the Lancia-Martini rally cars was persuaded to yield a reliable 470 bhp at 8000 revs, plus more than 333 Ib ft of torque.
The aim of using both a turbo unit and supercharging was to overcome the lazy low-speed response of the turbo. The supercharger looks after the provision of extra punch below about 3500 revs, and the turbocharger supplies an increasing amount of boost at higher rpm.
The competition S4 used exactly the same twin intercooler principles, but the transition from supercharging to turbocharging took place at higher engine speeds, between 5000 and 6000 revs. Developing the engine's mechanically driven supercharger and the exhaust-impelled turbo to the point where power and torque delivery were harmonious was a complex challenge. Fiat-Lancia-Abarth engineers eventually met it successfully, but as yet nobody else has repeated the experiment..."
Greetz Chris