Achieving yet another advancement in turbocharging technology, BorgWarner has designed the optimally tuned turbocharger used on Fiat Powertrain Technologies’ (FPT) new high-torque, 1.8-litre direct-injection gasoline engine. Providing excellent response in the lower engine speed range, the innovative BorgWarner turbocharger design allows the engine to achieve a maximum torque of 320 Nm at 1400 rpm – a worldwide benchmark – while eliminating the mechanical compressor required by standard turbochargers.

“Once again, BorgWarner has achieved a ‘first’ in turbocharger design, confirming our technological leadership in all aspects of turbocharging,” said Roger Wood, BorgWarner Engine Group President. “We are pleased to supply partners like Fiat with state-of-the-art technologies that greatly enhance driving performance and improve fuel economy.”

When developing their first direct fuel injection turbocharged gasoline engine, the Fiat engineers trusted the comprehensive experience and expertise of the BorgWarner developers in Kirchheimbolanden (Germany). A K03 turbocharger with wastegate was modified to be perfectly aligned with the engine and combustion requirements. In a special design feature, BorgWarner employed a welded joint to fix the cast manifold directly to the turbine housing for the first time, allowing each to be optimised separately. The turbine housing is made of a temperature-resistant alloy while the manifold is produced with a less costly alloy. Through BorgWarner’s considerable experience, engineers overcame the challenges of joining the different materials. In addition, the optimised turbo with a boost pressure control valve is less expensive and complex, which contributes to improved fuel economy without sacrificing pull-away dynamics.

Introduced at the Geneva Motor Show, the new engine complies with the Euro 5 emissions standard and is now available in the Lancia Delta and Alfa Romeo 159. Even with its impressive torque, the Lancia Delta attains 30 mpg (7.8 litres/100 km) and emits 185 grams of CO2 per km. The Alfa 159’s figures are similar at 29 mpg (8.1 litres/100 km) and 189 grams of CO2 per km.

BorgWarner is also responsible for the twin-stage turbo setup found on the Delta’s range-topping 1.9 MultiJet diesel, which employs R2S technology with two exhaust gas turbochargers. The complete system consists of one compact KP35 turbocharger, which boasts low inertia and offers fast response at low revs as the high pressure stage, and one K16 low-pressure turbocharger for the higher rev band. Below 1,800 rpm, the exhaust stream powers the smaller turbine, which ensures instant reaction without lag and therefore excellent performance at low engine speeds. The larger turbine also spins at low speeds. In the mid rev band from 1,800 to 3,000 rpm (depending on the driving conditions), the larger turbocharger is then engaged to ensure precompression of the air which subsequently flows through the smaller turbo and provides fast power delivery and response. Above 3,000 rpm, the small turbocharger is then deactivated to allow the large, low-pressure stage to release its full potential for the high performance band.