rose 45%. Changes to the turbocharged B engine included reducing the compression ratio to 7.5:1 with special pistons, and adding sodium-filled exhaust valves, a revised camshaft, an oil cooler and a Garrett AiResearch T3 turbocharger with oil-cooled bearings and the above-mentioned external wastegate. The turbocharged B engine was used in both the 99 and early 900 models. Dual-fuel An alternative-fuel version of the Saab 99 GL called the Petro was developed by the joint venture Saab-Valmet and built at the Valmet factory in Uusikaupunki. This model had dual fuel tanks - one for petrol and one for either kerosene or turpentine, the latter being produced from paper-mill byproducts in Finland, the only market where the car was sold. The engine was started on petrol, then automatically switched to the other fuel, although the driver could select petrol only with a manual override switch. Low-compression pistons from the Turbo were used in this version of the engine, as was the electronic ignition. The Petro first appeared in 1980. Running on 67 octane kerosene the engine produced at 5600 rpm. 3,756 Saab 99 GL Petros were built. B engine variants Motorsports Driver Stig Blomqvist won the 1976 Belgian Rally Boucles de Spa in a specially prepared 16-valve Saab 99. He then won the Swedish Rally in 1977 in a B engine-powered 99 EMS, and again in 1979 in a Turbo 99. The 1979 victory marked the first time a turbocharged car had won the Swedish Rally. In 1980 Saab withdrew from rally competition. B-powered 99s were also successfully campaigned in various SCCA classes. References Saab engines Gasoline engines by model Slant-four engines