|The crossover 9-4x features a turbocharged, direct injection, VVT engine.|
GM introduced its Saab 9-4X BioPower Concept at the North American International Auto Show, confirming Saab’s plans to enter the growing crossover market segment.
The 2.0-liter, all-aluminum, four-cylinder BioPower flexfuel engine combines the benefits of turbocharging, direct injection and variable valve timing for the first time with high-octane E85 fuel.
E85 has a higher octane rating (104 RON) than gasoline, making it more resistant to harmful pre-detonation, or “knocking,” when the fuel/air mixture is compressed in the cylinder. To fully exploit this advantage, the engine has a raised compression ratio, 10.5:1, instead of 9.2:1 for a gasoline-only application. It retains its flex-fuel capability because the Saab engine management system adjusts the ignition timing and turbo boost pressure to ensure there is no pre-detonation with gasoline.
Engine efficiency is also improved by the use of direct injection (DI) and continuously variable valve timing (VVT) on both the inlet and exhaust sides. DI delivers fuel directly into the combustion chamber, providing a more complete burn of the fuel/air mixture to give more power with reduced fuel consumption.
VVT enhances turbo response at low engine speeds, as well as contributing to an even wider spread of torque. On E85 fuel, the engine’s 295 lb-ft (400 Nm) of torque is generated from 2,600 to 5,100 rpm, with 85% available from just 2,000 rpm. While these figures may be matched by a much larger, naturally aspirated engine, the characteristic “tidal wave” of low-end torque is unique to the turbocharged power delivery. Maximum boost pressure at maximum torque is 1.2 bar.
Optimized for bioethanol (E85) fuel, the four-cylinder, 2.0-liter BioPower turbo engine delivers 300 horsepower (221 kW) and torque of 295 lb.-ft (400 Nm), together with substantially reduced CO2 emissions on a well-to-wheel basis.
When running on gasoline, the engine delivers 245 hp (180 kW) of power and 252 Nm (261 lb-ft) of torque. Combined cycle fuel consumption on gasoline is 10.5L/100km (22.4 mpg)
Active management in the Saab XWD drive system splits torque delivery between both the axles and the rear wheels, via an electronically controlled rear limited-slip differential (eLSD). This responsive system rewards the driver by giving an enhanced, “positive force” chassis balance.
GM also showed a Hummer flex-fuel concept at the show, the HX. The vehicle—more compact than a HUMMER 3—features a direct injection 3.6L V-6 VVT flex-fuel engine backed by a six-speed automatic transmission teamed with the 4WD system.