Amidst the auto industry’s efforts to satisfy horsepower cravings without sacrificing fuel economy, one solution is poised to gobble market share in double-digit abundance.
“We forecast that gasoline direct injection technology will make up 25% of light-duty vehicle production in North America by 2015,” said Sujit Jain, Senior Vice President of the Gasoline Systems Division for Robert Bosch. The North American light-duty passenger vehicle market share for the industry presently is less than 5%, according to Jain.
Bosch engineers point to the Cadillac CTS luxury sport sedan as an example of how gasoline direct injection (DI) technology can help increase power without costing fuel consumption. The 2008 CTS 3.6-L V6 engine is available with either port fuel injection (PFI) technology or DI technology. Using DI technology, the variable valve timing (VVT) engine improves horsepower (304 hp [227 kW] at 6300 rpm vs. 263 hp [196 kW] at 6200 rpm) and torque (273 lb·ft [370 N·m] at 5200 rpm vs. 253 lb·ft [343 N·m] at 3100 rpm). The estimated 26 highway mpg is the same whether the engine uses PFI or DI technology.
“We have the tools to get fuel economy improvement when employing gasoline direct injection (GDI) and the synergies of engine downsizing and turbo boosting. For instance, a Cadillac CTS powered with a 3.6-L V6 GDI engine—when retrofitted with twin-turbo boost enhancements—has the performance equivalent of a V8 with PFI, but with a 14% fuel-economy benefit in city mpg and a 10% combined mpg fuel-economy benefit. We’re also getting a significant improvement in low-end torque,” said Gottfried Schiller, Director of Engineering for Engine Management Systems at Bosch.
While direct injection can help improve fuel economy in gasoline-fueled vehicles, direct injection also could improve the fuel economy of ethanol-fueled vehicles. Since 2003, Bosch has reigned as Brazil’s market leader in ethanol-suited components for PFI. “Brazil is the largest user of ethanol, so that provided us with a customer base for ethanol-compatible components,” Jain said.
If ethanol becomes a popular fuel choice in other world markets, the lessons learned in designing ethanol-capable fuel injectors, fuel pumps, and other fuel-system components could net a hefty payback. “Using DI and the synergies of turbocharging and VVT, we want to optimize the effective compression ratio to the ethanol blend. Today’s engines are optimized for gasoline,” said Schiller.
The end result of achieving an optimized direct injection ethanol-fueled passenger vehicle is better mpg. “Bosch, Ricardo, and the University of Michigan are involved in a three-year collaborative program—sponsored by the U.S. Department of Energy—that will take a gasoline-optimized engine with DI and turbocharging and make the necessary modifications to build an optimized flex-fuel vehicle. We’re hoping to get ethanol mpg to match what gasoline mpg is today,” said Schiller.