Automakers look to turbochargers to help reduce emissions, maintain performance
WIM OUDE WEERNINK | Automotive News Europe
Posted Date: 10/8/05
MUNICH, Germany – European carmakers and suppliers see gasoline turbochargers as another weapon in the battle to reduce emissions.
By introducing turbochargers, automakers can offer smaller-displacement engines that consume less fuel and offer similar or better performance than today’s comparable powerplants.
Those smaller and more fuel-efficient engines, matched with vehicle weight savings, would help European automakers meet their voluntary pledge to the European Union to reduce carbon dioxide emissions to a fleet average of 140 grams per kilometer driven by 2008. In 2003, the average was 163 grams per kilometer.
CO2 is a greenhouse gas, which some scientists believe is responsible for global warming, that is generated by fuel combustion. The amount of fuel a car burns parallels the amount of CO2 it produces.
A turbocharger is an air pump. Exhaust gases drive a turbine, which forces more air into the cylinders to increase an engine’s performance.
The main advantage of turbocharging is that it boosts the output of smaller engines. So instead of using large, normally aspirated engines, automakers can choose smaller engines with turbos for the surge of power when needed, such as passing.
Turbocharged engines also emit 13 grams less of CO2 per kilometer.
“That is why the industry is refocusing on gasoline engines,” said Olivier Rabiller, director of turbo technology marketing at Honeywell Turbo Technologies in Morges, Switzerland.
Virtually all diesels sold in Europe are turbocharged. But only 8 to 10 percent of gasoline engines in Europe are turbocharged.
To increase market penetration, suppliers and automakers must overcome several hurdles. Those include higher costs, greater complexity, performance disadvantages and consumers who are unaware of the technology.
“The industry has recognized this,” said Guenter Kraemen, spokesman for BorgWarner Turbo Systems, Europe’s largest turbocharger supplier. “The whole industry is working on it.”
BorgWarner and Honeywell expect as much as 25 percent of gasoline engines in Europe will be turbocharged by 2010.
Volkswagen sees even more growth in markets such as Germany.
“Today, at VW and Audi about 20 percent of gasoline cars are turbocharged in Germany. We expect that to grow to 50 percent in 2010,” said Hermann Middendorf, VW development engineer for gasoline engines.
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VW will be the first European carmaker to bring to market a downsized turbocharged engine with additional mechanical supercharging.
With a 1.4-liter capacity, this so-called Twincharger has better power characteristics than a 2.0-liter normally aspirated engine but consumes 5 percent less fuel, VW said.
BMW AG and PSA/Peugeot-Citroen SA are working on a 1.6-liter turbocharged gasoline engine.
“Downsizing from about 2.2-liter capacity to a 1.4 to 1.6 liter with turbocharging is the trend,” Kraemen said.
Honeywell’s Rabiller thinks the future range could even be 1.2 to 1.5 liters.
Further downsizing is possible but not realistic.
But there are limits. For one, gasoline engines produce higher exhaust gas temperatures, putting engine durability at risk.
On diesels, the exhaust gas temperatures are between 750 degrees and 850 degrees Celsius. But gasoline engines have exhaust temperatures of more than 1,000 degrees Celsius.
“The general trend in r&d is on the material side, with higher working temperatures,” Kraemen said.
Suppliers are still exploring whether new variable turbos will need particle filters and enhanced nitrogen oxide-reducing catalytic converters because of the high working temperatures of small turbo engines.