Spark-ignited engine may replace larger diesel

  • 08-Sep-2009 11:23 EDT

Ricardo’s spark-ignited V6, designed with input from a team of engineers, can match the performance of larger diesels.

Ricardo has developed a spark-ignited V6 engine that matches the performance of a larger V8 diesel engine while also reducing costs. Its Ethanol-Boosted Direct Injection (EBDI) also has the potential to reduce aftertreatment size while letting operators use a range of fuels.

The technology, recently described at the U.S. Department of Energy’s 2009 Directions in Engine-Efficiency and Emissions Research (DEER) conference, was developed with aid from partners who provide a range of products and skills. Bosch provides the direct-injection fuel system and fuel pump, Delphi supplies the ignition system, and Honeywell provides the turbocharger.

In off-highway applications, the size reduction gained by replacing a 6.6-L V8 diesel with a 3.2-L six-cylinder spark ignition engine could be a major benefit given the engine bay constraints in many vehicles. Researchers currently feel the technology can be used to replace diesels with displacement of up to 8 L.

The engine can also be used in commercial vehicles as well as heavy duty pickups. “We’ve had a prototype running on a dyno for six months, and we hope to have a demo on a pickup in early 2010,” said Rod Beazley, Vice President of Spark Ignited Engines, Ricardo.

Though the EBDI moniker implies ethanol-only operation, the Ricardo engine also gives operators more flexibility. They can use either conventional gasoline or any level of ethanol. That’s an attraction for ag vehicles, where owners may prefer to burn ethanol.

One key factor in cost reduction is that with Tier 4 regulations looming, the cost structures for the aftertreatment and fuel systems are quite different between gas and diesel. Beazley predicted that when aftertreatment is added in, the spark-ignition technology could be $3000-$5000 cheaper than a comparable diesel system.

Power output would be roughly the same. Turbos play a significant role in performance.

“Better turbos today provide around 22-25 bar cylinder pressure. We increase that to 180 bar. To do that, we’ve changed the cylinder head, block, and pistons,” said Beazley. “We use a variable nozzle turbo that has faster response than turbos with a wastegate.”

The turbo’s performance changes significantly when different types of fuel are used. “We tailor the engine to take advantage of the octane of ethanol with a control strategy that alters the boost from the turbocharger,” said Beazley.

Ricardo executives predicted that the engine could start making a commercial impact as early as 2015 because it is a relatively straightforward design-in. In one of the prototypes, the engine’s deck height, bore spacing, and bank offset remained unchanged even though many engine components were changed.

“This can be a drop-in replacement, though there may be some challenges in the driveline,” said John Pinson, Vice President of Diesel and Large Engines, Ricardo. “There are changes in the torque attributes that need to be revisited.”

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