Ethanol Boosted Direct Injection (EBDI) Engine by Ricardo, Inc.

Rex Roywriter

Ricardo, Inc. is a leading independent provider of engineering technology for several industries including military, automotive and power generation. Presenting at the U.S. Department of Energy's 2009 Directions in Engine-Efficiency and Emissions Research (DEER) conference, Ricardo, Inc., Vice President John Pinson told participants that by 2015, advanced spark-ignited engines have the potential to become a major force for reducing fuel consumption in several categories, including the diesel-dominated medium-duty commercial truck and off-road segments.

So why does this matter to you?

While Ricardo's announcement focused on trucks, the technology in its prototype engine points toward the future of gasoline-fired passenger car and light-truck engines. Going forward, new technologies and improved uses of existing technologies will enable smaller engines to make much more power while achieving better overall fuel economy compared to today's gasoline and diesel engines.

"The technology now exists to build spark-ignited engines that can deliver performance, economy and durability that are competitive with diesel for a broad cross-section of applications. What will convince manufacturers and customers to switch are the lower cost and straightforward design of these powertrains," Pinson told the DEER attendees during the New Directions in Engines and Fuels panel discussion. "Adopters of the technology will be able to meet emissions regulations at a lower cost and offer their customers a compelling value proposition."

Introducing EBDIRicardo showcased its 3.2-liter V-6 Ethanol-Boosted Direct Injection (EBDI) prototype, which is capable of operating on gasoline or up to 100 percent ethanol. The goal of the new engine was to match the performance of a 6.6-liter turbo-diesel in power, while bettering it in fuel economy.

"The EBDI engine is focused on delivering optimal performance from any gasoline blend based on octane and/or ethanol content. The engine has overachieved its low speed torque performance goals on both ethanol and gasoline," said Rod Beazley, Vice President of Spark Ignited Engines at Ricardo. "This represents an archetypal change when considering the low speed torque output of the gasoline engine compared to the diesel engine - in actual fact the gasoline engine far outperforms the diesel in terms of specific torque performance."

The V-6 is turbocharged, and is based on the General Motors high-feature V-6, an engine that GM currently offers in 3.6- and 3.0-liter versions in vehicles as varied at the 2010 Cadillac CTS, 2010 Chevrolet Malibu, and 2010 Buick Enclave. Said Ricardo's Rod Harris, "There's little left of the original engine as we've replaced or modified nearly every component to deal with our engine's higher specific output." Harris is a Chief Engineer at Ricardo. A feature that was retained but modified includes the variable intake and exhaust valve timing, but Ricardo added variable valve lift.

To be competitive in terms of power with current large-displacement diesel engines, such as GM's 6.6-liter Duramax (665 lb-ft of torque), the Ricardo engine runs the engine's twin turbos on-boost at nearly all engine speeds. Currently available engines such as the turbocharged and DI GM 2.0-liter Ecotec and Ford's 3.5-liter EcoBoost engines, only run turbo boost under heavier loads.

A challenge for the Ricardo team was to regulate the temperature of the intake charge to prevent pre-detonation, a common issue with turbocharged motors. To cool the intake charge, the prototype uses cooled exhaust gasses and a specific intake-charge cooler (a type of intercooler). The engine's use of ethanol also helps here, as ethanol works as an effective retardant to pre-detonation while still providing significant fuel energy to feed the combustion process.

The Power TripComparing the torque produced per liter by various engines, the current Duramax diesel produces approximately 166 Nm and the 2.0-liter turbo DI Ecotec produces 175 Nm. The Ricardo 3.2-liter produces 288 Nm per liter, and the company says that low-end torque production is solid. Ricardo refers to the EBDI's power delivery as super-high low-speed torque.

When you do the math, the Ricardo V-6 out-torques the 6.6-liter turbo diesel Duramax. Fuel economy should match or exceed (by 10-percent) the Duramax and other current medium- and light-duty diesel engines.

For areas of the country where ethanol is widely available, Ricardo's engine improves the efficiency when running on that fuel. Instead of a mileage decrease (compared to gasoline) of nearly 33-percent, their engine is only 15-20 percent less efficient with running on ethanol. This more closely corresponds to the cost of ethanol compared to gasoline, while providing considerably more power.

Ricardo's engine also takes advantage of ethanol's higher octane rating, and the total Brake Mean Effective Pressure (BMEP, a measure that compares the power output of dissimilar engines) on ethanol is 35 bar compared to 30 bar running on gasoline. Many of today's production car and light-truck engines achieve a BMEP of 18-22 bar, with Porsche's latest flat-six turbo engines achieving a high mark of 25 bar.

Looking Ahead To ProductionRicardo does not believe that reliability of their engine should be an issue. The Ricardo engine's components have been beefed up to deal with cylinder pressures that are approaching those reached in diesel engines.

Another factor is cost. Compared to engines such as the Duramax, the Ricardo engine should be significantly less expensive to produce because the fuel injection system is less complex (it runs at 200 bar of pressure, compared to 2000+ for diesels with direct injection). Additionally, the EBDI's exhaust system requires only a three-way catalyst, a solution that is far less complex than the filters and after treatment needed by diesels to meet new diesel emissions standards.

In terms of dollars, the aforementioned differences currently account for $3,700-5,000 in added cost compared to components that can be used on an EBDI engine.

Ricardo is using its prototype to focus on some of this country's biggest fuel consumers. It makes sense to address the biggest consumers of fuel when introducing a technology that helps reduce fuel consumption. When fleet owners do the math, saving 10-percent on fuel for a vehicle that gets only 8 mpg over a yearly driving cycle of 40,000 miles is almost four times more valuable than increasing the fuel economy of a vehicle getting 30 mpg the same 10 percent if both are driven the same annual mileage. This explains the interest in improving the efficiency for medium- and heavy-duty trucks.

Luke Cruff, Ricardo Chief Engineer said, "This engines uses or modifies existing technology to deliver a better solution." The Ricardo team foresees that a production version of their EBDI engine could be introduced on a production vehicle within 3-5 years. The technology is scaleable, so the technology that makes EBDI work can be applied to any size gasoline engine and achieve similar performance results.

Looking beyond trucks to imagine the impact of this technology on cars, and high-performance cars, means that there's a bright future ahead despite present concerns over how exactly that future will arrive.

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