Ricardo and Growth Energy Collaborate On First Vehicle-Based Demonstration of Ricardo’s Ethanol Boosted Direct Injection (EBDI) Engine Technology
by Bill Cooke
|The 3.2L EBDI engine. Click to enlarge.
Engineering firm Ricardo and Growth Energy, a trade association promoting the use of ethanol fuel, are collaborating on two demonstrator vehicles incorporating Ricardo’s Ethanol Boosted Direct Injection (EBDI) engine technology (earlier post) showing that even for larger vehicles extreme optimization of ethanol combustion can enable engine downsizing of the order of 50% and still deliver substantial fuel economy and CO2 emission improvements from a cost-effective, high performance, inherently low emission powertrain.
Based on test work already carried out, Ricardo estimates that a fuel economy improvement of up to 30% is possible with no loss of power or performance, using a downsized EBDI engine in place of currently available gasoline powertrain technology. For the demonstrators, Ricardo plans to modify two GM Sierra 3500 HD heavy-duty pickup trucks and replace a base 6-liter gasoline V-8 in one with the heavily boosted 3.2-liter EBDI engine—resulting in up to a 16.8% fuel economy improvement. Ricardo is replacing a 6.6-liter turbo diesel V-8 in the other.
|One of the trucks. Click to enlarge.
For heavy-duty trucks engine torque is a key performance metric and Ricardo expects the EBDI engine to offer 1.5x the torque of the gasoline engine and match the torque of the 6.6L turbo diesel engine while weighing 400 to 500 pounds less than the diesel.
Following completion of the 10-month project, the demonstrator vehicles will be available for a range of demonstration, test and evaluation exercises to be organized by Growth Energy and Ricardo.
In the past, when people have created flex fuel engines they have taken the gasoline engine and converted it to burn varying degrees of ethanol. Since ethanol has only two thirds of the energy content of gasoline on a per gallon basis, fuel economy has suffered leading to customer dissatisfaction, but ethanol also has some inherent advantages such as high-octane and a higher heat of vaporization and by applying several cutting edge technologies Ricardo has been able to harness the full capabilities of ethanol to create an engine that gets high fuel economy with a domestically produced renewable fuel.—Kent Niederhofer, President of Ricardo
In volume production, the engine is expected to retail for $4,000 to $4,500 more than the base gasoline engine or approximately half the premium associated with a diesel engine. The diesel premium is expected to grow to $9,500 by 2013 in order to comply with more stringent air pollution standards. The EBDI’s price premium versus today’s gasoline engine would be offset by fuel economy savings over the life of the vehicle—allowing the owner to get the increased torque performance “for free”. Ricardo expects the EBDI technology to be compatible with existing plans to improve gasoline engines’ pollution performance.
Improving Ethanol’s Cost Performance and Carbon Footprint
The EBDI engine can accommodate ethanol blends ranging from 0 to 85% ethanol (E0 to E85). Ricardo is still collecting data but with an E40 (40% ethanol / 60% gasoline) Ricardo can achieve a mpg that approaches pure gasoline using a fuel with less energy gallon—i.e the E40 blend uses approximately 10% less Btus per mile (6,590 vs 7,260) than gasoline (see table below).
|Comparison of different ethanol blend levels in EBDI engine. Click to enlarge.
With today’s economics it would be a financial wash to use the E40 blend verses gasoline but since ethanol and gasoline come from two very different value streams (agriculture vs. petroleum) macro economics may drive significant price differences that the consumer could exploit at a later date. “It will provide consumers with a cost effective choice in fuel, said Rod Beazley, director of the Ricardo Inc. Spark Ignited Engines Product Group.
The most robust way to create various ethanol blends is to have blend pumps that would allow the consumer to choose their level of ethanol. In lieu of a blend pump, the more enterprising consumer could create their own approximate blend by filling up with equal amounts of E0 and E85 each time they refueled.
The customer would be able to tune their torque performance by using blends with more or less ethanol. Using E85, for maximum torque, the driver would have a peak torque of 660 lb-ft (895 N·m) and more than 500 lb-ft (678 N·m) of torque over a 3,600 rpm band (approx 1,400-5,100 rpm). Using E0, the torque would be 14% lower.
As points of comparison, the 6.0-liter gasoline V8 is rated at 353 hp (263 kW) and 373 lb-ft (506 N·m) of torque. The 6.6-liter diesel V-8 is rated at 365 hp (272 kW) and 660 lb-ft (895 N·m) of torque.
The EBDI engine will also improve ethanol’s carbon footprint by requiring less BTUs per mile since, for a given mode of ethanol production, the well to wheel CO2 emissions is directly related to fuel economy.
Development History and Real Horsepower
Ricardo has largely self funded the development of the EBDI engine and appreciates the technical support (parts and engineering) provided by the following companies:
- Federal Mogul: Piston, Rod, Bearings, Head Gasket
- Behr: Induction System and EGR coolers
- Grainger and Worral: Block and Head Castings
- Bosch: DI System Hardware
- Honeywell: Turbocharger Hardware
- Delphi: Ignition System
Ricardo has more than 700 hours of testing complete on the development engine and is ready to “take the technology to the streets” by building the two trucks and putting them through various extreme duty cycles. One of the trucks will be a dualie pickup with a fifth wheel trailer mount to prove that the 3.2 L EBDI system can haul up to 16,500 pounds which, according to Niederhofer, is equivalent to “four Clydesdales and a full-size horse trailer.”
We took the stock V-6 and redesigned every component. We are getting diesel-like performance out of an engine that was originally designed to be lightly turbocharged. With our heavy boost we have increased the cylinder pressures to diesel-like levels. We had to work on the bottom end and on the crank and in order to get enough of ethanol into the engine we had to use two fuel pumps. We have an integrated manifold with charge air coolers and EGR coolers help cool down the combustion system. We have two parallel/sequential turbochargers and although our block and heads look unchanged from the outside, inside they are highly modified with structural changes to support the higher cylinder pressures. We also have a high-voltage ignition system to ignite the large amounts of ethanol.—Rod Beazley
When asked how Ricardo can have different compression ratios for different fuel blends, Luke Cruff, Chief Engineer Gasoline Product Group, replied:
Compression ratio is a function of two things: geometric compression ratio and boosting pressure. The turbochargers and other variable devices can adjust the boosting pressure which allows you to have different effective compression ratios. Diesel engines today run about 17:1 compression ratio which is trending down because the emission regulations while this engine’s compression ratio is closer to 11 to 1.
In addition to the hardware development, Ricardo has significant intellectual property in the algorithms and control software. Niederhofer of Ricardo points out that “a lot of the breakthroughs the team has identified to get this engine to work will find their way into base gasoline engines” independent of ethanol blends. This engine represents an enhancement, not a redirection, of existing trends in automotive powertrains.
Ricardo expects this technology to be used in a variety of markets including agriculture equipment and commercial vehicles but they see automotive as being the lead. The Ricardo team in Europe is pursuing a similar program focusing on much smaller three and four-cylinder engines. Luke Cruff points out:
GM has just recently introduced a 1.4 L turbocharged engine for the Chevy Cruze. We believe that using EBDI technology, you could have a 1.4 L engine power a mid-size car. That would give you approximately the same engine displacement to vehicle weight ratio as the 3.2 L engine in the heavy-duty truck.