Ethanol V-6 Delivers Massive Torque

Devotees of displacement, your days may be numbered.

Ricardo plc recently unveiled a twin-turbo 3.2L V-6 that produces monumental torque — equivalent to the Duramax diesel V-8 and outgunning the Vortec gasoline V-8 available in General Motors Co.'s heavy-duty pickups.

While the Duramax runs on diesel fuel, Ricardo's Ethanol Boosted Direct Injection concept engine, soon to be installed in two GMC Sierra 3500 HD demonstrator pickups, is flex-fuel friendly, capable of running on any blend of gasoline or renewable ethanol.

Flex-fuel vehicles have been on U.S. roads for years as a way to help auto makers meet corporate average fuel-economy targets. But many owners of the vehicles rarely buy E85 fuel, consisting of 85% ethanol, even as it becomes more available.

Ricardo initiated the EBDI concept as an example of “extreme engine downsizing” to illustrate the potential for ethanol, says Rod Beazley, product group director-gasoline engines at Ricardo Inc.'s Detroit Technology Campus.

“Ethanol is a homegrown fuel and it's renewable. We're taking advantage of its positive properties to get the performance we need,” Beazley says. “People aren't developing powertrains to take advantage of ethanol. That's what we're trying to do.”

On paper, it appears Ricardo and its multiple development partners succeeded. Torque is the most important measure in medium-duty trucks, and Beazley says the 3.2L EBDI engine produces a staggering 664 lb.-ft. (900 Nm).

That's significantly more powerful than GM's 6.0L Vortec gasoline V-8, which makes 380 lb.-ft. (515 Nm) of torque in the Sierra 3500. And it's basically equivalent to the other stock engine, the 6.6L Duramax turbodiesel V-8, which produces 660 lb.-ft. (895 Nm) of torque.

The EBDI concept can achieve its 664 lb.-ft. with a full tank of E85. On regular unleaded gasoline, the torque drops to 590 lb.-ft. (800 Nm). With a less ethanol-rich fuel, such as E40, Beazley says the torque output falls somewhere in the middle.

The EBDI concept also is more compact than the Duramax and 450 lbs. (204 kg) lighter.

And there's bottom-line appeal, too. Beazley says the Duramax (with its expensive exhaust aftertreatment system) carries an $8,800 premium over the 6.0L gasoline V-8. In production, the EBDI engine should cost about $4,200 to $4,500 more than the gasoline V-8.

Consumer acceptance of ethanol has been lukewarm because vehicles using it generally suffer poorer fuel economy of about 30% in relation to gasoline.

And the price difference does not provide adequate justification: In Iowa and Minnesota, E85 currently is about 20% cheaper than gasoline, but in Michigan and much of the rest of the country, E85 is only 10% less expensive than gas.

“There's no advantage to ethanol at the moment,” Beazley admits.

The primary goal of the EBDI project is to improve the fuel efficiency of ethanol so the deficit in relation to gasoline is only 15%, rather than 30%.

“Then it becomes a different equation,” Beazley says. “We are giving consumers an alternative solution.”

The EBDI concept also can run on cellulosic ethanol, which is less expensive and produced from organic waste, such as wood fiber, lignin and corn stalks. Several companies are ramping up cellulosic production in the U.S. this year.

Until gasoline prices skyrocket once again and force consumers to seek less-expensive alternative fuels, it appears the market for ethanol is stalled.

But Beazley disagrees, saying the industry must meet the CAFE requirement of 35.5 mpg (6.6 L/100 km) by 2016 — a stretch target by any measure.

“The auto makers have to do something,” he says. “We feel the timing for this (concept) is perfect.”

Ricardo executives say they need more time to evaluate the concept before stating its fuel economy. Auto makers are not required to report fuel-economy numbers for heavy-duty pickups.

If an OEM hired Ricardo to engineer such an engine, it could be ready for production around 2014, he says. The two demo trucks will be completed this summer, one for Ricardo to test, the other for Growth Energy, an ethanol-advocacy group that worked with Ricardo on EBDI.

The concept closes the fuel-efficiency gap with gasoline by applying several advanced technologies that enable extremely high pressures within the cylinder.

The engine employs the latest boosting technologies, fueling strategy and combustion control, matching the effective compression ratio and in-cylinder conditions to precisely those required for optimal performance and fuel efficiency.

The induction strategy is led by two parallel sequential turbochargers, supplied by Honeywell International Inc.

From a standstill, the full capacity of the engine's exhaust is routed through one small turbocharger, forcing it to spool up much more quickly, effectively cutting in half the “turbo lag” sensation.

Once the engine achieves a particular load, the second turbocharger kicks in, adding more boost.

Also on board are a charge-air intercooler, two exhaust-gas recirculation valves and Robert Bosch GmbH-supplied next-generation direct injection.

The base engine is GM's 3.2L direct-injection High-Feature V-6, manufactured in Australia by GM Holden Ltd.

Ricardo heavily modified the block and heads and added a next-generation 2,900-psi (200-bar) fuel pump and a revised camshaft.

Federal-Mogul Corp. collaborated on the combustion chamber and supplied advanced pistons and connecting rods.

Oddly, GM did not collaborate on the engine project. Ricardo picked the engine, 6-speed automatic transmission and 3500 HD because the supplier worked on them and is very familiar with them, he says.

It's probably just as well that GM did not take a role in the project, allowing Ricardo to shop the concept more readily to a broad range of auto makers.