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The new technology was tested on a Caterpilllar heavy duty diesel engine. It achieved a thermal efficiency of 53 percent much better than the most efficient auto diesel engines (about 45 percent) and better even than the most efficient diesel engine in the world -- a turbocharged maritime engine that is 50 percent efficient.  (Source: Caterpillar Equipment)

The new engine could cut U.S. oil consumption by 4 million barrels a day -- roughly the amount that the U.S. imports from the volatile Persian Gulf.  (Source: Flickr)
New engine could get better gas mileage than mild hybrids even

Diesel and gasoline are both great fuels from a chemical standpoint, each with its own unique advantages.  Diesel burns more completely, lubricates the engine better, produces less carbon monoxide, and is safer as it does not produce as much flammable vapors.  However it has its disadvantages -- older engines can have a greater danger of incomplete combustion, overall engine power is a bit lower, and diesel engines weigh more.

Gasoline on the other hand burns faster and produces more power (due to the faster burn, not the energetic content).  However, it also typically yields worse gas mileage than diesel, combusts less completely (in well-maintained engines), usually requires a spark to ignite, and produces more pollutants and flammable vapors.

Researchers at the University of Wisconsin-Madison, led by Professor Rolf Reitz have come up with an innovative solution -- an engine which blends diesel and gasoline fuels to get the best of both worlds.  They have designed an engine which they say will be 20 percent more efficient than traditional gas engines, while also lowering the emissions.  The new engine works via a technique called "fast-response fuel blending", which means that the engine mixes the diesel and gas to the perfect ratio for the current conditions.

Heavy loads (like that of commercial trucks) would warrant a 85 percent gasoline to 15 percent diesel mix, while light loads would typically induce a roughly 50-50 mix.  Normally the gas wouldn't combust in a diesel engine, but by adding just the right amount of diesel fuel, combustion is achieved.  In fact, the special mix lowers engine temperatures by as much as 40 percent drastically reducing the amount of energy lost to waste heat.  This allows the diesel engine to use cheaper low-pressure injection (typically in gas engines only), and burns the fuel more cleanly, producing less pollutants.

The researchers estimate that if all cars and trucks in the nation adopted the new engine, it would cut U.S. oil consumption by a third -- by 4 million barrels per day.  States Professor Reitz, "That's roughly the amount that we import from the Persian Gulf."

The engine was developed using theoretical models, then built using a Caterpillar heavy-duty diesel engine as a base.  The new engine achieved 53 percent thermal efficiency, an admirable result, considering the best diesel engine -- a massive turbocharged two-stroke used in the maritime shipping industry -- gets 50 percent.

Professor Reitz concludes, "For a small engine to even approach these massive engine efficiencies is remarkable.  Even more striking, the blending strategy could also be applied to automotive gasoline engines, which usually average a much lower 25 percent thermal efficiency. Here, the potential for fuel economy improvement would even be larger than in diesel truck engines.  What's more important than fuel efficiency, especially for the trucking industry, is that we are meeting the EPA's 2010 emissions regulations quite easily."

The one major downside is that the engine necessitates a second tank.  However, in order to meet EPA nitrous oxide emission regulations the only alternative for large diesel vehicles would be urea injection -- which would likely be more expensive, less efficient, and still require a second tank.  While there's no telling how soon the engine will start popping up in cars and trucks, it appears to be the best solution yet and the best alternative to mild hybrids.  Of course it could be combined with hybrid electric technologies for even great fuel efficiencies.

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RE: The devil is in the details...
By SiliconJon on 8/4/2009 10:14:24 AM , Rating: 1
More likely the story, and its technology, will disappear for whatever reason (good theory/bad practice, IP gobbled up by other interests, just hype to begin with prior to a fundraiser...) Whatever happened to that high school mechanic shop that had a 50mpg sport diesel?

RE: The devil is in the details...
By 91TTZ on 8/4/2009 10:40:37 AM , Rating: 3
Usually press releases quote their most optimistic predictions. By the time it's more thoroughly tested, real world results usually show that it's not any better than what's currently out there, or the improvement isn't worth the added cost.

For ideas that do actually offer an improvement, they usually do catch on, such as hybrids.

RE: The devil is in the details...
By drewsup on 8/4/2009 11:04:58 AM , Rating: 2
RE: The devil is in the details...
By 91TTZ on 8/4/2009 11:58:28 AM , Rating: 2
Keep in mind that the article is using British measurements, and they use the imperial gallon. The US gallon is smaller. So 50 miles per imperial gallon would be closer to 40 miles per US gallon.

RE: The devil is in the details...
By Spuke on 8/5/2009 1:39:06 PM , Rating: 2
It only does 0-60 in 7.5 sec. Now I realize that this is only one aspect of a cars performance, but considering the potential cost of this car, it should be faster. BMW's 335d is quicker and probably cheaper although it would get 5-6 mpg less. The fuel economy difference isn't worth the performance penalty IMO. I read of some euro tuners getting 340 hp and 500 lb-ft of torque out of the 335d. There are some US tuners currently working on the US 335d's, apparently the US 335d uses a different ECU than the euro one's. Can't wait to see what happens on this front.

By Jimbo1234 on 8/4/2009 2:28:30 PM , Rating: 2
IP will be maintained by WARF.

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