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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: well but for vehicle usage
By rudolphna on 8/4/2009 11:15:44 AM , Rating: 2
We already have one. I live in upstate new york, we have alot of diesel pumps up here at gas stations. The diesel nozzle is much thicker around than the gas one does, and won't fit in. I know this, because one day I wasn't paying attention, and picked up the diesel nozzle, and it didn't fit. Good thing. I would have been stranded at HESS till I could get my tank drained. DOH. The real problem is going to be keeping people from putting gas in the diesel tank. Maybe a square nozzle for Gas, big round one for diesel, or something.

RE: well but for vehicle usage
By Lord 666 on 8/4/2009 12:37:43 PM , Rating: 2
There are actually two sized diesel nozzles; one for cars and the higher rate intended for trucks.

While I understand the idea behind it, as diesels become more popular, they do need to standardize on size/form factor. Driving to and from Florida last year, came across one station that only had the large nozzle off of I85. Other than that, all other stations have the smaller and some have both.

RE: well but for vehicle usage
By tastyratz on 8/4/2009 3:08:48 PM , Rating: 3
well that's just it. While we have one now, its usually seperate. Filling a tank like that would be cumbersome and generally loathed by the public.

A dual feed single connector fuel nozzle that plugged in 1 way with 2 outlets would be a good adaptation if enough manufacturers agreed to make these engines with a true market penetration.

RE: well but for vehicle usage
By monomer on 8/4/2009 4:57:54 PM , Rating: 2
Lots of older model Ford Trucks had dual gas tanks, and I realy never heard anyone complaining about them. In fact, some guys loved them since they could just run two pumps and fill in half the time than if they had only one tank.

RE: well but for vehicle usage
By MrPoletski on 8/5/2009 3:38:58 AM , Rating: 3
Here in the UK we simply colour code the pumps, green is unleaded petrol, red (used to be) 4 star leaded and black is diesel.

The nozzles are the exact same size.

If you screw up and put the wrong fuel in your car, it's your own stupid fault.

RE: well but for vehicle usage
By axeman1957 on 8/5/2009 11:59:49 AM , Rating: 2
Pretty sure the US does that too... every diesel pump I have ever seen has been green, and the unleaded are black

RE: well but for vehicle usage
By MrPoletski on 8/6/2009 5:26:42 AM , Rating: 2
Pretty sure the US does that too... every diesel pump I have ever seen has been green, and the unleaded are black

uh-oh, opposingly colour coded pumps, that's a recipie for disaster if coming over here to visit;)

but that's ok, we don't mind foreigners breaking their cars over here and having to pay our mechanics to fix it :)

RE: well but for vehicle usage
By Spuke on 8/5/2009 1:04:08 PM , Rating: 2
The nozzles are the exact same size.
The nozzles are a different size here but the color coding is the same.

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