AutoblogGreen

While I hope his claims are valid, I get sense of a snake oil salesman here. I will reserve judgement until an independent magazine or TV show validates his claim.

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I don't understand it, therefore it must be a scam.

I'm surprised that we even cook our meat and wear clothes.

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SUVs and pick-ups in the US generally feature high-displacement gasoline engines. These have to be severely throttled in part load to ensure the three-way catalyst can clean up the exhaust gases in order to meet emissions. Severe throttling leads directly to lousy fuel economy.

A diesel injects fuel just prior to ignition. That means it can support very high geometric compression rates, which improves thermodynamic efficiency. In addition, the engine runs lean to very lean and requires no throttling at all. These basic differences explain why diesels are so much more efficient in part load. The relatively cool engine-out exhaust gas temperatures, coupled with mass flow that depends only on RPM but not on load, mean diesels are ideally suited to turbocharging. This substantially increases available low-end torque, just what you want in a large, heavy vehicle.

The downside is that conventional diesel combustion generates a lot of NOx, particulate matter or both. Cleaning up LDV diesel emissions to meet EPA T2B5 / CA LEV II is extremely difficult and expensive. According to NPR piece, Mr. Goodwin injects a second fuel - (corn) ethanol - into the intake ports to achieve more rapid and complete combustion of the diesel. Coupled with high levels of externally cooled exhaust gas recirculation, this can indeed reduce both NOx and particulates at the same time. Optimize for biodiesel and you can afford to apply even more EGR.

Note, however, that all this comes at a stupendous conversion cost. Moreover, you have to maintain not one but two fuel tanks. Also, note that biodiesel is no miracle fuel - in an unmodified engine, it will produce just as much NOx (perhaps a couple of percent more) than dino-diesel, though engine-out PM, CO and HC emissions will be down. Unfortunately, three out of four is not good enough.

There is one silver lining to all this. There are now gasoline engine concepts in development that combine externally cooled low-pressure EGR with advanced turbocharging (VTG or sequential, using affordable alloys). These concepts will sharply reduce throttling requirements in part load, deliver a lot of low-end torque and still meet emissions with just a three-way catalyst. They will approach diesel fuel economy (based on fuel mass, not volume!) but should be cheaper to build. Moreover, because gasoline engines can rev higher, they will feature higher specific power.

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EGR in a Diesel? EGR is used to slow down the flame front, largely to prevent knocking. Diesel MUST knock, it's their sole source of ignition.

This seems odd to me.

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I have a Dodge Sprinter, and EGR is a main part of their efficiency. It also burns away lots of the bad stuff so it does not get to the exhaust system.

I am VERY interested in his new product. It's probably a one fits all filter setup that allows anyone to convert to 100% biodiesel. My Sprinter is a bit of a pain to convert because the standard fuel pump absorbs water (biodiesel has a 60% high water content than diesel) and it clogs the filter, which is a b!tch to replace on the road. I would love to see a simple in line filter system that allows you to run up to 100% bio without any ill effects on your engine or components. Probably still have to convert the fuel lines because Biodiesel wears out fuel lines faster.

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So what is this device and what does it do? If it can be added to any diesel engine what can it do for my TDI VW? It's great that he can claim doubling the mileage of a gas guzzler but, what would the numbers be on an already efficient vehicle?

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Is this just an alcohol injection kit? I read the article but I still don't know what that thing in his hand is. Looks like part of an automatic sprinkler system.

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kinda looks like a filter or pressurizer system or something. but after reading the CNN article (which actually had a sentence about this thing, I am more confused.

I was thinking it was to be a biodiesel conversion turnkey system (not that biodiesel isn't turnkey already, but it can reak havok on your fuel filters and leave you on the side of the road. Would love to see something that can universally be added to make anyone able to run any grade of biodiesel with ease.

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@ why not the LS2/LS7 -

gasoline knock refers to the *uncontrolled* auto-ignition of pockets of fuel-air mixture when they are compressed by the advancing flame front. In severe cases, this can lead to catastrophic engine failure in mere seconds and must therefore be avoided at all costs. Available strategies include using higher-octane fuel, reducing the geometric compression ratio, boosting + effective intercooling and externally cooled EGR at high load. However, the most common method is detecting the onset of knock acoustically and retarding the ignition accordingly. This is why putting regular gasoline in a car "optimized" for premium grade won't damage it, though peak performance will be a smidgen less and the higher fuel consumption will likely neutralize the lower price per gallon.

Diesel knock is something entirely different. It refers to the benign clatter of a cold or idling engine, when the ignition delay inherent in that fuel's properties allows more fuel to enter the chamber prior to combustion. Second- and third-generation common-rail designs typically adjust the fuel injection strategy to minimize this aesthetically undesirable diesel knock.

Modern diesel engines generally do feature externally cooled EGR plus mulitple high-pressure injections per cycle in a bid to reduce flame temperatures and the associated NOx production. The activation energy required for compression ignition is provided by the high temperature of the air-EGR mixture, assisted by the glow plug in the engine warm-up phase. The high fuel velocity serves mainly to maximize mixture preparation but it does also increase friction at the surface of the individual droplets. However, excessive EGR rates (> 20%) do lead to incomplete combustion, i.e. increased PM, CO and HC levels and reduced fuel economy.

The exception to the rule is diesel HCCI combustion, which uses extremely high externally cooled EGR rates (up to 50%) in part load to suppress ignition until a nearly homogenous air-fuel mixture has had a chance to form. The ensuing *controlled auto-ignition* has no flame fronts, so NOx production is minimal. PM formation is also minimal as there are no locally rich zones. CO and HC are comparable to gasoline engines and are neutralized by the two-way oxidation catalyst in the exhaust system. Unfortunately, mechanical stresses and combustion noise - already high in conventional CI - are even worse in diesel HCCI, so this technique can only be used in part load. AVL List expects it to become available in selected series production models before 2010.

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