Gasoline-powered diesel-like engine could boost fuel economy by 50 percent


May 20, 2012

Delphi's single cylinder Gasoline Direct Injection Compression Ignition (Photo: Delphi)

Delphi's single cylinder Gasoline Direct Injection Compression Ignition (Photo: Delphi)

With both gasoline and diesel engines having their own particular advantages and disadvantages, automotive component manufacturer Delphi is looking for a best-of-both-worlds solution with a gasoline-powered engine that uses diesel engine-like technology for increased fuel efficiency. According to MIT’s Technology Review, such an engine has the potential to increase the fuel economy of gasoline-powered cars by 50 percent and give hybrid vehicles a run for their money in the fuel economy stakes.

Gasoline engines use spark for ignition while diesel engines rely on the heat of compressed air to ignite the fuel. There have been numerous attempts to develop gasoline-powered engines that use compression ignition, it has been difficult to provide the level of control needed under a variety of loads – idling, accelerating, cruising, etc.

Known as gasoline-direct-injection compression ignition, Delphi's approach reportedly overcomes this problem by "combining a collection of engine-operating strategies that make use of advanced fuel injection and air intake and exhaust controls." This includes injecting gasoline in timed bursts to reduce noise and maximize the speed at which fuel is burned.

Delphi has already built a single-piston test engine to demonstrate the technology and is now commencing testing of a multicylinder engine that would be closer to a production engine. Estimates resulting from simulations of how a midsize vehicle would perform with such an engine indicate that the new engines have the potential to improve the fuel economy of gasoline-powered cars by as much as 50 percent.

Mark Sellnau, the engineering manager of advanced powertrain technology at Delphi, told Technology Review that gasoline-direct-injection compression ignition engines could also be used in hybrid vehicles to further improve efficiency – although he’s unsure whether this would be worth the added cost.

A Technical Paper [PDF] on the Gasoline Direct-Injection Compression-Ignition technology was presented at the 2011 SAE® World Congress.

Source: Technology Review, Delphi

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag. All articles by Darren Quick

What is this engine's difference from Mercedes' Diesotto? Maybe Diesotto has spark plug and the Delphi's does not?


how does not having a sparkplug, provide anything specifically?

it;s not like they use ANY energy at all

so why couldn;t this more efficient engine just go ahead and use spark plugs, since it seems to be a major problem to eliminate them, what problem does eliminating them solve?


What are the advantages of this engine over a pure diesel. Gasoline is an inherently dangerous liquid in comparison to diesel fuel.


Nothing new hee folks. Come on 50% improvement? At best 15% and likely 5% or so. They could do better by making low rolling resistance tires standard.

Next the 'hybrids' now available aren't. Only the Volt and Prius new plug in hybrids are true ones. The present 'Hybrids' just have electric boost.

What is really needed is the Toyota X-1 all composite Hybrid which will get over 100mpg. I'm building another 2 seat version that will get 200mpg in stronger than steel composites, EV drive, 80 mile range and rarely used unlimited range gas generator.

Sadly no one want to build these it seems and we need them as gas goes up with a bullet.


@cenkoskay direct injection is common to both, but the mercedes still uses spark for ignition


A very efficient engine to drive a generator, that feeds electric directly to the electric motors. One motor per wheel. Use 2 wheels when needed (taking off and getting up top speed), and then cutting back to one once you reach cruising speed. 4 motors could be used in cornering, or off road conditions. Polarity could be reversed and motors could be used to "generate" electric as well... ALL SORTS OF VARIATIONS COME TO MIND...

The efficient engines can run at lower, steady RPM's... And the concept is not new, it's been around about a hundred years. Just needs to be perfected, and with the advent of computer controllers, it should be a 100MPG car/engine concept.


An interesting idea. I'm glad that it works, because I presented a similar concept to the Advanced Research Projects Agency-Energy, also known as ARPA-E. They seemed to like my idea, and suggested that I apply for a grant. I'm 85, a WWII veteran, and do not know if I could see the project to its conclusion. My concept uses finely-atomized water as a fuel. The engine is to be made of vanadium, because vanadium can stand the heat of air compression without weakening or melting. Vanadium melts at 3,428 degrees F. Cylinders are paired--cylinder one to make heat of 1,400 to 1,600 degrees F. by compressing the same air over and over, and cylinder two to receive that heat via heat pipes. An alternative to using heat pipes is to circulate liquid gallium through the engine to transfer heat. Gallium liquifies at 86 degrees F., and will remain as a liquid all the way to 4303 degrees F. Atomized water is injected in 1/2000th of a second at piston TDC [same timing as a diesel] in cylinder two. As you know, each water molecule expands 1,600 time when converted into steam. During WWII, fighter jets injected water into their cylinders to give them an extra boost. Too much water for too long would blow the engine apart. Also, there are hundreds of patents for adding atomized water at the end of an exhaust stroke of an internal combustion engine. Steam exhaust drives a Tesla turbine before being routed to a condenser. The Tesla turbine operates electric generators and pumps. This diesel-type steam engine would use water as a fuel. Recycling the water would give vehicles equipped with the engine unlimited mileage. Homes and businesses could generate their own electricity with this engine, making centralized grids obsolete, and less vulnerable to attack. Needless to say, the military certainly would not have to plan the logistics of transporting fuel to the battlefronts. I'm leaving on a trip tomorrow, May22nd. When I get back in a week, I shall be interested in reading replies to my comments, if any. Origo


The difference all has to do with combustion speed.

In a spark ignited ignition a "slow" burning flame wall is ignited at the spark plug and works its way through the fuel creating pressure pushing the cylinder down.

In a compression ignited ignition all fuel immediately ignites in an explosion creating great instant force. This is what causes the loud pinging type sounds of older diesel engines.

It has the potential to increase performance if it can be controlled. Additionally it could prove to be useful in ultra lean burn technology which can greatly reduce the amount of fuel needed during a light cruise.

Darren Thiesen

Looks like a good deal. First, the compression ignition allows the compression ratio to head for the stratosphere - higher compression engines ARE more efficient. And then, with the injection determining the speed and power of the engine, the throttle can be deleted, and a straight-thru pipe substituted, which cuts down on the drag that occurs with the throttle partially open in a gasoline engine - this is one of the big advantages diesels have over gasoline engines.

Looks to be possible that it will get greatly increased mileage. We can hope.

Dave Head

Oringo...interesting concept

Michael Fulton

in my opinion, this design could complicate engine designs. the best compromise is to increase air/fuel mixing, hence, combustion. e.g. a free innovation for experimenters/enthusiasts. "the simplest solution for any problem is invariably the correct one" quote

automotive concerns

@Darren Thiesen

I think you are mistaken. Pinging is usually associated with ignition occurring on opposite ends within the cylinder and the sound is produced by the 2 flame fronts colliding. This generally happens in older engines with carbon buildup on pistons and in engines where the timing is retarded as compared to specifications. Also in cases when the auto advance does not work properly.


The advantage is not eliminating spark plugs... it is from the increased compression possible and resulting improved efficiency.. The efficiency of a internal combustion engine increases with compression ratio. But Gasoline fuel/air will spontaneously burn/explode when compressed beyond 10-1 or so.... this causes the 'knocking' from pre-combustion if too low octane gas is used..

Diesel engines avoid this by intaking air only until the compression is complete, whereupon the fuel is sprayed into the very hot compressed air, where the fuel burns immediately...

While direct injected gasoline engines are possible...why not just get a diesel engine?

Warren White

Origo1 Your system like any steam engine cannot use water as a fuel. A primary energy source has to be used to heat the water to steam temperature before it can expand and push against a piston or turbine. Water doesn't make the heat that turns itself to steam. Water doesn't burn, it is merely a way of converting energy from an actual fuel into a gas that can be valved into and out of a cylinder or channeled through a turbine. The efficiency of a steam engine depends on how much steam can be generated from the actual source of energy which can be anything hotter than 212 deg. F. More fuel has to be burnt to turn more water into steam to make more H.P. like with any engine. Water can be changed to steam by burning wood gas or focusing solar energy on a boiler. The water injected into internal combustion engines merely used some otherwise wasted heat to make steam that increased cylinder pressure; sort of a hybrid gas/steam engine used temporarily for brief bursts.

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