Building Your Basic Gasoline Diesel Engine

Gasoline direct injection compression ignition engineMost of you know, internal combustion engines are generally divided into two types: spark ignition and compression ignition, usually running on gasoline when we use a spark and diesel fuel when we don't, but a compression ignition gasoline engine? How does that work? Even more to the point, why bother? Engineers believe they may be able to achieve as much as 50 percent better mileage, as good as or better than a hybrid with much lower costs since there would be no huge battery or electric motor.

Diesel engines are 40 to 45 percent efficient at using the energy contained in their fuel while gasoline engines are around 30 percent efficient. That's why all of those diesel cars you see get such great mileage, but they do have a problem keeping the exhaust clean compared to the gas versions. Suppose you could get the efficiency of diesel with the cleanliness of gasoline, why not make a gasoline compression ignition engine?

Delphi, a major automotive parts supplier, is now experimenting by doing exactly that. They've taken a 500cc Ricardo Hydra single cylinder 4 valve engine and set it up to run in a gasoline direct-injection compression ignition (GDCI) configuration. Gasoline is injected in three bursts to control the too fast burning of the gasoline which reduces engine noise, while still burning faster than in a conventional spark ignition engine leading to lower emissions.

Exhaust gas recirculation is used to raise combustion chamber temperature for low speeds and soon after engine start, when it would otherwise be too low for compression ignition.

Results showed that triple injection GDCI achieved about 8 percent greater indicated thermal efficiency and about 14 percent lower specific CO2 emissions relative to diesel baseline tests on the same engine.

They are now moving to a multi-cylinder test engine, more like a production engine, to further develop the concept.

There was one interesting quote that also caught my eye:

Mark Sellnau, engineering manager of advanced powertrain technology at Delphi Powertrain, says the engine could be paired with a battery pack and electric motor, as in hybrid cars, to improve efficiency still more

Now, what were we just saying about both electric and gas together? Wouldn't an engine like this be perfect for running a generator so you could stop at a gas station for a fill up of electricity?

One takeaway of this story is developments like this would be impossible without precise computer controls, simple carburetors or fuel injection systems would never do.

High mileage, low emission, gasoline fueled diesel engines. Wow.

Thanks for the tip, Rob!

Link: Gasoline Direct-Injection Compression-Ignition (GDCI) (pdf) from Delphi via Technology Review


  1. Scotduke says

    There’s a Mercedes prototype car using gas/petrol as fuel for a compression ignition engine. This was unveiled 2-3 years ago and the claims for its fuel economy were pretty good as I remember. I’m not sure what stage the project is at now but I know Mercedes has been doing extensive testing.

    • GuitarSlinger says

      You’re spot on . Its progressing rapidly and you can most likely expect this tech to show up in their road cars sometime soon .

      Mercedes ( as well as BMW etc ) should be the shining example to the rest ! Dump Hybrids and E/V’s ( buy that tech from someone else’s development dollars to silence the buying public and critics temporarily ) and invest your time money and efforts into technology that Really Does have a viable and Genuine future . Diesel / High Efficiency Gas ( for the short term ) and Hydrogen ( for the future both in ICE’s and Fuel Cells

      And errrr ……. In the mean time … to all the Motorcycle manufactures trying to go down the E/V -M/C route . Wake up . Get a clue . Its a Dead End so get back to reality .

      More efficient motors
      Less emphasis on extreme performance numbers
      Improved Aero

      • Duncan Domingue says

        Electric motorcycles and electric vehicles are not a dead end. Electric motors have lots of qualities that make them absolutely great for motorcycles. What is a dead end are the current battery packs that electric motorcycles are using. So, electric motors = good, current battery packs = bad. Electric vehicles’ weakness right now is having to carry around their electricity in a less energy dense substance than gasoline.

        • says

          Your right but what Paul is on about is using a generator to directly drive an electric motor, no batteries.

          Essentially, replacing the clutch and some of the gearing with a generator and motor. Because you still need gearing between the electric motor and the rear wheel.

          Paul envisions this setup as the best of both electric and ICE systems. Carrying an on board generator does overcome the limitations on range of a pure electric vehicle, but with increasing loss of efficiency from the extra energy conversions, you’ll need an even bigger power-plant to get the same power to the rear wheel. And even more, as the weight goes up from carrying the generator and electric motor, not needed with a clutch.

          • Paul Crowe - "The Kneeslider" says

            As I commented before, you may still have a battery serving as a buffer, but the electricity primarily comes from the generator not from stored energy in a battery.

            • says

              Maybe the electric motor and battery could be thought of as a ‘turbo-boost’ mode. The electric motor would only cut in above, say, 3/4 throttle. The battery would be sized to provide power for just long enough to get up to highway speed in a hurry, or to pass a few cars. Then at half to 3/4 throttle, there would be no drain on the battery, and from none to half throttle the motor would become a generator to recharge the battery.

              • Josh says

                The idea of a standard hybrid is the use of the electric motor to take off with the gobs of torque from 0rpm-up with the combustion engine engaging when extra power/charging is needed. This is why the in town fuel economy is awesome with a frugal foot. Think of how much time you are at cruise/part throttle vs wide open. If you are able to run off of the electric constantly with the fossil fuel engine kicking in occasionally that is where the environmental impact is lessened.

  2. Paulinator says

    Diesel and gasoline have significantly different energy-densities when compared volumetrically. The gap lessens when compared by mass. Any measure between the two should be based on the units we see at the pump (IE, volume).

    I’ve always wondered why a conventional spark-ignition engine could not benefit from the higher energy-density of diesel by injecting some of it as the gas combustion process is initiated, during the rapid pressure/temperature rise within the cylinder. I understand that the theoretical Carnot efficiency will not be maximized because the compression ratio will still be based on the lower Otto cycle…but still.

  3. anon says

    I seem to recall Honda worked with this decades ago. I want to say HCCC or HCCI Or something like that. They had a desert racing XR400 test platform. I did a quick web-search but couldn’t find anything. I just got a bunch of those fake click-farm results.

    • Kenny says

      The Honda EXP-2, it was a pretty cool bit of kit. But I think Honda mothballed the project cause I haven’t heard anything about it after they raced it in the Paris-dakar, and baja 1000 way back in 98

  4. Nortley says

    Dual fuel diesels may be another way to go, using existing technique as a starting point. Essentially a dual injection system, liquid fuel is injected to begin combustion (it lights easily) and LPG (lights with difficulty) is injected to sustain combustion and produce power. Nothing particularly new here, it was done on steam powered LNG tankers decades ago. Admittedly the whole system could be heavy for a motorcycle, but it might make our rides more pleasant to be around cleaner traffic.

  5. Mean Monkey says

    The daily MIT Technology Review newsletter is my second favorite read behind the Kneeslider and I love looking over the newest transportation technology. Recently I found a site that proposes using an energy source that I already have paid for. I spend about $125 a month on dog food and it’s dog-gone time I got some return on the investment. ( No, it doesn’t convert the poop into bio-fuel, though that’s an good idea. Now, I wonder if I should harness my Labs to my Kaw Vulcan.

    Joking aside, I saw a young woman last summer going down the street in a sulky pulled by a Great Dane after visiting the local Burger King drive-thru.

  6. JSH says

    “Engineers believe they may be able to achieve as much as 50 percent better mileage, as good as or better than a hybrid with much lower costs since there would be no huge battery or electric motor.”

    I’m not sure where the idea that hybrid use “huge” batteries comes from. The battery in my Prius weighs 92 pounds. Yes it has two motor-generators but it also doesn’t have an alternator or a starter.

    Once GDCI is perfected, the next step will be to use it in a hybrid vehicle to get even better fuel economy than the GDCI engine alone. Hybrid technology is here to stay.

    • Paul Crowe - "The Kneeslider" says

      “huge battery”

      If you substitute the word “expensive” for huge you’ll get the point.

  7. Gearhead says

    I wonder what the figures would be if turbo compounding were added, I.E. run the spent exhaust gases to a recovery “turbo” connected to the front of the crank by a sprag for more energy available to drive things from the back of the crank.

    Its nothing new and was used on a couple airplane engines after WWII

  8. Tom Bows says

    Heck man, I just want it all. Gas, electric, hybrid. Overspecialization is boring. I want to see them all improved and used!

  9. zipidachimp says

    building better mileage cars may be futile anyway. newest conspiracy theory:

  10. Rob says

    Good to see this article here Paul. Thanks for the credit, anything to help maintain the high standards that this site delivers. And thanks Gearhead hadn’t heard of those piston/turbine hybrids before, very cool.

    • Paul Crowe - "The Kneeslider" says

      I’m not sure exactly what “concept” you’re referring to, but multi fuel is a concept common to many engines. The ability to run gasoline in a compression ignition engine is far different. You may want to read the above article again.

  11. Nuno Pereira says

    The article is about an engine that is as clean as a gasoline (Otto) one and as eficient as a gasoil (diesel) one. Diesel fuel is too reactif and mixes poorly with air so it´s very dirty, on the other gasoline used in a conventional engine might detonate if compression is set too high. Strange for some that gasoline which detonates should be used in a so called diesel engine. Well the truth is gasoline resists compression far better than diesel fuel and the best of all it vaporizes well and is a short length hydrocarbon fuel. Those qualities turns gasoline into one of the best fuels for HCCI engines or LTC (low temperature combustion) engines. What Delphi and its partners are trying to do is the most obvious joining the more eficient engine design (the so called diesel engine) with the clean burning of a well mixed mixture of air and fuel.
    I hope to see this new type of clean combustion and eficient energy conversion engines on the roads very soon.