• 30
Ford's EcoBoost engines use direct injection technology... Ford's EcoBoost engines use direct injection technology (Ford).
Gasoline direct injection is one of those technologies that make you think, "Why the heck didn't they figure this out sooner?" It's a simple fix to the regular old combustion engine, and it saves a lot of fuel. Instead of mixing air and gasoline outside the combustion chamber, the system sprays gasoline directly into the chamber. The result is literally more bang for your buck. (Don't worry, we'll explain this all in detail in a little bit).

Actually, engineers in the auto industry did think about it earlier. Mercedes-Benz used it in their 300Sl Gullwing in the 1950s. It's been primarily used in diesel engines ever since. But most U.S. drivers are not familiar with diesel passengers cars.

How does it work?

The combustion engine works by mixing air and gasoline and shooting it into the combustion chamber. Gasoline needs air, otherwise it won't explode. And you need a series of controlled explosions to get the pistons on the engine moving, which is what ultimately moves your car.

Direct injection sprays gasoline directly into the combustion chamber, while air comes in through a valve nearby. That results in what engineering geeks call a "leaner" burning process. In other words, the engine needs less gas to make the same powerful bang that pushes the pistons.

And because the gas doesn't have to travel as far to get inside the combustion chamber, it's cooler. And cooler gas can be compressed tighter to create more power. Think of it as kind of a Jack-in-the-box: If you push that guy down in the box harder, when you let go, he'll bounce back harder and higher than normal.

Why would I want it?

Because it gives you fuel economy and power at the same time. When GM introduced the Cadillac CTS in 2008, it offered one 3.6-liter V6 engine with direct injection, and one with standard fuel injection. The direct injection engine got 304 horsepower and the standard got 263 horsepower. But both engines got the same 26 miles per gallon fuel economy. That's as easy a real-world explanation of the value of direct injection as we can think of.

Is there any downside?

It costs a couple hundred dollars more to put it under your hood, because it's a little more complex to manufacture and uses some more expensive parts. It also needs a more sophisticated computer system to manage the engine and flow of fuel, further adding to the cost.

Automakers probably won't pass that cost on to consumers, because they're under a lot of pressure to meet higher fuel economy standards in the next few years. But the engines could be more expensive to repair if anything goes wrong.

What vehicles offer it?

Audi and Buick offer it on their full lineup. Volkswagen markets its models with direct injection engines with the initials "TSI." Ford calls its direct injection engines "EcoBoost", and luxury models like BMW, Lexus, Mercedes and Porsche offer it on most of their models. Ferrari offers the technology on the $230,000 458 Italia if you can afford that.

Bottom line

Direct injection is a true win-win for the internal combustion engine, offering both greater power and improved fuel economy.


I'm reporting this comment as:

Reported comments and users are reviewed by Autoblog staff 24 hours a day, seven days a week to determine whether they violate Community Guideline. Accounts are penalized for Community Guidelines violations and serious or repeated violations can lead to account termination.


    • 1 Second Ago
  • 30 Comments
      horsedrag
      • 3 Years Ago
      Wish everyone would accept the fact that "Clean Diesel" is far superior to all the pie in the sky solutions to our energy problem. Diesel fuel lubricates and has more power per drop then gas. The more time and effort wasted on hydrogen, electric, and diesel like systems only complicate and far stall the reality that was understood for over 100 years when the original one ran on peanut oil. Diesel is the most efficient engine and can achieve 70 mpg cleanly right now.
        dknowles60
        • 3 Years Ago
        @horsedrag
        hear! hear!
        joynerz
        • 3 Years Ago
        @horsedrag
        In high-traffic areas diesel exhaust is the primary 'odor'.
          khangus
          • 3 Years Ago
          @joynerz
          @horsedrag ..... yes, perhaps the diesel is better. However, I live in Asia, and we have huge numbers of diesels .... and they, not being "clean diesels", stink stink stink. The trend here is to go to NGV (natural gas) on commercial vehicles like buses and taxis .. it's made a huge difference. MUCH better than diesel. For that reason, I'm not a huge diesel fan.
          horsedrag
          • 3 Years Ago
          @joynerz
          I beg to differ. Modern clean diesels are equipped with exhaust systems that treat the exhaust so it is clean and odorless. I have a 2011 Ram truck and after 20,000 miles you can rub your finger in the tail pipe and it is spotless. Besides if the vehicle is more efficient it is polluting less.
      D9241943
      • 3 Years Ago
      It's nice you give credit to the DI system; however', a large part of the performance also comes from the twin turbocharger system tha is integral to eco boost. I don't understand how you can only talk about a part of the "SYSTEM"
        kimallman
        • 3 Years Ago
        @D9241943
        So True. It's the combination of the two items in tandem. The throttle body injector was a vast improvement over the carb, and the direct injection is an improvement over the throttle body. It appears the the smallish turbo diesel is the wave of the future for mpg's.
      cautomo200
      • 3 Years Ago
      click here for the 80 mpg Focus in Europe... http://media.ford.com/news/fordrevealsnewfocuseconeticeuropesmostfuelefficientcompactcar.htm
      alfredschrader
      • 3 Years Ago
      This is why it works...when the piston rises on the compression stroke, the air inside the cylinder becomes hot. Anything over 8 to one compression ratio, and the gasoline/air mixture pre-ignites before the piston and crank are in the downward power stroke position. The result is the nausiating "ping" sound of the piston banging the side of the cylinder wall. But, if you time the injection of the gasoline so the piston is heading down on the powerstroke, you can increase the compression ratio. The higher the compression ratio, the greater the expansion from a smaller space and better efficiency and power. But what no one knows, is why the air gets hot when you compress it. That is, no one but me. Why ? Because I discovered why in my lab here in Florida. It's called photon-exchange technology and it's worth billions....Alfred-
      lindacharliebb
      • 3 Years Ago
      1st auto man to couple compressed air to the drivetrain will see a true 100 mpg vehicle the public would buy . batteries are too costly , and hydrogen is , well , hydrogen.
      scott
      • 2 Years Ago
      You forgot to mention the big downside... carbon build-up on the backs of the intake valves. Since there's no fuel washing over them, they quickly cake up with carbon causing rough running and power loss. This can happen in as little as 30,000 miles, then you will need to pay several hundred dollars to have the dealer remove the intake manifold and clean out as much crud as possible. This will continue to happen over the life of the vehicle in roughly the same intervals. The amount of build-up is dependent on PCV design and type of driving. Do some searches on MINI and Audi/VW owner woes around this issue. And also note that Toyota doesn't have any DI systems, they use a port/direct injection system on some engines, the port injector is there to keep the intake valve clean.
      jking41198
      • 3 Years Ago
      This feat is more difficult in a gasoline engine than meets the eye. Diesel engines can combust a small mass (quantity) of fuel in as much compressed air as you want. The system adds more fuel to the fixed amount of air to produce the power you need or want. Gasoline engines traditionaly must use a specific ratio of fuel to air or the engine will misfire. Worse, the engine may "ping" itself to death. It may backfire. Ford has been working on the concepts to overcome this for many years as have others. (Chemical Engineer and retired member of Society of Automotive Engineers)
      • 3 Years Ago
      Re fuel injection: The aircraft industry utilizes this technology for powerng aircraft engines for a number of years. Use in short; cooler operation, less worn parts, fuel efficienty, ( the fuel costs 9$ a gallon), added horse power per engine weight, higher altitude operation,( the carburator air/fuel mix creates icing and clogs the mix to the cylinders and stop the engine) Fuel injected into cylinders prevents this at hi altitude operation. Not many places to land!!! True: Automotive engines since 2000 now have fuel injection tech for more miles/gallon, and more power to the wheels. An professional aircraft technician.
      Cool people
      • 3 Years Ago
      Makes sense.
      cautomo200
      • 3 Years Ago
      Our own EPA has placed the biggest choke-hold on fuel economy...all you have to do is look to Europe to see what we are missing....In Europe if it's not a Diesel, it won't sell....why would they want a low fuel economy gas ******* engine? Oh and so you know any ethanol blended fuel reduces fuel economy further...Ethanol has reduced BTU's as compared to gasoline....Take a look at the 50 mpg ford focus in Europe...go ahead & Google it...and see what we are missing out on...
        Chris Young
        • 3 Years Ago
        @cautomo200
        I agree the EPA is a goverment agency that has worn out its welcome. Their MPG tests are no where near real world. Even the fuel they use is nothing like unleaded. Its some super refined fuel that will never be used by the public.
      estimatorone
      • 3 Years Ago
      It seems to me that the net result to save fuel is to cost you more then you save? Fuel prices keep going up, almost exponentially it seems. Cars cost more and more to put all of the electronics/hardware to eek out this fuel economy. We are not even considering the costs to maintain these cars. So, where are the savings?
      a214943
      • 3 Years Ago
      Where have you been for years? My 87 Buick Garnd National had this feature. The fuel injectors shot the fuel directly into the combustion chamber. I thought most GM vehicles have had this for years? Sounds like a marketing ploy from FORD.
        Calvin
        • 3 Years Ago
        @a214943
        yup thats fuel injection not direct injection
        khangus
        • 3 Years Ago
        @a214943
        Sorry .. wrong ..... it had port fuel injection .. NOT direct (into the combustion chamber) injection.
    • Load More Comments