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Carburetor's future

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  1. Apr 22, 2015 #1
    I recently heard from my professor that the carburettors are getting obsolete in terms of their use in modern days auto-mobiles. Auto-mobile manufacturers are moving towards alternatives like direct fuel injection into the intake manifold or intake ports even if the fuel is gasoline. Is it true? If yes then why? Why are these alternatives better than carburettors?
     
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  3. Apr 22, 2015 #2

    jedishrfu

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  4. Apr 22, 2015 #3

    billy_joule

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    This happened quite some time ago. my first car, an 82 Nissan silvia was injected. I'd be surprised if any mass produced car if the last 20 years wasn't. You can read about why here:
    http://en.m.wikipedia.org/wiki/Fuel_injection
     
  5. Apr 22, 2015 #4
  6. Apr 22, 2015 #5

    SteamKing

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    Most fuel injection systems for gasoline engines used to be so-called port injection designs, where the fuel injectors were installed in the intake manifold and positioned such that the atomized fuel would be aimed at the intake valve.

    Diesel engines, by design, were set up so that fuel was directly injected into the cylinder as the piston reached top dead center, and the amount of fuel injected was precisely metered to produce a nearly constant pressure in the cylinder as the piston began its power stroke.

    Newer gasoline injection systems, the so-called direct injection systems, are designed to closely resemble diesel injection in that the fuel injectors send fuel directly into the cylinders instead of the intake manifold. These systems are more costly than the older port injection systems, but they make the engine more fuel efficient.
     
  7. Apr 22, 2015 #6

    SteamKing

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    As far as 4-wheeled vehicles go, NASCAR finally switched to electronic fuel injection from carburetors in 2012.
     
  8. Apr 23, 2015 #7
    Is there a proper experimental study or theoretical analysis to comply this? Or is it just an observation?
     
  9. Apr 23, 2015 #8

    SteamKing

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    Many studies and experimental systems have been done over the years. This type of fuel injection is actually one of the oldest such methods applied to gasoline engines, starting with aero engines in the early Twentieth Century:

    http://en.wikipedia.org/wiki/Gasoline_direct_injection

    High cost and lack of electronic controls limited the use of such systems in mass-produced engines previously.

    You know, as far as scientific research goes, often it is an observation of a phenomenon which occurs first, then theories and further experiments are developed to see if the phenomenon is understood. :wink:
     
  10. Apr 23, 2015 #9
    Yes! We always do that.
     
  11. Apr 23, 2015 #10

    Ranger Mike

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    I would not bet on the carburetor going totally obsolete. There are some critical things to consider on fuel injection.
    The orifice on the “ injector is super small when compared to the huge fuel jet a carb uses. Typically dirt is a bad thing in the fuel system but a very expensive killer on injectors. You need a micron mesh fuel filter. a high pressure fuel pump must be used. We are talking about excess of 85 psi pressure. These are mostly electric and located in the fuel tank. If you go mechanical pump it is a high parasitic drag item. You need high pressure fuel line to plumb it to the engine. You need a computer to monitor and control the injectors.
    The venerable old carb needs a supply of gasoline and in some cases gravity feed is good enough to supply the gas. A paper fuel filter is good enough to keep out the big clumps of dirt. The venturi vacuum action is enough to suck the gas into the intake. Very simple to operate , trouble shoot and repair. And it is cheap. So I think the carb will be around for a long time.
     
  12. Apr 23, 2015 #11

    SteamKing

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    Mebbe.

    Since carbs are pretty much obsolete as OEM equipment, their numbers are necessarily dwindling over time. There are only so many old cars in use or which can be restored which still use carbs. The pollution and emission regs in inspection states are also stacked against carbs. Are there enough units still in use to keep a manufacturer like Holley in business over the long term?

    Dirt's not good for any fuel system, carb or injected.

    When I drove my '84 Camaro Z28, the Rochester 4-bbl worked OK, but you didn't want to get any dirty fuel in it, otherwise you would be looking at a carb overhaul. Due to emission regs., these carbs also had electronic controls which kicked in the minute you first turned the ignition key in the morning. The car would go immediately into a fast idle of about 900 RPM to get the cat. converters up to operating temperature, after which you could blip the throttle and get the idle speed down to a lopey 600 RPM or so.

    The cost of FI systems is built into the price of a new car, and what you describe would be the outlay to convert a vehicle with a carb. to FI, which is an ambitious project under any circumstance. Still, there were some aftermarket kits made to adapt carbureted engines to use a throttle body injector in place of the carb.

    A one time, Chevy made special crate motors that came complete with FI and the ECU which could be dropped into older cars made without FI, as a resto-mod, or as a replacement engine for newer cars which needed a boost in horsepower:

    http://www.chevrolet.com/performance/crate-engines/small-block-ram-jet-350.html

    After I parked the Z28, I bought a '97 Ford T-bird with the 4.6 SOHC EFI motor. A much smoother and more comfortable cruiser than the Camaro. The only FI problem I had was the idle air control valve would go out periodically, which meant the car would stall unless you kept your foot on the throttle. Still, this valve was easy to replace with simple hand tools, and the injectors, fuel pumps, and ECU always worked perfectly.
     
  13. Apr 26, 2015 #12
    Carburetors, I suspect, will continue to be OE equipment on things like lawn mowers and trimmers for a long time. Considering my lawn mower cost only $120, a fuel injection system would have made at least 2 or 3 times more expensive. I only burn a couple gallons of fuel per year in it, so a fuel injection system would, at best, save a few ounces of fuel per year. Multiplied by a 10 year life span, total fuel savings would be a half gallon or less over the life of the mower.

    Fuel injection in applications like this will be completely impractical for some time.
     
  14. Apr 26, 2015 #13

    SteamKing

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    And nobody is saying that small IC engines should be fuel injected. The OP was concerned with the future of carburetors being used on automobiles.
     
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