TBI the same as a carby?

my friend and I were just arguing over the TBI and carby designs. I say that TBI is a type of electronic high fuel pressure carb with no need for venturis etc. while my friend reckons that they are completely different and TBI is more part of the EFI family. Odd question i konw...your thoughts


Thanks for your opinions... you sure made me look like a fool. I guess i'll concede and say TBI is not a modern carb.

3 Answers

  • bkg
    Lv 5
    9 years ago
    Favorite Answer

    TBI (throttle body injection) is pretty much the same as EFI (electronic fuel injeciton). They both spray the fuel through a nozzle atomizing the fuel for an efficient fuel combustion. Carburetors meter the flow of the fuel coming into the intake from the fuel pump through a needle valve. The fuel is then pulled into the engine by the vacuum created by the motor. Some carbs have an annular discharge ring which helps to break up the fuel, but they are still not as efficient as fuel injectors.

    Source(s): ex-mechanic
  • 9 years ago

    A Carburetor is a mechanical device which mixes the fuel and air being drawn into an engine into the correct mixture to burn.

    Carburetors utilize the venturi principal to draw the fuel from the reservoir or float bowl into the airstream at a rate proportional to the rate of the airflow entering the engine, the airflow rate is controlled by the throttle valve at the bottom of the carburetor.

    Carburetors were the primary means of creating the fuel air mixture on virtually all gasoline fueled engines before the middle to late 1980's. They are still common on small engines of the type used on lawnmowers and other small power equipment.

    There were a few available fuel injection systems prior to that time but they were mechanical in operation and very expensive - generally used only in professional race cars.

    They have been replaced by electronic fuel injection systems on modern engines because the electronic systems provide better mixture control and faster response to changing conditions resulting in both better performance and economy in addition to reduced exhaust emissions, which were the driving force in the development of electronic fuel injection systems because carburetors are inherently sloppy and not consistent in the blending of the fuel air mixture which resulted in high levels of hydrocarbon emissions from the tailpipe.

    Both SFI Sequential Fuel Injection and TBI Throttle Body Fuel Injection are electronic fuel injection systems which benefit greatly from the electronic system feedback response time abilities.

    I would place TBI at around 2/3 of the SFI advantage over the Carburetor equipped engine but definitely associate it more with the EFI class than the carb class...

    Source(s): 40 years behind the wrench and wheel
  • the carb you understand for the most part at least but the throttle body is really an efi with one or two injectors. really the only similarities is location in the intake an function of delivering fuel to the incoming air stream.

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