whats better tbi or carbureted?

horsepower wise, i know that tbi is more fuel efficient.

1 Answer

  • Texas
    Lv 7
    4 years ago
    Best Answer

    MPFI = multiport fuel injection is the best, particularly with computer controls it automatically adjusts for altitude air density differences. Self optimizing.

    TBI = throttle body injection is an intermediate form that you basically don't see much anymore, but in summary it is a fuel injection system that will bolt in place of a carburetor, and with feedback loop computer controls it can respond and adapt to air density difference. Self optimizing, but not as good as MPFI because there is more intake manifold/port length between the injector and the intake valve and fuel may turn corners and fall-out of the mixture or be distributed unevenly.

    Carburetor is worse in the general case, Carburetor Jets are chosen for the environmental location, altitude, temperature etc. And then if you drive it to higher altitude it runs lean or to lower altitude it runs rich. So carburetor is not the ideal cross country travel support, but if you always run your car at a particular local drag strip that has fairly steady temperature/weather conditions and you get your jetting dialed in for that track then it will be consistent. NASCAR for years has required use of carburetors, and to some degree different tracks may require different carburetor tuning to optimize it.

    For fuel economy, optimal fuel/air mix is 14.7:1. In the 80s era when TBI was popular, computers were either non-existant or not very advanced, and TBI cars were typically hard wired to produce 14.7:1 mix for optimal fuel economy. So for RACING purposes, the advantage of the Carburetor over TBI is that you can jet it richer about 12:1 mix provides more horsepower and the additional fuel cools the intake and the engine also runs cooler, but this also produces some visible black smoke out the exhaust so isn't really suitable for street especially if you are in a state where you need to pass emissions inspections. In this regard MPFI is still better, because it is computer controlled and you can adjust the chip / flash the firmware to tune the mix, and if you need to pass emissions you can flash it back to stock settings for the test.

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