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Differences in TBI, MPI, TPI, etc All FI types

Discussion in 'The Garage' started by Leadfoot, May 24, 2002.

  1. Leadfoot

    Leadfoot 1/2 ton status Premium Member

    Nov 28, 2000
    Likes Received:
    Western Massachusetts
    I know TBI is Throttle Body Injection which basically amounts to an electric carb. And I know MPI is Multi Port Injection and TPI is tuned Port Injection, but what are the differences and pros/cons of MPI vs. TPI. Also other than TBI is there any other style of FI I'm missing besides the old MFI (Mechanical Fuel Injection)?
  2. HarryH3

    HarryH3 1 ton status Author

    May 31, 2000
    Likes Received:
    Georgetown, TX
    TPI is mechanically the same as MPFI. They both have a single injector located at each cylinder. The "Tuned Port" in TPI is the length and size of the intake runners that you get with all that tubing on top of the engine. /forums/images/icons/wink.gif The entire intake tract is "tuned" to provide lots of torque at low RPM. The long, narrow runners provide good velocity for the incoming airsteam, so it really packs into the cylinder when the intake valve opens.

    I did a quick search and came up with this link that explains intake tuning in much more detail. /forums/images/icons/cool.gif

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