Porting the stock Throttle Body

How to bore out your stock TB for imporved throttle response.

Time Required:
Unknown

Tools Needed:

  • Flat head screw driver
  • #30 Torx driver
  • #25 Torx driver
  • Dremel with grinding heads
  • Fine sandpaper
  • Compressed air (like the air dusters for compters) or vacuum

    • Procedure:

    Additional Materials

    1. Disconnect battery
    2. Remove the intake from the throttle body. Release the hose clamps on the end of the intake pipe near the engine using the flathead screwdriver. Pull intake pipe up, away from throttle body.
    3. Remove the 4 screws holding the throttle body on with the #30 Torx driver. Be careful not to damage the screws or where thye go into the plastic intake manifold.
    4. Disconnect throttle cable and throttle position sensor (TPS). The TPS is on the drivers side of the throttle body. The TPS just snaps off with the push of a release tab. For throttle cable, pull away small metallic clips around the cable ring. Pull the ring out. Use the #25 Torx to remove the cable holder from the throttle body.
    5. Use aluminum foil to cover openeing in to intake manifold and the bottom of the throttle body. THis prevents debris from getting in there to ruin your engine!
      Note:Do not touch inside the manifold or throttle body. There is a lubricant on them that is necesary. Do not try to clean this off.
    6. OPTIONAL
      Remoce the fins from the inside of the throttle body with a grinding wheel on the dremel tool. GO SLOW. Stop often to allow the plastic to cool so it doesn't melt. Use the compressed air or vacuum to remove the plastic dust.

    Making the throttle body a circle

    When looking at the throttle body you will see that the entrance for the air is not a perfect circle. The outside of the throttle body dips in toward the rear of the car where the obstruction is. To prevent creating a hole you will need to shape the throttle body with the epxoy.

    Fill the backside of the throttle body with the epoxy. Allow the epoxy to set.

    Slowly using the dremel grind away at the bump to make it a circle. Do not grind the opening larger than the butterfly in the throttle body. You will get through the plastic of the throttle body and into the epoxy that you applied. Be sure to blow or suck out the dust often.

    Do not alter the rectangular opening on the opposite side.

    Try to get the curve as smooth as possible. Do a final polish with a fine sandpaper. Clean the upper, uncoated, side of the throttle body.

    Putting it back on

    Bolt the throttle cable holder back on to the throttle body. Bolt the throttle cable back on.

    Put on the metal clips and the TPS sensor.

    Gently crew the throttle body back on. This is metal going into delicate plastic.

    Reconnect the battery. Reconnect the intake pipe. Start the car and listen for any whistling sounds or other unusual sounds. If so you may have a leak.

    If you think you have a leak recheck throttle body mounting. Check for holes in the throttle. Check for a solid connection of the intake pipe to the throttle body.

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