What is an airfoil?
Simply put, all airfoils are designed with one objective in mind, better, improved airflow into the intake of the engine. With this comes the expectation of better throttle response and claimed horsepower gains. The Hypertech/TPIS style airfoil is the type that is held into the throttle body by a bolt and special nut that’s dropped from the top of the throttle body (removing the top plate.) The following instructions demonstrate how to install this type of airfoil on 305/350 TPI engines.
Installing your Hypertech/TPIS type airfoil. Start off by popping the hood and gaze at your beautiful TPI engine. Before we get started, make sure your ignition is not on. Underneath the air intake snorkel, disconnect the connector to the MAF sensor on MAF equipped engines (1985 to 1989 TPI). Turn each of the keylocks (3 on each side) 1/4 turn counter-clockwise to unlatch the air intake on the filter side. With a standard screwdriver, loosen the clamp on the snorkel to the throttle body. Remove the air intake snorkel assembly. With a T-20 torx screwdriver, remove the 6 screws holding the throttle body plate. Carefully remove the plate as to not tear or damage the gasket if you plan on reusing the gasket again. Ensure you have all 3 pieces. The airfoil, bolt and special nut. In the hole on top of the throttle body, carefully set the bolt, flat side towards the front. Notice the nut goes in to where it’s nearly flush with the rest of the surrounding area. Again, flat side towards the front. Holding the airfoil in place, hand thread the bolt to the nut you just placed in the throttle body. Using an Allen head screwdriver, thread in the bolt until snug. Ensure the airfoil is lined up and even on both sides. Tighten down the bolt. Be careful to not over tighten, we are talking about aluminum here. And there you have it. Your airfoil is in place and now we’re ready to put it all back together. Using the T-20 torx screwdriver, secure the 6 screws holding the throttle body plate in place. After placing the air intake snorkel assembly, turn each of the keylocks (3 on each side) 1/4 turn clockwise to latch the intake on the air filter side. Tighten the clamp on the snorkel to the throttle body. DO NOT FORGET to reconnect your MAF (if equipped). And we’re back to normal. Before No airfoil. Air can get trapped in openings between the bores into the plenum. After Airfoil installed. Obviously, air will travel much more smoother in hopes of increasing airflow. Thus resulting in better throttle response and claiming a few extra ponies.