think of the TB as a boost jet/welding tip. Whether the restriction is 1/8" or 1" it is the same. Velocity will increase within the restriction. Boost will be higher on the IC piping side of the TB and lower on the plenum side.The best IC piping would be sized the same as the TB opening so that there wouldn't be lag (pressure drop) on the compression(boost) side. Larger IC piping will create greater volume and will require a bit more time to bring up the boost. If volumetric efficiency truely exists within the size of the upper and lower plenum (the last point of entry into the cylinder), the IC piping and the TB's should be sized relative to that efficiency.
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