Abstract: An in-line treble port venturi connector provides a low flow, low pressure inlet port for drawing supplemental fluid into a main flow path. The connector includes a main flow tube having a mixing channel restricting flow and lowering pressure between an upstream port and a downstream port. A baffle projects into the main flow tube from the inner surface of the mixing channel at a location upstream of an inlet port, obstructing main flow to create a separation zone in the low pressure area, causing rotational flow within the separation zone and lowering the average flow rate in the direction of main flow. A pressure differential allows supplemental fluid to be drawn into the mixing channel through the inlet port. The connector may be used to introduce hydrogen or oxygen gas from an on-board generator into a main flow of hydrocarbon fuel in the intake manifold of an internal combustion engine.