The "T3/T4 hybrid" is the darling and legend of the import performance world; almost purpose-built for four-cylinder performance, this turbo combines the boost and power potential of a big compressor with the quick spooling of a smaller one. This makes it a perfect match for small-displacement engines, giving any motor that can handle it an easy 400-plus-horsepower potential. Bolting one on can be fairly straightforward if you already have the right flange -- a bit less so if you don't.
Measure the size of the opening in the flange using a tape measure or ruler. The opening on a T4 flange is 2.98 inches wide, while the opening on T3 flanges is 2.37 inches.
Measure the length of the flange. T4 flanges are 4.25 inches long, while T3 flanges are 4.3 inches long.
Measure the distance between the small openings on the flange. On T4 flanges, 1.95 inches separate the openings, while there is a separation of 2.75 inches on T3 flanges.
