Garrett GTX4508R Turbochargers

What the Garrett GTX4508R is

The GTX4508R is a Garrett GTX-series turbo with the original GTX compressor wheel design, a dual ceramic ball bearing cartridge, an 80 / 108 mm (55 trim) compressor wheel in a 0.69 A/R housing and an 87 / 80 mm (85 trim) turbine wheel. Garrett rated it at 700 to 1,250 horsepower on engines of 2.0 to 8.0 liters, calculated from compressor flow, with a maximum speed of 100,000 rpm, and sold it as a supercore (800270-5001S) without turbine housing, for divided, free-float T4-inlet housings. Garrett’s current online catalog no longer shows the GTX4508R; these figures are from its archived page.

This page lists GTX4508R turbos with the full-size or the compact 42-frame compressor housing and divided T4 or stainless V-band turbine housings from 1.01 to 1.30 A/R, drag-race versions (800270-1 and -2), a version without turbine housing and a turbine housing. Garrett’s own guidance on turbine housings: a smaller A/R gives quicker boost response and more turbine power at low engine speed; a larger A/R lets the wheel flow more, with lower back pressure and more power at high engine speed.

Sources: Garrett GTX4508R page (archived) · Garrett catalog Vol. 5 (archived PDF) · Garrett: Turbine Housings 101

GTX4508R models compared

Wheel sizes are inducer / exducer, taken from the specification published for each part number. The turbine housing sizes are the ones on the listings above; the same turbo is sold with several.