Garrett G40-900 Turbochargers

What the Garrett G40-900 is

The G40-900 is a Garrett G-Series turbo with a dual ceramic ball bearing with steel cages, a 62 / 88 mm, 51 trim compressor wheel in a 0.80 A/R housing and a 77 / 70 mm, 84 trim Inconel turbine wheel; Garrett rates it at 500 to 900 horsepower on engines of 2.0 to 6.0 liters, with a maximum speed of 125,000 rpm, and says the G-Series compressor flows up to 32% more than the GTX4088R’s. Garrett sells it as a standard-rotation supercore (860777-5003S) with free-float turbine housings, V-band or divided T4, in 0.85, 0.95, 1.06 and 1.19 A/R. Garrett’s newer G-Series II turbo in this size is the G40-1000.

This page lists complete G40-900 turbos with each of those V-band and divided T4 turbine housings, the supercore and the CHRA. 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 G40-900 catalog page · Garrett: G-Series II G40, G42, G45 · Garrett: Turbine Housings 101

G40-900 specifications

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.

On G Series turbos the number after the dash is Garrett's horsepower rating: a G30-660 is rated for up to 660 hp.