Garrett G25-550 Turbochargers

What the Garrett G25-550 is

The G25-550 is one of Garrett’s G-Series turbos, which Garrett calls the most powerful small frame turbocharger on the market. Garrett rates it at 300 to 550 horsepower on engines of 1.4 to 3.0 liters, with a 48 / 60 mm, 65 trim compressor wheel in a 0.70 A/R housing, a 54 / 49 mm, 84 trim Mar-M turbine wheel and a maximum speed of 185,000 rpm. Garrett sells it as a supercore (858161-5002S standard rotation, 871388-5001S reverse) or as a complete turbo with an internally wastegated turbine housing and a 0.5 bar actuator (0.49 A/R T25 or 0.72 and 0.92 A/R V-band). Garrett’s G-Series II G25-585 is the newer turbo in this size.

This page lists Garrett’s complete standard and reverse rotation turbos with 0.72 and 0.92 A/R V-band housings, a version with a T3-inlet housing, the CHRAs, bolt-on kits for the Ford Focus ST 2.0L EcoBoost, and T3-inlet turbine housings. 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 G25-550 catalog page · Garrett: G-Series II · Garrett: Turbine Housings 101

G25-550 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.