Garrett G25-700 Turbochargers

What the Garrett G25-700 is

The G25-700 is the larger of Garrett’s G-Series II G25 turbos, rated at 350 to 700 horsepower on engines of 1.4 to 3.0 liters, with a 54 / 67 mm compressor wheel, a 54 / 49 mm Mar-M turbine wheel, stainless turbine housings rated to 1,050 °C and a maximum speed of 160,000 rpm. Garrett says G-Series II keeps the Gen I turbine wheel and turbine and compressor housings with a new compressor wheel (up to 10% more compressor flow), so a Gen I owner can upgrade with just the CHRA, and that an ECU calibration is required after fitting a G-Series II CHRA.

Garrett sells it as a supercore, a CHRA or a complete turbo with an internally wastegated turbine housing and a 0.5 bar actuator, and this page lists each: complete turbos in standard rotation (0.49 A/R T25, 0.72 and 0.92 A/R V-band) and reverse rotation (0.72 and 0.92 A/R), both supercores and both CHRAs. 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 G25-700 catalog page · Garrett G-Series II · Garrett: Turbine Housings 101

G25-700 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.