The Ishikawajima-Harima Heavy Industries (IHI) F3 is a low bypass turbofan engine developed in Japan by Ishikawajima-Harima Heavy Industries for the Kawasaki T-4 jet trainer aircraft.

The developmental engine was named the XF3, and it was selected over the SNECMA Turbomeca Larzac in 1982 to power the XT-4 trainer.

[5] Beginning in 1999, IHI began upgrading the fielded engines with a new high-pressure turbine to increase their service life.

It was designed to be a higher performance, afterburning version of the XF-3, producing around 7,600 lbf (34 kN) of thrust.

Adding the afterburner is the primary reason why the maximum thrust of the -400 is much higher than the -30.

[3][6] Unlike the fan, the five-stage compressor differs between the F3 and the XF3-400, with the advanced XF3-400 benefiting from 3D computational fluid dynamics (CFD) improvements.

The low-pressure turbine blades, like the high-pressure compressor, were improved between the F3 and the XF3-400 using 3D CFD.