The International Harvester IDI (from Indirect Injection) engine is a four-stroke diesel V8 engine used in International Harvester school buses, trucks, Ford F-Series pickups, and Ford E-Series vans from the 1983 to 1994 model years.

In 1981 Ford signed an agreement with International Harvester to produce diesel engines for their light truck line.

The remainder of what was International Harvester was renamed Navistar, which concentrated on engine and medium/heavy truck development.

[7] This engine features numerous improvements over the 6.9, with most of the changes located in the heads; the block received an increased bore and select-fit pistons, while the heads received an enlarged prechamber, enlarged valve stem shields, harder valves, and other minor upgrades.

For 1993, Ford made available a turbocharged variant of the 7.3 L featuring an internally wastegated AR.82 Garrett T3 series turbo.

A primary limiting factor to the performance potential of the engine is a highly restrictive stock down-pipe.