International Harvester IDI

The International Harvester IDI (from Indirect Injection) engine is a 4-stroke 8-cylinder Diesel engine used in International Harvester trucks and Ford F-Series pickups from 1982 to 1994. The engine had two displacements: 420 cubic inches (6.9 litres), which was used in Ford trucks from 1983 until 1987, and 444 cubic inches (7.3 litres), which was used in Ford trucks from 1987 until 1993 (naturally aspirated) and in 1993 and 1994 (turbocharged). These engines were replaced in 1995 by the Navistar T444E (7.3L) engine, which was also marketed under the Ford Power Stroke name.

History

In 1981 Ford signed an agreement with International Harvester to produce diesel engines for their light truck line. This led directly to the production of the 6.9 liter IDI diesel. The engine was developed as a low cost, light weight diesel that fit where a V8 gas engine would, to try to convert their gas engine customers to diesel and to sell to Ford for use in F-Series light duty trucks and E-Series/Econoline vans. Before it could be sold to Ford however, Tenneco Inc. purchased in the "Harvester" division of International Harvester which was moved within their Case heavy equipment line. The remainder of what was International Harvester was renamed Navistar, which concentrated on engine and medium/heavy truck development. Consequently, these are actually International-Navistar IDI engines.

The engine is very loosely based on the MV446 gasoline engine, in a similar fashion to the Oldsmobile 350 c.i. V8 diesel being based on the Oldsmobile 350 c.i. gasoline engine. In both cases, while based on their gasoline cousins, the components were designed with the stresses of a diesel in mind. Unlike the failed GM diesels, these engines were completely reworked, with piston oil injection, a hardened nodular iron crankshaft, four bolt main crank caps, and roller lifters.

7.3

In 1987, the 6.9 liter engine was supplanted by the 7.3 liter upgrade, with over 300,000 6.9s shipped to Ford and countless numbers installed into medium-duty trucks, school buses, and the like. This engine features numerous improvements over the 6.9 liter, with most of the changes located in the heads; the block received an increase bore and select-fit pistons, while the heads received an enlarged prechamber, enlarged valve stem shields, harder valves, and other minor upgrades. The front cover was revised to reduce seepage.

Finally, in 1993 Ford made available a turbocharged edition of the 7.3. The turbocharging system was produced by ATS, which produced three turbocharging systems for the International-Navistar IDI engine; The ATS 085 and 088 turbo kits, both of which are wastegate-less designs, and the ATS 093, which included a wastegate. The Ford factory turbo system utilized the 093 and was detuned from the ATS kit. ATS formerly sold a turbine housing upgrade kit but this appears to have been discontinued. This detuning job is believed to have been due to Ford's impending use of the T444E (Power Stroke) engine. A 7.3 liter IDI in good tune with an ATS 088 turbo kit makes approximately the same power as the T444E, though it makes it at higher RPMs due primarily to turbocharger design. Factory turbo vehicles received numerous additional improvements. Pistons had an enlarged ring, added intermediate rings, an enlarged ring land and wrist pin, as well as an anodized piston face; other improvements included tweaks to the injection pump and injectors, and an upgraded oil-coolant heat exchanger.

Fuel system

These engines are unusual today in that the fuel system is entirely mechanical, though this was the standard for diesels of the day and indeed for the earliest fuel-injected gasoline vehicles. The fuel system also utilizes indirect injection which made it quieter than its predecessor. The indirect injection fuel system makes this popular among drivers who choose to run vegetable oil rather than petroleum fuel (the dual fuel tanks that some Ford trucks are equipped with further makes running vegetable oil easier). Both 6.9 and 7.3 liter engines use the Stanadyne DB-2 injection pump fed by a cam-driven lift pump.

References

• Brewer, Tom (October 23, 2008). "Know your IDI History, Ford Diesel - 101", http://www.moddedraptor.com/, Retrieved from http://www.moddedraptor.com/community/off-topic/2805-know-your-idi-history-ford-diesel-101-a.html