6.9L IDI Diesel

International/Navistar 6.9L IDI Specs & Information


International began development of the 6.9L IDI diesel in 1978. It was not until 1983 that Ford offered the 6.9L in its 3/4 & 1 ton trucks (the International/Ford partnership was created in 1982). Displacing 420 cubic inches, the natually aspirated (no turbocharger) diesel offered peak torque ratings in 1986, producing 170 horsepower & 315 lb-ft. of torque at a extremely low 1,400 RPM. The 6.9L is known for being simple in design & making torque low in the powerband, both large feats for a V8 diesel. Though the performance of the 6.9L seems low by today's standards, it was a solid performer during its time & has a history of reliability/dependability. Furthermore, the 6.9L IDI became an iconic engine in the diesel industry & helped reshape tarnished image of diesel trucks.


6.9L IDI Specs


International Harvester

Production Years:

1983-1987 (for Ford Trucks)


Ford F250, F350



Block/Head Material:

Cast iron block & heads


420 cubic inches, 6.9 liters


20.7:1 (1983) 21.5:1 (1984+)


4.00 inches


4.18 inches


indirect injection (IDI), Stanadyne rotary pump


naturally aspirated, non-turbo


860 lbs. (approx)

Peak Horsepower:

170 HP @ 3,300 RPM

Peak Torque:

338 lb-ft. @ 1,400 RPM


Reliable, durable, powerful for time period

















Ford 6.9L IDI Info

• The 6.9L was bored out to 7.3L in 1987, eliminating it from the engine line-up in 1988.

• The 7.3L & 6.9L are almost completely identical in design, except that the bore of the 7.3L was increased to 4.11 inches.

• The heart of the injection system on the 6.9L was a Stanadyne DB2 rotary injection pump.

• By the time the 6.9L reached production, engineers had tested the design for a combined 52,000 hours, and racked up 815,000 miles worth of field testing.




Related Topics:

7.3L IDI Diesel

6.2L Detroit Diesel

Ford Diesel Timeline

6.5L Detroit Diesel