6.9L IDI Diesel

The Foundation of the Ford/International Partnership

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:

Manufacturer:	International Harvester
Production Years:	1983-1987 (for Ford Trucks)
Applications:	Ford F250, F350
Configuration:	V-8
Block/Head Material:	Cast iron block & heads
Displacement:	420 cubic inches, 6.9 liters
Compression:	20.7:1 (1983) 21.5:1 (1984+)
Bore:	4.00 inches
Stroke:	4.18 inches
Injection:	indirect injection (IDI), Stanadyne rotary pump
Aspiration:	naturally aspirated, non-turbo
Weight:	860 lbs. (approx)
Peak Horsepower:	170 HP @ 3,300 RPM
Peak Torque:	338 lb-ft. @ 1,400 RPM
Reputation:	Reliable, durable, powerful for time period

Additional 6.9 L Information:

• 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.