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The Ford 6.9L & 7.3L IDI Diesel Engine

6.9L IDI Ford Diesel:

International began development of the 6.9 L in 1978. It was not until 1983 that Ford offered the 6.9 Diesel option in its 3/4 & 1-ton trucks. The 6.9 L displaced 420 cubic inches, features indirect injection (IDI), and had no turbocharger. Horsepower & torque ratings peaked in 1986, producing 170 horsepower @ 3,300 RPM & 315 lb-ft. @ 1,400 RPM. The 6.9 was known for being simple in design & making great power at a low RPM (peak torque @ 1,400 RPM from a V-8 diesel). Though the performance of the 6.9 is far from today's standards, it was a solid performer of its time and has a history of reliability & dependability.

  • The 6.9 was bored out to 7.3 L in 1987, eliminating it from the engine line-up in 1988.
  • The 7.3 L & 6.9 L are almost completely identical in design, except that the bore of the 7.3 L was increased to 4.11 inches.
  • The heart of the injection system on the 6.9 L was a Stanadyne DB2 rotary injection pump.
  • By the time the 6.9 L reached production, engineers had tested the design for a combined 52,000 hours, and racked up 815,000 miles worth of field testing.

Applications:

  1. Ford Pickup 83-87

  2. Ford Van 84-87

  3. Commercial Applications

  4. Custom Applications

Manufacturer: International Harvester
Production Years: 1983-1987 (for Ford Trucks)
Applications: Ford F250, F350
Configuration: V-8
Block/Head Material: Cast-iron/Cast-iron
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

7.3L IDI Ford Diesel:

By increasing the bore of the 6.9 L to 4.11 inches, the 7.3 L IDI was born. It replaced the 6.9 L in 1988. Like its predeccesor, the 7.3 L was naturally aspirated, indirect injected. In 1993, a turbocharged version of the IDI was introduced, but short-lived since the IDI was replaced mid-1994 by the 7.3 L Power Stroke. The 7.3 L Power Stroke was turbocharged, direct injected, and featured computer controlled engine & injection management.

  • Though the 7.3 L IDI and 7.3 L DI Power Stroke share the same displacement, the engines are ultimately very different:

     

    7.3 L IDI

    7.3 L DI Power Stroke

    Displacement:

    444 ci, 7.3 L

    444 ci, 7.3 L

    Compression:

    21.5:1

    17.5:1

    Aspiration:

    non-turbo, turbocharged in 1993

    Turbocharged

    Injection:

    Stanadyne rotary injection pump, indirect injection

    HEUI injection system, high pressure oil pump, direct injection

    Peak Horsepower:

    185 hp @ 3,000 RPM
    190 w/turbo

    275 hp @2,800 RPM

    Peak Torque:

    360 lb-ft @ 1,400 RPM
    388 w/turbo

    525 lb-ft @ 1,600 RPM

 

  • Ford introduced the turbochared 7.3 IDI in 1993 to stay competitive with GM's turbocharged 6.5 L & Dodge's turbocharged 5.9 L diesel powerplants.

  • The 7.3 L IDI had very respectable performance for being a naturally aspirated diesel engine.

  • Ford's 6.9 L & 7.3 L IDI diesels proved extremely reliable powerplants during their 12 years of production, setting high standards for future designs by all manufacturers.

  • Though a stock 7.3 L IDI seems lacking in performance, rumors exist of one enthusiast pumping 1,200 horsepower out of his IDI, using extensive modifications, proving the overall capability of these trucks.

  • Aftermarket solutions have long existed that can transform a non-turbo IDI into a turbocharged, intercooled truck, boosting performance dramatically.

Applications:

  1. Ford Pickup 88-94

  2. Ford Van 88-94

  3. Ford Pickup 93-94 Factory Turbo

  4. Commercial Applications

  5. Custom Applications

Manufacturer: International
Production Years: 1988-1994
Applications: Ford F250, F350
Configuration: V-8
Block/Head Material: Cast-iron/Cast-iron
Displacement: 444 cubic inches, 7.3 Liters
Compression: 21.5:1
Bore: 4.11 inches
Stroke: 4.18 inches
Injection: indirect injection (IDI)
Aspiration: naturally aspirated, non-turbo (turbo version 1993-1994)
Weight: 920 lbs (approx)
Peak Horsepower: 185 HP @ 3,000 RPM (190 w/ turbo)
Peak Torque: 360 lb-ft. @ 1,400 RPM (388 w/ turbo)
Reputation: Reliable, later became 7.3 Power Stroke
 

IDI Diesel Engine Timeline:

 

Year Significant Changes/Notes
1983 6.9 L IDI introduced
1984 6.9 L compression increased to 21.5:1
1985  
1986 6.9 L power ouput increased to 170 hp & 315 lb-ft torque
1987 6.9 L bore increased to 4.11 inches, increasing displacement to 7.3 L (444 ci)
1988 7.3 L IDI replaces 6.9 L
1989  
1990  
1991  
1992 7.3 L IDI output increased to 185 hp & 360 lb-ft. torque
1993 7.3 L IDI recieves turbocharger
1994 7.3 L IDI replaced by 7.3 L Power Stroke mid-year

   

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