6.9L IDI vs. Cummins 12v vs. GM 6.2L


6.9L IDI International

5.9L Cummins 12v

6.2L General Motors

Production Years:*

1983 - 1987

1989 - 1998

1982 - 1993


International Harvester


Detroit Diesel (Detroit Diesel was a division of General Motors during this time)

Block/Head Material:






Inline 6



6.9 liters , 420 cubic inches

5.9 liters, 359 cubic inches

6.2 liters, 379 cubic inches

Compression Ratio:

21.5:1 (20.7:1 for 1983 only)



Bore x Stroke:

4.00 x 4.18 inches

4.02 x 4.72 inches

3.98 x 3.80 inches

Injection System:

Indirect injection (IDI)

Direct Injection

Indirect injection (IDI)


Naturally aspirated

Holset Turbocharger

Naturally aspirated


over head valve, 2 valves per cylinder

over head valve, 2 valves per cylinder

over head valve, 2 valves per cylinder


860 lbs (approx.)

970 lbs (approx.)

700 lbs (approx.)

Peak Horsepower:**

170 horsepower @ 3,300 RPM

160 horsepower @ 2,500 RPM (1989)

143 horsepower @ 3,600 RPM

Peak Torque:**

338 lb-ft @ 1,400 RPM

400 lb-ft. @ 1,600 RPM (1989)

257 lb-ft @ 2,000 RPM


The mighty 6.9L Ford provoked the great diesel war that is still underway today. By today's criteria, the HP & torque ratings may seem sub-standard. However, the 6.9L was the workhorse of its era. It generates peak torque at an ultra low 1,400 RPM and features the same bullet proof design of the modern 7.3L Power Stroke. These engines are reliable, powerful, and built to work; and that's just what they do.

The 12-valve Cummins kicked off Dodge's diesel convoy, and to this day remains a crowd favorite. Dodge was the first to offer a turbocharged diesel out of the Big 3 automakers. The engine's features include a strong design and generation torque at a low RPM.

At the time that the 6.2L was put into production, GM's diesel repuation was on the rocks. The 6.2L was introduced as the infamous 5.7L Olds was being tossed out of the line-up. Though the engine's power output did not compete well with other automakers, GM created & marketed the 6.2L to be a fuel efficient engine option rather than a work horse.


Ford F250 & F350

Dodge 3/4 & 1 ton trucks

GM/Chevrolet C/K trucks, Hummer H1


*Production years refers to the years of production for specific application. Engines may have been produced for other applications before/after these years.

**Peak horsepower & torque refers to the highest advertised power output during the engine's production unless otherwise noted.



You may also be interested in the following articles:

Dodge Diesel - Old vs. new

Ford Diesel Old vs. New

GM Diesel Old vs. New