7.3L IDI vs. Cummins 12v vs. 6.5L GM

Old School Diesel Shootout


7.3L idi

7.3L IDI International

Cummins 6BT

5.9L Cummins 12v

6.5L GM
6.5L General Motors

Production Years:

1988 - 1994

1989 - 1998

1992 - 2001 (still produced for some military applications)




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

Block/Head Material:






Inline 6



7.3 liters , 444 cubic inches

5.9 liters, 359 cubic inches

6.5 liters, 395 cubic inches

Compression Ratio:



18.0:1 -21.3:1 depending on year & application

Bore x Stroke:

4.11 x 4.18 inches

4.02 x 4.72 inches

4.06 x 3.82 inches

Injection System:

Indirect injection (IDI)

Direct Injection

Indirect injection (IDI)


Naturally aspirated, optional turbocharger introduced in 1993

Holset Turbocharger

Naturally aspirated & turbocharged versions available


over head valve, 2 valves per cylinder

over head valve, 2 valves per cylinder

over head valve, 2 valves per cylinder


920 lbs (approx.)

970 lbs (approx.)


Peak Horsepower:*

185 horsepower @ 3,000 RPM
190 horsepower @ 3,000 RPM w/ turbocharger

215 horsepower @ 2,500 RPM (1998)

215 horsepower @ 3,400 RPM (turbocharged)

Peak Torque:*

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

440 lb-ft. @ 1,600 RPM (1998)

440 lb-ft @ 1,800 RPM (turbocharged)


The 7.3L IDI has a reputation of reliability in the workforce. The 7.3L direct injection Power Stroke is based on the IDI design. A turbocharged version of the 7.3L was released in 1993, which increased the power output.

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.

Based on the 6.2L design, the 6.5L was also built for fuel economy rather than payload. Turbocharged and naturally aspirated versions of the 6.5L engine were made available. Some 6.5L diesel engines tended to have overheating problems due to insufficient cooling systems, which lead to reliability issues.


Ford F250 & F350

Dodge 3/4 & 1 ton trucks

Chevrolet & GMC C/K trucks, 2500/3500 trucks, AM General Hummer, & large SUV applications.


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




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6.7L Cummins vs. 6.7L Power Stroke

Ford Diesel - Old vs. New

Dodge Diesel - Old vs. New