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13 Things About the 7.3 Power Stroke Engine You May Not Have Known

Jake Mayock

Meet Jake

Jake is a founder of 8020 Media and one of the lead writers at DieselIQ. He has over 10 years of experience in the automotive industry and is the proud owner of a 2002 F-350 7.3 PowerStroke. When Jake isn’t working, he’s usually wrenching on his PowerStroke, single turbo BMW, or Miata track build. Jake delivers tons of knowledge and hands-on experience and is a valuable asset for those looking to take their diesel to the next level. He is highly knowledgeable on Powerstroke and Duramax diesels.

1. Due to its popularity, nearly 2 million 7.3 Power Stoke engines were produced from International’s Indianapolis plant.

Powerstroke is the marketing name that Ford came up with for its diesel engine line. The 7.3 powerstroke is actually a Navistar T444E which is made by Navistar International, formerly International Harvester. In addition to Ford Super Duty trucks, the 7.3 is used in school buses, transit buses, and other large commercial vehicles.

2. It has a 17.5:1 compression ratio.

The compression ratio is the difference in the volume of air in the cylinder when the piston is at the bottom of the stroke vs. the top. Higher compression ratios allow for more power with lower exhaust gas temperatures. The higher the compression, the hotter the air is within the cylinder, which means it requires less fuel to ignite and create combustion.

Because the 7.3 powerstroke uses glow plugs instead of spark plugs higher compression ratios are necessary to increase the air temperatures enough for ignition to take place. Compared to the Duramax and Cummins engines of the time, the 7.3’s compression ratio is right in line.

Check out our specs guide for more 7.3 PowerStroke engine specs and info.

3. The 7.3 Liter Power Stroke has a dry weight of approximately 920 lb (420 kg).

At 7.3 liters, this engine is the largest mass production diesel engine (not including commercial vehicles). Additionally, it is one of the largest production engines of its time, only falling short to the Bugatti Veyron’s 8.0L 16-cylinder engine, and the SRT Viper’s 8.4L V10 engine. 

Surprisingly enough, at 920lbs it is actually lighter than Cummins 5.9L V6 12v of the time and it’s successor, the 6.0 powerstroke

4. From the factory, the 7.3 Power Stroke engines produced up to 250 hp (190 kW) and 505 lb·ft (685 N·m) of torque in automatic-transmission trucks during the last years of production, and 275 hp (205 kW) and 525 lb·ft (712 N·m) of torque in manual-transmission trucks.

While by today’s standards for diesel power these numbers might be low, the powerstroke held its weight compared to its competitors. For those seeking more power, the 7.3 can easily add approx. 100whp for less than $2,500.

5. In 1999, an air to air intercooler was added to cool the charged air from the turbo for increased air density. 

Model year 1999-2003 7.3 powerstrokes had significantly higher performance capabilities due to the addition of the intercooler and higher flowing injectors. Check out our guide on some of the best 7.3 powerstroke mods out there.

6. The 7.3 Power Stoke utilizes a cast iron block and cast iron cylinder heads.

At 7.3L, this thing is a big chunk of iron. If you ever notice your 7.3 taking a long time to start in cold weather, it’s due in part to how big the engine block is. Cast iron blocks have better durability but worse heat transfer which means the glow plugs have to work extra hard to fire up the 7.3 in cold weather.

7. The Power Stroke is an electronically controlled, direct injection engine with a 4.11 in (104 mm) bore and 4.18 in (106 mm) stroke creating a displacement of 444 cu in (7.3 L). 

8. It utilizes a single turbocharger with a turbine housing size of 1.15 A/R.

1994.5-1997 models used a fixed geometry Garrett TP38 turbo, which did not have a wastegate. In 1999, along with the addition of the intercooler, the TP38 was upgraded to have a wastegate. And again in 1999.5, the 7.3 turbo was further upgraded to the GTP38 wastegated Garrett turbo.

9. The 7.3 Power Stroke is based on International’s T444E engine (the name “Power Stroke” is unique to Ford vehicles)

Powerstroke, or formally “Power Stroke” is purely the marketing name used by Ford for the diesel engines in its Super Duty trucks. The engines were actually manufactured by International Harvester, which became Navistar International in 1986 after a restructuring. As of today, Navistar is owned by Volkswagen. Learn more about the Navistar T444E here.

After the perilous 6.0 and 6.4 powerstroke engines, Ford cut off their partnership and began manufacturing the Power Stroke in house, starting with the 6.7.

10. Production of the 7.3 Liter Power Stroke engine ceased in 2003 in order to meet emission regulations.

Throughout the 2000’s diesel engine variants have had relatively short-lived life cycles. The increasing strictness of emissions regulations mean that diesel engines have to be constantly innovating to be more eco-friendly. Diesel emissions standards are the reason diesel’s of today have advanced systems such as DPF, SCR, DEF, etc.

Part of the reason the 7.3’s are still so valuable today is because of the lack of emissions equipment. Diesel emissions systems have known to be very problematic and costly to repair, which causes a lot of owners to either delete the emissions systems or search for older diesel trucks. 

11. Fuel for the 7.3 Power Stroke engine is provided by Direct injection, HEUI (hydraulic electronic unit injection) Injectors.

While the HEUI system has since been retired for more advanced injection systems, it was a marvel of the time. The HEUI system allowed the 7.3’s injection system to pressure diesel fuel 7x greater than the oil pressure. Without getting into technical details, the HEUI system had numerous advantages:

  • Electronic controlled compared to typical camshaft controlled which creates more flexibility and control of injection events
  • Higher injector pressure: 21,000psi of pressure compared to less than 5,000 for the Cummins and Duramax engines of the time
  • Better fuel economy

12. The serial number of a 7.3 Liter Power Stroke engine is located on the rear oil cooler pad (driver’s side rear of engine, the “pad” is where the oil filter assembly mounts to the engine block). 

13. The 7.3 Power Stroke engine firing order is 1-2-7-3-4-5-6-8 . 

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One Comment

  1. Did you know the 7.3 international powerstroke engine was actually the 1100 series Caterpillar motor. Cat sold the design to international they down sized it and sold them to ford. D

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