If you owned a Ford F series truck in the 1990s or early 2000s, you know the significance of the 7.3 Liter Power Stroke V-8 engine. You probably think it is one of the best engines ever made, certainly one of Ford’s best.
What you might not know, though, is that of that date range, what 7.3 Power Stroke was the best engine of the lot?
While the 7.3 Power Stroke is regarded as a superior engine no matter what year, 1999 stands out as better than the rest, and here is why.
The 7.3 Power Stroke was the Ford Answer to the Navistar T444E
Ford introduced the 7.3 Liter Power Stroke/T444E V-8 in 1994. It was a replacement for the 7.3 Liter IDI V-8 and was Ford’s version of the Navistar T444E turbo-diesel V-8.
The Power Stroke/T444E was a complete redesign. The only components of the engine that were the same as the IDI diesel was the bore and stroke dimensions.
The 7.3 Liter Power Stroke/T444E ran three-quarter-ton and larger F series trucks and Econoline products.
7.3 Power Stroke Details
The Power Stroke engine produced up to 250 horsepower with automatic transmissions. It got 275 horsepower with manual transmission and 505 and 525 pound-feet of torque, respectively. Additionally, the engine was electronically controlled and direct injection. Size-wise, it took up 444 cubic inches and weighed over 900 pounds.
The 7.3 Liter Power Stroke also had forged connecting rods up through 2000. That is significant as the powdered rods had several vulnerabilities that reduced the engine’s potential.
The 1999 Version
From 1999 through 2003, the 7.3 used a deadhead fuel system and split-shot injectors. The split-shot injectors released a preliminary fuel shot to initiate combustion before the injector released the main load. The pre-injection helped reduce NOX emissions because it burned hotter and more completely.
The 1999 version also had an air-to-air intercooler. The air-to-air cooler was added to help cool charged air and increase the internal air density, allowing for greater horsepower potential. A side benefit was it reduced exhaust gas temperatures. The 1999 version also had 140 cc injectors, an increase from 120, which increased the high-pressure oil pump capability.
Why Is 1999 Considered the Best Year for the 7.3
The short answer to that is the 1999 7.3 Liter Power Stroke V-8 was the last year the engine worked under old assumptions regarding environmental controls, customer expectations, and overall ease of maintenance. While the Power Stroke is generally considered a superior engine, by 1999, the engine had almost a decade of service under its belt, and any kinks were worked out.
The result was a durable workhorse of an engine that responded well to virtually any challenges thrown at it. Plus, it was diesel, which brought all its advantages to the table. There were specific benefits to the 7.3, however.
The Power Stroke used quality parts and a simple design to produce an engine that would win zero street races but was good for 400,000 to 500,000 miles. The engine had to be unmodified and well maintained to get that type of mileage, but even if abused, the 7.3 Power Stroke engine was still good for 300,000 miles at a minimum.
Few Emissions Controls
Emissions controls are great for the environment but bad for truck engine longevity. The 7.3 Power Stroke relied upon an internal engine computer system to regulate NOX emissions. It also had a catalytic converter. That was it, however, for emissions control features.
By contrast, future Power Stroke engines had a gas recirculation system with several problems, including valve issues, cracked coolers, tainted oil, and premature fouling of coolant. Future models also had diesel particulate filters. Those two controls alone all but assured an owner of a truck with a 7.3 was not getting super high mileage.
Basic but Reliable
The 7.3 Liter V-8 will win no awards for technical complexity or exotic components. The 1999 version was no different. Compared to engines today, the 7.3 Power Stroke was primitive.
Its block material was gray iron, the crankshaft forged steel. The rods through 2000 were forged-steel. The pistons were cast aluminum. It had a traditional V-8 seating for one camshaft, two-valve, two pushrod cylinders, and simplistic hydraulic lifters that did not need calibration or break.
Compared to engines today, the 7.3 was underpowered, but that was a blessing when it came to longevity. It had none of the bells and whistles that today’s engines possess. Its computer system was basic and simple. All that added up to an uncomplicated engine that just did its job for years and years.
It Ran Cool
Lower horsepower and torque rating reduced stress potential in the 7.3 and also aided in keeping exhaust gas cooler. In 1999, the 7.3 received an air-to-air intercooler, which cooled things down even more.
Cooler Oil Via an External Oil Cooler
The engine oil in a 7.3 worked very hard. A high-pressure circuit raised the PSI of engine oil to 3,000. The incredible pressure made engine oil heat up very quickly. To combat this, the 7.3 had an external air cooler. Not only was the oil-cooled by external air, but the cooler also had wide corridors that never plugged up.
A 7.3 Liter V-8 had an injector sequence of providing an initial setup burst of fuel before the full load was released. This created a hotter, more complete burn and more power for the engine. However, it had a very simple design, which meant the plunger only had to work once per combustion event, even though there were two injections.
The design enabled a very reliable fuel injection system with injectors that lasted a very long time, reducing maintenance costs and providing performance consistency.
The Deciding Factor
When you get down to it, considering all of the above, one theme stands out regarding the 7.3 Liter Power Stroke V-8: Reliability. Up through 2000, any vehicle with a 7.3 Power Stroke engine was going to get very high usage miles.
What makes 1999 so special in regards to the 7.3 is that year was the culmination of one of the best engines ever made, with the bugs worked out before modifications were made to the core engine. Those modifications led to a much less reliable engine.
The 1999 model 7.3 design was simple and easily maintained. It would work in any weather conditions. Even if an owner beat on it, it still ran smoothly for years. If they did not and treated it according to the manufacturer’s recommendations, the engine would routinely produce 300,000 miles and often was good for 400,000 miles or more.
It cannot be stressed enough that any 7.3 Liter Power Stroke V-8 was a superior engine and was the best in its class, given the parameters of the day. It was not until 2000 that the 7.3 showed any vulnerabilities when additional characteristics were adopted.
Of all the good years, 1999 stood out as the best. It had its bugs fixed. It had modifications that added to the engine rather than challenged it. While any pre-1999 7.3 Liter Power Stroke engine was superior, 1999 was the year it was perfected.