It has been more than 15 years since the name “Power Stroke” was introduced to the automotive world. I am confident to say that if you were to ask anyone on the street what a Power Stroke was, they would have to relate it to the Ford mid-size truck. This was great marketing by Ford and the Navistar Corporation when this Diesel engine was introduced. But, the Power Stroke quickly gained a reputation for being a truly loved workhorse. It offered great horsepower and torque along with fuel efficiency. This was an engine that quickly earned respect for its reliability. If you owned a Power Stroke, people knew you were serious about your pulling needs. Dodge and General Motors also had reputable Diesel engines, but nothing to compare with the pulling power of the Power Stroke. Often, owners of other brands were trading their vehicles for one of these Ford trucks.
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This engine set the benchmark for Diesel technology that is still used today. When this powerplant was introduced, it was not your typical Diesel engine. It had computercontrolled engine management that had never been seen before. Turbocharging was a standard option, along with a direct-injection fuel system that, when combined, made for a very efficient and potent package. Regarding the internals of the engine, a lot of engineering firsts had taken place. The cylinder heads, pistons, and fuel system had all undergone major changes that are still being used today. There were so many things that Diesel engineers had discovered and introduced as a great package, it took the Ford truck a step above the competition.
In the past twenty years, having a Diesel engine in a mid-size truck has gained tremendous popularity. Whether it is in a 3/4- or 1-ton chassis, the Diesel option is becoming an industry standard. With this increasing popularity, many technological advances have brought the Diesel where it is today. I am sure we all remember the Diesel engine the way it used to be. The Diesel in the late 1980s and early 1990s was a rattling and clacking bucket of bolts by comparison to today’s smoother running designs.
The Diesels of the past were not really sought after among consumers. The only good thing they offered was longevity. The maintenance costs were somewhat high and the fuel economy poor. The horsepower and torque were not that great when compared to the same-size gasoline engines. When considering a Diesel truck, people were often afraid of the unknown. There were not too many dealerships that could confidently repair the vehicle if there was a problem.
This is where Ford took bold steps into the Diesel truck market. This engine was produced by International Harvester Corporation. It was 6.9 liters in displacement (420 ci). International actually started developing this engine in 1978, but it was not offered as an option in Ford F-series trucks until 1983. The 6.9 was noted for being simple in design and making great low speed power.
It produced 338 ft-lbs of torque at 1,400 rpm and 170 hp at 3,300 rpm. It was definitely not in the ballpark of today’s Diesels, but it was known for its dependability.
In 1988, the 6.9 was replaced by the 7.3-liter version. The engines were very similar; the only changes being the cylinder bore diameter and compression ratio. By increasing the bore from 4.00 to 4.11 inches and compression from 20.7:1 to 21.5:1, the 7.3 was born. Now this engine made 185 hp at 3,000 rpm and 360 ft-lbs at 1,400 rpm. In 1993, International produced a turbocharged version, which made 190 hp at 3,000 rpm and 388 ft-lbs at 1,400 rpm. This was done to stay competitive with the new General Motors and Dodge engines that were also turbocharged. This engine was also known for its reliability, but short-lived by being replaced with the “Power Stroke.”
The Power Stroke engine is a totally different animal from earlier Diesels. Ford offered the Power Stroke in two versions. The first was the 7.3-liter from 1994 until 2002. The second version was a 6.0-liter offered from 2003 until 2007. These engines are very unique in design and do not interchange with any other Diesel offered in a Ford truck. On these engines turbocharging was standard. These engines are outfitted with direct injection (DI), where fuel is injected directly into the combustion chamber.
When comparing the two versions of the Power Stroke, the 7.3 has the most respect among Ford owners. This engine carries the same bore and stroke of the original 7.3 DI with a totally different block design. The compression ratio was lowered to 17.5:1 and had a totally redesigned fuel system. The 7.3 DI makes 275 hp at 2,800 rpm and 525 ft-lbs of torque at 1,600 rpm.
With tightening emissions standards, Navistar created the 6.0 DI. This engine still functions like the 7.3 DI only in a smaller package. The bore size is 3.74 inches with a stroke of 4.13 inches. This engine makes 325 hp at 3,300 rpm and 570 ft-lbs of torque at 2,000 rpm.
The Power Stroke engines have proven to be reliable, durable powerplants when they are well maintained. They are responsive to enthusiast upgrades that are wellengineered and can deliver impressive fuel economy when driven conservatively. Ford’s Power Stroke Diesels are not necessarily simple engines, but their performance justifies rebuild efforts and expenses. If they are rebuilt carefully, both the 7.3 and 6.0 can provide hundreds of thousands of miles of reliable service.
Written by Bob McDonald and Republished with Permission of CarTech Inc