Vinnie The Hitman
June 6, 2007
Photos By: Courtesy of Ford Motor Company, International Engine Group
Ford's newest Super Duty is available with the motherload of all engine options, the new 6.4L Power Stroke. Rated at 350 hp and a staggering 650 lb-ft of torque, the newest member of the Ford engine family is a true powerhouse that compromises little for optimum performance. As shown here in a new F-350, nothing can hold it back.

It seems like yesterday, but just 25 short years ago, Ford and International teamed up to offer a light-duty diesel truck for the growing needs of Americans. The first engine, a 6.9L diesel V-8, featured simple technologies, such as mechanical indirect injection and natural aspiration. Its short list of features didn't make it the most powerful or technically advanced, but it was torquey and tough as nails. The early generation diesel engines also laid the groundwork for today's award-winning Power Stroke engines. Over time, Ford's diesel engine program would showcase the most sophisticated engine technologies in the industry and later, innovative all-new designs that would boost refinement and power output.

So, let's take a look at how our favorite oil burner evolved into its current 6.4L, twin turbocharged glory.

Humble Beginnings
The party started back in 1982 when Ford offered its first diesel engine option in its pickups, vans, and special service vehicles (i.e. ambulances and buses). Ford chose Navistar, the parent company of the International Engine Group, to provide a solution in the form of a powerful V-8 that would allow many hard-working Joes like us to benefit from a reliable and economic diesel-powered truck. The 6.9L, 420-inch V-8 produced 175 hp and 318 lb-ft of torque with 20.7:1 compression. It featured IDI (Indirect Diesel Injection), which used a mechanical pump-line nozzle injection system that metered fuel into a small pre-chamber in the head before it was mechanically injected into the combustion chamber right before TDC. In 1984, a boost in compression to 21.5:1 jumped torque to 338 lb-ft, but there was no horsepower gain. These engines were typically good for 250,000 miles when properly maintained.

It all started in 1982, when we first got our hands on this 6.9L V-8. It was available in 31/44- and 1-ton E- and F-series trucks and produced 175 hp and 318 lb-ft of torque. Despite its simple indirect mechanical injection, these were typically good for 250,000 miles between overhauls. Dual batteries and an incredibly stout starter were mandatory to overcome the 20.7:1 compression ratio and later, 21.5:1 (resulting in 20 more lb-ft of torque). Minted by the tens of thousands until the '87 model year, these powered countless Ford products.

In 1988, the 6.9L was bumped up to 7.3L (444 cubic inches), thanks to an increase in bore size from 4.00 to 4.11 inches. Stroke remained at 4.18 inches and peak horsepower increased slightly to 185 hp at 3,300 rpm. The peak torque rating stayed the same, but the engine had more available torque at lower engine speeds. This enhanced off-idle response with little sacrifice in fuel economy. By 1991, dealer-installed turbo kits started to appear, and it was the sign of the times as buyers were now looking for more power. It forced Ford's hand to get more power, and turning to the turbocharged route would be the most effective way to satisfy customer requests.

The calendar flipped to 1993 and things started to head in the right direction when Ford introduced a turbocharged version of the 7.3L from the factory. By adding boost, power ratings were now at 190 hp at 3,000 rpm and 388 lb-ft of torque at 1,400 rpm. Modified to accept the added boost, the engine still proved incredibly reliable. This was a one-year-only engine and the only way to tell was to look for the small "TURBO DIESEL" emblems on the fenders. The '93 engine package satisfied the customers and gave extra time for Ford and International to put the finishing touches on a new combination-one that would change everything.

The Birth of the Power Stroke
The new dawn of diesel performance began in 1994 when Ford and International released its first computer-controlled diesel engine, the Power Stroke. It forever changed the playing field in the light truck market and its competitors are still trying to catch up. The Power Stroke, circa '94, featured an electro-hydraulic injector in each cylinder; fuel was directly injected into the cylinder's combustion chamber, increasing efficiency and cleaning up the combustion process due to a more accurate burn within the chamber. Electronic engine management and powertrain management for the transmission also debuted as nearly every aspect of control was administered by the PCM.

To find out more about how the Power Stroke engine got underway, we decided to contact Tim Cooney of the International Engine Group. His hands-on experience both as the manager at the Indianapolis manufacturing plant from 1985-1992 and as current vice president of Worldwide Sales and Marketing makes him the most credible person to explain how things went down. As he recanted, "We noticed increased competition in the marketplace as GM and Dodge both entered the market in the late '80s with turbocharged diesels. Ford wanted to capture the retail market as things started to trend from the commercial side to the retail side, as consumers were now looking for more towing capability. The Power Stroke was born as a Ford Motor Company name and we developed and supplied the engines."

Now that everyone had a taste of the 6.9L's uncanny ability to lug around anything we dared to drag behind it, consumers wanted more power. Ford and International responded with the 7.3L V-8 in 1988. The bore increase resulted in 185 hp at 3,300 rpm and 338 lb-ft of torque at just 1,600 rpm. Produced until 1992, this engine put Ford on the map as a serious player in the light-duty diesel truck wars.

Needless to say, this was the start of something great. With incredibly accurate computer-controlled injection and 17.5:1 compression, the rowdy bad-boy of diesels was now churning out 215 hp and 425 lb-ft of torque for power-hungry enthusiasts and Carhartt-wearing Americans alike. The response wound up being incredible. International, which had averaged just 81,327 engines a year for the previous 12 model years, had shipped 119,700 engines to Ford in 1994 alone. The public fell in love with the trucks and the word on the street was that the Power Stroke diesel was a modern-day legend. Luckily for Ford, 1995 also fared very well as International supplied 151,400 engines to the Blue Oval boys. By 1998, the last year of the traditional body style F-series truck, International delivered 206,000 engines.

In 1999, Ford introduced an all-new Super Duty F-series truck with an aggressive options list and handsome good looks. This opened up huge opportunities for both Ford and International, who could start adding more power by installing a huge air-to-air intercooler in the new truck's larger snout. Output was now upped to 235 hp and an incredible 500 lb-ft right out of the box. The truck sold like free beer on St. Patrick's Day and by model year '02, International was on a tear by upping horsepower to 275 and torque to 525 lb-ft. It quickly became known that by adding a few easy bolt-on aftermarket parts, power would shoot up to 300-plus and torque went over 600 lb-ft at the wheels. The freshly designed trucks were selling at a record rate. If people couldn't buy them new, they bought them used, upping the resale values for any Power Stroke Ford. The last of the 7.3L Power Strokes came off the assembly line in 2002, taking with them the end of the Two-Valve era.