The 7.3L's immense popularity...
The 7.3L's immense popularity led to the production of nearly 2 million Power Stroke engines from International's Indianapolis plant.
Replacing Displacement: The 6.0l Power Stroke
Although the 7.3L was available as an option for the '03 model year, the 6.0L Power Stroke came on the scene as a modern, technologically advanced engine that, with the use of exhaust gas recirculation (EGR), met new emissions requirements that the 7.3L couldn't. Comprised of an iron block and heads, the 363ci engine differed greatly from the 7.3L. The 6.0L is classified as a "bridge motor" with its overhead four-valve design utilizing bridges to connect both intake valves and exhaust valves together above each cylinder head. The four-bolt per cylinder head design also differed from the 7.3L. The engine's bore and stroke measured 3.74 x 4.13 inches, and its compression ratio was 18:1. The 6.0L's wet weight was 1,005 pounds.
Familiar Fuel System, Advanced Induction
While the 6.0L utilized a Siemens fuel injection system (similar to HEUI) consisting of two oil pumps, the location of the high-pressure oil pump was moved to the rear of the engine under the turbo. The variable geometry turbo (VGT) was controlled electronically, which provides quicker spool-ups and more low-end power than was possible from the 7.3L turbo, allowing the 6.0L some compensation for its lack of cubic inches.
The second-generation 7.3L...
The second-generation 7.3L came with an intercooler, a higher flowing high-pressure oil pump, and higher flowing fuel injectors (flowing 120cc as opposed to 90cc on first-generation engines).
Utilization Of EGR
One of the big differences in the third-generation Power Stroke is its use of exhaust gas recirculation to meet tougher emissions standards. Relative to gas engines, the EGR process consists of reintroducing exhaust gases into the intake manifold in order to reduce nitrogen oxide (NOx) deposits into the air. Like most EGR systems, the 6.0L came equipped with an EGR valve as well as an EGR cooler, which was designed to cool returning exhaust temperatures prior to reentry into the intake.
Overall Impression
Certainly not lacking in the power department, the first 6.0Ls put out 325 hp at 3,300 rpm and 560 lb-ft of torque at 2,000 rpm. They were known to leap off the line and build power quicker than the 7.3L. However, when the aftermarket made it possible to add even more juice to these already potent engines, 6.0L owners discovered they were not bulletproof. Early engines were prone to head gasket or EGR cooler failures when subjected to 100-plus horsepower gains or prolonged, extreme towing conditions. The head gasket problems have been blamed on both the engine's four-bolt per cylinder head design and its torque-to-yield head bolts, which are designed to flex in order to keep even pressure on the head gasket. Later versions of the 6.0L proved to be more reliable, experiencing fewer, if any, problems. Torque increased to 570 lb-ft at 2,000 rpm for the '05 model year due to revisions in the engine's electronic control system.
Although the 7.3L was an option...
Although the 7.3L was an option in Ford Super Dutys for the '03 model year, most customers chose the new, more powerful and advanced 6.0L Power Stroke.
6.4L Compound Turbo
The current Power Stroke option gracing Super Duty engine compartments is the 6.4L four-valve common-rail V-8. The iron block and head engine displace 390 cubic inches, has a compression ratio of 17.5:1, a bore and stroke of 3.87 x 4.13 inches, and a wet weight of 1,130 pounds. The new mill puts out 350 hp at 3,000 rpm and 650 lb-ft at 2,000 rpm. Like the 6.0L before it, the 6.4L Power Stroke utilizes EGR technology, but also features the latest in clean diesel technology: a diesel particulate filter (DPF).
Common-Rail Fuel System And Twin Turbos
The 6.4L features common-rail injection. Fuel is fed to piezo injectors via a high-pressure, rotary-style fuel injection pump located at the rear of the engine. This results in the quietest Power Stroke yet. The induction system consists of two BorgWarner compound turbochargers designed to give the best of both worlds. The first turbo, labeled a high-pressure variable geometry turbocharger, gets the truck moving off the line and at lower rpms, while the second-a fixed-geometry, low-pressure turbocharger-takes over at higher engine speeds. As far as air intake is concerned, for the first time, the Power Stroke's air box sits on the passenger side.