People like to say that the 7.3L was the best Power Stroke engine, and to ask “Why don’t they bring the engine back?”.Some Blue Oval supporters who have lived through the diesel era for the past 15 or 20 years call themselves “Diesel fans.”. In their lifetimes, they witnessed Ford’s first Power Stroke being replaced with a much more infamous engine: the 6.0L Power Stroke
Ford’s first turbo-diesel engine was a 7.3 Turbo, built by Navistar. In addition to producing 210 hp and 425 lb-ft of torque, the engine bore 4.11 inches and stroke 4.18 inches, resulting in a displacement of 444 cubic inches from the factory. This was Ford’s second Navistar-built turbo-diesel engine, the first having been the 7.3L PowerStroke delivered in the 2002 model year. Engine measurements are 3.74 inches in bore and 4.13 inches in stroke, resulting in a displacement of 365 cubic inches.
It has taken dozens of technical service bulletins, relentless recalls, and word-of-mouth to reach this point. As a result, the public quickly learned of all the problems that plagued the 6.0L engine: blown head gaskets, ticking turbos, failed exhaust gas valves, cracked exhaust gas recirculation coolers, and bad injectors among others.
THEY STOPPED BUILDING THE 7.3L FOR WHAT REASON?
Effluent. The 6.0L engine was selected as Ford’s best option for meeting the new standards that went into effect in 2004. It would be equipped with a variable geometry turbocharger, electronic gas recirculation, and fuel injection system with more efficiency.
There was no guarantee the 7.3L could’ve been reused, even if the basic architecture and design had been the same, or had it been made to deliver more power than 300 hp. The 7.3L had 210 horsepower when it was introduced in mid-1994.
There were three different versions of the 7.3L Power Stroke in the pickup truck segment (from ‘94.5 to ’03), each with a fixed geometry Garrett turbocharger with a 60 mm compressor wheel (inducer). Turbochargers like this one would be found on engines made between 1999 and 2003.
In contrast to its snappy spool up on the 6.0L, the turbo’s fixed geometry makes it less responsive at very low rpms. However, despite having some laggy aspects at stock and slightly above stock power levels, this turbocharger was extremely reliable.
On the 6.0L PowerStroke, there is a Garrett turbocharger that has variable geometry technology (VGT). Because of this, the size of the turbine housing (exhaust) can vary with throttle position. A vane-style turbine house houses the turbo engine’s 6.0L turbocharger, where steel vanes can be changed via electronic command to alter an exhaust gas’ velocity as it hits the turbine wheel.
Turbine housings differ in the sense that they drive the compressor (intake side) of an turbocharger, providing the best of both worlds when it comes to performance. Housings are more restrictive at lower rpms (i.e., responsive), and are less restrictive at high rpms (which allows full exhaust flow).
INJECTION OF 7.3L
With both the 7.3L and the 6.0L Power Stroke engines, an electronic unit injector (referred to as HEUI on the 7.3L power stroke) fires the fuel injectors through the engine oil. A high-pressure oil pump drives the system. An engine with 7.3L displacement uses a fixed displacement, gear-driven pump located just in front of the lifter valley. In the picture above is Diesel Site’s Adrenaline high-pressure oil pump designed for applications with stock or larger injectors.
INJECTION OF 6.0L
Unlike the 6.2L, the oil pump on the 6.0L is gear driven to operate at high pressure, but it is located in the rear of the engine. There is no way this pump will compare to the ones used on the 7.3L. A failure of this pump is a big issue (since the pump is actually located under a cover underneath the turbocharger).
7.3L fuel injectors utilize a poppet valve to trigger the fuel injection event because oil is used to actuate the fuel injection event. A valve like this one allows high-pressure oil into the injector (as high as 3000 psi in factory form), which begins the chain of events culminating in a 21,000 psi injection pressure exiting the injector. Injector Driver Module energizes the electronic solenoid up top when it’s time to fire (via the electronic solenoid). Injectors on 7.3L engines are known to last at least 200,000 miles thanks to the poppet valve, which is one of the biggest wear items.