6.0L Power Stroke is torque of the town - Engine Technology - diesel engine from Ford

Rob Wilson

This is the latest salvo fired in the war for domination of diesel-powered full-size pickups in North America. It's the new 6.0L Ford Power Stroke Diesel produced for Ford by International Truck and Engine Corporation at its Indianapolis engine plant.

Indianapolis has produced more than 1.5 million Power Stroke Diesels of the 7.3L displacement since 1994. Before that it built the 6.9L, which evolved into the 7.3. Right now the plant is ramping up on the 6.0L diesel but still building 7.3s as well. Some weekend next month, production of the 7.3 will cease altogether and the plant will be dedicated to the 6.0L.

The 6.0 is an all new engine platform, Current capacity is 250,000 per year, or about 1,060 per day. In addition to engine assembly, the plant also handles machining of principal parts such as the block, head, camshaft, crankshaft and connecting rods.

From an engine development perspective, it is remarkable to consider that the 7.3 had orating of 190 hp when introduced in 1994 with the original HEUI (hydraulically-actuated electronic unit injectors) common rail fuel injection system. Now here comes the 6.0L replacing the 7.3 and it has a rating of 325 hp at 3,300 rpm right out of the box. Output per liter has grown from 26 hp/L to 54 hp/L. So power density has more than doubled in less than 10 years.

But it's likely the engine will be even better known for its output torque of 560 lb. ft. at 2,000 rpm. With that rating, Ford easily claims king of the hill status in the full-size (over 8,500 lbs.) pickup, van and SUV markets. The engine begins availability in early 2003 in Ford's F-Series Super Duty trucks and Excursion SUV models.

The new engine is teamed with Ford's all new five-speed TorqShift automatic truck transmission, the model R5. It replaces the four-speed automatic which simply couldn't handle the higher torque level of the new engine.

The new gearbox features a wider ratio speed range and advanced electronic control. The transmission is produced in Ford Motor Company's Sharonville, Ohio, transmission plant where $81 million has been spent on tooling and equipment. Capacity is also 250,000 per year.

We visited the Indianapolis and Sharonville plants in August and had a follow-up conversation with Charles Freese, Ford's chief engineer for the Power Stroke program. Let's take a look at the basic engine architecture.

The new Power Stroke has a V-8 configuration like its predecessor but shares little else. The engine is a slightly undersquare design with a bore and stroke of 3.74 X 4.13 in. (95 X 105 mm). It is a pushrod engine with four valves per cylinder driven by a single camshaft through hydraulic rollers, Compression ratio is 18.0:1.

Heads and block are of cast iron. The crankshaft is forged steel and induction hardened. For increased stiffness, it mounts to the block via a bedplate with five main bearings. The forged camshaft drives 32 valves with hydraulic rollers. The cam mounts low in the block just above the crankshaft and is driven through a relatively short gearset. Gears are straight and not helical.

Connecting rods from Metaldyne are of forged powder metal with a teepee-type split end, providing more bearing surface. Forged powder metal con rods, while normal practice for gasoline engines, are novel in diesel applications.

Pistons from Karl Schmidt Unisia have a three-ring pack and are cast aluminum with a Ni-resist insert for the compression ring. The top ring has a keystone shape and is chrome plated. The oil control ring is a spring expander type. Pistons are jet cooled on the underside and piston skirts have a special coating to assure a smooth break-in period.

One could say the basic engine layout, while robust and modern, is also fairly conventional. And Charles Freese would agree with that assessment. "The beauty of this engine is the harmony of the subsystems," Freese tells us. "With the new Power Stroke Diesel, we have brought together the air management and fuel management with unique state-of-the-art systems.

"We have more than one dozen sensors providing inputs to the electronic control module to direct the functions of the new advanced fuel injection system, The electronic variable rate turbocharger (EVRT) and the exhaust gas recirculation (EGR) system.

"The Power Stroke has great breathing capability because of the four valve-per-cylinder design. You can't have any restrictions and still properly flow your EGR. And with the variable geometry turbo, you get performance over the complete load and speed range.

"In essence, you have a large turbo for peak power and a smaller turbo for performance at launch, The result is an engine with lower emission, higher output and torque and yet approximately a 10 percent fuel economy advantage."

Taking a closer look at the air management system, it consists of an intake air filter, the Garrett EVRT, charge-air cooler, aluminum intake manifold, EGR cooler, EGR valve and closed crankcase breather,

Air is drawn through the filter into the engine and past The crankcase ventilation system and into the turbocharger compressor: Air Then is directed to The charge air cooler (CAC) where it condenses and becomes more dense. From the CAC, air moves into the manifold leading to the intake ports in the cylinder heads.

The intake manifold contains a path for coolant from the EGR cooler to the front cover, It also has a passage for the EGR gases to travel to the EGR valve where they mix with compressed intake air.

On the exhaust side, combustion gases move through the exhaust manifold to drive the turbine side of the EVRT. When exhaust back pressure is higher than intake manifold pressure, the EGR valve opens and part of the exhaust gas is bled through the EGR cooler back into the intake manifold and combined with intake air. The purpose of all this, of course, is to reduce [NO.sub.x] emissions.

The EVRT is electronically controlled, but hydraulically actuated, By closing and opening the turbine vanes, the turbo can provide variable boast to adapt to speed and load conditions in addition to altitude compensation and shorter engine warm-up cycles.

The fuel system is also electronically controlled and hydraulically actuated. Ford and International refer to it as a hydraulic rail fuel injection system rather than a common rail system since it does not pressurize fuel in a common rail. Hydraulic oil is pressurized instead.

Principal components include the ECM, injector drive module (IDM), high-pressure oil system, lubrication system, fuel supply system, unit injectors and 13 different sensors, In the system, pressure is supplied via a Bosch Rexroth high-pressure hydraulic pump.

But the Siemens G-2 injectors are perhaps the most interesting components in The system. They employ The digital latching valve technology first developed by Eddie Sturman of Sturman Industries. This technology uses the properly of residual magnetism to hold the fast-acting spool valves in either of two positions--open or closed.

Two 48-volt 20-amp coils control The position of the spool valve. They are pulsed by the IDM for approximately 800 [micro]sec The injector multiplies the pressure in the oil rail by a factor of 7.1. So with the oil rail pressure of a maximum of 260 bar (3,770 psi), the injection pressure is intensified to as high as 1,800 bar (26,100 psi) during injection.

The engine lubrication system has an integral oil cooler mounted in the Vee of the engine under the oil filter. It has an oil pressure test port in front of the oil cooler. There are oil passages on the outside of the crankcase to reduce the chance of oil leaks.

The cartridge style oil filter from Racor mounts on the top of the engine and drains to the oil pan during servicing. When the filter is removed the oil filter housing drain valve opens automatically to drain most of the oil from the housing. The element changes out pretty much like a printer ink cartridge. Clean as a whistle.

The same filtration system is employed on the new five-speed automatic gearbox, although there it is chassis mounted.

"The new five-speed is just as important as the engine," claims Ford's Freese. "The significant changes between the four-speed and the new gearbox are in the cooling and filtration systems. In some cases, the coolant passages have been doubled. Keep it cool. Keep it clean. Those are basics."

The oil pump actually has a capacity of 5 gpm. Ford has upgraded friction materials and new revised clutch packs have more torque handling capability. The R5 only shares 15 percent carryover parts from the R4. Gear ratios on the R5 run from 3.09:1 in first gear to 0.71:1 in fifth. The PTO operates in all gears.

Shifting is claimed to be silky smooth. Electronic solenoids actuate the clutch elements and these are close coupled to the clutches to optimize response time. There is a selectable "Tow-Haul" mode where the up-shift schedule can be tailored to more demanding conditions. In this mode, the vehicle senses when increased engine braking is required and automatically schedules a downshift.

"It's the way the systems communicate that brings about the best in class performance." believes Freese. "If you load it up to maximum gross weight vehicle and start hauling it up a mountain, you can't believe how quiet it is inside the vehicle. The engine speed stays fairly low because of the way the torque curve is designed and the way it interacts with a combination of the transmission and the vistronic fan clutch.

"We can vary the ratio of the fan speed to the crankshaft speed, modulate it as needed. All this keeps the noise down considerably compared with competitive trucks. With best in class torque at 2,000 rpm, the engine just doesn't seem like it's working that hard. The systems are just so well synchronized."

The new Power Stroke program is just getting underway in 2003. A lot of technology has been brought to bear on this high torque diesel/five-speed combo. We won't have to wait long to see if buyers turn on to the sound of drivetrain harmony.

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