3-VALVE TECHNOLOGY IMPROVES MODULAR V-8 EFFICIENCY, PERFORMANCE

• All-new three-valve cylinder-head architecture designed to enhance both power and efficiency.
• Combination of engine technologies produces 300 peak horsepower – a 15-percent improvement in peak horsepower over the previous 5.4-liter engine.
• Seven-percent improvement in low-speed torque, and 5 percent increase in peak torque.
• Torque curve is higher across the entire rev range than competitive pickup truck engines.

The new 5.4-liter Triton V-8 engine that will power Ford’s next-generation F-150 is designed with three valves per cylinder, variable-cam timing and a host of other features that provide increased power along with improved refinement and fuel efficiency.

The net result is an engine that delivers 300 horsepower at 5,000 rpm, and 365 ft-lb of torque at 3,750 rpm, both best in class for a full-size pickup. The all-new, aluminum cylinder head — with two intake valves and one exhaust valve per cylinder for 24 valves in total — and a new cast-iron block balance this impressive power with better fuel efficiency and quieter operation.

This new technology builds on Ford’s award-winning modular V-8 engine platform, while taking advantage of the capabilities offered by modern electronic controls. It is important to note that it isn’t a single technology, but rather a suite of enhancements that deliver these consumer benefits.

The new 24-valve engine – will be Ford’s first modular V-8 to use variable-cam timing (VCT). The VCT design allows Ford engineers to optimize intake-and exhaust-valve actuation across the rev range. It represents the industry’s first mass application of dual-equal variable-cam timing, which shifts the intake and exhaust valve timing together.

In combination with precise control of spark timing, fuel injection and use of electrically controlled Charge Motion Control Valves in the intake ports, this technology produces class-leading power and torque, particularly at the lower engine speeds that are so important to applications such as towing and heavy hauling.

Three-valve cylinder head improves power

Why did Ford engineers choose a three-valve-per-cylinder architecture for their next generation of V-8 engines?

The modular V-8 engine family is one of the most important products in Ford’s powertrain lineup. Ford produced more than 1.3 million of these engines in the 2001 calendar year.

While the two-valve modular V-8 line continues to deliver solid, efficient performance, Ford Motor Company’s premium V-8 engines – such as the Mustang Mach I and Cobra, Mercury Marauder or Lincoln Aviator powerplants – have shown the performance potential of multi-valve arrangements.

The use of two intake valves enhances fuel-air mixing prior to combustion. This helps to squeeze all the energy out of each combustion event, improving power delivery and fuel efficiency.

Multiple valves also enhance the engine’s ability to “breathe” – that is, to move large volumes of air in and out of the cylinders – which is a key to generating maximum horsepower. Four-valve engines remain Ford Motor Company’s first choice for luxury and high-performance applications, where horsepower and acceleration are prime concerns.

Yet they require considerable complexity, including two camshafts per cylinder head, which adds both weight and additional moving parts.

Ford engineers discovered they were able to get many of the benefits of a four-valve design – such as a central spark plug and symmetrical combustion chamber – using two intake valves and a single exhaust valve – with reduced weight and complexity compared with four-valve designs. The two intake valves allow peak airflow of approximately 350 cubic feet per minute, compared with about 250 cubic feet per minute in the 5.4-liter Triton V-8, which uses a single intake valve per cylinder. This represents a 40-percent improvement.

As an example of the engine team’s holistic approach, this improvement in peak flow also is due to a completely redesigned intake port, which provides a much straighter path to the cylinder – very similar to the approach taken in racing engines.

With an all-aluminum head, single camshaft, magnesium cam covers and a clean-sheet design approach, Ford’s engineers were able to develop a three-valve head that has virtually no weight penalty over the two-valve V-8 engines. The three-valve head is actually dimensionally smaller and somewhat lighter than the two-valve design for the 5.4-liter engine, while offering more rigidity and strength. It also is easier to manufacture, with simpler drilling angles and straight-machined surfaces.

Variable-Cam Timing (VCT) offers multiple benefits

Ford’s new three-valve cylinder head uses a single overhead camshaft for each bank of cylinders. The cams press down on roller-finger cam followers to open the intake and exhaust valves, which are closed by coil springs as in all Ford’s V-8 engines.

Conventional camshafts are permanently synchronized with the engine’s crankshaft so that they operate the valves at a specific point in each combustion cycle. In Ford’s modular two-valve 5.4-liter V-8 engine, the intake valve opens slightly before the piston reaches the top of the cylinder and closes about 60 degrees after the piston reaches the bottom of the stroke on every cycle, no matter what the engine speed or load is.

Variable-cam timing allows the valves to be operated at different points in the combustion cycle, to provide performance that is precisely tailored to the engine’s specific speed and load at that moment. The timing is set to allow the best overall performance across the engine’s normal operating range.

If conditions require earlier valve opening and closing, for example to achieve more low speed torque, the Powertrain Control Module (PCM) commands solenoids to alter oil flow within the hydraulic cam timing mechanism, which rotates the camshafts slightly. If the valves should open later, to generate more high-speed power, the mechanism retards the cams as needed.

The result is enhanced efficiency under low-load conditions, such as at idle or highway cruising, and increased power for brisk acceleration or times of high demand.

“When you’re driving, you can’t tell that the cams are changing,” said Pete Dowding, Modular Engines Manager. “But you can certainly tell that there’s more power when you ask for it.”

The ability to control valve timing as well as spark timing allowed Ford engineers to design a combustion chamber with a higher compression level than in the two-valve V-8 engines – again, while still using regular gasoline octane levels. Higher compression ratio produces greater efficiency, delivering more power and improved combustion efficiency.

Among the other advantages generated by variable-cam timing and electronic spark control:

• A special “cold-start” strategy allows the new three-valve engine to bring the exhaust catalyst to operating temperatures more quickly, reducing emissions in the first minutes of operation.
• Variable-valve timing reduces pumping losses, the work required to pull air in and push exhaust out of the cylinder.
• This design automatically channels a portion of burned gases back into each cylinder, to improve efficiency and reduce emissions. In addition to eliminating the external exhaust gas recirculation (EGR) circuit, this design reduces temperatures inside the intake manifold. Cooler intake air has higher density, which enhances power and efficiency.
• Engineers were able to shape a torque curve that is higher at low revs, without sacrificing high-end power. “We make as much power at 1,500 RPM as our competition makes at their peak,” Dowding said. Torque increases at a relatively steady rate throughout the operating range.

The Charge Motion Control Valves, shown in closed position, increase turbulence in the air-fuel mixture at low engine speeds.

Charge Motion Control Valves improve low-speed combustion

The air-fuel mixture entering an engine behaves differently at different engine speeds and loads. At low engine speeds and light loads, relatively little air-fuel mixture is drawn into the cylinders in a given time period, so it moves relatively slowly through the intake runners and into the cylinders. At high engine speeds, the intake mixture speeds up, as a larger volume passes through the intake runners over the same time period.

One of the challenges involved in squeezing the utmost efficiency out of each drop of fuel is to assure that it mixes thoroughly with air, in the right ratio, before it is burned in the cylinders. This is easiest when the air is moving quickly.

At lower speeds and lighter loads, the new three-valve engine uses an electronically controlled metal flap at the end of each intake runner – eight in all. This Charge Motion Control Valve was specially shaped, through CAD modeling and testing, to speed up the intake charge and induce a tumble effect in the combustion cylinder. This causes the fuel to mix more thoroughly, and to burn quickly and efficiently, with reduced emissions, particularly at idle.