The Ward's 10 Best Engines competition celebrates 13 years of recognizing outstanding powertrain development. In this ninth of a series, Ward's talks withengineers about the company's family of modular V-8s. Watch for features on the other 2007 winners throughout the year.
Flathead, Boss, Cobra Jet.
Motor Co. has built a fine history for memorable V-8s.
But by most measures — either engineering or emotional — none of those storied mills has anything on Ford's current 4.6L SOHC V-8, fitted in several Ford and Lincoln-Mercury models, but most convincingly in the new-generation Mustang.
The power-dense, gorgeously vocal 4.6L SOHC V-8 has been a Ward's 10 Best Engines winner since its “upgrade” to the 3-valve-per-cylinder valvetrain for the '05 model year.
But some variant of the engine, coming from Ford's “modular” V-8/V-10 architecture, has accounted for a 10 Best Engines trophy for 10 of the competition's 13 years.
That bit of trivia probably doesn't surprise Terry Wagner, Ford's manager-modular 4.6L and 5.4L engine programs, V-Engine Engineering. Wagner knows the design is a winner.
“The original 4.6L V-8 design started in the mid-to-late '80s with the vision of creating a modern, overhead-cam V-8 to be competitive on fuel economy, torque, horsepower and emissionability,” he says.
Financial commitments to the program were in place by mid-1987.
Ford's first V-8 from the new modular engine family, a 4.6L, cast-iron block, 2-valve-per-cylinder unit, launched three years later in the summer of 1990 for the all-new Lincoln Town Car, Wagner says. An aluminum-block, 4-valve variant came in 1993 for the Lincoln Mark VIII — and its first use (and many believe best) for the Mustang in 1996.
There was more. A stroked block created the 5.4L (2-valve V-8), which launched in the '97 F-150, followed by the 6.8L, 2-valve V-10. Then a 4-valve cylinder head was used for the 5.4L V-8 in the Lincoln Navigator.
“Supercharged versions of the 4.6L 4-valve and 5.4L 4-valve have been developed and used on many niche programs — the most recent of note, the Ford GT,” Wagner adds. The 5.4L “Triton” V-8 and the supercharged variants also have been 10 Best Engines winners.
But the most recent iteration of Ford's modular V-8/V-10 — the 3-valve-per-cylinder variant — has had a major impact in making the engine a volume-production benchmark for the industry.
Wagner says the 3-valve layout was introduced on the 5.4L V-8 for the '04 F-150 fullsize pickup; the new variant teamed a new combustion system and variable camshaft timing to generate 300 hp. But he says the upgrades also improved the base engine's fuel efficiency.
Wagner agrees adopting the 3-valve design was an important watershed. “The 3-valve was very significant in that it is a common technology spanning three displacements — 5.4L, 4.6L, and 6.8L,” he says. “It enabled significant engine performance and fuel-economy improvements for all three displacements, and its commonality gave us significant investment efficiency.”
In fact, Wagner believes the 3-valve design may be the best engineering solution to fulfill customer demand for performance and now — more than at any time since perhaps the last oil crisis in 1979 — improved fuel economy. He says today's customers who seek a powerful V-8 also expect good fuel economy. It's more than a little paradoxical.
Is it possible to keep V-8s relevant in this era of intense focus on fuel economy? Wagner believes so.
“It has to be done in the constext of the customer,” he says. “The customer, especially in North America, wants confidence in the powertrain's performance and good fuel economy.
“They want little engines to be ‘big’ on performance, and they want big engines to act ‘little’ on fuel economy.”
He says the current challenge is to deploy the right technology for engines in the right displacement range. And “V-8s that can improve light-load fuel economy with technologies like cylinder deactivation,” can fulfill the mission of being a big engine that “acts” small at the gas pump.
The 4.6L SOHC V-8 certainly is on the smaller end of today's V-8 displacement spectrum, yet delivers high specific output and reasonable fuel economy.
Wagner says that's not happenstance: Initial design decisions are crucial for engines that must endure a decade or more in the market. And the market's priorities are almost certain to change in the functional lifespan of an engine architecture.
“Displacement is clearly a very important factor to get right because of the level of investment involved, and that it is the foundation for the architecture, especially the bore,” says Wagner.
“It sets the stage for airflow and, ultimately, output. The fuel consumption piece is then managed for a given displacement by what other technology you deploy, such as the number of valves, cam phasing, compression ratio, etc. For example, the 3-valve 4.6L has cam phasing and combustion control devices to hit the sweet spot on torque and still provide improved fuel consumption, and meet emissions over a 2-valve (that does not have) cam phasing.”
The matter of displacement — how to settle on a fitting engine size “envelope” and how to ensure that architecture remains useful for many years — is vital to ensuring an engine family suits a wide range of potential needs, both present and future, Wagner says.
“There are some key technology decisions to be made, and displacement is the most strategic starting point,” he says.
That means, don't look for Ford's seminal 4.6L SOHC V-8 to get “downsized,” currently a discussion hot button as the powertrain community studies how best to deal with the upward trend in fuel prices.
“There's a limit to how much you would downsize a V-8,” Wagner says. “At some small displacement, it becomes a weak value proposition. You're paying for parts for eight cylinders, and the power-to-engine-weight ratio becomes unfavorable.”
Wagner doesn't think the customer's zest for performance will moderate in relation to the desire for enhanced efficiency, however. “The horsepower benchmarks will always be there and provide bragging rights to certain customers” he says.
Wagner says the 2-valve 4.6L started out in 200-plus-hp territory, and for nearly a decade 300-plus to 400-plus hp was offered only with supercharging and four valves per cylinder.
“As technology evolved and became more affordable, 300 hp became the cost of entry for a V-8 and is rapidly becoming the cost of entry for V-6s,” Wagner insists.
He says the industry may make “adjustments” on how today's power- and efficiency-enhancing technologies are used to balance power and fuel economy. “But I don't think the customer will ever stop demanding performance from their vehicle. And it is doable — just look at the expectations and delivery in the European market for both fuel economy and performance.”
Wagner will not yet pull back the curtain to detail how Ford powertrain engineers plan to evolve the award-winning 4.6L SOHC V-8 to address the future, or speak much about whether Ford's long-rumored new “Boss” V-8 engine program has much in common with today's modular V-8/V-10 engines.
But he vows the V-8s we find evocative today will make the cut. “We intend to meet customer demand in the immediate and long-term future,” Wagner says.
Ford Motor Co.
4.6L SOHC 90° V-8
Displacement (cc): 4,604
Block/head material: aluminum/aluminum
Bore × stroke (mm): 90.2 × 90
Horsepower (SAE net): 319 @ 5,750 rpm
Torque: 330 lb.-ft. (447 Nm) @ 4,500 rpm
Specific output: 71 hp/L
Compression ratio: 9.8:1
Assembly site: Romeo, MI
Application tested: Ford Mustang Shelby GT
Fuel economy (mpg): 16/23
For more details on Ward's 10-Best engines: http://wardsauto.com/reports/2007/tenbest