Powertrain

A new V-8 engine pumps the Mustang GT up to an impressive 300 horsepower and 315 foot-pounds of torque – enough to get any muscle-car enthusiast’s heart racing. It marks the first time the mainstream Mustang GT offers 300 horsepower – formerly exclusive Mach 1, Cobra and Boss territory.

The GT’s 4.6-liter, three-valve MOD V-8 packs 40 more horsepower than the current V-8 and more than 50 percent more power than the fiery small-block 289-cubic-inch V-8 that propelled the 1964 model to stardom.

This new level of performance – on regular gas – is made possible by intelligent application of modern technology, including all-aluminum construction and a new head design that incorporates three valves per cylinder and variable cam timing.

The V-6 Mustang customer hasn’t been forgotten either. The new 90-degree, single-overhead-cam 4.0-liter engine produces 202 horsepower standard – up from the prior pushrod engine’s 193 hp – for a new level of performance. Peak torque is 235 foot-pounds, 10 more than the prior model’s 225.

The High-Tech Road to 300 Horsepower
Mustang’s new 4.6-liter, three-valve MOD V-8 has its roots in Ford’s modular engine family that spawned stalwarts like the F-150’s workhorse 5.4-liter Triton™ V-8s and the 6.8-liter V-10 found in Super Duty F-Series pickups.

The V-8’s deep-skirt, lightweight aluminum engine block provides optimum stiffness and strength, saving 75 pounds compared with a cast-iron design. Computer-aided engineering was used to reinforce key areas of the block, adding rigidity without weight.

The lightweight hypereutectic aluminum pistons have short skirts, with an anti-friction coating that assures more of the power is delivered to Mustang’s rear wheels and less is lost to friction. High-tension piston rings provide better cylinder sealing for long-term durability and low oil consumption. The connecting rods use Ford’s cracked powdered metal manufacturing technique for precise fit. Five main bearings with cross-bolted main bearing caps further ensure durability and reduce flex. A tray attached to the main bearing caps baffles oil flow in the pan, reducing aeration and assuring proper oil feed to the crankshaft during the kind of sustained lateral maneuvers encountered in performance driving.

For refinement, both the V-8 and V-6 engine are installed using hydromount bushings on either side of the block. These liquid-filled engine mounts are tuned to quell specific unwanted vibration. The V-6 engine, with its narrower 60-degree V-angle, also uses a computer-designed, triangular cast-aluminum engine mount bracket.

In addition to offering more power and improved efficiency, Mustang’s engines will meet Ultra Low-Emission Vehicle II (ULEV II) standards, which govern evaporative and tailpipe emissions. This makes the new Mustang a big part of Ford’s growing environmental success story. On average, the 2005 fleet of Ford Mustangs will emit 57 percent less smog-forming pollution than the 2004 model year fleet.

Let It Breathe – Large-Port Heads Improve Efficiency
With 4.6 liters (281 cubic inches) of displacement, the Mustang GT engine generates more than 65 hp per liter. This compares with the 42 hp per liter that wowed enthusiasts when Ford first wedged a fiery, small-block 289-cubic-inch V-8 and four-barrel carburetor into the Mustang in 1964.

One of the keys to producing 300 horsepower from this relatively small displacement is Mustang’s new single-overhead-cam, three-valve cylinder head design with variable cam timing. The new head gives the engine a higher compression ratio than previously possible on regular 87 octane gasoline.

Air equals engine power, and the V-8’s heads use two intake valves per cylinder to move more air into the engine. A new, tuned-length exhaust manifold offers optimized exhaust flow to help scavenge burned gases from the cylinders.

The center-mounted sparkplug, for a symmetrical flame, is a Ford innovation. Longer and narrower than previous designs, it can extend down to the center of the cylinder head, while leaving as much room as possible for the valves. The compact coil-on-plug ignition system frees space under the hood and allows more precise spark control.

The three-valve heads are smaller than the previous two-valve heads, reducing weight. They also offer a more direct, "ported" style path to the valves for better air flow at peak engine speeds. Magnesium cam covers suppress valve train noise and reduce weight. Taking weight out at the top of the engine helps lower the car’s center of gravity and its roll-center axis, improving handling.

Ford’s modular engine architecture lets Mustang share its aluminum heads with the new, 5.4-liter, three-valve Triton V-8 of the F-150, benefiting manufacturing efficiency. The heads in the F-150 and Mustang GT engines even share the same part number, including camshaft. However, sophisticated electronic controls, including the ability to regulate camshaft timing, allowed Ford powertrain engineers to tune both engines quite differently to achieve their individual missions.

The Mustang’s torque curve is steeper and peaks at 315 foot-pounds at 4,250 rpm. The Triton delivers more total torque, at 365 foot-pounds, with peak torque coming in more quickly at 3,750 rpm.

The 4.6-liter, three-valve MOD V-8 engine has the same cylinder bore diameter as the 5.4-liter, three-valve Triton, but a much shorter stroke – 3.54 inches vs. 4.17 inches. This gives it free-revving performance characteristics well-matched to a performance car.

Variable Camshaft Timing – Power Without Penalty
Variable camshaft timing was a key in the quest to wring more power from the Mustang’s 4.6-liter, three-valve MOD V-8 engine, while simultaneously improving efficiency and reducing emissions. VCT lets allows the valves operate at optimum points in the combustion cycle, tailored to the engine’s speed and load at that instant.

The Mustang VCT system allows up to 50 degrees of cam variation in relation to the crankshaft angle. Ford’s "dual-equal" variable cam timing design shifts timing of both the intake and exhaust valves together, with one camshaft per cylinder head. This provides all the benefits of, but creates far less complexity and adds less weight than, VCT systems that actuate the intake and exhaust valves separately.

The cams operate both sets of valves using low-profile roller-finger followers, helping reduce friction and keep the overall engine height – and thus, hood line – low. Cam position is controlled by an electronic solenoid that modulates oil pressure to advance or retard the cam timing based on input from the engine’s electronic control computer.

Tuning the Mustang Sound
Topping off each engine is an all-new intake manifold, specifically tuned for the Mustang. Powertrain and NVH engineers worked together using computer-aided design and engineering, along with sound-quality studies, to achieve the right balance of sound characteristics and maximum airflow, assuring the Mustang engines sound as good as they perform.

For the 4.6-liter, three-valve MOD V-8 engine, the new manifold incorporates a low-profile, dual-bore throttle body that draws cold air from outside the engine compartment and uses tuned intake runners for maximum power and efficiency.

The composite integrated air-fuel module incorporates a flat, stainless steel fuel rail with charge motion control valves at the end of each intake runner. The air-fuel mixture entering an engine behaves differently at different engine speeds and loads. At low engine speeds and light loads, these specially shaped CMCV flaps are closed to speed up the intake charge and induce a tumble effect in the combustion chamber. This causes the fuel to mix more thoroughly, and burn more quickly and efficiently. At higher engine speeds, they open fully for maximum flow into the combustion chambers at wide-open throttle.

Electronic Throttle Control – Steady Hand on the Power
Mustang’s sophisticated electronics system – five times faster and boasting up to eight times more memory than the previous generation EEC-V powertrain control module – constantly monitors an array of sensors to make thousands of split-second decisions.

The most important sensor for the all-new electronic throttle control system is the one at the driver’s right foot.

Mustang’s powertrain computer infers the driver’s intent from the position of the accelerator pedal. It continually matches this information against other data – like engine speed and load – and electrically operates the throttle-body at the front end of the intake manifold to achieve results the driver demands.

Mash the pedal, and the throttle body will open as fast as the engine can handle the inrushing air. At the same time, the powertrain computer optimizes the variable cam timing, fuel flow and transmission shift points to match.

This system – called torque-based electronic throttle control – is a direct descendant of technology first used in fighter aircraft. It delivers improved efficiency and better acceleration, compared with systems that simply mimic the action of a mechanical throttle linkage.

Throttle control is tuned to deliver consistent response over a wide range of operating conditions, including temperature and altitude, which influence engine response and power. Although lower density air still limits peak engine power, part-throttle response does not degrade with high altitude or high temperatures. The transmission shift schedule also changes to compensate.

"The benefit of electronic throttle control to the driver is an effortless feeling that gives drivers more of what they want, when they want it," said Eric Levine, Mustang V-8 Engine supervisor. Because the stiff metal cable between a traditional accelerator pedal and the engine is eliminated, so is a traditional pathway into the cabin for noise and vibration.

The ETC system has numerous safety features, including redundant sensors and double return springs at the accelerator pedal, dual sensors at the throttle valve, a closed-throttle-default actuator, backup microprocessors and self-diagnostic software. Multiple fail-safe mechanisms are provided by the software and hardware, and the system is fault-tolerant – if a problem is detected, a "limp-home" mode allows the car to move under its own power.

4.0-liter SOHC V-6 – Anything but Basic Performance
With technologies like electronic throttle control, traction control and an available five-speed automatic transmission, the base Mustang’s new 4.0-liter SOHC V-6 powertrain is anything but basic. And with 200 horsepower and 235 foot-pounds of torque, the V-6 engine offers real Mustang performance at a more economical price.

The 4.0-liter V-6 offers improved NVH, higher power output and a more compact package than the previous Mustang’s 3.8-liter pushrod V-6. It features low-profile heads with single overhead cams driven by a slave shaft mounted in the "V" of the engine. This results in a lower overall engine height than a conventional overhead cam setup.

As in V-8 applications, a new composite intake manifold was developed specifically for duty in the Mustang. The 4.0-liter V-6 also gets a unique camshaft grind, new tuned-length exhaust manifolds, a new flywheel and an oil pan. In addition, Mustang engineers designed an enhanced fuel injection system with reduced evaporative leakage, a new EGR system and revised cooling circuit for the 4.0-liter V-6.

Key noise-reducing features of the 4.0-liter SOHC V-6 include a girdled crankcase for increased strength and rigidity, a dual-mode crankshaft damper, coated skirt pistons, optimized bearing clearances and isolated composite cam covers.

Research with current and potential customers played a role in achieving the sound quality buyers expect from a Mustang engine. Listening studies were conducted with current and potential Mustang owners to determine precisely what engine sounds were "powerful." The resulting sound reinforces the American muscle-car personality of the 2005 Mustang.

Close-Ratio 5R55S Automatic – One Smooth Operator
For the first time, Mustang is available with a five-speed automatic transmission. The 5R55S automatic, also used in the Lincoln LS and Ford Thunderbird, has closely spaced ratios that keep the engine in its power band to produce better acceleration, with a wide ratio that provides remarkably good highway fuel economy. The new powertrain control computer delivers benefits in the transmission, as well as the engine, by precisely controlling shift duration and shift timing. Throttle position, engine speed, load, environmental factors and other parameters guide the transmission shift schedule.

A new electronic interface lets the powertrain control module communicate with the automatic transmission 10 times faster than before. For the first time, powertrain engineers could match transmission controls with other sophisticated features like variable cam timing and electronic throttle control. As a result, the entire powertrain works together to deliver smooth performance.

Slick-Shifting Five-Speed Manuals
For those who prefer to compute their own shift points, five-speed manual transmissions are standard on both the V-6 and GT versions of the 2005 Mustang.

The V-8 powered GT is equipped with a rugged Tremec 3650 gearbox; the V-6 cars get a Tremec T-5 manual. Both have been improved for shift quality and efficiency. For example, they now use a flange coupling instead of a splined drive with the driveshaft that results in better balance and reduced lash. An all-new shift linkage is designed to provide quick engagement of the gears, producing a solid feel and none of the "notchiness" apparent on some previous Mustangs.

The boosted hydraulic clutch reduces pedal effort while still offering a performance feel. The V-6 clutch has new plate materials for durability, and the V-8 clutch has been enlarged to handle the 300 horsepower of the new 4.6-liter, three-valve MOD engine.

In both automatic and manual transmission cars, Mustang GT models use a two-piece driveshaft that can withstand higher engine speeds and torque. V-6 models use a slip-in-tube driveshaft.

The rear axle ratio is 3.55:1 for the Mustang GT when equipped with a manual transmission. All other Mustangs use a 3.31:1 final drive ratio. The Mustang GT comes standard with a traction-lock 8.8-inch rear axle for smooth launches and better grip on loose or slippery surfaces.
Mustang V-6 models use 7.5-inch ring and pinion gears. All axles have a robust ring-and-pinion gear and feature a stiff differential case to reduce flex during cornering.

‘Just Enough’ Traction Control
Under some conditions, Mustang drivers may find they need a little help in harnessing all the excitement the 2005 edition has to offer.

That’s where the new all-speed traction control system comes in. Standard on GT and bundled as an option with the antilock braking system on V-6 models, the traction control system takes advantage of the new Mustang’s high-speed communication network by using sensor information from both the engine controller and the ABS to quickly detect whether the vehicle is on dry pavement or is negotiating a slippery surface. The new electronic throttle system and brake system thus work smoothly in concert to reduce wheel spin.

But this is a muscle car, after all, so Mustang’s traction control is tuned a little differently. On dry pavement, the system allows more rear wheel slip under acceleration, enhancing the performance feel of rear-wheel drive. This means drivers still can "hang it out" a bit when the going gets particularly spirited. If the system detects slippery conditions associated with snow, ice or wet roads, it acts more aggressively to help the driver maintain stability.

On those occasions when traction control isn’t desired – such as a smoky burnout at the drag strip – drivers can deactivate the system with a button conveniently located on the instrument panel’s center stack, just to the right of the gauges. Another push will turn the system back on; otherwise, it will activate automatically the next time the vehicle is started.