Ford Ecoboost Six Cylinder - Sick Six!
Twin-Turbos. Direct Injection. 365 HP. 25 MPG. Will Ford's Better Idea Doom The V-8?
From the October, 2009 issue of Popular Hot Rodding
By Stephen Kim
Photography by Courtesy of the manufacturers
Just like that, General Motors has morphed into Government Motors, and Chrysler is counting on Tony to fix it again. If the thought of buying a car from a government-owned automaker, with a loan from a government-owned bank, and driving it back to your government-refinanced house doesn't get you excited, what will? In the midst of all this madness, a leaner and meaner Ford is asserting itself once again, recently selling off ballast such as Jaguar, Aston Martin, and Mazda to reduce overhead and dedicate its focus on the Blue Oval brand. As the only U.S. car manufacturer that hasn't been bailed out or gone bankrupt, it's not surprising that Ford seems the best adapted to meet the daunting market challenges ahead. Chief among them are new 35.5-mpg CAFE standards that will be phased in by 2016, and the public's growing demand for more fuel-efficient vehicles. All this doesn't bode well for the V-8, and new car manufacturers are already rolling out a new wave of high-output six-cylinder engines in response. Ford is in on the action, too, having just introduced its 3.5L EcoBoost V-6 in the 2010 Lincoln MKS.
Utilizing twin turbochargers and gasoline direct injection, the EcoBoost V-6 produces 355 hp at 5,700 rpm and 350 lb-ft of torque from 1,500-5,250 rpm. Not only is that 40 hp and 25 lb-ft more than the Mustang GT's 4.6L V-8, the EcoBoost weighs roughly 150 pounds less than its mod motor counterpart. Furthermore, the EcoBoost-powered MKS beats out rivals like the Lexus GS460 and Infiniti M45 in gas mileage, with an EPA city/highway rating of 17/25 mpg. That's slightly better than the Mustang's 16/24 figure, despite lugging around an extra 800 pounds of heft. Although it's premature to declare that the new crop of small-displacement, high-output engines represent the future of performance cars, their implications on the survival of the American auto industry and their potential impact on hot rodding is profound.
Duratec To EcoBoost
In a hobby where big displacement reigns supreme, the idea of downsizing-and actually getting excited about it-is an outrageous concept. Unlike the '70s, however, the breadth of modern technical aptitude means that giving up cubic inches for improved gas mileage doesn't have to come at the expense of performance. Ford's EcoBoost V-6 proves the point, and it's one bad little dude to say the least. This 3.5L mill features twin Garrett GT15 turbos, direct-injection, 24-valve heads, variable intake valve timing, a die-cast aluminum block, six-bolt main caps, a forged crank, and 10.0:1 compression. Compared to a V-8 of similar output, Ford says that the EcoBoost offers up to a 20 percent improvement in gas mileage and a 15-percent reduction in CO2 emissions. "The beauty of EcoBoost is that it enables us to downsize for fuel efficiency, yet boost for power. The turbos allow us to decrease the size of the engine-installing a V-6 versus a V-8 for instance-and deliver the power and torque of a larger engine," says Ford's Vice President of Global Product Development Derrick Kuzak.
Compared to a standard Duratec...
Compared to a standard Duratec 3.5L V-6, the EcoBoost's aluminum block features additional reinforcement ribs to reduce potential flex. The block's open-deck design is a consequence of the die-casting procedure. A die-cast block requires far less finishing machine work, as the contours of the die and block can be made much more precisely, however, unlike sand that can easily be drained from the cavities inside the block after casting, a reusable die must actually be pulled out of the finished block, making it very difficult to cast water jackets inside a closed deck. Since the cylinder sleeves in an open-deck block are only supported at the bottom, deck reinforcements must be wedged between the sleeves and the block to reduce distortion when subjected to high boost. Import racers have been doing this for quite some time.
Although the EcoBoost's crank...
Although the EcoBoost's crank is forged, its direct-injection system and precise engine management computer enable using less exotic powdered metal rods and hypereutectic pistons. The lower thermal expansion rate of the hypereutectic pistons allow running tighter piston-to-wall clearance for reduced blow-by. This also enables Ford to use low-tension rings.
Like most late-model motors,...
Like most late-model motors, the EcoBoost relies on a coil-on-plug ignition system to light the air/fuel mixture. The cylinder heads' hemispherical OHC layout positions the plugs centrally in the combustion chamber. The EcoBoost's advanced Bosch engine management computer can retard timing up to 20 degrees instantaneously.
When Ford engineers embarked on the EcoBoost program six years ago, they plucked the 3.5L Duratec V-6 out of the corporate engine lineup to use as a starting point. The naturally aspirated Duratec is plenty capable in its own right, putting out 265 hp and 250 lb-ft. Despite the extra 100 hp that the EcoBoost was projected to produce, only minor revisions were necessary. The EcoBoost retains the Duratec's 3.64x3.41-inch bore and stroke dimensions, but the block has been fortified with additional reinforcement ribs. Likewise, Ford beefed up the crank and rods by using an alloy with greater nickel and chromium content. The pistons, while cast, feature a low-friction coating on their skirts, and are cooled by oil squirters positioned in the crankcase. Furthermore, the cylinder heads were fitted with 1.456/1.220-inch Inconel valves, and modified to facilitate fitment of the high-pressure fuel injectors. In addition to a slight drop in compression ratio, multi-layer steel head gaskets have been added to help seal the chambers under boost.
Of course, the EcoBoost's impressive output wouldn't be possible without the twin Garret 48mm turbos mounted on each bank of cylinders. Their wastegates are controlled electronically, allowing precisely regulating boost between 8-12 psi for an extremely flat torque curve and a linear power band. Additionally, to reduce mass Ford opted for stamped-steel exhaust manifolds instead of cast iron. The insulating effect of the twin-wall stamped manifolds help retain heat in the turbos for improved thermal efficiency and quicker spool up.
When running down the 3.5L EcoBoost's spec sheet, some of the most surprising revelations are its 10.0:1 static compression ratio and ability to run on 87-octane fuel. Most hot rodders wouldn't dare to run that much compression in a naturally aspirated carb motor with iron heads, let alone a forced-induction application pushing 12 psi of boost. Likewise, the absence of forged rods and pistons is sure to raise some eyebrows. What makes it all possible is gasoline direct injection, and despite what that vague description may imply, it has far more to do with the entire fuel delivery and management process than the placement of the injectors themselves.
Gasoline direct injection draws heavily from advancements in modern common-rail diesel technology. As with a diesel, fuel is drawn from the tank at conventional pressure until it reaches a cam-driven injection pump positioned just before the fuel rails. On the EcoBoost, the injection pump is mounted on the driver side cylinder head, and boosts fuel pressure up to 2,200 psi. Depending on the needs of the engine, an electronically operated piston on the pump can reduce rail pressure down to 200 psi. While the operating pressure of a gasoline direct-injection system is substantially less than the 26,000 psi of a diesel, it's still quite a bit more than the 40-60 psi at which most late-model EFI systems function. When combined with injectors positioned in the combustion chamber, right below the intake valves, the result is a very fine spray pattern exactly where you need it. "By bringing the fuel injector right into the combustion chamber, the air is cooled right where you're going to burn it," says EcoBoost Design Manager Brett Hinds. "This action both improves the breathing of the engine and minimizes knocking. Since the fuel is directly introduced into the combustion chamber, you don't get fuel wetting of the combustion wall like with port fuel injection, you don't saturate the ports, and you don't get droplets that might recombine and add to saturation."
In a direct-injection engine,...
In a direct-injection engine, precisely directing a stratified fuel charge near the spark plug is critical. This enables running a locally stratified air/fuel mixture near the plug under light load, while leaning the air/fuel mixture surrounding the plug. The contours of the EcoBoost's pistons help accomplish just that.
As engine load and rpm increases,...
As engine load and rpm increases, a direct-injection engine transitions from a stratified fuel charge in the chamber to an evenly distributed homogeneous mixture. This precise fuel control is why the EcoBoost can run just fine on 87 octane, despite 12 psi of boost pressure and a 10.0:1 compression ratio.
A direct-injection EFI system...
A direct-injection EFI system is very similar in principle to common-rail diesel technology. Fuel is first pumped to the motor at conventional pressure levels, then bumped up to nearly 2,200 psi by an injection pump mounted on the driver side cylinder head. The pump is driven off of a separate lobe integrated into the intake camshaft, and uses an electronically operated piston to vary pressure between 200 and 2,200 psi, depending on engine load.
Improved atomization is just part of the equation. High operating pressure combined with powerful engine management electronics allow precisely manipulating the shape and location of the fuel charge in the chamber. This is accomplished by making multiple injections in the combustion chamber every intake cycle, and varying fuel pressure anywhere between 200-2,200 psi. In other words, direct-injection fuel systems have the ability to administer fuel in multiple spurts at any point between TDC on the intake stroke and TDC on the compression stroke. A standard port fuel injection system, on the other hand, can only introduce fuel into the chamber when the intake valve is open, which is dependent on the profile of the cam lobes. "By injecting fuel directly into the combustion chamber and under high pressure, the fuel can be directed to exactly where we want it to be for a given combustion cycle," Hinds adds.
So how exactly does this translate into improved fuel economy and power? It's all in direct-injection's ability to separate the combustion chamber into separate zones. At idle and under part-throttle, the fuel charge is stratified, which means that it's concentrated near the spark plug. Conversely, the layer of air surrounding this zone is extremely lean. The result is an air/fuel mixture that's lean overall, yet stoichiometrically ideal near the spark plug. Under part-throttle operation and at idle, this reduces fuel consumption by up to 40 percent. As throttle input and load increases, a direct-injection system transitions to a homogeneous fuel charge, in which fuel is dispersed evenly throughout the entire combustion chamber. In addition to reducing emissions during cold starts by warming up the catalytic converters more quickly, the leaner overall air/fuel mixture boosts torque by about five percent. "The EcoBoost engine is constantly controlling the rail pressure to a target level based on what the customer is demanding from the engine," explains Todd Rumpsa, EcoBoost calibration supervisor. "As the driver increases demands on the engine, higher rail pressures maintain optimized combustion performance by delivering the best atomization of fuel and precise injection duration." For extra peace of mind, the Bosch engine management system used in the EcoBoost can retard timing up to 20 degrees on the fly, which negates the need for costlier forged rods and pistons.
Mounted in the cylinder heads...
Mounted in the cylinder heads directly between the intake valves, the EcoBoost's high-pressure injectors spray an ultra-fine mist of fuel through a six-hole nozzle. Unlike a carbureted or port fuel-injected motor, direct injection can still administer fuel even after the intake valves are closed. In order to handle the extra heat generated by the turbos, Inconel valves have been fitted to the heads.
Variable valve timing is accomplished...
Variable valve timing is accomplished on the EcoBoost through the use of phasers mounted to the front of the intake camshafts. The exhaust cams' valve events are fixed. To save space, Ford ditched the cam followers used on many OHC designs in favor of mechanical lifters that actuate the valves directly. Ford calls the system DAMB (Direct Acting Mechanical Buckets), and the tappets never require adjustment.
The Garrett GT15 turbos strapped...
The Garrett GT15 turbos strapped to the EcoBoost are small, which limits maximum power potential in the hands of hot rodders, but this arrangement increases exhaust velocity into the turbine at low rpm to minimize turbo lag. The insulating properties of the twin-wall manifolds help retain heat in the turbos to further enhance response. Note the twin fluid lines, one for oil and the other for coolant. The water-cooled turbo bearings eliminate the need to idle the engine after it has reached operating temperature, and reduce the potential of oil coking.
During WOT, the turbine wheels...
During WOT, the turbine wheels can reach speeds up to 170,000 rpm and temperatures up to 1,740 degrees F. As the turbos reach peak boost, electronically actuated internal wastegates bleed off exhaust gases before they reach the turbine wheels to limit boost pressure. Ford rates the life expectancy of the EcoBoost's turbos at 10 years and 150,000 miles.
Lifting off the throttle in...
Lifting off the throttle in a turbo motor creates a pressure spike in the intake tract. This shock can decelerate and potentially damage the turbine/compressor wheel and bearing. Anti-surge valves mounted between the intercooler and throttle body help relieve this pressure. Taking things one step further, instead of relying on vacuum pressure, Ford actuates the valves electronically. Consequently, Ford is able to open and close the anti-surge valves not only to relieve pressure spikes, but also to smooth out boost delivery and reduce the whistling noises often associated with turbos.
Since boost pressure masks...
Since boost pressure masks its displacement handicap, the EcoBoost's intake manifold features relatively short intake runners and reduced plenum volume to minimize turbo lag and improve hood clearance. A drive-by-wire throttle body is used in conjunction with electronically controlled wastegates to smooth out power delivery.
For the 2010 model year, Ford...
For the 2010 model year, Ford will roll out the 3.5L EcoBoost in the Taurus SHO, Flex crossover, and Lincoln MKS and MKT. Next year, the EcoBoost V-6 will be available in the F-150 as well. Depending on how the motor is received, Ford could very well drop it in future performance cars.
Despite the rigorous testing all OE engines are subjected to, some readers raised on big-honkin' V-8s may still have reservations about the long-term durability of a small cubic inch engine in a large car. Fear not, for Ford has punished the EcoBoost V-6 more severely than you can imagine. During the R&D process, Ford engineers ran the EcoBoost at WOT for 10 minutes, then abruptly shut the motor down to halt the flow of oil and coolant to the turbos. This test-in which the turbos hit temperatures of nearly 1,800 degrees F-was repeated 1,500 times without once changing the oil. Upon disassembling the turbos afterward, the bearings showed no signs of abnormal wear. "Every 10 minutes, the test alternates between peak power at max exhaust temperature, and completely cold motoring," explains Keith Plagens, Ford turbo systems engineer. "The goal is to verify that the turbochargers can withstand extreme thermal cycling without affecting their performance. It's pretty brutal and extreme, but it's important to prove out durability. In another test, we ran the motor at WOT for 15 days straight, and it passed with flying colors."
Is The V-8 Doomed?
Ford has big plans for the EcoBoost platform, and will begin offering the 3.5L V-6 variant in the Taurus SHO and Flex crossover, as well as the Lincoln MKS and MKT, in this year alone. None of these vehicles will be available with a V-8, and it's no coincidence. Ford's simple downsizing strategy calls for replacing V-8s with V-6s, and V-6s with inline-fours. Already in the works is a turbocharged 2.0L EcoBoost four-cylinder motor-also equipped with variable valve and direct injection-poised to replace its line of V-6s in the next few years. This potent four-banger produces 275 hp and 280 lb-ft while boasting superior gas mileage to the six-cylinder engines they'll one day replace. "While the 3.5L EcoBoost is our primary focus right now, it's just the first phase in a much broader plan to improve the fuel economy of our vehicles. By 2013, our goal is to offer either a four- or six-cylinder EcoBoost motor in 90 percent of our vehicle lineup," explains Ford spokesman, Jay Ward.
For traditionalists, the obvious question is if Ford will eliminate V-8s entirely. After all, none of Ford's current line of naturally aspirated 4.6L or 5.4L mod motor V-8s can match the output of the 3.5L EcoBoost. According to Jay Ward, Ford is committed to producing V-8s well into the future, but in far lower quantities. "In applications where customers demand a V-8, such as in Mustangs and trucks, we will continue to offer them, however, you will start seeing smaller-displacement engines where you might not have expected in the past. In 2010, the F-150 will be available with an EcoBoost V-6."
As with any engine equipped with forced induction from the factory, extracting a few extra ponies is as easy as cranking up the boost. With the EcoBoost's maximum psi regulated by an electronically controlled wastegate, it's simply a matter of the aftermarket hacking into its engine management computer. In an effort to reduce lag in a small-displacement application, the Ford V-6 uses relative small Garret GT15 turbos. While they're each rated at a modest 200 hp a piece, there's still enough spare capacity in them to conceivably wring out an additional 50 hp over the factory's 355-365hp rating. As far as the virtues and limitations of the factory short-block and cylinder heads are concerned, we'll have to wait until these motors fall into the hands of hot rodders to find out.
Ford won't confirm whether or not the 3.5L EcoBoost may someday be offered as a crate motor through Ford Racing, however, some enthusiasts are bound to put their V-8 predispositions aside and contemplate an EcoBoost swap into a muscle car once they hit the second-hand market. In this regard, the little V-6 has a lot going for it. Although its external dimensions weren't available for a direct empirical comparison, Ford engineers did confirm that the EcoBoost V-6 is smaller in almost every dimension than both SOHC and DOHC variants of the 4.6L mod motor V-8. Obviously, the EcoBoost's smaller bore spacing and lack of two cylinders factor into the equation, but the acute 60-degree angle of its block provides extra room between the shock towers compared to the 4.6L V-8, even with the turbo hardware attached.
In addition to running the...
In addition to running the EcoBoost at WOT for 15 straight days during torture testing, Ford ran the motor at temperatures ranging for 40 degrees F below 0, to 110-plus degrees.
The EcoBoost looks like it...
The EcoBoost looks like it was built with engine swaps in mind. There is no need for a front-mounted accessory bracket, as the alternator, A/C compressor, and idler pulley attach directly to the block. The water pump is situated behind the front cover.
During real-world dragstrip...
During real-world dragstrip testing, Ford managed a 13.9-second pass at 104 mph in a 4,400-pound, EcoBoost-powered, 2010 Lincoln MKS. Drop an EcoBoost in a muscle car that's 1,000 pounds lighter, and solid 12-second e.t.'s are a given.
The General's Rebuttal
GM's current predicament is the product of corporate mismanagement, and hardly reflects upon the competence of its powertrain engineers. For decades, the company has been churning out world-class engines, but it rarely built quality containers to put them in. The 3.6L direct-injection V-6, currently available in the Cadillac CTS and Chevy Camaro, is a prime example of GM's engineering talents. This DOHC, 24-valve six-banger with variable valve timing kicks out 304 hp and 273 lb-ft of torque. In the Caddy, it delivers 17 mpg around town, and 26 mpg on the freeway. Likewise, the direct-injected 2.0L turbo four-cylinder offered in the Pontiac Solstice and Saturn Sky-also equipped with a four-valve-per-cylinder head and variable valve timing-produce 260 hp and 260 lb-ft while knocking down 19 mpg in the city and 28 mpg on the freeway.
Arguably the best example of all is GM's already-legendary LS-series small-block V-8. Although there are more than two dozen variants in existence, they all share several things in common: outstanding power, excellent fuel mileage, low mass, and compact external dimensions. To further improve the output and fuel economy of the LS engine platform, they're now available with features such as variable valve timing, and active cylinder deactivation. In the Pontiac G8's 6.0L V-8, it all amounts to 361 hp and 385 lb-ft of torque. Fuel economy is rated at 15 mpg in town and 24 mpg on the interstate. Granted that's a bit off the mark when compared to the Lincoln MKS' EcoBoost V-6, despite the fact that the G8 is nearly 400 pounds lighter, those figures would surely see a nice boost with the integration of a direct-injection fuel system. This begs the question, is the V-8 really a problem, or is it merely suffering from an image problem from a green-happy general public? Hopefully the Feds will let GM's engineers freely go about their business so we'll one day find out. -Stephen Kim
Cafe Con Leche?
Don't worry, the staff here at PHR has no intention of transforming into wienies who care more about camshaft and valve count than the actual power an engine puts out. In fact, we constantly have to talk ourselves out of putting a big-block into every project car we build. That said, we very much embrace fuel-efficient, small-displacement engines for one simple reason: CAFE standards. Corporate Average Fuel Economy is merely the average fuel economy of an automakers' entire fleet of car models. The exact figure a manufacturer's fleet must meet is determined by the Feds. Once the 35.5-mpg CAFE standard kicks in come 2016, a car that achieves less than the required corporate average can be offset by a car that gets more than the corporate average. In other words, a manufacturer that builds a large number of cars that deliver greater than 35.5 mpg has the flexibility to produce performance cars that get less than 35.5 mpg. With the 35.5 CAFE target in mind for 2016, new car makers can now set a long-term game plan of how to offer a diverse mix of fuel-efficient vehicles and performance machines. Like we said, if boosting the mpg of the average commuter cars improves the odds of performance cars sticking around, we're all for fuel-efficient, small-displacement engines. -Stephen Kim
|BY THE NUMBERS |
|Engine: ||3.5L EcoBoost |
|Type: ||60-degree V-6 |
|Displacement: ||213 ci |
|Block: ||deep-skirt, die-cast aluminum with six-bolt main caps |
|Head gasket: ||multi-layer steel |
|Bore and stroke: ||3.641x3.413 inches |
|Compression ratio: ||10.0:1 |
|Crankshaft: ||forged steel crankshaft |
|Connecting rods: ||powdered metal |
|Pistons: ||cast aluminum with coated skirts |
|Cylinder heads: ||cast aluminum |
|Intake manifold: ||cast aluminum |
|Throttle body: ||65mm drive-by-wire |
|Valvetrain: ||DOHC, 24 valves, variable intake timing |
|Valve diameter: ||1.456/1.220 inches |
|Ignition: ||coil-on-plug |
|Fuel delivery: ||Ford/Bosch gasoline direct-injection |
|Exhaust: ||stamped-steel manifolds |
|Power adder: ||twin Garrett GT15 turbochargers with air-to-air intercooler |
|Boost pressure: ||12 psi maximum |
|Horsepower: ||365 at 5,500 rpm (Taurus SHO) |
|Torque: ||350 lb-ft maintained between 1,500 and 5,250 rpm |
|Max engine speed: ||6,200 rpm |
|Fuel requirement: ||87 octane minimum, 91-plus recommended |
|Oil capacity: ||6 quarts |
|EPA fuel economy: ||17/25 mpg (city/hwy) |
While the traditionalist in us sees high-tech, small-displacement engines as a complicated method of achieving underwhelming horsepower figures, the more progressive side in us embraces any form of technology used to maximize performance, regardless of an engine's displacement. Engineers tend to do their best work in the face of insurmountable odds, and nowhere is this more evident than in Formula 1 racing. Most Americans aren't too interested in watching oversized go-karts racing on the other side of the world, but F1 engines are arguably the pinnacle of small-displacement engineering. During the early '90s, F1 regulations banned all forms of forced induction and limited displacement to 3.5L. Nonetheless, thanks to the advent of pneumatic valvesprings that enabled engine speeds up to 16,000 rpm, these naturally aspirated V-10s and V-12s produced in excess of 800 hp. By 1995, the sanctioning body reduced displacement to 3.0L, but with rpm approaching to the 20,000 mark, these V-10s eclipsed 900 hp. Displacement was reduced once again to 2.4L in 2008, in addition to a limit in max rpm of 18,000, but these tiny V-8 engines are already approaching 800 hp. This is despite the fact that F1 engines must now last an average of two full races, where in the past teams used separate qualifying and race engines each weekend. Furthermore, new for the 2009 season is an optional hybrid assist motor. These Kinetic Energy Recovery Systems, or KERS, use a generator attached to the car's transmission to charge up a battery. When the driver hits a button, the transmission-mounted generator converts the battery's electrical energy back into mechanical energy to boost engine output by 80 hp for up to 6.5 seconds per lap. It's like an electric nitrous system that recharges by itself.
Regardless of the V-8's future in production cars, it will always exist in some form or another. There are plenty of cores still sitting around in salvage yards-waiting to be rebuilt-and everything from old-school Hemis, to small-block Chevys, to big-block Fords can be built entirely from aftermarket parts. Despite the assault on our hobby waged by overzealous greenies, performance cars aren't going anywhere. If enough consumers demand performance in addition to excellent fuel mileage, engineers will find a way to deliver it, whether it's in the form of four-, six-, or eight-cylinder engines. -Stephen Kim