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Ford's Next Police Engine EcoBoost
EcoBoost™ is the new Ford engine technology planned for most of their future vehicles, including everything from small cars to large trucks. The EcoBoost family of Gasoline Turbocharged Direct Injection (GTDI) 4-cylinder and 6-cylinder engines uses turbocharging and direct injection for the same horsepower and torque as larger engines but up to 20 percent better fuel economy than those larger engines. By 2013, more than 90 percent of Ford’s North America product lineup will be available with some version of the GTDI EcoBoost I4 or V6 engine.
Engines simply must have a smaller displacement to improve fuel economy. A larger engine, even with cylinder shutoff technology (cylinder deactivation) simply cannot equal the fuel economy of a smaller engine. So Ford has downsized the engine to improve gas mileage, and then used direct injection and turbocharging to equal the power of the larger engine when power is needed.
To put an EcoBoost engine in perspective, this Ford 3.5L EcoBoost V6 produces more horsepower and almost as much torque as the 340 hp 5.7L HEMI® V8 used in the 2006-2008 Dodge Charger, and much more power than a 4.6L V8—the 3.5L GTDI V-6 will produce 2 mpg better mileage than the CVPI’s 4.6L V-8, and produce 100 hp more power.
The first EcoBoost engine police fleet managers will see is the 365 hp, 3.5L V6. This is an option for the Sedan Police Interceptor and an option on the F-150 pickup. The Sedan PI will be available in early-2012 as a 2013 model, while the F-150 got the EcoBoost for 2011.
The EcoBoost engine uses direct injection. That means the gasoline charge is injected directly onto the top of the piston at extremely high pressures. The fuel injection pressure on a standard engine is between 70 and 100 psi. The GTDI injectors operate at 2000 psi. Six spray jets of fuel per cylinder are targeted at individual locations inside the combustion chamber.
Direct injection is especially helpful during a cold start under extremely cold conditions. Direct injection can be electronically controlled (tuned) where those injections should take place to deliver the strongest possible start. The fine mist from each of the six tiny outlet holes cools the incoming air, which reduces the tendency for engine knock and allows more aggressive ignition timing. This spray also forms a better mixed air-fuel mixture for optimum ignition.
Among its other advantages, direct injection allows a higher, 10:1 compression ratio, where most turbocharged and supercharged engines have lower, 8.5:1 or 9:1 compression ratios. Direct injection also allows up to a 12-psi turbo boost, where most turbo and supercharged engines operate at an 8-psi boost.
Direct injection is not really “new” technology for Ford. Ford already has several direct injection 4-cylinder engines in production, including a 1.8L engine launched in the 2003 Ford Mondeo (UK), and a 2.3L turbocharged engine developed by Mazda for the MazdaSpeed6. However, this is Ford’s first use of direct-injection on a V-6 engine and the first direct injection engine produced in North America.
No Turbo Lag
But what about turbo lag, that slow throttle response at low rpm? These are not the turbos of the 1980s that delivered lots of torque but had delays between stepping on the gas pedal and feeling the increase in power. These turbos are smaller, spin up faster, kick in at lower engine rpms, operate at higher turbine rpms, and are fully connected to modern powertrain controllers. All that means improved throttle response.
Based on over 1,000 miles of traffic enforcement we put on a retail Taurus SHO, and 1,300 miles of patrol use on an F-150 SuperCrew, these EcoBoost engines have no turbo lag. Of course, modern engine controllers, peak torque at diesel rpms, and six speeds to choose from all added to the instant throttle response.
The V6 EcoBoost engine uses two turbos, one per bank. These fixed vane turbos operate in parallel, that is, they operate independently of one another. This is unlike Ford’s diesel truck engines that use a turbo mounted in series, that is a smaller, variable-vane, high-pressure turbo to feed a larger, fixed-vane, low-pressure turbo.
Smaller turbos also spool-up faster, allowing peak torque faster, and reducing (eliminating) turbo lag. By being mounted close to the cylinder heads, the NHV (noise, vibration, harshness) of the turbo operation is improved over older systems. Small turbos also reduce underhood heat.
Flat Torque Curve
The overall effects of fast spool-up turbos, higher compression ratios, increased spark advance and the precision of direct injection increases torque. The EcoBoost engine has both more peak torque and more low end torque, i.e., direct injection produces a remarkable flat torque curve. The torque comes on faster and it rises higher.
The EcoBoost engine achieves its peak torque at just 2500 rpm, which is a much lower rpm than all turbos and most supercharged engines. Ford’s 3.5L EcoBoost V6, for example, can deliver 350 lb.-ft. of torque across a wide engine range (2,000 to 5,000 rpm) versus 270 to 310 lb.-ft of torque for a conventional naturally aspirated 4.6L V8 over the same speed range.
The EcoBoost engine produces 90 percent of its peak torque between 1,550 and 5,500 rpm. About 98 percent of all driving is between 1,000 and 3,000 rpm. In this rpm range, the 3.5L EcoBoost produces more torque than the Ford 4.6L V8, the Chevy 6.0L V8 and the Dodge 5.7L V8.
Durability and Reliability
No American police car has ever been powered by a supercharged or turbocharged engine. In the minds of many police fleet managers, the use of a turbo causes flashbacks to horror of Chrysler’s 2.2L turbo I4 from the 1980s. The mere mention raises all kinds of durability and maintenance questions.
Just as fuel injection and engine controller electronics have drastically improved in the past 30 years, so has turbocharging. And, turbos are not new on Ford passenger car engines. Ford of Australia has used turbos on its gasoline-powered Falcon sedans since 2002. Of course, Ford of Europe has used turbo diesels for ages. Forget the Chrysler 2.2L turbo engines. Turbo problems from the 1980s were solved in the 1990s, a generation ago.
The EcoBoost engine uses two Honeywell GT15 turbochargers with water-cooled bearings. These water-cooled and oil-cooled turbos are quite unlike the turbos from the 1980s that were cooled only by engine oil. The EcoBoost turbo bearings are water-cooled in the same coolant loop as the engine to bring turbo temperatures down.
The EcoBoost engineering design life is 10 years and 150,000 miles. This series of engines uses standard grades of oil; synthetic oil is not required. The EcoBoost engine uses the same 5W-20 engine oil as most Ford gasoline engines. The EcoBoost engine has the same 7,500-mile oil change intervals as other retail Ford engines. It runs on regular grade, 87 Octane fuel; mid-grade and premium are not required. The turbos do not need any separate, different or more frequent scheduled maintenance.
Introduced in 2010, the 3.5L V6 EcoBoost was recognized as one of Ward’s Ten Best Engines. The EcoBoost engine uses the base engine architecture from the Duratec 3.5L V-6, itself one of the previous Ward’s Ten Best Engines. Of course, to handle the extra torque, upgrades were made to the block, crankshaft, connecting rods and exhaust valves. The EcoBoost engine has about 75 new, different or redesigned components to improve reliability and durability compared to the naturally aspirated 3.5L V6. After all, it needs to handle an additional 100 hp!
Engine coolant is responsible for about 60 percent of the engine cooling, while engine oil handles about 40 percent of the cooling. Ford has a unique twist on this. The EcoBoost engine delivers a short spray of oil to the underside of each piston. Squirt jets deliver a 25 psi dose of oil on each piston stroke. This does two things. On a cold start, this helps to quickly warm the oil to operating temperatures, which lowers internal friction and improves fuel economy. Under normal operating conditions, of course, the oil squirt keeps the piston temperatures under cooler.
The EcoBoost engine will see plenty of retail use to get the bugs worked out before police use. The EcoBoost engine is already in retail vehicles like the Lincoln MKS, Ford Flex, Taurus SHO and just introduced for the F-150. Remember the EcoBoost engine has passed all of Ford’s durability standards for a retail vehicle. Remember, too, that some of these retail durability tests are run twice on Ford police package vehicles.
Turbo Durability Testing
The durability testing for the twin turbo, EcoBoost engine included 20 different dynamometer tests run at maximum engine speed and maximum turbo boost under a wide variety of coolant and oil temperatures. For example, cold start and immediately run at Wide Open Throttle. For example, run at Wide Open Throttle and suddenly shut down. In all, the EcoBoost engine has had 12,000 hours (500,000 miles) of dyno testing and the equivalent of 500,000 miles of on-track testing at Ford’s Romeo Proving Grounds, which totals 1 million miles of durability tests.
With the turbos from the 1980s, oil “coking” could occur in the turbo bearings. The oil was essentially baked in the hot bearings, especially the center bearing, when the engine was shut off. The result was coke, which is the solid residue formed on the bearing surface when oil breaks down due to extreme heat. This solid residue damaged bearings and early bearing failure. The bearing operating temperatures were simply too high for conventional oil and passenger car driving habits.
Of course, that was 30 years ago, making those old turbos as different from today’s turbos as the 1981 Ford LTD is from the 2011 Taurus…a 30-year leap in technology. The turbo problems of 25 years ago were solved 15 years ago. The EcoBoost engine does not have to be idled at all before shutting the engine off.
Cooled by Thermal Siphoning
The EcoBoost twin turbos are water cooled. Water cooling the bearings solved the problem. During normal operation, engine coolant is cycled through the center bearing. When the engine shuts off and the water pump stops, the coolant flow reverses and the EcoBoost uses thermal siphoning for water cooling. Coolant near the extremely hot bearing picks up heat, boils and flows away from the bearing water jacket. This pulls fresh, cooler coolant into the bearing water jacket, which picks up heat and cools the bearings. This cooling process continues silently until lower temperatures are reached, providing key-off protection for the turbo bearings.
To test this thermal siphoning process, Ford ran the EcoBoost engine at Wide Open Throttle and maximum boost for 10 minutes. Then the engine and all the cooling was abruptly shut down. The turbos were allowed to “bake” after this high-speed operation. This is exactly the conditions that would “coke” a center turbo bearing from the 1980s. They repeated the test 1,500 times without an oil change. A teardown of the turbo and inspection of the bearings validated the method of water cooling the turbo bearings.
The retail customer might operate the engine at peak power for just a few seconds, while in police use, the engine may run at peak power for a few minutes. The durability testing during Ford’s development was based on operating at peak power for hundreds of hours. The old standard used to be to test at Wide Open Throttle for a tank full of gas. Today’s durability and reliability standards are tougher. For example, a standard engine durability test was to operate the EcoBoost engine at Wide Open Throttle and at maximum turbo boost and at maximum rpm for 362 hours. That is the 24 Hours of LeMans for 15 days straight. The turbos themselves got a separate, hot-cold cycling durability test. For the thermal shock test, the turbos were warmed up to operating temperature (1740 deg F) and run at peak boost, peak power. Then every 10 minutes, the turbo alternated between peak power at maximum exhaust temperature and then at peak power at cold start temperatures. This test went on for 150 hours, about 1,000 hot-cold cycles. During the Road Cycle Durability Test, the EcoBoost engine was started cold then run at peak power and peak torque for an hour.
During the test, the coolant temperature ranged from 50 deg F to 200 deg F, i.e., normal operating temperatures. This cold start-maximum output test was done 1,000 times, for 1,000 hours of engine testing, which represents about 60,000 miles of driving.
In addition to the dynamometer and durability testing conducted at Romeo and Dearborn, Ford conducted high-altitude driving tests in Colorado, where more than 1,000 peaks are over 10,000 feet high. Then they ran extreme hot weather tests at the Arizona Proving Grounds and extreme-cold weather tests at Florida’s Elgin Air Force Base. Using a wide variety of fuels, the engine testing was performed at temperatures from minus 40 deg F to 110 deg F, and at altitudes up to 12,000 feet.
Published in Police Fleet Manager, Sep/Oct 2011
Rating : 9.8
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