|The 2.0-liter EcoBoost I-4 Ti-VCT. Click to enlarge.|
Ford is unveiling the refreshed 2011 Edge at the Chicago Auto Show. An all-new powertrain lineup includes North America’s first application of Ford’s global 2.0-liter EcoBoost I-4 engine (earlier post), plus the new 3.5-liter Ti-VCT (Twin Independent Variable Camshaft Timing) V-6 and 3.7-liter Ti-VCT V-6 for Edge Sport. The 3.7L Ti-VCT is similar to the one added to the 2011 Ford Mustang. (Earlier post.)
With the introduction of the 2.0-liter EcoBoost I-4, fuel economy on the new Edge will be 30% better than it was at launch in 2006. Plus, Ford’s newest EcoBoost engine will deliver on the promise of 15% fuel economy improvements versus the Edge’s current 3.5-liter V-6 engine while offering the performance feel of a six-cylinder.
|2011 Ford Edge Limited. Click to enlarge.|
2.0L EcoBoost. The 2.0-liter I-4 engine with direct fuel injection and a single turbocharger will deliver fuel economy benefits at least 10% better than a comparable V-6 but with class-leading power and torque for an I-4, according to Ford.
The 2.0-liter EcoBoost I-4 engine employs many of the basic principles of Ford’s original 3.5-liter EcoBoost V-6 engines (earlier post), starting with turbocharging and direct fuel injection. Just like the first-generation EcoBoost engines, the EcoBoost I-4 will spool up quickly to maximum torque and maintain it across a broad range—estimated from 2,000 rpm to 5,500 rpm, according to preliminary Ford data.
The 2.0-liter EcoBoost I-4 engine also adds Ti-VCT (Twin Independent Variable Camshaft Timing) technology. This strategy, because of its efficiency, is incorporated into several normally aspirated (non-boosted) engine programs that debut this year, including the Ford Edge, Ford Mustang and Lincoln MKX.
The combustion system has been completely redesigned and re-engineered to take advantage of the EcoBoost system’s increased performance. The high-pressure fuel pump operates up to 2,200 psi—more than 50 times the norm seen in a conventional I-4 engine. The high-pressure pump is a cam-driven mechanical pump with a single piston and an electronic valve that controls how much fuel is routed into the fuel rail to the injectors.
As demands on the turbocharged 2.0-liter EcoBoost I-4 engine are increased, the control system responds to maintain optimal combustion, timing and injection duration. On each stroke, six individual jets on each fuel injector spray fuel directly into the combustion chamber, mixing with the incoming air. The fuel injectors are located on the side of the combustion chamber.
When the fuel is injected into the cylinder, it evaporates and cools the air that’s been inducted into the cylinder. The improved charge cooling allows the direct-injected turbocharged engine to run a higher compression ratio than was possible on port fuel-injected boosted engines. That higher compression ratio equates to improved fuel economy across the operating range of the engine.
The direct injection of fuel into the cylinder also helps provide a well-mixed air-fuel charge, increasing engine efficiency. Direct injection provides several benefits in terms of fuel burn and lower emissions. The spray pattern for the fuel was optimized after extensive computer modeling work, with the angle of how the fuel is sprayed key to the process.
The turbocharger operation paired with the direct-injection system helps to virtually eliminate turbo lag, Ford says. The turbocharger spins at up to 200,000 rpm and is designed for a life cycle of 150,000 miles or 10 years.
Turbocharger “whoosh” is mitigated by electronically controlled anti-surge valves that proactively relieve the boost in the intake, which can range up to 13 psi. Careful software calibrations manage the pressures in the intake manifold.
Overall, the 2.0-liter EcoBoost I-4 engine is about 55 pounds (25 kg) lighter than a comparable normally aspirated 3.5-liter V-6 engine. The 2.0-liter EcoBoost I-4 also will benefit from a six-speed transmission specially calibrated to take advantage of the EcoBoost. The gearbox features a new torque converter for improved driving feel, smooth shifts and improved fuel economy. Engineers also installed revised gear ratios for a balanced driving feel in all situations. The new ratios complement the revised torque converter.
The 2.0-liter EcoBoost I-4 is the first engine in the EcoBoost lineup to go truly global. Already announced is the 2.0-liter EcoBoost in the S-MAX and Galaxy, two people-moving products on sale in Europe. In addition, the same engine will join the powertrain lineup for the 2011 Ford Falcon on sale in Australia. (Earlier post.) Later in the year, the second application for North America will be announced.
Since being introduced in 2009 on four vehicles—the Ford Taurus SHO (standard) and Lincoln MKS full-size sedans and the Ford Flex and Lincoln MKT crossovers—EcoBoost engines have proven popular. The Ford Taurus SHO has a conquest rate of 45%, and since launch, in terms of volume, 48% of Lincoln MKT sales are with the EcoBoost option. Altogether, nearly 6,000 EcoBoost-equipped vehicles have been sold since introduction.
3.5L and 3.7L Ti-VCT. Both the Edge 3.5-liter V-6 and Edge Sport 3.7-liter V-6 use advanced engine valvetrain technology (Twin Independent Variable Camshaft Timing, or Ti-VCT) and clever control strategies to increase horsepower and torque.
The 3.5-liter V-6 produces 285 hp (213 kW) and 253 lb-ft (343 N·m) of torque while the 3.7-liter V-6 delivers 305 hp (227 kW) and 280 lb-ft (380 N·m) of torque—all on regular fuel. As a comparison, the the 3.5-liter V-6 with Ti-VCT technology delivers highway fuel economy that is 15% better than the Nissan Murano but produces 20 hp more.
Transmissions. All three engines are mated to a six-speed automatic transmission. The SelectShift Automatic transmission is standard on the 2011 Edge SEL and Limited series, with paddle activation of the SelectShift standard on the 2011 Edge Sport.
The 2.0-liter EcoBoost I-4 also will benefit from a six-speed transmission specially calibrated to take advantage of the EcoBoost engine.
Other powertrain system contributors to the improved fuel economy and performance of the engines include:
Aggressive deceleration fuel shutoff; torque-based deceleration control. This control strategy shuts off the engine when the customer doesn’t command engine torque, which helps save fuel. A typical maneuver when this comes into play is during deceleration at freeway speeds when in fifth or sixth gear. The fuel flow seamlessly resumes when the vehicle reaches a low speed or when the driver accelerates again. All other powertrain, braking and electrical systems continue to function normally while the fuel delivery is stopped.
The system uses the torque delivered to the transmission to keep the engine running at a low, more efficient point whenever possible, using the momentum generated rather than more fuel to keep the vehicle moving.
Battery management: Smart Charging. This system allows the battery to be charged or discharged at optimal opportunities instead of allowing the alternator to continuously charge the battery independent of customer use, which wastes energy. Smart Charging increases the alternator output when the vehicle brakes or decelerates, converting the vehicle’s kinetic energy into electric energy without having to use additional fuel.
Smart Charging improves the life of the battery because it keeps the battery at a more consistent level of charge, which in turn aids in reliable starting. The one-touch starting in the 2011 Ford Edge enables starts of around seven-tenths of a second with precise fuel delivery for maximum fuel economy and minimal emissions.
Engine hardware improvements. These include new or changed piston-cooling jets; polished valvetrain buckets; improved intake manifold; Ti-VCT hardware; and improved cylinder head with increased port flow.
The piston-cooling jets spray oil on the underside of the pistons and enable faster oil warm-up and a higher compression ratio; the polished valvetrain buckets reduce friction, which in turn aids fuel economy and also improves durability (wear) of the cam and bucket tappet; the improved intake manifold and cylinder head optimizes engine breathing, contributing to overall system efficiency.