2011 3.7L I-5 VVT (LLR)
Vehicle Applications
Chevrolet Colorado
GMC Canyon
Product Highlights
· Aluminum-intensive inline architecture
· Dual overhead camshafts
· Balance shafts for smooth operation
· Camshaft phasing
· Advanced electronic throttle control
· Integrated exhaust manifold and catalytic converter
· Coil-on-plug ignition
· 58X ignition system
· 242 horsepower (180 kW) at 5,600 rpm
· 242 lb.-ft. of torque (328 Nm) at 4,600 rpm
Overview
The power of a six-cylinder and the efficiency of a four – that’s the performance advantage of the 3.7L I-5 offered in the Chevrolet Colorado and GMC Canyon. It is rated at 242 horsepower (180 kW) at 5,600 rpm and 242 lb.-ft. of torque (328 Nm) at 4,600 rpm. On the highway, the engine helps deliver EPA-rated 23 mpg in 2WD models
More importantly for the trucks the 3.7L powers, its robust torque enables great capability, including a maximum 5,500-pound (2,495 kg) towing capacity.
The 3.7L is part of a modular family of inline engines that includes a 2.9L I-4 and previous I-6 versions. The family uses many identical parts between them, with primary differences based on the specific requirements for different displacements and the number of cylinders. The 3.7L, for example, shares about 85 percent of its parts with the 2.9L I-4, including many direct-mount accessories, connecting rods, pistons and more.
Along with their modular design, GM’s inline truck engines feature advanced technologies that optimize performance and efficiency, including:
· Aluminum-intensive construction, including the cylinder block and head
· Dual-overhead camshafts
· Variable valve timing
· Electronic throttle control
· Coil-on-plug ignition.
A pair of counter-rotating balance shafts smoothes operation of the 3.7L to give it exceptional noise, vibration and harshness characteristics. It all adds up to one of the most advanced and refined engines offered in the midsize truck segment.
Cylinder Block and Rotating Assembly
The 3.7L’s aluminum cylinder block is manufactured with a lost-foam process that provides great dimensional accuracy, requires less machining and allows easier recovery of the sand for greater materials recycling. The block features a ladder-type main bearing design that promotes rigidity, for greater engine durability and reduced vibrations.
Like other members of the 3.7L’s modular family, the engine features a 3.76-inch x 4.00-inch (95.5 mm x 102 mm) bore and stroke, with the final displacement determined by the number of cylinders. The connecting rods and pistons are the same for all engines, although the cast nodular iron crankshaft is specific. Forged powder metal makes up the connecting rod material, while hypereutectic aluminum is the composition of the pistons. The pistons’ material is strong, lightweight and helps reduce engine noise through tighter tolerances within the cylinders, which minimizes the chance for the “piston slap” noise that can come with forged aluminum pistons.
A stiff, lightweight die-cast aluminum oil pan is integrated with the cylinder block and serves as a structural member of the assembly.
Balance Shafts
Balance shafts, counterweights that offset the inherent imbalance forces of an inline engine, are used in the 3.7L to minimize engine disturbances and vibrations. The pair of shafts rotates in opposite directions at twice the engine speed to cancel vibrations and noise that might otherwise be transmitted into the interior.
The balance shafts are chain-driven off the rear of the crankshaft to take advantage of efficiencies in the 3.7L’s modular engine family, allowing a common design for the front crank hub and cam drive on other engines built on the architecture. In fact, the chain-drive mechanism that spins the balance shafts, chain, sprockets and tensioner is identical to the system in the similar 2.9L I-4 and has been designed to minimize friction and parasitic power loss in both engines. The only difference is the shape and weighting of the balance shafts themselves, which are tailored to the specific engines.
Aluminum Cylinder Head with Dual Overhead Camshafts
The 3.7L features an aluminum cylinder head with dual overhead camshafts, which is the most direct, efficient means of operating the valves. Four valves per cylinder increase airflow in and out of the engine. When designing the cylinder head, special attention was dedicated to the structural strength and cooling, as well as the facilities required to accommodate the engine’s camshaft phasing.
The cylinder head’s design incorporates carefully designed combustion chambers and airflow ports that enable regular-grade gasoline to be used with a relatively high 10.0:1 compression ratio. Typically, high-compression engines require high-octane gas to produce maximum power, or to avoid the potentially damaging effects of spark knock or detonation. The engine’s advanced engine management system is also a contributor to this optimized performance.
Camshaft Phasing
The 3.7L features variable valve timing, maximizing engine performance for given demands and conditions. The camshaft phaser changes exhaust cam lobe timing relative to the cam-drive sprocket, which varies exhaust valve timing on the fly. At idle, for example, the exhaust cam is at the full advanced position for minimum intake-valve overlap. That allows exceptionally smooth idling. Under other operating conditions, the phaser adjusts to deliver optimal exhaust-valve timing for performance, driveability and fuel economy. The result is linear delivery of torque, with near-peak levels over a broad rpm range, and high specific output (horsepower per liter of displacement) without sacrificing overall engine response or driveability. Because it manages valve overlap at optimum levels, cam phasing also eliminates the need for an Exhaust Gas Recirculation (EGR) system.
The 3.7L’s vane-type phaser is actuated by hydraulic pressure from engine oil and managed by a solenoid that operates to a calibrated duty cycle. It uses a wheel with four vanes (like a propeller) to turn the camshaft relative to the cam-sprocket. The solenoid directs oil to pressure points on either side of the four vanes; the vanes, and camshaft, turn in the direction of the oil flow. The more pressure, the more the phaser and camshaft turn – up to 24 degrees relative to the sprocket.
Advanced Electronic Throttle Control
GM has led the industry in applying electronic throttle control (ETC). With ETC, there is no mechanical link between the accelerator pedal and the throttle body. A sensor at the pedal measures pedal angle and sends a signal to the engine control module (ECM), which in turn directs an electric motor to open the throttle at the appropriate rate and angle. ETC delivers a number of benefits to the customer.
With the ECM measuring throttle pedal angle and monitoring other data, including the transmission’s shift status and traction at the drive wheels, the ETC system can deliver outstanding throttle response and greater reliability than a mechanical connection, which typically uses a cable that requires adjustment – and sometimes breaks. Cruise control electronics are integrated into the system, further improving reliability and simplifying engine assembly.
Returnless Fuel Injection
The LLR is equipped with a “returnless” fuel injection system, also known as a demand system, that helps optimize performance and emissions. It delivers only the amount of fuel needed by the injectors, and returns no fuel to the gas tank, which essentially eliminates heat transfer from the engine to tank. This reduces the amount of vapor generated in the tank and captured by the vehicle's Onboard Refueling Vapor Recovery (ORVR) system.
Integrated Exhaust Manifold and Catalytic Converter
A unique feature of the 3.7L is a one-piece exhaust manifold/catalytic converter, which helps the converter reach operating temperature – also known as “light off” – more quickly for reduced emissions. Because the exhaust ports and exhaust manifold heat more rapidly than any part of an engine, moving the catalytic converter closer to the manifold allows the catalyst to heat more quickly. The 3.7L’s cast-nodular iron exhaust manifold and catalytic converter are welded together and installed as one part, taking the close-coupled concept to its practical limit. The engine also has a second, underfloor catalyst downstream from the integrated manifold/converter.
Coil-On-Plug Ignition
The 3.7L’s individual coil-on-plug ignition features an individual coil for each spark plug. The system delivers maximum voltage and consistent spark density, with no variation between cylinders. The spark plugs are located in the center of the cylinder head and a single fastener holds each ignition coil to the camshaft cover above its respective plug, making it easy to remove and obtain access to the plugs.
58X Ignition System
The LLR has an advanced 58X crankshaft position encoder to ensure that ignition timing is accurate throughout its operating range. The 58X crankshaft ring and sensor provide more immediate, accurate information on the crankshaft’s position during rotation. This allows the engine control module to adjust ignition timing with greater precision, which optimizes performance and economy. Engine starting is also more consistent in all operating conditions.
In conjunction with 58X crankshaft timing, the LLR applies the latest digital cam-timing technology. The cam sensor is located in the front engine cover, and it reads a 4X sensor target on the cam sprocket. The target ring has four equally spaced segments that communicate the camshaft’s position more quickly and accurately than previous systems with a single segment.
The dual 58X/4X measurement ensures extremely accurate timing for the life of the engine. Moreover, it provides an effective backup system in the event one sensor fails.
Simpler Oil Changes
Located toward the front of the engine on the right side, the oil filter is easily accessible from underneath. In addition, the filter is mounted pointing straight down, reducing the likelihood of spillage when the filter is removed.
The 3.7L incorporates GM Oil Life Monitoring System, so an owner should never again pay for an unnecessary oil change nor worry that the engine oil has degraded to the point where it
has lost its lubricating properties. That, in turn, can significantly reduce the amount of motor oil used, and the amount of used motor oil that must be recycled. The industry-leading GM Oil Life
Monitoring System calculates oil life based on a number of variables, including engine speed, operating temperature, load or rpm variance and period of operation at any given load and
temperature. It then recommends a change when it's actually needed, rather than by some pre-determined mileage interval.
In extreme operating conditions, such as short periods of operation in very cold temperatures, the GM Oil Life System might recommend a change in as few as 3,000-3,500 miles (4,800 to 5,600 km). When the engine runs under less severe conditions, the system might not recommend an oil change for 15,000 miles (24,000 km).
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