GM 3.6 Liter V6 Bi-Fuel LFR Engine

The 3.6L LFR engine uses the same lightweight components that contribute to fuel efficiency and performance of the 3.6L V6 LFX engine. An integrated cylinder head/exhaust manifold design, for example, saves about 13 pounds compared to a non-integrated design, while a composite intake manifold saves about 5.5 pounds vs. an aluminum intake. Additionally, a lightweight structural front cover and high-strength connecting rods save additional weight.

Engine highlights include:

• Aluminum Engine Block and Integral Oil Pan: the 3.6L V-6 VVT’s engine block is cast from A319 aluminum alloy. This aluminum-intensive construction means less weight and greater efficiency than conventional cast-iron engines as well as improved vehicle fuel economy. The sand-cast block features strong cast-in iron bore liners, six-bolt main caps, and inter-bay breather vents. A cast aluminum oil pan is stiffened to improve powertrain rigidity and reduce vehicle vibration.
• Rotating Assembly with Oil-Spray Cooled Pistons: the crankshaft is made of forged steel, while the connecting rods are made of powdered metal with a higher ratio of copper, which makes them stronger and lighter. The pistons are made of lightweight cast aluminum and feature a friction-reducing polymer coating on the skirts, as well as fully floating wrist pins, which also reduce friction. Less weight in the pistons means less reciprocating mass in the engine, resulting in less inertia and greater operating efficiency. Three jet assemblies in the engine drench the underside of each piston and the surrounding cylinder wall with an extra layer of cooling, friction-reducing oil. The jets reduce piston temperature, allowing the engine to produce more power without reducing long-term durability.
• Integrated Cylinder Heads/Exhaust Manifolds: the cylinder head design has an intake port design that enhances airflow to the combustion chambers. Larger valves that stay open longer allow more of the air to be pulled into the combustion chamber for a more powerful combustion. An optimized fuel system equals more power and fuel economy, while an efficient combustion means reduced emissions. The exhaust manifold is incorporated with the cylinder head and saves weight, reduces complexity and promotes a quicker light off of the catalytic converter, reducing emissions.
• Fuel system: two unique fuels systems have been packaged into the cylinder head intake manifold providing independent operation in either CNG or gasoline while allowing seamless fuel mode transitions when either fuel is unavailable or the driver requests a specific fuel mode via a selectable switch. Fuel range and economy is calculated for each specific fuel and displayed via the Driver Information Center.
• Dual Overhead Cams with Four Valves per Cylinder and Silent Cam Drive: four valves per cylinder and a silent chain valvetrain contribute to smoothness and high output. Four-cam phasing changes the timing of valve operation as operating conditions such as rpm and engine load vary, resulting in smooth, even torque delivery, high specific output (horsepower per liter of displacement) and excellent fuel consumption. Cam phasing also pays big dividends in reducing exhaust emissions. By closing the exhaust valves late at appropriate times, the cam phasers create an internal exhaust-gas recirculation system. The 3.6L V-6 VVT meets all emissions mandates without complex, weight-increasing emissions control systems such as EGR and air injection reaction (AIR).
• Variable Valve Timing: variable valve timing (VVT), or cam phasing, helps deliver optimal performance and efficiency, and reduced emissions. It allows 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. It also provides another effective tool for controlling exhaust emissions. Because it manages valve overlap at optimum levels, it eliminates the need for an Exhaust Gas Recirculation (EGR) system.
• Composite Intake Manifold and Fully Isolated Aluminum Camshaft Covers: the upper intake manifold is made from composite material that provides mass savings over an aluminum manifold, with a carefully designed structure that provides quiet engine operation. Cam covers are aluminum and were shaped to limit noise. The covers use isolating perimeter gaskets, and isolating radial lips around the tubes to accommodate the spark plugs. These effectively de-couple the covers from vibration generated during combustion.
• Engine Control Module (ECM): the LFR is controlled by a new bi-fuel capable E18 engine control module. It is a torque-based engine management system that calculates optimal throttle position, cam phasing positions, ignition angle, fuel injection mass and other operational parameters to optimize engine output, based on the driver’s positioning of the gas pedal.