GM 2.7 Turbo Engine Review
GM has been introducing new truck engines in recent months. The Silverado 1500 and Sierra 1500 trucks have recently received a 2.7-liter I4 turbocharged engine. This engine features a new turbocharger inlet design, different cam profiles (including cylinder activation), and a new coolant management system. The engine’s current output is 310 horsepower @ 5,600 rpm and 348 lb-ft torque @ 1,500 rpm.
Copper-alloy exhaust valve guides are used for exhaust valves to improve heat transfer and valve cooling. GM’s Sliding Cam Valve Lift System (SCS), which has three operating modes, High Lift, Low Lift, and AFM (Active Fuel Management), is used in the 2.7L L3B valvetrain. High Lift mode makes all cylinders active and all valves open to their maximum lift. Low Lift mode (3mm less) reduces the time it takes to open the intake valve, which helps to reduce fuel consumption in medium load conditions. AFM mode makes cylinders 2 and 3 inactive, which reduces fuel consumption lower in light loads. The intake and exhaust sides also have continuously variable valve timing management.
Improved Performance of GM 2.7 Turbo Engine
Other engine technologies that support the engine’s efficiency and performance include:
- Dual-volute turbocharger housing for better throttle response and low-speed torque.
- A variable-pressure oiling system with a continuously variable-displacement vane oil pump improves efficiency. It optimizes oil pressure as a function of engine speed and load. It matches the oil supply to the engine requirements, rather than the excessive supply of a fixed-disposition, conventional oil pump.
- Active Thermal Management is GM’s first application. It allows the engine to warm up faster and reach its ideal engine temperature for efficiency and performance. This system uses a rotary valve system to distribute coolant in a targeted manner through the engine. It sends heat to the engine where it is needed to heat it up to reduce friction and heat the cab. It also cools it down when needed for high power operation. This results in improved engine performance at both hot and cold temperatures.
- An electric water pump is a first for GM trucks. It supports the Active Thermal Management system and improves engine performance and efficiency. It also eliminates parasitic drag that comes with a traditional, engine-driven water pump. It allows for continuous cabin heating even if the engine is disabled by the stop/start feature.
- Direct fuel injection is used to optimize efficiency and performance. Direct injection allows for a higher compression ratio (10.0 to 1) as the fuel vaporizes in the combustion chamber. This reduces the charge temperature and improves resistance to spark knock. Direct ignition allows for gas scavenging from the combustion chambers to turbo quickly for a quick response.
- Dual overhead camshafts contribute to the 2.7L Turbo’s smoothness and high output. Dual independent continuously variable valve timing works in conjunction with the valvetrain to ensure optimal performance and efficiency. Dual-independent valve timing allows the intake and exhaust valves to be phased at different rates. This promotes linear delivery of torque with near peak levels over a wide rpm range and high specific output (horsepower per liter displacement) without sacrificing engine response or driveability.
- An integrated exhaust manifold that is part of the cylinder head assembly. It recovers exhaust heat and speeds up engine and transmission warmup.
- Oil jets are located in the block to control temperature and performance. These jets target the underside of pistons as well as the cylinder walls. They are coated with an additional layer of friction-reducing, cooling oil. The jets reduce piston temperature, which allows the engine to produce more power and increase durability.
- This technology automatically stops the engine in stop-and-go traffic for better fuel efficiency and enhances city driving fuel economy. The driver-selectable system shuts down the engine at stoplights and other stop- and-go situations, which saves fuel. When the driver takes their foot off the brake, the engine will automatically restart when they take their foot from the brake.
What is the valvetrain of a 2.7 Turbo engine?
An innovative double overhead cam valvetrain is the cornerstone of Turbo L3B’s 2.7L Turbo Turbo L2B. These three technologies have resulted in GM giving the engine’s valvetrain the TriPower moniker.
- GM’s first use of Active Fuel Management (cylinder activation) on a four-cylinder engine.
- Both high- and low-lift valve profiles.
- Variable valve timing.Continuously variable valve time.