GM 2.0 Liter Turbo I4 Ecotec LTG Engine
The 2.0 liter I4 engine (production code LTG) is a four-cylinder engine produced by General Motors for use in a broad range of vehicles. It is part of the large-displacement four-cylinder Ecotec engine family.
The turbocharger is capable of generating up to 20 pounds of boost and its twin-scroll design helps deliver the usable power from the engine — effectively eliminating the universally-hated turbo lag while supplying a broad power band. This gives allows the LTG to respond rapidly to throttle input — a quality often associated with a higher-displacement naturally aspirated high-performance engine. Performance and efficiency are further optimized by electronically controlled supporting components including the wastegate and bypass.
The LTG is not related to the outgoing 2.0 liter turbo Ecotec LHU, with even the blocks being different. Compared to the LHU, the LTG reduces overall engine friction by 16 percent.
Engine highlights include:
- Engine Block: the Ecotec 2.0L turbo’s sand-cast cylinder block is a superior refinement of previous Ecotec engine block castings. It is dimensionally similar to previous Ecotec turbo block variants, while providing improved structural support, as well as enabling greater control of noise, vibration and harshness. The main bearing bulkheads, which support the crank bearings, as well as the cylinder bore walls have been significantly strengthened to support increased engine loads. Refinements to the oil distribution system enable improved oil flow throughout the engine and an expansion of the coolant jacket, along with the use of cast-in-place bore liners, allows more precise bore roundness and improves the block’s ability to dissipate heat.
- Rotating Assembly: the crankshaft is made of drop forged steel with induction heat-treated fillets and cross-drilled chamfered oil passages for racing-grade lubrication characteristics. Forged powdered metal connecting rods incorporate a larger, forged I-beam cross section for added strength in this turbocharged application. The pistons in the 2.0L turbo are lightweight cast aluminum, which reduces reciprocating mass inside the engine. This enhances efficiency and the feeling of performance as the rpm increases. The tops of the pistons have a dish shape that deflects injected fuel. Each piston has its own directed jet that sprays oil toward its skirt, coating its underside and the cylinder wall with an additional layer of lubricant. The extra lubrication cools the pistons, reduces both friction and operational noise and bolsters the engine’s durability.
- Rotocast Aluminum Cylinder Head with Sodium Filled Exhaust Valves: the LTG Ecotec 2.0L turbo’s A356T6 aluminum cylinder head is cast using a Rotocast process for high strength, reduced machining and improved port flow. A similar method is used in the casting of the supercharged Corvette ZR1’s LS9 cylinder heads. The head is also designed specifically for direct injection. In other Ecotec engines, the fuel injectors are mounted in the intake ports but the LTG 2.0L turbo head has unique injector mounting locations below the ports. Apart from injector installation, the head has conventional port and combustion chamber designs, with both being optimized for direct injection and high boost pressure. The head uses stainless steel intake valves that are nitrided for improved durability and undercut to improve flow and reduce weight. The exhaust valves have sodium-filled stems that promote valve cooling. At normal engine operating temperatures, the sodium inside the valve stem fuses and becomes liquid. The liquid sodium improves conductivity, promoting heat transfer away from the valve face and valve guide to the cooler end of the stem, where it more readily dissipates. This helps maintain a lower, more uniform valve temperature, reducing wear on the valve guide for better alignment and a consistent seal between the valve seat and valve face over the life of the engine. Performance was the priority with the LTG Ecotec 2.0L turbo, so the exhaust manifold mounted to the cylinder head is made of cast stainless steel. It is extremely durable and delivers exceptional airflow qualities.
- DOHC with Continuously Variable Valve Timing: overhead cams are the most direct, efficient means of operating the valves, while four valves per cylinder increase airflow in and out of the engine. This arrangement is integrated on the LTG Ecotec 2.0L’s lightweight aluminum cylinder head. Continuously variable valve timing optimizes the engine’s turbocharging system by adjusting valve timing at lower rpm for improved turbo response and greater torque delivery. Both the intake and exhaust cams have hydraulically operated vane-type phasers that are managed by a solenoid and directed by the engine control module (ECM). The phasers turn the camshaft relative to the drive sprocket, allowing intake and exhaust valve timing to be adjusted independently. Cam phasing changes the timing of valve operation as conditions such as rpm and engine load vary. It allows an outstanding balance of smooth torque delivery over a broad rpm range, high specific output and good specific fuel consumption.
- Direct Injection: direct injection moves the point where fuel feeds into an engine closer to the point where it ignites, enabling greater combustion efficiency. It fosters a more complete burn of the fuel in the air-fuel mixture, and operates at a lower temperature than conventional port injection. This allows the mixture to be leaner (less fuel and more air), so less fuel is required to produce the equivalent horsepower of a conventional, port-injection fuel system. Direct injection also delivers reduced emissions, particularly cold-start emissions, by about 25 percent. The higher compression ratio with direct injection is possible because of a cooling effect as the injected fuel vaporizes in the combustion chamber, which reduces the charge temperature to lessen the likelihood of spark knock. The direct injection fuel injectors have been developed to withstand the greater heat and pressure inside the combustion chamber, and feature multiple outlets for best injection control. The fuel system operates at pressure as high as 2,250 psi, compared to about 60 psi in conventional port-injected engines.
- Cam-Driven High-Pressure Fuel Pump: a high-pressure, cam-driven pump provides the fuel pressure required of the LTG Ecotec 2.0L turbo’s direct injection system. The engine-mounted fuel pump is augmented by a conventional electrically operated supply pump in the fuel tank. The fuel delivery system features a high-pressure stainless steel feed line and a pressure-regulated fuel rail without a conventional fuel return line from the engine to the tank. Fuel pressure varies from about 750 psi at idle to 2,250 psi at wide-open throttle.
- Two-Stage, Variable-Displacement Oil Pump: the variable-flow oiling system helps maximize fuel efficiency. Rather than the linear operation of a conventional fixed-flow pump, the variable-flow system features a crankshaft-driven oil pump that matches the oil supply to the engine load. The engine’s variable-flow pump changes its capacity based on the engine’s demand for oil. This prevents using energy to pump oil that is not required for proper engine operation. An engine oil cooler helps maintain optimum oil temperatures. It has a heat exchanger incorporated into the oil filter housing. Coolant to the heat exchanger is provided by the engine’s coolant circuit. The design optimizes oil cooling with a minimal pressure loss. During cold starts, the system also enables faster heating of the engine oil for an earlier reduction of internal engine friction.
- Twin-Scroll Turbocharger: an advanced, electronically controlled turbocharger with a unique twin-scroll design is used to increase power in the LTG Ecotec 2.0L turbo. Each of two scrolls on the turbine is fed by a separate exhaust passage – one from cylinders one and four, the other from cylinders two and three – virtually eliminating turbo lag at low engine speeds, giving the engine immediate throttle response associated with a naturally aspirated high-performance engine. The turbocharger generates maximum boost of about 20 psi. Because direct injection cools the intake process compared to port injection, it allows the LTG Ecotec 2.0L turbo to safely operate at higher boost and a relatively higher compression (9.2:1) than a conventional turbo engine, increasing both output and efficiency.
- Air-to-Air Intercooler: an intake charge cooler enhances the power-increasing benefits of the turbocharging system. The LTG Ecotec 2.0L turbo’s air-to-air intercooler draws fresh air through a heat exchanger – much like a radiator – to reduce the temperature of compressed air that’s forced through the intake system by the turbocharger. Inlet temperature is reduced as much as 212 degrees F (100 degrees C). Cooler air is denser, which means more oxygen is packed into the cylinders for optimal combustion and, consequently, greater power.
- Cam-Driven Vacuum Pump: a cam-driven vacuum pump ensures the availability of vacuum under all conditions, especially under boost, when the engine produces the opposite of vacuum. The pump is mounted at the rear of the cylinder head and is driven by the exhaust camshaft via a flexible coupling.
|Displacement:||1998 cc (150 CID)|
|Engine Orientation:||Longitudinal or Transverse|
|Valve configuration:||Dual Overhead Camshafts (DVCVP)|
|Valves per cylinder:||4|
|Assembly site:||Tonawanda, NY; Spring Hill, Tennessee|
|Valve lifters:||Hydraulic roller finger follower|
|Firing order:||1 – 3 – 4 – 2|
|Bore x stroke:||86.00 x 86.00 mm|
|Fuel system:||SIDI (Spark Ignited Direct Injection)|
|Fuel Type:||Premium recommended|
|Applications||Horsepower hp (kW)|
|Cadillac ATS:||272 hp (203 kW) @ 5500 rpm SAE Certified|
|Chevrolet Malibu:||259 hp (193 kW) @ 5300 rpm SAE Certified|
|Applications||Torque lb.-ft. (Nm)|
|Cadillac ATS:||260 lb.-ft (353 Nm) @ 1700-5500 rpm SAE Certified|
|2013 Chevrolet Malibu:||260 lb.-ft (353 Nm) @ 1700-5500 rpm SAE Certified|
|2014 & newer Chevrolet Malibu:||295 lb.-ft. (400 Nm) @1700-5500 rpm (pending SAE Certification)|
|Maximum Engine Speed:||7000 rpm|
|Emissions controls:||Evaporative system|
|Catalytic converters (close coupled and underfloor)|
|Positive crankcase ventilation|
|Block:||Cast aluminum 319T7|
|Cylinder head:||Cast aluminum 356T6 Rotocast|
|Exhaust manifold:||Cast stainless steel|
|Main bearing caps:||Iron inserts cast into Bedplate|
|Connecting rods:||Forged powdered metal|
|Additional features:||Extended life spark plugs|
|Extended life coolant|
|Electronic throttle control|
|Variable valve timing|
|Belt Alternator Starter system capable|
|2-stage thermostat (90 C & 105 C)|
|2-stage variable displacement oil pump|
|Modular balance shaft system in oil pan|
|Precision sand cast block with cast-in-place iron liners|
|Spin on oil filter|
|Integrated N&V cover on intake manifold|
|Integrated front engine mount for transverse installation|
|Exhaust on left-hand side and intake on right-hand side|
|Electronic bypass valve|
|Cadillac ATS Sedan||MYA-6L45|