Chevrolet LFX Specifications
| Engine Model: Chevrolet LFX |
| Engine Type: 4-cycle 6-cylinder DOHC 24-valve liquid-cooled gasoline |
| Total Displacement: 217.4 cu.in (3.56 L) |
| Rated Engine Power: 301-323 Hp (224-241 kW) at 6800 rpm |
| Fuel System Type: Spark ignition direct injection (SIDI) |
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The Chevrolet LFX is a second-generation 3.6-liter V6
engine belonging to General Motors’ High Feature (HFV6) engine family.
Introduced for the 2012 model year, it replaced the LLT as a lighter, more
refined, and higher-revving powerplant. Its development focused on reducing
complexity and mass while increasing structural rigidity.
The LFX achieved this through the integration of exhaust manifolds into the
cylinder heads, the use of a composite intake manifold, and a revised block
casting. This engine is distinguished by its broad power band, direct injection,
and continuous variable valve timing, making it a versatile unit for
rear-wheel-drive sports coupes, front-wheel-drive sedans, and body-on-frame
trucks.
Engine Type: 60-degree V6, Gen II High Feature, naturally aspirated
Displacement: 3.6 L; 217.4 cu.in (3,564 cc)
Bore x Stroke: 94.0 mm x 85.6 mm (3.70 in x 3.37 in)
Compression Ratio: 11.5:1
Firing Order: 1-2-3-4-5-6
Horsepower: 301-323 hp (224-241 kW) @ 6,800 rpm
Torque: 262-278 lb-ft (355-377 Nm) @ 4,800 rpm
Maximum Engine Speed (Fuel Cutoff): 7,200 rpm
Fuel Type: Regular unleaded; Flex-fuel (E85) capability on selected variants
The cylinder block is constructed from sand-cast
aluminum (A319-T7) with cast-in-place gray iron cylinder liners. A structural
aluminum ladder frame (windage tray) reinforces the lower crankcase, integrating
with the main bearing caps to increase bottom-end rigidity. The block features a
deep-skirt design, where the cylinder walls extend below the crankshaft
centerline, providing superior support for the rotating assembly.
Deck thickness was optimized to accommodate the high cylinder pressures of
direct injection. The water jacket features a cross-bolted configuration around
each cylinder to improve core stability during casting and enhance thermal
management. Internal oil passages are drilled to supply piston-cooling jets and
variable valve timing actuators.
The cylinder heads are manufactured from cast aluminum
(A356-T6) and incorporate integrated exhaust manifolds, a defining feature of
the Gen II architecture. This integration eliminates traditional manifold
flanges and gaskets, reduces weight, and accelerates catalytic converter
light-off for emissions control. The valvetrain utilizes a Dual Overhead
Camshaft (DOHC) design with four valves per cylinder.
Intake valves measure 35.0 mm (1.38 in) in diameter, while exhaust valves
measure 29.0 mm (1.14 in). Hollow-stem sodium-filled exhaust valves are utilized
to manage thermal loads effectively. The system employs four independent cam
phasers (one per camshaft) providing Continuous Variable Valve Timing (VVT) with
a range of up to 62 deg of cam rotation. Valve lash is maintained via hydraulic
roller finger followers.
The engine utilizes Spark Ignition Direct Injection
(SIDI) operating at a high pressure. A single high-pressure fuel pump, mounted
on the front of the right cylinder head and driven by a dedicated lobe on the
exhaust camshaft, pressurizes the fuel rail. System operating pressure varies
from 2.9 to 22.5 MPa (4,200 to 3,260 psi) depending on engine load and
conditions.
Each cylinder is served by a centrally mounted solenoid-actuated fuel injector
that delivers fuel directly into the combustion chamber. The fuel rail is
rubber-isolated from the intake manifold to dampen the acoustic signature of the
injector operation. Most variants are equipped with flex-fuel sensors and
hardened valve seats to allow operation on up to E85 (85% ethanol).
The lubrication system is a fully pressurized,
variable-displacement design. A cam-driven, variable-displacement vane-type oil
pump is mounted on the front timing cover. This pump adjusts its output based on
engine speed, load, and temperature to reduce parasitic loss and optimize oil
flow to the VVT phasers, piston-cooling jets, and main bearings.
The system utilizes a structural aluminum oil pan with internal baffling for
consistent oil pickup under high lateral acceleration. Piston-cooling oil jets
are installed in the cylinder block, directing a continuous stream of oil to the
underside of each piston crown to manage thermal stress under high load.
The cooling system is a high-efficiency cross-flow
design with a single-circuit configuration. The water pump is mounted directly
to the cylinder block and driven by the timing chain. Coolant flows from the
pump into the cylinder block, circulating around the cylinders before moving
vertically into the cylinder heads. The integration of the exhaust manifolds
into the cylinder heads necessitates a dedicated cooling passage surrounding the
exhaust ports to manage local heat concentration.
A coolant control valve assembly, an electrically actuated rotary valve,
replaces the traditional thermostat housing in many applications, providing
precise temperature management for the cylinder heads and block independently to
reduce warm-up time and improve cabin heating.
0A composite (glass-reinforced nylon) intake manifold
is used for weight reduction and thermal insulation. The manifold features dual
plenums and long, tuned runners to enhance low-end torque. A single
electronically controlled throttle body (ECT) manages air intake.
| Ignition and Electrical System |
Ignition System: The ignition system utilizes
individual coil-on-plug (COP) modules mounted directly over each spark plug. The
system is controlled by the Engine Control Module (ECM) with ion-sensing
feedback, allowing the ECM to detect misfire and spark knock without a separate
knock sensor in certain calibrations.
Electrical System: The engine management is governed by a 32-bit ECM (E39 or
E39A) utilizing CAN bus communication for integration with the vehicle’s
transmission control module and body control systems.
Dry Weight: 167 kg (368 lbs)
Overall Height (from crankshaft centerline to top of intake manifold): 545 mm
(21.5 in)
Overall Length (front of accessory drive to rear of flywheel housing): 685 mm
(27.0 in)
Overall Width (across valve covers): 630 mm (24.8 in)
Engine Oil Capacity (with filter): 5.7 L (6.0 qt).
Recommended Oil Viscosity: SAE 5W-30 (dexos1 Gen 2 or 3 certified).
Coolant Capacity: 9.5-11.0 L (10.0-11.6 qt), depending on vehicle platform.
Spark Plug Type: 41-109 (Iridium).
Spark Plug Gap: 1.0 mm (0.040 in).
Spark Plug Replacement Interval: 161,000 km (100,000 mi).
Drive Belt Routing: Serpentine, automatic tensioner.
Oil Change Interval: 12,000 km (7,500 mi) under normal conditions; 5,000 km
(3,000 mi) under severe service or E85 usage.
Cylinder Head Bolts (Stage 1): 30 Nm (22 lb-ft)
Cylinder Head Bolts (Stage 2): 90-degree rotation
Cylinder Head Bolts (Stage 3): 70-degree rotation
Main Bearing Cap Bolts (M8): 25 Nm (18 lb-ft) + 45-degree rotation
Main Bearing Cap Bolts (M10): 50 Nm (37 lb-ft) + 60-degree rotation
Connecting Rod Cap Bolts: 20 Nm (15 lb-ft) + 45-degree rotation
Camshaft Cap Bolts: 10 Nm (89 lb-in) + 30-degree rotation
Intake Manifold-to-Head Bolts: 10 Nm (89 lb-in)
Spark Plugs: 15 Nm (11 lb-ft)
Oil Pump Bolts: 10 Nm (89 lb-in) + 40-degree rotation
Chevrolet Camaro: 2012-2015 (LS, 1LT, 2LT)
Chevrolet Impala: 2012-2016 (LS, LT, LTZ); 2017-2019 (LS, LT)
Chevrolet Colorado: 2015-2016 (LT, Z71)
Chevrolet Equinox: 2013-2017 (LT, LTZ)
Chevrolet Traverse: 2012-2017 (LS, LT, LTZ)
GMC Acadia: 2012-2016 (SLE, SLT)
GMC Terrain: 2013-2017 (SLE, SLT)
GMC Canyon: 2015-2016 (Base, SLE, SLT)
Cadillac CTS: 2012-2015 (Luxury, Performance, Premium)
Cadillac ATS: 2013-2015 (Standard, Luxury, Performance)
Cadillac SRX: 2012-2015 (Base, Luxury, Performance, Premium)
Buick LaCrosse: 2012-2016 (Premium I, Premium II)
Buick Enclave: 2012-2017 (Convenience, Leather, Premium)
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