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Variable Camshaft Timing
This engine has the ability to vary the camshaft position versus the piston position. If you chose to use the Chevrolet Performance
engine controller kit, then it will vary camshaft timing to improve emission and fuel economy, while still producing great power. At
idle, for example, the cam is at the full advanced position, allowing exceptionally smooth idling. Under other conditions, the phaser
adjusts to deliver optimal valve timing for performance, drivability and fuel economy. At high rpm it may retard timing to maximize
airflow through the engine and increase horsepower. At low rpm it can advance timing to increase torque. Under a light loads, it
can retard timing at all engine speeds to improve fuel economy. A vane-type phaser is installed on the front of the camshaft to
change its angular orientation relative to the sprocket, thereby adjusting the timing of valve operation on the fly. It is a dual-equal
cam phasing system that adjusts camshaft timing at the same rate for both intake and exhaust valves. The system 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 drivability. It also provides another effective tool for controlling exhaust emissions.
Engine Oil Pump System
Engine lubrication is supplied by a variable displacement two-stage vane-type oil pump assembly. An oil control solenoid valve,
controlled by the ECM, mounted to the oil pump provides two stage functionality. The oil pump is mounted on the front of the
engine block and driven directly by the crankshaft sprocket. The pump rotor and vanes rotate and draw oil from the oil pan sump
through a pick-up screen and pipe. The oil is pressurized as it passes through the pump and is sent through the engine block oil
galleries. The variable pressure/flow oil pump must be controlled by the ECM in order to maintain proper lubrication and minimize
excessive oil delivery to the cylinder heads and PCV system. There are several devices on the LT1 that use oil pressure to
maintain proper functionality. The ECM controls engine oil pressure and flow for oil spray piston cooling, variable valve timing,
cylinder deactivation along with crankshaft and camshaft bearing cooling. The default mode for the oil pump is high flow and high
pressure. This can lead to excessive oil consumption thru the PCV system.
The LT1 Gen-V engine feature oil-spray piston cooling, in which eight oil-spraying jets in the engine block drench the underside
of each piston and the surrounding cylinder wall with an extra layer of cooling, friction-reducing oil. The oil spray reduces piston
temperature, promoting extreme output and long-term durability. The extra layer of oil on the cylinder walls and wristpin also
dampens noise originating from the pistons.
Powertrain Cooling
Coolant Type
40/60 coolant/water mixture of clean, drinkable water and use only DEX-COOL® Coolant.
Engine Cooling System
A surge tank is recommended for removing air from the engine coolant, but as long as the radiator or surge tank is the highest
point in the system, then air will be evacuated from the coolant. The highest point, meaning that either the radiator or the surge
tank have a portion higher than the top of the cylinder heads. If they are not, then air can be trapped within the cylinder heads and
cause portions of the cylinder heads to overheat, which will be detrimental to engine performance and longevity. Coolant is drawn
from the radiator outlet and into the water pump inlet by the water pump. Some coolant will then be pumped from the water pump,
to the heater core, then back to the water pump. This provides the passenger compartment with heat and defrost.
Caution: Never block off the heater ports at the coolant pump. If no heater is desired, loop the inlet port to the outlet port
at the coolant pump. If blocked, the system will not operate properly and overheating of the engine will occur.
Coolant is also pumped through the water pump outlet and into the engine block. In the engine block, the coolant circulates
through the water jackets surrounding the cylinders where it absorbs heat. The coolant is then forced through the cylinder head
gasket openings and into the cylinder heads. In the cylinder heads, the coolant flows through the water jackets surrounding the
combustion chambers and valve seats, where it absorbs additional heat. From the cylinder heads, the coolant is then forced to
the thermostat. The flow of coolant will either be stopped at the thermostat until the engine is warmed, or it will flow through the
thermostat and into the radiator where it is cooled and the coolant cycle is completed. The cylinder head air bleed needs to be
routed to the highest point in the cooling system. This will assist in removing air from the cylinder heads.
Performance Crate Engine
TITLE
ALL INFORMATION WITHIN ABOVE BORDER TO BE PRINTED EXACTLY AS SHOWN ON 8 1/2 x 11
WHITE 16 POUND BOND PAPER. PRINT ON BOTH SIDES, EXCLUDING TEMPLATES.
TO BE UNITIZED IN ACCORDANCE WITH GM SPECIFICATIONS.
19416593
IR 02MY18
PART NO.
DATE
02MY18
Initial Release - Rocko Parker
4
SHEET
REVISION
27
OF
AUTH
N/A
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