CHEVROLET L8T HD V-8 Gasoline Engine Instruction Manual

LT8 Crate Engine
I Sheet P/N 19433749

L8T HD V-8 Gasoline Engine

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This publication provides general information on components and procedures which may be useful when installing or servicing your crate engine. Please read this entire publication before starting work.
This crate engine is assembled using brand new, premium quality components. It is based off the Chevrolet Generation V L8T Series architecture and utilize such modern technologies as individual ignition coil per cylinder and direct fuel injection. Due to the wide range of small block applications, if you are retrofitting a previous small block application, you may encounter installation differences between your crate engine assembly and the previous version. These differences may require modifications or additional components not included with the engine, including cooling, fuel, electrical, and exhaust systems. Some fabrication work may be required.
The L8T crate engine requires an engine control system which is available from your Chevrolet Performance Parts dealer. Check with your dealer or on www.chevroletperformance.com for the control system packages that are currently available. It is not the intent of these specifications to replace the comprehensive and detailed service practices explained in the Chevrolet service manuals. For information about warranty coverage, please contact your local Chevrolet Performance Parts dealer.
Observe all safety precautions and warnings in the service manuals when installing a crate engine in any vehicle. Wear eye protection and appropriate protective clothing. When working under or around the vehicle support it securely with jack stands. Use only the proper tools.
Exercise extreme caution when working with flammable, corrosive, and hazardous liquids and materials. Some procedures require special equipment and skills. If you do not have the appropriate training, expertise, and tools to perform any part of this conversion safely, this work should be done by a professional. This publication is intended to provide information about this crate engine and related components. This manual also describes procedures and modifications that may be useful during the installation of an L8T crate engine system. It is not intended to replace the comprehensive service manuals and parts catalogs which cover Chevrolet Performance engines and components. Rather, it is designed to provide supplemental information in areas of interest to “do-it-yourself” enthusiasts and mechanics.
This publication pertains to engines and vehicles which are used off the public highways except where specifically noted otherwise.

Legal and Emissions Information

Federal law restricts the removal of any part of a federally required emission control system on motor vehicles. Further, many states have enacted laws which prohibit tampering with or modifying any required emission or noise control system. Vehicles which are not operated on public highways are generally exempt from most regulations, as are some special interest and pre-emission vehicles. The reader is strongly urged to check all applicable local and state laws. Many of the parts described or listed in this manual are merchandised for off-highway application only, and are tagged with the “Special Parts Notice” reproduced here:
Special Parts Notice
This part has been specifically designed for Off-Highway application only. Since the installation of this part may either impair your vehicle’s emission control performance or be uncertified under current Motor Vehicle Safety Standards, it should not be installed in a vehicle used on any street or highway. Additionally, any such application could adversely affect the warranty coverage of such an on-street or highway vehicle.

INSTALLATION INSTRUCTIONS:

Engine installation
This crate engine is assembled using brand new, premium quality components. It is based off the Chevrolet Generation V L8T Series architecture from a 2021 Chevrolet Silverado 2500 Series and utilize such modern technologies as individual ignition coil per cylinder and direct fuel injection. Due to the wide range of small block applications, if you are retrofitting a previous small block application, you may encounter installation differences between your crate engine assembly and the previous version. These differences may require modifications or additional components not included with the engine, including cooling, fuel, electrical, and exhaust systems. Some fabrication work may be required.

Oil Fill Cap and Tube
This kit is supplied with the engine oil fill tube and cap (1).
Oil Level Indicator and Tube
This kit is supplied with the engine Oil Level Indicator and tube. Use the bolt to install the tube. Torque to 25 Nm (18lb-ft).
Cylinder Deactivation – Not Used With Chevrolet Performance Engine Control Kit This engine is used in the 2021 Chevrolet Silverado 2500/3500 Series. In production, to provide maximum fuel economy under light load driving conditions, the engine control module (ECM) will command the cylinder deactivation system on to deactivate engine
cylinders 1, 7, 6, and 4, switching to a V4 mode. The engine will operate on 8 cylinders, or V8 mode, during engine starting, engine idling, and medium to heavy throttle applications. This system requires many inputs (weight of vehicle, tire size, final drive ratio, etc.) to work properly. These parameters are unknown when selling the Chevrolet Performance engine controller kit. Due to these unknown parameters as well as the need to tune the motor mounts and exhaust system for operation in both V8 and V4 modes. The Chevrolet Performance engine control kit disables this feature.
The engine has not been changed, so cylinder deactivation hardware is still present.

Ignition System
The Gen-V has an advanced 58X crankshaft position encoder to ensure that ignition timing is accurate throughout its operating range. The 58X crankshaft ring and sensor provide more immediate, accurate information on the crankshaft’s position during rotation. This allows the ECM to adjust ignition timing with greater precision, which optimizes performance and economy. Engine starting is also more consistent in all operating conditions. In conjunction with 58X crankshaft timing, the Gen-V applies the latest digital cam-timing technology. The cam sensor is located in the front engine cover, and it reads a 4X sensor target on the camshaft phaser rotor which is attached to the front end of the camshaft. The target ring has four equally spaced segments that communicate the camshaft’s position more quickly and accurately than previous systems with a single segment. The dual 58X/4X measurement ensures extremely accurate timing for the life of the engine.
Moreover, it provides an effective backup system in the event one sensor fails. Air Induction Humidity Sensor: This new feature ensures optimal combustion efficiency, regardless of the surrounding air’s humidity. Coil-on- Plug Ignition: The Gen-V’s individual coil-near-plug ignition features advanced coils that are compact and mounted on the rocker covers, although they are positioned differently than on Gen-IV engine.
An individual coil for each spark plug delivers maximum voltage and consistent spark density, with no variation between cylinders. Iridium-Tip Spark Plugs: The spark plugs have an iridium electrode tip and an iridium core in the conductor, offering higher internal resistance while maintaining optimal spark density over its useful life. The electrode design improves combustion efficiency.

Fuel System

Low Pressure (Fuel Tank to Engine)
The production system uses a return less variable flow/pressure system that has been incorporated in the Chevrolet Performance engine control kit. A return less fuel system reduces the internal temperature of the fuel tank by controlling the speed of the fuel pump and not returning hot fuel from the engine to the fuel tank. The engine control kit included Fuel Pump Power Module, to regulate fuel pressure.

• Fuel supply connection (1)

High Pressure (On Engine)
A fuel flow rate of 45 G/H (Gallons per hour) at 72 psi (500 kPa) is recommended for optimum performance. Because this is a dead headed system, a pressure relief set at 84 psi (580 kPa) must be included in the fuel line between the tank pump and engine mounted high pressure pump. It is not recommended to use a low pressure fuel system that is not controlled by the FPPM (Fuel Pump Power Module). A pump with excessive capacity may result in cavitation at low flow due to the pump repeatedly stopping and starting instead of controlling to a speed/pressure. If a FPPM is not used, diagnostic codes will be set in the ECM (the MIL light may not be illuminated).
Excessive fuel hearing and potential startability/drivability issues may result from a pump operating at constant high pressure. A fuel pressure relief set to 84 psi (580 kPa) should be installed between the low pressure supply fuel pump and the engine mounted high pressure fuel pump.
Alternatively, a fuel system operating at a fixed 72 psi (500 kPa) could be used and a fuel pump relay may be triggered by the Green/Gray wire in cavity 2 of the FPPM (Fuel Pump Power Module) connector. The Green/Gray wire is a 12 volt positive side control for a fuel pump relay. Do not use or install the Fuel Pump Power Module if using this alternate method. Diagnostic codes will be set in the ECM if the FPPM is not used, but may not illuminate the MIL (malfunction indicator light). Note that excessive fuel heating and potential startability/drivability issues may result for constant high pressure.

The high fuel pressure necessary for direct injection is supplied by the high pressure fuel pump. The high pressure fuel pump is mounted on the rear of the engine under the intake manifold and is driven by a three-lobe cam on the camshaft. This high pressure fuel pump also regulates the fuel pressure using an actuator in the form of an internal solenoid-controlled valve that is controlled by the ECM.
Positive Crankcase Ventilation (PCV) System
A closed crankcase ventilation system is used to provide a more complete scavenging of the crankcase vapors. Fresh air from the air filtration system (air cleaner) is supplied to the crankcase, mixed with blow-by gases, and then passed through a crankcase ventilation valve into the intake manifold. There are two ports, one each per valve cover that need to be connected as shown. The Foul Air PCV hose should be installed between the Left (drivers) side valve cover and the port on the top side of the throttle body. Do not connect to the purge solenoid. The Fresh Air PCS hose is connected to the Right (passenger) side valve and somewhere on the inlet air system between the Mass Air Flow meter (MAF) and the engine throttle body. The air for PCV needs to be measured by the MAF, for proper engine operation. See image for proper installation.
Reference 2021 Chevrolet Silverado 2500/3500 Series L8T for additional parts.

• Fresh Air PVC Hose (1)
• Foul Air PVC Hose (2)

Evaporative Emissions Valve
The evaporative emissions system can be used with the Chevrolet Performance engine control kit but is not required for proper engine operation. This port must be either plugged or connected to a vapor canister.
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 L8T 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 L8T 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.

• Pump Inlet (1)
• Pump Outlet (2)
• Heater Inlet Pipe (3)
• Heater Outlet Pipe (4)

Engine Oil Cooling
The engine is not delivered with an engine oil cooler. It is not required but recommended that an axillary cooler be added. Reference the 2021 Chevrolet Silverado 2500/3500 Series L8T for additional parts.
Pilot Bearing (if using a manual transmission)

You must install a pilot bearing in the rear of the crankshaft, if the engine will be used with a manual transmission. The pilot bearing aligns the transmission input shaft with the crankshaft centerline. A worn or misaligned pilot bearing can cause shifting problems and rapid clutch wear.
There are two different Chevrolet pilot bearings for the L8T. 14061685 is for a long input shaft transmission and 12557583 is for a short input shaft transmission. Verify fit prior to installing the transmission or damage will occur.

Brake vacuum port
The L8T engine does NOT have a dedicated vacuum port in the intake manifold. If a vacuum source is needed for proper brake operation, an external vacuum source must be used.
Starter Motor
A starter motor is not provided with the engine. The 12724248 can be used. Reference a 2021 Chevrolet Silverado 2500/3500 Series with a L8T engine for current heat shield part numbers.

• Starter Motor and Bolts (1)
• Heat Shield and Bolts (2)

Front Accessory Drive Kit
Front accessory drive kit can be purchased thru your Chevrolet Performance Dealer.
Please refer to the Chevrolet Performance Parts catalog.

Valve cover noise insulators
Valve cover insulators can be purchase for your installation. Please refer to a 2021 Chevrolet Silverado 2500/3500 Series for correct part numbers.

• Valve Cover Insulators (1)

Lower exhaust manifold heat shields

Lower exhaust heat shields can be purchase for your installation. Please refer to a 2021 Chevrolet Silverado 2500/3500 Series for correct part numbers.

• Exhaust Manifold Heat Shields (1)

Use only Mobil 1 5W-30 engine oil.
Safety first, if the vehicle is on the ground, be sure the park brake is set, the wheels are chocked and the car cannot fall into gear. Verify everything is installed properly and nothing was missed.
IMPORTANT: This engine assembly needs to be filled with oil. After installing the engine, ensure the crankcase has been filled with the appropriate motor oil to the recommended oil fill level on the dipstick. Also check and fill as required any other necessary fluids such as coolant, power steering fluid, etc.

1. The engine should be primed with oil before starting. The use of Kent-Moore engine preluber kit J45299 is the preferred process for priming.
   a. Remove the engine oil filter and fill with clean engine oil. Save for later.
   b. Ensure the oil drain plug (2) is installed and tightened.
   c. Install EN-47971 Oil Pressure Gauge Adapter (1) and hand tighten.
   d. Attached EN-45299 Engine Preluber to EN-47971 Oil Pressure Gauge Adapter using the supplied fittings.
   e. Pump the handle on the EN-45299 Engine Preluber to flow a minimum of 1-1.9 liters (1-2 quarts) of NEW engine oil. Observe the flow of engine oil through the flexible hose and into the engine assembly.
   f. Close the valve and remove EN-45299 Engine Preluber and adapter from the EN-47971 Oil Pressure Gauge Adapter.
   g. Remove EN-47971 Oil Pressure Gauge Adapter (1).
   h. Oil Filter (1) Install NEW and tighten 3/4 to 1 turn after gasket contacts the sealing surface.
   i. Fill the engine oil to the proper level with NEW engine oil.

2. In the absence of a preluber kit, the following process can be used. Disconnect the fuel and disconnect the ignition control system (removing power from the ignition control module is generally recommended but check your ignition control system information for additional details).
   Note: Removal of the spark plugs will allow the engine to spin faster and build oil pressure faster.

3. Once the ignition control system has been disconnected, crank the engine using the starter for 10 seconds and check for oil pressure. If no pressure is indicated, wait 30 seconds and crank again for 10 seconds.

4. Repeat this process until oil pressure is indicated on the gauge.

5. Reconnect the ignition control system. Start the engine and listen for any unusual noises. If no unusual noises are noted, run the engine at approximately 1000 RPM until normal operating temperature is reached.

6. When possible, you should always allow the engine to warm up prior to driving. It is a good practice to allow the oil sump and water temperature to reach 180°F before towing heavy loads or performing hard acceleration runs.

7. The engine should be driven at varying loads and conditions for the first 30 miles or one hour without wide open throttle (WOT) or sustained high RPM accelerations.

8. Run five or six medium throttle (50%) accelerations to about 4000 RPM and back to idle (0% throttle) in gear.

9. Run two or three hard throttle (WOT 100%) accelerations to about 4000 RPM and back to idle (0% throttle) in gear.

10. Change the oil and filter. Replace the oil per the specification in step 1, and replace the filter with a new PF64 AC Delco oil filter. Inspect the oil and the oil filter for any foreign particles to ensure that the engine is functioning properly.

11. Drive the next 500 miles (12 to 15 engine hours) under normal conditions. Do not run the engine at its maximum rated engine speed. Also, do not expose the engine to extended periods of high load.

12. Change the oil and filter. Again, inspect the oil and oil filter for any foreign particles to ensure that the engine is functioning properly.

L8T Engine Specifications

Information may vary with application. All specifications listed are based on the latest production information available at the time of printing.

L8T Crate Engine Instructions
IR 07SE22
PART No. 19433749

Documents / Resources

| CHEVROLET L8T HD V-8 Gasoline Engine [pdf] Instruction Manual
L8T HD V-8 Gasoline Engine, L8T, HD V-8 Gasoline Engine, Gasoline Engine, Engine
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References

• Genuinegmpartsregistration.com
• Engines, Transmissions, Components and Upgrades | Performance

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