LS Engines

L20 4.8L Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs & More

2012 chevy silverado L20 4.8L engine bay


Mechanically similar, General Motors’ LS and LS-based Vortec engines wound up on almost every branch of the GM family tree: Chevy, Pontiac, GMC, Cadillac, Buick—heck, even Saab, Hummer, and Isuzu got some LS love.

Since LS and Vortec engines are so common, they’ve become the go-to performance and swap engines of the modern era.

These motors are capable of making a lot of horsepower, and respond well to upgrades like turbos, superchargers, high-flow cylinder heads, intake systems, cams, and nitrous oxide.

The aftermarket is strong for LS swap engines. Crate engines are available, and used motors are often cheaply sourced through junkyards.

Summit Racing has created a series of comprehensive guides for each engine in the LS family, so engine builders and tuners can have a handy reference for their projects.

This guide is specifically about the GM L20 4.8L iron block engine. You can find our other LS engine spec guides and LS-related tech articles here.

(Summit Racing’s Paul Spurlock and Brian Nutter contributed to this article.)

GM L20 4.8L Engine Specs

The L20 replaced the LY2 in 2010. It was upgraded with Variable Valve Timing (VVT) and Flex Fuel technology. It was available in GM pickups and vans until 2014. It was also known as the Vortec 4800.

These engines are strong and durable. Many people use them with boost or nitrous. With upgraded internals, the blocks can handle over 1,000 hp.

The L20 4.8L has a 3.780 in. bore diameter. The cylinders can be bored to LS1 size (3.898 in. +). However, that will thin out the cylinder walls. A smaller bore size will keep the block strong and rigid.

The information listed below is for the stock engine.

L20 Performance Specifications

L20 Engine Ratings
Compression Ratio8.8:1
Horsepower Rating260-302 hp
Torque Rating295-305 ft.-lbs.

L20 Applications

L20 Applications
VIN 8th DigitYearMakeModel

L20 Engine Block Specs

L20 Block Specs
Casting Number12576177, 12576178, 1589779
Displacement4.8L / 293 c.i.d.
Bore Dia. 3.780 in.
Stroke3.267 in.
Deck Height9.240 in.
Bore Spacing4.400 in.
Thrust Bearing Location#3 Main
Main Cap Style6-Bolt
Main Housing Bore Dia.2.751 in.
Cam Housing Bore Dia. Bore 1/5 = 2.346 in. Bore 2/4 = 2.326 in. Bore 3 = 2.307 in.
Cam-to-Crank Centerline4.914 in.

L20 Rotating Assembly

L20 Rotating Assembly Specs
Piston MaterialHypereutectic Cast Aluminum Alloy
Piston StyleFlat Top with valve reliefs
Piston Volume+3cc
Wrist Pin Dia.0.9431 in. (Full Floating)
Connecting Rod MaterialPowdered Metal
Connecting Rod StyleI-Beam
Connecting Rod Length6.098 in.
Connecting Rod Housing Bore2.225 in.
Connecting Rod BoltsM9 x 1 x 43
Connecting Rod Casting Number (last three digits)121
Crankshaft MaterialCast Iron
Crankshaft Casting Number (last three digits)482
Crankshaft Main Journal Dia.2.559 in.
Crankshaft Rod Journal Dia.2.100 in.
Reluctor Wheel58x

L20 Cylinder Heads

L20 Cylinder Head Specs
Casting Numbers799, 243
Combustion Chamber Volume65cc
Intake Port ShapeCathedral
Intake Runner Volume210cc
Exhaust Port ShapeD-Port
Exhaust Runner Volume75cc
Intake Valve Diameter2.000 in.
Exhaust Valve Diameter1.575 in.
Cylinder Head Bolt StyleTorque to Yield (TTY)
Cylinder Head Bolt Size (10) M11 x 2 x 100, (5) M8 x 1.25 x 45

L20 Camshaft Specs

Duration @ .050 in. (int./exh.)191°/190°
Valve Lift (int./exh.)0.457 in./0.466 in.
Lobe Separation Angle114°
Cam Gear Attachment1-Bolt
Cam Gear Poles4x
Active Fuel Management (AFM)No
Variable Valve Timing (VVT)Yes

L20 Valvetrain

L20 Valvetrain Specs
Lifter StyleHydraulic Roller
Lifter Link StylePlastic Lifter Tray
Lifter Body Diameter0.842 in.
Pushrod Length7.385 in.
Rocker Arm Mounting StylePedestal
Rocker Arm StyleDie-Cast, Roller Fulcrum
Rocker Ratio1.7
Rocker OffsetNone
Valve Spring StyleBeehive
Valve Spring ColorNatural
Valve Angle15 Degrees
Intake Valve MaterialSteel, Solid Stem
Intake Valve Dia.2.000 in.
Exhaust Valve MaterialSteel, Solid Stem
Exhaust Valve Dia.1.575 in.

L20 Throttle Body, Fuel Injector Specs & More

Intake ManifoldTruck-Style
Throttle Body87mm, 4-bolt
Throttle Control Electronic, Drive-by-Wire
Fuel Injector Part Number 12613411
Fuel Injector Flow32 lb./hr. @ 43 psi, 36 lb./hr. @ 58 psi
Flex Fuel CapableYes
Fuel Injector Length Between O-Rings 1.900 in.
Fuel Injector Connector EV6
Crankshaft Reluctor Ring58x
Camshaft Sensor LocationFront mount, 4x on Cam
Oil Pan
Deep Rear Sump
Oil PumpStandard Flow
(0.96 c.i. per rev.)
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One Comment

  1. WHY is it So F’ing DIFFICULT to find Engine Assembly WEIGHTS ?!? I’ve been googling for TWO HOURS, trying to find out the weight of the 4.8 , 5.7 Vortec, 5.3 , and 6.0

    Can you HELP ?

    Same for Ford’s 5.0 , 4.6 , 5.4 , and 6.8

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