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

The L20 is a 4.8L Gen. IV iron block truck engine. It 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 engine specs and information listed below is for the stock L20 engine.

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.

[Looking to upgrade your L20 engine? Check out L20 4.8L Engine Upgrade Guide: Expert Advice for L20 Mods to Maximize Performance.]

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.)

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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.