LS4 Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs & More

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, 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 LS4. 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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Chevy LS4 Engine Specs

The LS4 engine is a Gen. 4, 5.3L, aluminum small block engine used in GM cars between 2005 and 2009. It is unique because it was the only LS engine used in FWD vehicles.

The LS4 had cathedral port cylinder heads and used Active Fuel Management (AFM). The engine was not Flex Fuel (E85) capable and did not use Variable Valve Timing (VVT) technology.

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To make this engine work, GM made several modifications to the engine:

• The engine was mounted in a transverse position, using unique motor mounts.
• The intake manifold was smaller than other LS manifolds and reversed, placing the throttle body over the flexplate.
• The engine used a metric, 60-degree, Chevrolet V6 bellhousing.
• The starter was mounted on the transmission, not the engine block.
• The timing cover, crankshaft, and accessory drive were all modified to fit in the FWD engine bays.

Because of its unique configuration, the LS4 is usually NOT a good candidate for an engine swap.

The information listed here is for a stock engine.

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