L8T Engine

Specifications

The GM 6.6L V8 L8T engine is a Gen-V small-block gasoline engine engineered specifically for heavy-duty truck applications, producing 401 horsepower at 5,200 rpm and 464 lb-ft of torque at 4,000 rpm. Designed for strength and long-term durability, it features a cast-iron engine block, aluminum cylinder heads, and a forged steel crankshaft. Internally, the L8T uses forged powder-metal connecting rods and hypereutectic aluminum pistons, providing a strong balance of durability and efficiency. The engine utilizes direct fuel injection and a 10.8:1 compression ratio to deliver consistent power and responsive performance under load.

The L8T does not use Active Fuel Management (AFM) or Dynamic Fuel Management (DFM), enhancing reliability and making it a preferred choice for long-term ownership. Primarily found in Chevrolet and GMC 2500HD and 3500HD trucks, the L8T is a robust gasoline engine well-suited for towing, hauling, and commercial-duty use where dependable performance is critical.

Engine Variants

Chevrolet Silverado 2500HD / 3500HD (2020–Present)

In the Silverado HD lineup, the 6.6L L8T V8 delivers 401 horsepower and 464 lb-ft of torque, tuned for strong low-RPM pulling power. Paired with a 6-speed heavy-duty automatic transmission, it features a cast-iron block, direct fuel injection, and variable valve timing, making it well-suited for towing, hauling, and demanding job-site use.

GMC Sierra 2500HD / 3500HD (2020–Present)

The GMC Sierra HD uses the same L8T 6.6L gasoline V8, producing 401 hp and 464 lb-ft of torque with an emphasis on durability and smooth power delivery. Matched to a 6-speed automatic, the engine supports high payload and towing applications while offering simpler maintenance compared to diesel alternatives.

Chevrolet Low Cab Forward (LCF) Trucks (2021–Present)

In Chevrolet LCF commercial trucks, the L8T engine is optimized for vocational duty cycles, delivering consistent torque for urban delivery, box trucks, and upfits. The naturally aspirated 6.6L V8 provides dependable performance, compatibility with PTO applications, and long service intervals —ideal for fleet operations.

Chevrolet Express 2500 / 3500 Vans (2024–Present)

For the Chevrolet Express vans, the L8T 6.6L V8 offers robust gasoline-powered performance for cargo and passenger transport. With 401 hp and 464 lb-ft of torque, it supports heavy payloads and frequent stop-and-go driving, making it a reliable option for commercial fleets, shuttle services, and work vans.

Frequently Asked Questions