General Motors 8.1L Vortec V-8

GM 8.1L Vortec Engine Specs, History, & Information

Someone of importance at General Motors suggested they take the quintessential Chevy 454 big block V-8 and make it even bigger - apparently, the concept got an overwhelming nod of approval. Enter, the 496; a big block V-8 based on the 454's 4.25 inch bore, but with a longer 4.37 inch stroke. You read right, a whopping 496 cubic inches of American Muscle for the 2500/3500 Chevrolet Silverado and GMC Sierra. The engine's obvious downfall? Fuel economy...

If you purchase an 8.1L V-8, do you really need to question the fuel economy? GM circumvented the requirement for publishing EPA certified fuel economy ratings by only offering the engine in 3/4 and 1 ton applications where the vehicle's GVWR exempts them from the regulation. At its peak, the 8.1L Vortec produced 340 horsepower and 455 lb-ft of torque, coming within 50 lb-ft of the 6.6L Duramax during its introduction for the 2001 model year and far surpassing its power rating.

As far as production engines go, the 8.1L Vortec is the Big Block of Big Blocks. Because of the engines substantial torque rating, it was been used in various marine and motorhome applications as well as being offered as an alternative to more expensive diesel options in GM's medium duty products. The engine uses sequential multi-port fuel injection and its 2 valves per cylinder and operated by a standard OHV pushrod camshaft (cam-in-block). In GM trucks and SUVs, the engine was backed by the 4L85E four speed automatic transmission - a manual transmission was not offered.

GM 8.1L Vortec V-8 Specs (Vortec 8100)


90° V-8

8.1L Vortec horsepower and torque curve

2005 Gm 8.1L Vortec horsepower and torque curves

RPO Code:



2001 - 2006:
• Chevrolet Silverado 2500HD/3500HD
• GMC Sierra 2500HD/3500HD
• Chevrolet Suburban 2500 (3/4 ton)
• GMC Yukon 2500 (3/4 ton)
• Chevrolet Express 2500/3500
• Chevrolet Avalanche 2500
• Chevrolet Kodiak

2001 - 2009:
Various marine and motorhome applications


8.1 liters, 496 CID


4.25 in


4.37 in

Block Material:

Cast iron

Cyl Head Material:

Cast iron

Firing Order:


Compression Ratio:

9.1 : 1


OHV, 2 valves per cylinder

Engine Oil Capacity:

6.5 qts w/ oil filter

Max Engine Speed:

5,000 rpm (truck/SUV applications)


2001 - 2003

340 hp @ 4,200 rpm

2004 - 2006

320 hp @ 4,200 rpm


2001 - 2003

455 lb-ft @ 3,200 rpm

2004 - 2006

440 lb-ft @ 3,200 rpm


8.1L Vortec V-8 vs 6.6L Duramax Diesel

Model Year

8.1L Vortec HP/TQ*

6.6L Duramax HP/TQ


340 hp/455 lb-ft

235 hp/500 lb-ft


340 hp/455 lb-ft

235 hp/500 lb-ft


340 hp/455 lb-ft

235 hp/500 lb-ft


320 hp/440 lb-ft

310 hp/520 lb-ft


320 hp/440 lb-ft

310 hp/520 lb-ft


320 hp/440 lb-ft

360 hp/650 lb-ft

*Excludes commercial, marine, motorhome, and medium duty applications.