One could argue that the Vortec's major disadvantage is its fuel economy; or lack thereof. However, those that acquire a vehicle with such an engine must obviously have needs that don't include fuel efficiency and the performance of the engine, particularly its low-end torque, is a more pertinent factor. Because the engine is only found in vehicles with a gross vehicle weight rating (GVWR) greater than 8,500 lbs, GM was not required to provide estimated fuel economy ratings through the EPA. Owners can expect to see MPGs peak in the mid-teens on the highway and drop into single digit territory with heavy towing.
The 8.1L's substantial torque rating and flat torque curve also make it suitable for marine and motorhome applications, typically as an economical option to more expensive diesel powertrain offerings. In GMC and Chevrolet SUV applications (including Suburban and Yukon 2500 models), the engine was mated exclusively to the GM 4L85E four speed automatic transmission. In Silverado and Sierra HD applications, the 8.1L Vortec was available mated to either the Allison 1000 automatic or ZF 6 speed manual transmission. GM retired the engine internally following the 2006 model year, but continued to manufacturer the engine for applications outside GM vehicles through 2009.
GM 8.1L Vortec V-8 Specs (Vortec 8100)
| Type/Configuration | 90° V-8 | |
| RPO Code | L18 | |
| Applications | 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 |
|
| Displacement | 8.1 liters, 496 CID | |
| Bore | 4.25 in | |
| Stroke | 4.37 in | |
| Block Material | Cast iron | |
| Cyl Head Material | Cast iron | |
| Firing Order | 1-8-7-2-6-5-4-3 | |
| Compression Ratio | 9.1 : 1 | |
| Valvetrain | OHV, 2 valves per cylinder | |
| Engine Oil Capacity | 6.5 qts w/ oil filter change | |
| Max Engine Speed | 5,000 rpm (truck/SUV applications) | |
| Horsepower | 2001 - 2003 | 340 hp @ 4,200 rpm |
| 2004 - 2006 | 320 hp @ 4,200 rpm | |
| Torque | 2001 - 2003 | 455 lb-ft @ 3,200 rpm |
| 2004 - 2006 | 440 lb-ft @ 3,200 rpm | |
8.1L Vortec Horsepower& Torque Curve
8.1L Vortec V-8 vs 6.6L Duramax Diesel
| Model Year | 8.1L Vortec HP/TQ* | 6.6L Duramax HP/TQ |
| 2001 | 340 hp/455 lb-ft | 300 hp / 520 lb-ft |
| 2002 | 340 hp/455 lb-ft | 300 hp / 520 lb-ft |
| 2003 | 340 hp/455 lb-ft | 300 hp / 520 lb-ft |
| 2004 | 320 hp/440 lb-ft | 300 hp / 520 lb-ft (LB7) |
| 2005 | 320 hp/440 lb-ft | 310 hp/520 lb-ft |
| 2006 | 320 hp/440 lb-ft | 360 hp/650 lb-ft |
*Excludes commercial, marine, motorhome, and medium duty applications.