Last week, GM Authority was first to tell you that the new 6.6L V-8 GM engine for use in the all-new 2020 Chevrolet Silverado HD and 2020 GMC Sierra HD was assigned RPO Code L8T. Today, we have specifications of the new gasoline mill.
Here are the basics: the L8T features 8 cylinders and displaces 6.6 liters via an OverHead Valve (OHV) layout, otherwise known as push-rod. The GM engine is based on The automaker’s fifth-generation Small Block engine architecture initially introduced by the 6.2L V-8 LT1, albeit with a few key differences.
Unlike other Gen V Small Black GM engines that have aluminum blocks (like the LT1), the L8T has a cast iron block. The other big difference is in the stroke: the L8T has a bore of 103.25 mm and a stroke of 98 mm, while the LT1 measures in at 103.25 x 92 mm. Finally, the L8T’s compression ratio runs at 10.8:1, while that of the LT1 is 11.5:1.
Without any further ado, behold the specs for 6.6L V8 L8T GM engine.
|GM RPO Code:||L8T|
|Type:||6.6L V-8 gasoline|
|Bore & Stroke (in / mm):||4.06 x 3.86 / 103.25 x 98|
|Block Material:||Cast iron with nodular iron main caps|
|Cylinder Head Material:||Cast aluminum|
|Valvetrain:||Overhead-valve, two valves per cylinder, variable valve timing|
|Fuel Delivery:||Direct fuel injection|
|Power (hp / kW @ rpm):||401 / 299 @ 5200 (SAE certified)|
|Torque (lb.-ft. / Nm @ rpm):||464 / 629 @ 4000 (SAE certified)|
|Predecessor:||6.0L V8 L96/LC8|
In the 2020 Silverado HD and 2020 Sierra HD, the L8T makes an SAE-certified 401 horsepower (299 kW) at 5200 RPM and 464 pound-feet of torque (629 Nm) at 4000 RPM. It will be mated to the GM 6-speed automatic transmission (6L90) driving either the two rear wheels or all four wheels.
Stay tuned to GM Authority as we learn more about the L8T, and for more GM news.