Genuine GM L8T Forged Steel Crankshaft, 3.858" Stroke (LS Stroker Crank)

GM 12708884

This crank can be fitted to all LS engines ( some needing to be clearanced)

When fitting this crank to a LSA or LS3 with a 4.065 bore the new engine capacity will be 6.6L or 400Ci.

Suits 3.860" L8T Stroker
8 bolt rear flange
58 tooth reluctor wheel installed
This crank has an LSA style snout
- Use CS8LSA-SR or CS8LSA timing chain sets
- Use 12636325 flex plate crank

The factory L8T crankshaft is a stout piece. Made from forged steel, with centre counterweights and a 3.858-inch stroke, we felt no need to exchange it for an aftermarket crank.

The crankshaft in the 6.6-liter L8T is a forged steel unit that offers a slightly longer stroke to get the extra displacement over its 6.2-liter little brother. The stroke measures 3.858 inches, which is 0.236 inches more than the 5.3-liter and 6.2-liter LTs. But this crank is more than a baby-stroker crank from the factory, it is designed to not break a sweat while towing heavy loads, so GM designed it with centre counterweights to make it more stable at high-load.

When in development, GM subjected the L8T engine to rigorous durability testing. One such test forced the engine to cycle between the peak torque and peak horsepower at 110 percent of its max-rated load for a continuous 600 hours without fail. This translates to a crankshaft that is stronger than other LT engines and a block that offers features that we can utilise to build a bottom-end that can handle high boost applications.