New from Katech – the sleeved LT1 cylinder block. This block supports greater displacement and is built to handle whatever you throw at it. See more details below.

Official Release:

Katech’s new “sleeved” LT1 cylinder block supports greater displacement Gen V LT1 engines and serves as the foundation for 427-cubic-inch (7.0L) engine combinations – including Katech’s own 700-hp Street Attack 427 crate engine.

“We developed this sleeved block for our 427 crate engine package and now we are offering it to the public for your own build,” said Jason Harding, director of aftermarket operations, Katech. “It maintains an optimal bore/stroke ratio for high-revving performance and excellent durability. And with stronger sleeves than the originals, you can add power with the confidence the block will stand up to the pressure.”

Katech starts with a brand-new LT1 aluminum cylinder block and replaces the stock grey cast iron cylinder liners, which feature a 4.06-inch bore dimension, with stronger centrifugally cast ductile iron liners offered rough-bored to 4.120 inches or finish-honed to 4.125 inches or 4.130 inches.

Along with an approximate tensile strength of 120 ksi, the ductile iron sleeves flex more than the more-brittle original liners, which helps prevent cracking under very high cylinder pressures. Additionally, the bottom of the sleeves are machined to allow the use of a 4.000-inch stroke crankshaft.

With 4.125-inch bores and the 4.000-inch stroke, the enhanced LT1 block delivers the same dimensions as the previous-generation LS7 to create a 427-cubic-inch (7.0L) displacement.


  • Double vacuum-impregnated
  • Surface decked
  • Camshaft bearings installed
  • Machined for piston squirters