Horsepower Research in McKinney, Texas has made quite a name for itself building large displacement late model LS and LT based Chevrolet engines for drag racing, road racing and all around hot street cars. One of their newest builds is a 468 cubic inch C7 Z06 LT engine for a local customer who was dissatisfied with the performance of his Corvette. While fast, the supercharged car created excessive heat when run hard at the track. He didn't like that and asked the Horsepower guys to find a solution.
After investigating various cooling upgrades they decided to pursue a different path by completely replacing the supercharged engine with a big cubic inch normally aspirated engine capable of meeting or exceeding the output of the factory powerplant. The existing engine was removed and saved for another project and the team proceeded to engineer a normally aspirated 468 cubic inch engine designed to exceed the power of the supercharged engine while handily removing weight from the front of the car.
The core structure of this engine is a new GM Gen V LT1/LT4 cylinder block both of which share the same part number. As seen here, the new LT block is immediately machined to accept large bore Darton sleeves which permit a larger 4.185-inch bore and longer cylinders to accommodate the increased stroke.