The biggest part of any engine build is the block. In our case it’s this GM Gen IV 6-liter LS2 block. We could have used the block from the old engine, but that would have meant taking the car off the street. To save time we picked up this brand new one from a buddy for $1,000. If you’re looking for a block, shop around because the deals are out there. Keep in mind that while the blocks from GM do include things like cam bearings and main bolts, they come with almost nothing else; such as sensors and LS-specific plugs.