Originally Posted by G0at
Im not really into chevies so I have no clue whats the different betweem both of them but i made a fast research and got two different answers. If it is about the block material the 408 is iron block. If it is about the pistons shape i have no idea
A 408 is normally a 4.030" bore and a 4" stroke. You can take an LS2 block out to 4.030", but usually a 408 is built using a 6.0L iron block. That would be the heavier block as the LS1/2 blocks are aluminum.
With an LS2 block, 4.005" bore is more common with the stock sleeves, which ends up being a 403 with the 4" stroke.
An LS1 can only go to about 3.905" on the stock sleeves, which would be a 383 with the 4" stroke.