Originally Posted by radz282003
While I agree with most of this, I've read that later LS1 blocks are more desireable on the whole because the larger windows cast into the bulkheads were considered by engine builders to be a little weaker. They aided in high RPM breathing and lowered pumping losses, however the block is produced differently than the LS1 block and I believe the aluminum is a little different too.
the difference is in the density of the aluminum... the LS6 blocks are denser than the LS1 blocks... as you mentioned, this was done to counteract the fact that the larger windows were in the LS6 blocks... by increasing the density of the block, they were able to maintain the same, and sometimes better, durability... hence what I said about the LS6 blocks being more tolerant to spray.
the way it was told to me was: "if you're going to go big cube, use the LS1 block... if you're going to go spray or power adder, go with the LS6 block"