LS1 Block years and differences
I am looking at a wrecked 99 Firebird for its motor and trans locally and dont want to buy the wrong gen LS1
any help is much appreciated thanks in advance.
I am looking at a wrecked 99 Firebird for its motor and trans locally and dont want to buy the wrong gen LS1
any help is much appreciated thanks in advance.

Understand that there is nothing "shitty" about the 806 heads vs. 853. They are exactly the same other than the perimeter bolt valve covers and individual coil packs vs. center bolt valve covers and coil rails. Internally, neither is superior to the other.
Only the 241s were *marginally* superior in stock form, due to the improved casting process. But this is a small thing, and is negated once the heads have been ported. All LS1 heads (806/853/241) have the same potential once worked.
Either way, the '99 engine would have come with 853s stock.
The sticky linked above gives futher details on this.







