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Old 03-01-2008, 04:29 PM   #16
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Originally Posted by sickboy View Post
There's some misinformation in this thread here... and I'm a stickler for details so:
Yes some of the later Fbods got the LS6 block, but there's no real advantage of having it since everything else (except LS6 intake) was still LS1 spec. Ls6's had different heads and cam at the very least. There are only minor differences in the LS1 block vs the LS6 block (see No Fbody ever got LS6 heads.
LS6 heads are 243 castings and have different valves/springs than the 241 castings of the Fbody's --> Earlier Fbods got 853 or 806 casting heads. The LS6 heads had special springs/valves allow them to safely rev higher. Incidentally LS-2's also got the 243 casting heads but with different valves.
almost completely correct.

the LS1 vs. LS6 block is a debate that will live forever, but here are the facts:

1. the LS6 block has vents at the bottom of the cylinders to allow for better backpressure dissipation... the LS1 block did not have this.

2. the LS6 blocks that wound up in the f-bodies were made from the denser casting, and therefore were more prone to tolerate nitrous... the LS1 blocks were almost equally tolerant of nitrous, but were made from a less dense product run.

3. the way to tell if your block is an LS6 block is to look at the casting number at the top, back of the block and on the driver's side... the LS6 casting number is 12561168... anything else is the LS1 casting number.

4. LS6 heads were only available on f-bodies through aftermarket companies like GMMG built cars.

5. LS6 block f-bodies tend to have a better time at high RPMs than LS1 block engines do... we have one of each in a 2001 and 2002 Z28... I've driven both when they were stock and there really is a difference.

dont believe everything you read on LS1Tech... a site with that many people is bound to have a bunch of trolls on it that post stuff that they've heard to be true and then it spreads like wildfire.

oh, and there is rumor that the cylinder vents were added to the LS1 casting during the 2001 model run... having never seen one of these engines with one, and having seen several 2002 LS1 engines without them, I cannot confirm or deny this rumor... but this was originally stated by a GM employee who should know the facts... my only guess is that the LS1s that I ran across in 2002 cars were leftover blocks that wound up in the 2002 model cars... and probably have an incorrect date stamp to match up to the 2002 f-body.
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