LS6 blocks

[qwik240z]

I saw a motor on eBay that advertises that a 2002 Camaro SS LS1 came with an LS6 block and that 25% of the LS1's came with that block. Is this true? Does anyone know the block numbers of the LS6 blocks to verify this? Other than the bulkhead windows in the LS6 block are there any differences or advantages between the LS1 and LS6 blocks? Thanks!

[Guest the_dj]

Yes, it's true. The later model LS1's (all since 01 I believe) can with the LS6 intake as well. Power didn't go up (much) because the stock cam is smaller in those cars.

[Phantom]

I thought that LS1 & LS6 shared the same block but that LS6 had improved intake manifold & heads. What is difference between LS1 & LS6 block?

[Mike kZ]

Here is some info on the differences:

http://www.idavette.net/hib/ls6/page3.htm

[Phantom]

Thanks Mike! Excellent article. It will definitely affect how I spend my money in the future.

[qwik240z]

I did some research on LS1tech.com and I found out that indeed GM did use some LS6 blocks in place of LS1 blocks in some 2001 and 2002 F body cars. In 2001 there were about 15% of the f Bodies that came with LS6 blocks and in 2002 about 25% had the LS6 block. You can tell the LS6 block by it's casting number on the block.

The block is stamped "12561168"

 

It seems that the LS6 bare block was used to build the LS1's as there was a shortgage of LS1 blocks. The difference in the blocks are: LS1 blocks have a 28.5 mm ventilation hole drilled through the center of all 5 bulkheads, close to the crank, for bay-to-bay breathing. LS6's have a much larger cast in holes (or "cast-in hone-over hole travel vent window" in GM talk) through the 2,3, and 4 bulkheads towards the bottom of the cylinder bores on both sides. According to GM, the 2,3, and 4 bulheads are the only ones that have an affect on bay-to-bay breathing. This change created 87% more ventilation over the LS1 block and less pumping loss at high RPM's. No official HP gains were reported, but the end factor is that the LS6 blocks durability was increased drastically over the LS1 block." The blocks are also cast using a different process. (all information taken from GMHTP July 2003 pg. 11 and summarized.)

 

Also, all 2001 and up LS1's came with the LS6 intake manifold. (better flow)

 

 

The motor I am buying has the LS6 block for what it's worth. I can't wait to get it home.