According to article in High Performance Pontiac on page 16 that arrived yesterday 10% of 2001 F cars and 25% of 2002 F cars have LS6 block. A casting # 12561168 denotes LS6 block. The number is located on driver's side, at back of left hand deck above transmission flange. Pretty hard to get a look at the number the way our engines are set back. I am surprised GM did this, if true.

 

If you do a search on any of the LS1 sites, you'll see that this has been floating around for about 2 weeks.

Easiest way to tell ... look for the bulls-eye (or lack thereof)

 

Yep, its true. A couple of Pontiac F-body owners in my area have the #12561168 casting. However, these's no real performance advantage in having a LS6 block while the rest of the motor is LS1.

It's not unusal at all for GM to subsitute identical (or nearly so) parts even though they may have different casting/stamped numbers. They've been doing it since the 1950's.

A #12561168 block in a F-body DOES NOT make a LS6 in a F-body.

Enjoy your cars.

 

Yeah uhuh. Thats what they want you to think. Its an LS6 all right. Yup u betcha. No wonder my tranny broke, it couldnt handle the power of the LS6. The price you hafta pay with 400+ hp. Also, I always kinda wondered why I ran a 12.2 bone stock.

 

OK so bullseye = LS1 block right??

 

Huh?

Sooo...you're saying that you got an LS6 in your Z right from the factory?

Factory LS6 powered Z28:

 

Notice the roll eyes in my post. I was being sarcastic.

 

Yup.

My 2001 WS6 was built in October 2000. It has the LS1 block.

 

<---Has an LS6 block in his SS...Well its not in yet...But gimme some time to get it here first...

 

So where is this bullseye located? How big is it, etc.?

 

Here's a couple of pics -

LS1 -

LS6 -

that were posted on ls1tech.com. The bullseye most visible is on the passenger side front of the block just at the corner of the head.

 

I've got bulls-eyes alright. Thanks for the link to the pics. So the bulls-eye means I've got an LS1 block right?

 

Yes that is correct...

I have a LS6 block in my WS6

 

You should put it in your sig.

 

This is very interesting. After reading this thread I went out to my garage and took a look at my car, and then took a look at Frezza's car (I am storing his 2002 in my garage for the winter).

My block (LS6 block)
Frezza's block (LS1 block)

Kinda interesting.

Now the the flood of questions....

So what advatages does having the LS6 block have? None? Stronger block?

What are the major differences between the two?

I know that the 2002s have the LS6 intake, so what would it take to make my car have a true LS6 (not from the factory, obviously). Is it basically just heads and cam or is there more to it than that?