I have been searching for the past couple of days and have got several different answers out of this. Wut is the stock bore size on the LS1. I just want to make sure wut is right. Thanks in advance.

 

3.897"

 

3.898

 

3.898, now you have a majority.

 

Thanks

 

Whats the largest you can bore it too?

 

When I checked with GM Older LS1's where capable of .005 honing and the later Ls1's could take .010 ( According to GM) not sure what year it changed.

 

1999 can take the .010
1997 and 1998 can only take the .005

 

Okay, now I am confused. Is it 99 or 00 block that can take more? 3.898 is your bore size btw. I have heard .010 for 99 or 00 and older and .020 for either 00 or 01 and newer. Which is correct? I know that in 01 some f-bods had ls6 blocks, is this why?

 

98- go .005 over
99-02- go .010 over

I wouldn't go more than that. The ls6 came in some f bodies in 01-02 from what I heard was a shortage of ls1 blocks. The ls6 block is really no better than an ls1 strength wise, but would not need modified to run ls6 valley cover like an ls1 does.

 

I thought the LS6 block was 3.905???

 

3.905 is the most common size for aftermarket pistons. You want .003" difference in the bore and piston. So a 3.898 + .010= 3.908 and 3.908 - .003" difference = 3.905. Makes perfect sense now doesn't it? Cleared myself up as well.

Am I right or not? I think it is though.

 

98 blocks

3.898
+.005
-----
3.903

So for a 98 block you would want to order 3.900" pistons

And for 99+ blocks

3.898
+.010
-----
3.908
So order a 3.905 piston

This also varies for n2o cars I know but I am not sure about FI cars. I think n2o cars need a little more room in the bore so a 3.900-3.903 piston would be correct for them depending on shot right?

 

some good information i just learn.i know for head gasket cometic sells 2 diffrent sizes of bores right?but is it needed to bore over the block?can it just be clean and thats it without boring it?

 

I believe cometic sells one for 3.9" and one for 4" bores, roughly. You would need the 3.9" for your application. Unless you had your block sleeved with Dart and then you'd need the bigger ones. Til then stick with the regular size ones.

 

No, pistons are ordered on a bore size, not the piston size. Stock bore on a LS1 is 3.898, but the pistons are smaller than that. If you are getting 3.903 pistons you are getting pistons that are designed for a 3.903 bore which in reality the pistons are only 3.900 or something like that. http://www.mahle.com/obj.nsf/6626520.../mmscat03c.pdf All the manufactures do that.

 

hmmm, I didn't know the manufactures automatically did that. My machine shop told me otherwise. Hell, it made sense to me, the whole .010 bore = 3.908 then taking away the .003" from the piston = 3.905". Are you 100% sure about that?