We are having a discussion over on the truck forum about squeezing the most out of the 5.3L in naturally aspirated form.

One guy said that though there are differences in the bare block (iron vs. aluminum), the rotating assemblies are completely the same in both build specs and material, except that the 5.3L pistons are a little smaller. This would mean that the 5.3L has LESS reciprocating weight than the LS1, and SHOULD therefore be able to rev higher.

This has brought me to question if I should raise my shiftpoint from 5900 to 6300 or so b/c I am really cutting off my cam.

Now to the questions:
Are the reciprocating components IN FACT the same?
What does GM claim to be the redline of the LS1?
What do you guys say is the **SAFE**SAFE**SAFE** MAX RPM on a stock bottom end of an LS1 and also a 5.3L

Also, with an LS6 cam, springs, and retainers (are those retainers even different than the 5.3?) at what RPM would I begin to see valve float?

Thanks a lot!
-Derek

 

Nobody wants to help out the truck guys?

 

as far as max safe rpms (ls1), it depends how lucky you feel. >6500 rpms, rod bolts are on borrowed time. some do it with out problems, some don't. in fact some are shifting at 7k.

as far as valve float you should throw it on a dyno. won't be too hard to see where it starts.

 

borrowed time @ 6500 w/ rodbolts..... ehhh, that almost scares me off there.

 

Well, if the components really are the same, then MAYBE I'ld be okay to move it to 6300 on stock bolts....

I really wish there were just definative answers here.

Some say go, others say no.

Can any1 tell me what GM says the LS1 redline is?

Thanks again guys,
Derek

 

6250 or 6300 i cant remember

 

The stock auto shift point for my 2000 was 6k rpm. The 5.3's after and including 2001 are identical to the 5.7 except for the pistons. The 2000 and before are pretty close but the cranks are solid and weigh a little bit more (3lbs). I would say 6300 rpm would be no problem with some upgraded springs (maybe some 918's).