I want a sanity check to make sure i'm not making things up:

It seems like from most of the reading ive done on this forum and ls1tech, most H/C lt1s like somewhere between 35-38* max total timing at WOT (as reported by a scanner) whereas most h/c ls1s like a signifcantly lower amount -- something like 25-28* max.

Is this consistant with what y'all have seen?

 

Yup. I've seen that too. I've read that for whatever reason, the LS1s require less advance then the LT1s.

 

Cool -- have you ever seen any info on why?

I would think its a combination of the LT1's reverse-flow cooling and the LS1's better combustion chamber design.

 

Most likely has to do with the flame propagation from the plug. And that depends on the shape of the combustion chamber, shape of the piston top, the location of the plug, the turbulance of the charge caused by inlet valve swirl and the quench/squish, etc.