Here's my understanding (correct me if I'm wrong) - I think a "small block" is referring to any block based on classic small block Chevy V8 introduced as a 265 in 1955. Over the years the displacement ranged from 262-400. A 262 can share many parts with a 400, although some machining/different bearings may be needed, and there are mains (2 and 4 bolt). So it isn't exactly necessarily directly linked to displacement. Here's a link I found with a history of the small block Chev - it's a good read, and not very long:

http://www.afn.org/~afn14222/sbchist.htm

A 396 is not a small block, while a 400 is. A Pontiac 350 or 400 uses the same block as a 455 which isn't the same block as a small block Chevy 350 or 400. I know Oldsmobile made an aluminum rocket block in the mid-90's that could be bored and stroked to a 455, which could use small block Chevy parts. So, basically, it's a confusing mess.

Technically, I suppose an LS1 is not a classic small block, but I think since Chevy has kind of created a tradition, and since the LS1's don't seem to be good for any more cubic inches than the small blocks, it will probably still be considered one, even though the parts can't be shared. It's really just an evolution of the push rod engine.

Travis

 

I was under the impression that you could switch out the pistons, heads and cam on and of the LS-1 engines. I might be wrong, I just thought that was the only difference.

 

in order to change a 4.8 to a 5.3 you basically need to buy a new crankshaft and connecting rods. the 4.8L is just a destroked 5.3

the heads between the two engines have the same combustion chamber size i believe. Even if they didnt change the heads still wouldnt change the displacement, only the compression ratio.