i searched and basically came up with nothing useful. the results were so wide-spread it is making my head hurt. i have some specific questions regarding the 5.3 engines, any help is appreciated.

what year(s) of the 5.3 came with flat-top pistons?
anyone know the largest cam to fit in that longblock?
are the rod bolts of this engine a weak link like the other ls motors?

you don't hear of as many ppl blowing these engines up and basically finding every weak link, like the ls1. i know my way around the ls and lq motors very well. i assume the 5.3 is just a smaller displacement version. the stock short being able to spin 7k fairly easily with the obivous upgrades (rod bolts, oil pump, timing chain, etc).

i see a ton of ls1 and lq4/9 swaps into cars, but not very many 5.3s. why is that? they are cheap and i assume would make comparable power to an ls1 when all is said and done. maybe even offer a few rpm up top due to less reciprocating mass. ultimately i'd like to buy a swap car and remove ls1/lqwhatever and replace it with a stock short 5.3 with a serious h/c/i upgrade. i think these engines are discredited and very underrated because of their big brothers.

 

the 4.8l pistons are flat top and you can use those with the 5.3l rods and crank. the h o 5.3 have flat tops.

replace the rod bolts!! chep insurance. if you want to spin over 6k replace them.

you dont see people going from the ls1 to the 5.3 because you are going to a heavyer motor with less cid.

 

Couldn't have said it better myself.

 

If you are seriously entertaining this idea you would be looking for a L33 pullout motor, the 5.3l H.O. is based on an aluminum block - essentially a LS1 block with thicker cylinder liners for the smaller bore. This motor also comes with 799 or 243 cylinder heads, which would match well with your high rpm intentions. This engine also comes with flat top pistons for a 9.9 to 1 compression ratio.

 

I'm going to jump in here and correct you two. You cannot use 4.8l flat top pistons on a 5.3l rod and crank combo. The pistons compression height will not be correct, and will be sticking to far out of the bore. Just use the L33 pistons on a set of LQ9 rods with a set of ARP rod bolts, they are beefier than the stock 5.3L rods.