I have a stock 93 camaro z28 and was want know if the stock piston rods can handle up to 400hp?

 

Assuming you mean the connecting rods:

If you mean 400hp measured at the flywheel, yes.

If you mean 400 at the wheels, probably -- depending on a lot of details (and a touch of luck). There are guys making 600-800hp with forced induction on LT1s with stock rotating assemblies. There are also guys who've thrown a rod at stock power levels.

 

Probably not a problem.

In 93, the LT1 was using the older "pink" forged/shot-peened connecting rods. Strong, but not as good as the powder metal (PM) rods that GM started using in the LT1 engines during the 1994 model year. My "very late" 94 had the PM rods. But there is no defined changeover date. There are reports of the pinks being found in 1996 LT1's.

In any case, 400 HP at the flywheel is not problem, 400 at the rear wheels (closing in at 500 HP at the crank) is marginal. The PM's are stronger. I have seen two well-documented examples of PM rod failure, and both occurred at about the 600 HP level. And HP isn't the only factor to consider.... the higher the RPM, the higher the loads on the rods.