I'm building a 305 and I'd like to add some NOS to it, I'm thinking 100hp-150hp shot. what I was wondering is, if I balance the rotating assembly and use forged pistons will that be ok? or will I need a complete forged crank/rods? the engine is going to be a 305(maybe.06 over) whte 9:1 compression around 220dur. cam, headers performer rpm intake and a holley carb.

 

You should be alright running even a 150 shot without forged internals...but if you got the money...

 

Forged pistons can only make your engine stronger so why not do it? I think its well worth the insurance. It sucks breaking something in the bottom end so you might as well make it as strong as your wallet permits so you dont have to take it apart a few years down the road cause you detonated and damaged a piston.

 

All forged pistons are not created alike. Talk with a piston manufacturer regarding their pistons for nitrous use. The thickness of materials is criticle here... for example, one of the car mags caved in the top of a TRW forged piston a while back... I think it was a 150 or 175 shot in a 350 ci motor. The thickness of the material above the rings is also important for nitrous use... ring land failure is not a good thing. Dont forget to look into the correct ring gap... it will be different than for a n/a motor. And last but not least, that 305 has a smaller bore than a 350... this equates to more cylinder pressure than with a motor with a larger bore for the same sized shot. IE: for a given sized nitrous jet a given quantity of fuel/nirous will be injecten into the motor... this mixture contains a given ammount of energy that is deposited over the surface area of a piston... as the area of the piston decreases the PSI on top of it increases proportionally. In other words, your piston selection is more important with the 305 than it would be with a 350.

Make sure you do some cost analysis before you rebuild that 305... a 350 or 400 will be worth 25-100+ hp depending on the build.