[chevelle4542speed]

have 454 .30 trw forged pop ups. comp is between 10.5 - 11 to 1.
cast rods shot peened, magnu fluxed , beams ground downed, arp rod bolts.
cast crank 10/10 10 thousands end play, yea i know. king racing bearings. motor already making about 500 to 575 hp spinning to 6500 rpms
so what would be the best shot i could use , thinking about 150 to 200hp
shot.

 

[Ron Golden]

150-200 shot shouldn't be a problem. However you'll need to retard the total timing about 8-10 degrees when you dump the nitrous to it. Cylinder pressure and temperature goes way up and the engine needs less timing. Be sure you DON'T use extended tip spark plugs with that much nitrous or you could get preignition then detonation. Put a fuel pressure gauge where you can see it when you dump the nitrous to it. Make DAMN sure your fuel pressure doesn't drop during your run. If the engine goes lean from lack of fuel you'll be building a new engine. Have fun.

Ron