I'm going to be building another motor for my 240 this summer and i'm trying to plan out my fuel system.

I have some 50lb injectors right now.. how big is that in cc?

I need to pick some up that can take me up to 500hp.. I'm only going for 400 though.

Generally how big of injectors should i need?

 

850cc or roughly 80lb injector size will take you to 500hp at 85% duty cycle and a .55 bsfc (brake specific fuel consumption...FI car usually use 0.55, n/a uses 0.45). A 50lb. injector should be close to a 550cc injector or around there.