I'm putting afr lt4 heads, cc xfi268 cam , roller rockers, 58 mm throttle body and exaust to stock bottom end. I think 30lb injectors will work fine but next year i will replace with 383, or should i go with 42 lb or will the 30lb be fine for what I hope would be in the 500 fwhp range.

 

Rough guideline that works pretty well, in lieu of actual engine dyno BSFC for your engine is to multiply flywheel HP by 0.07 to get your minimum injecotr size. That assumes a moderate 0.476 #/HR/HP BSFC and a maximum duty cycle of 85%.

Sizing the injectors for your future needs.....

500 flywheel HP X 0.07 = 35 #/HR

....minimum. Larger will not hurt.

 

thanks for info I will look at that range.