what size injectors do i need for mod's in sig? are the stock ones big enough? also if i build a 383 this summer will the injectors i buy have to be replaced again?

 

Your stockers are ok for now.Definitely need to upgrade with a 383.

 

Im going with 36's for my 383...stock ones are generally good up to 400-425 crank HP....after that the duty cycles tend to get too high.

 

thanks for the info. so there isnt any benifit from bigger injectors with only a measly hotcam

 

This calculator is pretty handy for injector sizing:

http://www.smokemup.com/auto_math/fuel_injector.php

 

so would 30 lbs injectors work on the steup i have and the future stroker.

 

Yes

 

I would say 30 lbers if you plan on a NA 383 or 36lbers if you plan on spraying it.

 

I have good logged data before and after a switch to 30# SVO injectors. I was seeing 90+ duty cycle between 3400-4400 at 85% throttle with stock injectors. Since changing to 30's with fuel pressure at 44psi I have set computer injector constant to 33.13 to get blm's right at part throttle. I have monitored a 68% duty cycle between 5100-5600 at 100% throttle. I have not pushed the new engine too hard. I would think this would support 150 dry nitrous with the fuel pressure at 48 or so. If you don't want to jiggle the fuel pressure you would probably want a true 36# or 38# injector rated at 43.5 for any dry nitrous. The 30# SVO's I am using are rated 39.5 psi.

 

With a wet kit the 30# would still suffice , but a fuel pump upgrade would be needed wet or dry.