Hey guys I am trying to figure out if I need to run bigger injectors or not. I have a 4.8 with a whipple and I wanna run it at 8-9psi with a 100 wet shot of nitrous. I have the 8.1L 29lb/hr injectors and I wanted to know if those would be enough for that? I am also going to run a water alki kit to help with detenation. Just wondering with those mods would those injectors hang? Also if I upped the fuel pressure could I get more flow outta those injectors? Thanks!

 

ANYONE?

 

I would not worry about the injectors allthough with a WET shot you will be fine with those. You may have a fuel delivery issue with the stock pump running that. But that will be the least of your worries after you hit the gas the first time, it will probably blow the engine into shreads. The 4.8 pistons are weak. The cylinder pressures with that much n20 in a blown application will be catastrophic. Keep in mind adding nitrous to a FI engine will effectivly double the shot. So at 8-9 psi = ~350 rw + 200 n20 = ~550 - 580 rw = shreaded 4.8 and tranny if the engine lasts that long. About the max I would push a stock internal 4.8 would be 400rw and that won't last long.

 

Well I am not going to be running a 200 shot! hehe What if I just run 9psi and a 50 or 75 shot? My main concern is the injectors right now. Would they be able to deliver enough fuel for that kinda setup? Thanks!

 

Here is a quick formula:

lbs/hr = (BHP × BSFC) ÷ (No. of Injectors × DC)

Where:
BHP = Peak Brake Horsepower
BSFC = Brake Specific Fuel Consumption
DC = Injector Duty Cycle

Based on this formula, a 29 lb/hr injector on a V-8 application @ 80% duty cycle would be good for 371.2 HP @ a brake specific of .5

 

Also, consider that you have a pair of additional injectors with the Whipple system if in fact you are running those. I believe those are 50 lb/hr, I just don't know @ what point they come online. Those 2 injectors should give you the capacity for another 160 HP @ 80% duty cycle.

 

hey I have a 5.3 and I run 10-11psi and a 115 shot wet kit for a while now. I had to put 37lbs injectors and a 255lph intake fuel pump in. 55psi is what is running to my fuel rails at idle. yours would need to be like 45. important to check that.

 

I thought the pistons in the 4.8 and 5.3 were they same

 

I am pretty sure the whipple injectors are 40lb. The only ones that come with there 50lb. are the 8.1's.

 

Yeah, I knew they used 50's I just didn't know if they used them for all their kits.