Hey guys I'm considering getting a "Retro Tech" fuel injection system for my 350/455. The system runs at 42psi, and I'm considering leaving my Cheater Plate system on the motor for a small shot in the 100 range. The question is what is my best bet to plumg the fuel for the nitrous system? How much fuel pressure can I run with a "plate". Will the high fuel pressure affect the spary pattern/efficiency? Should I just run a seperate fuel system all together for the nitrous? And still run the standard fuel pressures in the 5-7 range? I know I would have to Jet down the fuel jet to compensate for the pressure difference, and I ran some jetting through a calculator already and I seem to have the needed jets already! My turbo car uses them for the nitrous side. Thanks in advance guys.
if your using efi you would you the jett setting for efi setup. they are different than low pressure like a carb, just go to a website like holley or nitrous express and see what they list as the jetting size you need for the hp you intent on running using the efi chart, not carb.
Jetting isn't my concern that is the easy part, my concern is running 42psi through my cheater plate. My turbo car is Fuel injected and nitrous as well, and I'm familiar with jetting and using Fuel Pressure as a major factor in jetting the nitrous.
I have this setup already, and I have a separate fuel system for the nitrous. First of all, the pumps for fuel injection are a big issue. To get a pump with sufficient flow for a big HP engine PLUS nitrous is probably impossible unless you go with the Aeromotive pump (and don't mind a helluva noise). There are a bunch of other fuel-system considerations also. Are you going to put your fuel pumps in the tank? If so, you MIGHT be able to get enough flow with a dual-pump setup (lots of grand nationals do this). I have a sump in my gas tank tank, with an outlet that feeds a dedicated (nitrous-only) Holley Blue pump, with a 3/8" line that goes up to a regulator at the engine. You don't need a return line for that setup. I also have a fuel pressure sensor (switch) after the regulator that will kill the nitrous solenoids if fuel pressure drops below the threshold. I don't know what kind of car you have, and whether you already have a return line for the fuel system, but this will be required for FI. -Bob C.
Thanks for the input Bob. I just went through what I could find on your car on the board and you seem to have a port fuel injected car. The Retro Tek system is different, basically a new higher tech version of the TBI sytems of the past. Has 4 injectors in what looks like a Holley double pumper housing, available in either 750 or 1200 cfm units with. They also offer a returnless style fuel system that is good up to 550hp at 42psi fuel pressure. So I don't need a return line for the system as long as I stay under that horse power level, according to them. The system uses a Wideband O2 sensor to calibrate it self to learn the car and is permanently installed in the car. The system comes preset to 12.5afr WOT and 14.0afr cruise/part throttle. You can maunually change these perameters in the system with a laptop and some basic software that they provide with the system. You can also go in further and change certain "cells" as you like to fatten or lean out parts of the curve beyond the basic settings if you like as needed. My main concern is running 42psi through a plate on the fuel side? Obviously the nitrous side can handle it, I guess the fuel side can handle 42. Otherwise I will just leave my electric pump in the car I have now and install a small 1 gallon fuel cell in the trunk and use that as a dedicated fuel system for the nitrous.
Fuel pressure is irrelevant to the spraybar. The jet will act as a restrictor to deliver whatever VOLUME of fuel is necessary- the higher the upstream pressure (that is, upstream of the jet), the smaller the jet orifice (meaning it was a higher pressure drop). At the end of the day, fuel pressure at the spraybar has nothing to do with fuel pressure before the jet. Anyhow, it sounds like you are in for trouble with a non-return fuel pump system. I have never heard of a 42PSI electric pump that can work without a return, without overheating. BTW I ran a Holley Projection for many years prior to my current setup, which was a TBI system at 18 PSI. Even then I ran a complete standalone fuel system for the nitrous. -Bob C.
They have a controller for the fuel pump that regulates voltage, to lower out when not needed as much. As for the fuel pressure I was thinking something along the lines you just said, was just looking for someone else to bring that up. I think I"m going to buy the system and just use a stand alone nitrous fuel system for it. THanks Bob.
