[Blue70SS]

Originally Posted by Warhorse

Don't want to hijack OP's thread. We can take this through PM if necessary.

Are you using a dedicated fuel cell with your direct injection setup? and what fuel pressure are you using? I'm just about to complete new LSx build with direct port and still on the fence with which boost referenced fuel pressure to go with for nitrous fueling. The fuel jets get very small when your at a 250 shot and less. Would not take very much trash in fuel to cause a disaster. Low pressure fuel ex. 7 to 10 lbs would at least require jet sizes almost twice that of high pressure 43-58 lb fuel,

Have you ever looked at how small a 10, 12, 14 etc. size fuel jets is? Scary!

Direct injection via 4 spray rails inside the RDS spacer (wet system). Each rail's single jet supplys the spraybar for N2O or fuel for the whole bank (so jets are ~ 4x bigger than yours), via spray holes in the bar at the inlet runners. Only the squash twins being used, primary boost reference fuel pressure regulator at 60 (climbs to ~80), return from 60 psi regulator feeds the 2nd regulator for the N20 set at 35 psi and climbs to ~ 62 psi under max boost (60 regulator seem to respond to boost a little more than the 35), then return line from the 35 goes back to the tank.

Steve from Inductions Solutions that flowed the system said I needed to drop the N2O fuel pressure for the exact reasons you're talking about. (60 primary, 35 nitrous side..... boost referenced)

Running 91 octane for the blower only. Since changing from the 109 shot to the 151..... I now mix Sunoco 110 leaded 50/50 with 91 for racing with the nitrous. Flip a switch and pump the fuel out for another race day and go back to 91. Only problem I've found is the primary regulator would go stupid on long drives in the heat or from long stop & go traffic.... problem was the regulator getting hot on the firewall and distorting the rubber inside. Fixed it by using the vented hood, no rear seal below the hood, heat insulated the fuel lines inside the engine bay, and rebuilt both regulators.

I datalog everything and the fuel to the nitrous doesn't show a hint of not keeping up with pressure.... curve mimics the primary fuel pressure curve well. Safetys are setup to kill the N2O system if AFR stays at 12.3 or higher for longer than .6 sec (allows initial lean spike), N2O fueling ever drops below 30 psi, or max nitrous time set.