I am building a boosted f22b2 with a vtec f23 head on it. I am going to run around 7 or 8 psi on it with stock innternals. For the fuel managment I am using the Vortech FMU. My question is what ratio diaphram should I use in it for 7 or 8 psi? the one I have has a 12:1 ratio diaphram in it and I know the it is going to run way to rich. Vortech make a 4:1, 6:1, 8:1, 10:1, and a 12:1. I am pretty sure that, for instance, on the 4:1 ratio diaphram for every one psi of boost the fuel pressure is raised four psi. For 6:1, for every one psi of boost the fuel pressure is raised six psi.

 

12 to one