Technical Boost Referenced Fuel Pressure Regulator

veer90

Lieutenant
Nov 16, 2016
1,000
763
25
West Nyack, NY
Ride
e90 335i 6MT
Question:
For boost referenced FPRs, is there any ratio available other than 1:1?

Context:
I'm eventually planning on putting together an overkill fuel system for 35+ psi with ST and e85: triple walbro 450s, FPR with return line, ID1000s or 1300s on the PI rail, etc etc. If I used a 1:1 FPR and a base fuel pressure of 72 psi which is factory, the fuel pressure at full boost would be over 100 psi. ID says 100 psi is the max fuel pressure for their injectors.

A lower ratio on the FPR would be ideal, say 2:1. I was also thinking about dropping base fuel pressure to around 50 psi, which will make the car set 2AAF fuel pump plausibility at low load but otherwise be fine.

Input/ideas appreciated
 

veer90

Lieutenant
Nov 16, 2016
1,000
763
25
West Nyack, NY
Ride
e90 335i 6MT
don't you need to maintain a pressure difference for the injectors? at 75 psi static FP 35 psi boost the pressure difference across the injector is only 40 psi. or does it not matter?
 

veer90

Lieutenant
Nov 16, 2016
1,000
763
25
West Nyack, NY
Ride
e90 335i 6MT
interesting...

at 80 psi did the car throw any codes? I know it's real finicky when the fuel pressure is not factory.