ok im looking for a way to reduce the fuel pressure on my SPi engine
im fitting a larger injector and as such i need a way to lower the pressure so it doesnt overfuel
i know folks use the FSE valves on TB setups to adjust the fuel pressure but will these allow me to reduce the pressure to the throttle body by placing it on the incoming fuel line rather than the return to increase the pressure?
that wont work. the FSE will have to totally replace the standard regulator so you can drop the pressure. pressure is governed by whatever is creating the most restriction, and that will be the standard reg.
i would have thaught tho that if u placed a extreme restriction BEFORE the original regulator then the original regulator would essentially be overridden since the pressure is lower than its limiting value
the fuel pressure is governed by the pressure at the actual injector/fuel rail - if u place a restrictor before the fuel rail as opposed to after it like a normal setup then the pressure will remain at 0.8 bar if not higher in the line from the pump to the reg but after the regulator it will be at the new pressure
ie the original limiter is set at 0.7 bar, if i placed the FSE before this (ie on the incoming fuel line) and set it to 0.5bar then there isnt 0.7 bar for the original regulator to limit so the whole system AFTER the FSE which would include the injector would run at 0.5 bar no?
fuel regulators pressurise the pipe/rail before the point of restriction. If you fitted a regualtor in the fuel feed youd have X bar in the fuel feed line then feck all after it. the car most likely would not run. regulator HAS to be in the return.
dont think spi even has a fuel rail anyway, its just a carb with an injector instead of jets. the pressure regulator slots into the side of the throttle body.