Quote: Originally Posted by
gottasrt4 
IMO, this's gotta be one of the most informative threads I've read....I gotta admit, I did notice that when I installed my walbro.....accelleration was
MUCH smoother!!! I'm still runn'n stock turbo and stock injejctors, but push'n somewhere 'round 280whp / 320wtq with support'n mods (I had two HUGE exhaust leaks that I've fixed since my last dyno).
now, I'm pretty new to bOOsted cars my damn self, so since this thread's answered it's original question and then some, I wanna introduce another: what does the FPR do?? now, it would seem obvious by it's name, but after learn'n that the fuel pump opens via voltage sent from the ECU, I'm not too sure. but my guess is that the FPR tells the fuel pump how much to push.....how close am I!?
also, would this turn out to be a good supporting mod, kinda like the walbro and return line?? thanks!!!!
the fpr limits the pressure to a static rate, this allows the "tuner" to know how long to open the injector for to get the approprite amount of fuel in the combustion chamber (for correct A/F ratio) this makes tuning a somewhat simple task for the "tuner". without a fpr it would be imposible to tune a car
pulse with x fuel pressure x injector flow rate= the amount of fuel entering the engine
]
the fuel pump is always pumping at 100% (yes their are a couple of exceptions)
the injectors are either 100% open or 100% closed, the mesurment of fuel is from how long they are kept open "pulse with"
a fuel pressure regulator stabilises the fuel pressure, if the psi drops it will compensate by raising the pressure untill it reaches the set limit, and vise versa
a return line allows your pump to push more volume and keep it on demand, this "almost" eliminates any pressure variations at the injector by shortening the distance of supply "this makes the tank closer"
a 1:1 fpr or "rising rate" FPR raises the fuel pressure for every psi of boost it raises, this will compensate "partialy" for boost (this is not a tuning device and has pit falls for turbo cars)
