Jurand wrote:"Walbro High Pressure/High Volume 255 LPH Fuel Pump (recommended) or Vortec FMU (connections not included due to user placement of FMU). Either of these units provide the extra fuel needed for those with an aftermarket boost controller who plan on exceeding the stock Stage I kit's 7 PSI of boost. "
Is this really true? I would think the 270cc injectors would barely support 7psi on your turbo, even with the HPHV fuel pump or an FMU. In fact, I would love to see a dyno chart with wideband air/fuel ratios. I'm sure others would like that info as well and would be convinced to get your stage I kit as a result. Also, what kind of numbers can we expect from the stage I kit at 7psi?
Adam
It works and has been proven.. Stock fpr will add 1 psi of fuel pressure to the fuel rail upon 1 psi of boost.. SO that means if ur pushing 5 psi of boost, the injector will PASS 5 more psi of fuel pressure....
When u add an FMU that allows u to ADD more than 1:1 ratio. You can go 2:1, 3:1 or more.. If u have it set to 7:1, that means when u pull 5 psi of boost, u will add 35 MORE psi of fuel pressure to the fuel rail which means when those injectors open, MORE fuel can pass thru at that given time... I would seriously NOT advise 7:1
But this FMU is only recommended for low boost applications...!!! Think about the math using a 7:1 fmu at 15 psi..... 105 psi fuel pressure present at the fuel rail / lines...... OMG ( mushroom cloud i see )
That is how u can run 7-8 psi under stock inj...
My opinion, i would NOT use an FMU at all. I would just go with larger injectors and ecu re-program. ( if u can afford )
And to stump u even more, i ran 10 psi on 370cc inj with stock fuel pump and stock FPR...!!! Think about it..! And i had room to spare...
I just decided to upgrade to the walbro cause 15 psi was comming very soon and i was not gonna risk pushing the stock fuel pump past 45 psi of fuel pressure, although they claim it can do 50 psi...