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RUSSIAN FOR HIRE
2000 Impreza RST
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2,425 Posts
Discussion Starter #1
Hey guys,

going to be running a vf11 w/o intercooling or a td04 w/ small core fmic on my ej18, going to run about 5-6 psi, (dont have a hood scoop)

ive built a turbo rs with a map sensor but this is my first MAF encounter

ive searched high and low for what the best ratio to go with for the fmu (rrfpr) i will be going with a vortech fmu because it worked great in my last setup.

on the rs i was running a 12:1 but i heard that with MAF you run around 6:1 generally?? i would love to hear from somebody with a 1.8 turbo setup to know what ratio has worked best for them.

ive searched most of the threads on rs25 and nasioc for 1.8t stuff to find the answer with no real hard numbers to show for it.

thanks in advance
 

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99 22B replica
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1,322 Posts
You've probably got more knowledge than me in boosting engines but I am at the same juncture you are in getting an RFPRR. I just purchased a 6:1 Vortech for my 2.5 phase II. I went with 6:1 because I wanna run max 7 psi on the rebuilt engine. That should put me in the 84 psi fuel pressure range at max boost. At 100psi the injectors lock up and a 12:1 ratio would do so around 5psi. Too close a margin for me. I don't think this makes a lick of difference what engine it's going to, fuel pressure is fuel pressure. I figured a 6:1 ratio would be a good safe number to start with and if the Wideband says its running lean ill go for a richer ratio disc. I'm just a noob to boost but this is my plan for what it's worth.
 

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needs more cowbell
95L, 07 2.5i, R6
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9,315 Posts
Check with JoeJoe69, he boosted his 1.8
 

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96 L Turbo Wagon
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3,641 Posts
You'll probably want a 6:1. Maybe 7:1 if you run the td04.

Sent from my DROID X2 using Tapatalk 2
 

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05 Baja,95 Impreza L,04&02 wrx
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69 Posts
I'm of no help, I run a cartech on my ej18t, so it's adjustable without discs.
 

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4,438 Posts
that is a ridiculous amount of fuel pressure to be running imho

what size are the injectors stock? what fuel pump are you planning on running?

The higher your pressure, the worse the pump flows - and it makes that pump work harder as well

my old '99 RS, Supra pump, stock injectors, 2:1 RRFPR by Magnetti Marelli. Fuel was never once an issue, and that car ran up to 18 psi on a T3/T04E. Even doubling fuel pressure make things high, quickly. We did it simply because we were at the track, in a pinch to run more boost, and at that point in the RS world, no one had yet discovered what injectors could be swapped in.
 
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