Fuel pump and FMU - Boost Forum

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Fuel pump and FMU
Sunday, March 13, 2005 9:03 PM
I've searched the post and haven't found exactly what i'm looking for, i have a 2001 cavy z24. I want to turbo it, only between 5-7 psi. I know i need a FMU but do i need to replace the fuel pump also or is the stock one fine? i was looking at the 320cc RC Engineering fuel injectors are those ok also? what would you reccomend as far as FMU Settings? 12:1, 10:1, or 8:1?

Thanks for all the help

Re: Fuel pump and FMU
Sunday, March 13, 2005 9:12 PM
Buy an adjustable FMU, then you don't have to screw around with different disks.

Think of it this way:

Running 5 psi, 12:1 disk, 40psi base fuel pressure. At full boost WOT, your fuel pressure is 100 psi. 320cc injectors are 30.5lbs/hr at 45psi. At 100 psi (if your pump can even put that out), your injectors are putting in 67.7 lbs/hr of gas. Talk about flooding it out.

Even at 8:1, 40psi base pressure, full boost at WOT your fuel pressure is 80 psi. Your injectors are putting out 54.2 lbs/hr. Still flooding it.

I had calculated that I would need about 4:1 on my FMU to get the fuel pressure I want for 6psi. Thats still 70psi on a set of 320's and still pretty rich, but good enough till I get it to a dyno.

Stock pump is good to about 65ish psi (fuel, not boost). After that you are pushing it.





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