Thread: LPFP Tech info
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      12-26-2012, 12:48 PM   #21

Drives: X1, 335i
Join Date: Sep 2006
Location: SF Bay, CA

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Originally Posted by drfrink24 View Post
What are the limitations of the HPFP?
There is a physical flow limit to the HPFP. Which means that there comes a point that the injectors can demand more fuel than the HPFP can deliver which will result in a reduction in fuel rail pressure. But this is at a pretty high power level. The bigger constraint is the 72psi input pressure it requires at all times. That's a pretty tough job for most streetable fuel pumps.

Originally Posted by Aridk View Post
Merry Christmas to you all

Just a couple of questions:
1. How noisy is this in-line pump in the trunk? Will it be annoying in a daily driven car?
2. with all this extra flow of fuel running through the oem fuel lines will it be beneficial to run a fuelcooler at some time?
3. When wil we see a RB 100% E85 with this upgrade?

Keep up the good work Shiv, donīt let all the negative folks get to you

1) It's not noisy at all once the seat cushions go back on. If you listen carefully with the car stationary and with the radio off, you may hear a very subtle hum but you'd be hard pressed. The only time when its obvious is when the fuel pump primes as you unlock the doors first thing in the AM.

2) Continuous fuel flow is only increased in the 2-3" long section of fuel between the two sides of the fuel tank (between the pump output and the FPR). The long line that runs under the car (to the HPFP) only sees fuel flow in proportion to power output. Fuel coolers can always help (especially when running E85) but i don't think they are necessary at this point.

3) As soon as I get my hands on one. Either that or a Vargas Stg2 which should be hitting the streets soon around here.