feul pressure ?

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BlueR/T
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Post by BlueR/T » Sat Oct 25, 2008 1:52 pm


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wesker
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Post by wesker » Sat Oct 25, 2008 2:32 pm

thanks,btw what are compression levels supposed to be?im getting 150-160 across,hope thats good,now that i have the money for the right stuff,i didnt want my engine to be burnt out again.again,thank you.shoulda just bought the right stuff off the bat.

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Post by wesker » Sun Oct 26, 2008 8:33 pm


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Post by wesker » Sun Oct 26, 2008 10:11 pm

well i lost the bidding on the rrfpr,so can i use my vortech 1:1 fmu?didnt come with directions,bought it from a guy on neons.org.didnt think i could use it,just checking though.

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Post by wesker » Mon Oct 27, 2008 4:11 pm

http://www.vortechsuperchargers.com/pro ... &cat_key=5
this is what i have.do i need a seperate fpr to set base,or should this unit do it?

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Post by BlueR/T » Mon Oct 27, 2008 6:14 pm

well, that one is a step better, you can adjust the static pressure, but rate of gain is not adjustable,

unlike a BEGI where you set static , then rate of gain, the vortech makes you pick one of a few preset rates of gain, then set static,

this works on a supercharger, but not a turbo

a supercharger does not have to worry about pushing through the zero point, the engine is continually spinning it faster and faster

A turbo does, without the right amount of fuel in the zero point, the engine will not produce a sufficient combustion to spool the turbo through the zero point

the vortech unit is better then nothing, but it still wont work for your setup, you need to adjust your rate of gain to somewhere between 4:1 and 6:1,

if you get set into 1 specific rate of gain, you will be too rich or too lean

5:1 does not equal "somewhere between 4:1 and 6:1"

you may need to be at 4.3:1 or 5.9:1

also the "optimal" static for the vortech unit is 38-40 PSI, this is too low

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Post by wesker » Mon Oct 27, 2008 6:28 pm

i know its still half assed,but im working towards it.at least sumthing is coming through the block in my head.thanks for the help.btw,does it set base,or will i use my aftermarket fpr?

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Post by BlueR/T » Mon Oct 27, 2008 10:17 pm

it sets static pressure, base pressure is based on the amount of vacuum and rate of gain,

once you set static, you connect the vacuum line and adjust it to be at your needed idle pressure,

so the higher the rate of gain, the lower your idle fuel pressure, (i think, i may have that backwords)

there is NO base pressure when using a FMU there is these three:

Static: the pressure you set to with the vacuum line disconnected to set the 'zero point' pressure

Idle: the pressure at idle with the vacuum line connected (should be lower then static)

Boost: the max fuel pressure at full boost (should be higher then static)

so for example, on my setup i set my static to 54 psi, and at idle i'm at 35 PSI and my boost is somewhere between 75 and 95, (im not really sure as i pay more attention to my wideband)

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Post by wesker » Tue Oct 28, 2008 8:48 am

yeah,that is the next thing im buying,should have thought this through better before doing it.do i need a feul pressure gauge or can i use my fpr after the sfmu?because when i turned it on it started chugging and blowing purple and heavy black smoke.feul right?
http://www.jegs.com/i/Innovate+Motorspo ... 5/10002/-1
would this be a good enough wideband?it'll be what i get.thanks for any help.

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Post by wesker » Wed Oct 29, 2008 6:01 pm

cant get the sfmu to work,just shoots gas fumes out the pipe.do i need a stock fpr?or can i use my aftermarket 1?if so what do i set it to?

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Post by DOHCRT » Sat Nov 01, 2008 12:08 am

There is nothing wrong with the vortech SFMU. It's exactly what you need. I used it for over a year. Rate of gain is adjustable. You don't need a beji. Make sure you have it hooked up right.

The three screws will allow you to fine tune rate of gain, onset of gain, and vacuum bleed.
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Post by wesker » Sat Nov 01, 2008 9:16 am

so i dont need a stock fpr?or a fpr at all?

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Post by DOHCRT » Sat Nov 01, 2008 2:30 pm

The SFMU is an FPR. Its a type of FPR referred to as an RRFPR (rising rate fuel pressure regulator). Any FPR that raises fuel pressure according to manifold pressure is an RRFPR, even a 1:1. You may also see an RRFPR referred to as an FMU (fuel management unit), as is the case with the Vortech Super Fuel Management Unit (SFMU).

There is no need to get over-technical with the terms. Almost everyone will refer to static fuel pressure as base pressure, so don't worry about the technical differences for now. You wont be setting base pressure with vacuum in your application.

You need to use a check valve on the vacuum line so that the SFMU will not get a vacuum reference, only boost pressure. The stock PCM is designed to adjust injection time based on a fuel pressure that does not change according to manifold vacuum. For the best drive-ability when the engine is in vacuum, the fuel pressure should remain constant. Once manifold pressure rises above atmospheric pressure, the fuel pressure should begin to rise as well.

There are two different springs available for the SFMU. One is for higher base pressures and the other is for lower base pressures. You will want to get the spring for lower base pressures. The SFMU includes multiple "tuning disks" to allow you to change the units base rate of gain. You best bet is to start with the 6:1 disk and adjust the rate of gain down with the "boost" bleed screw. This screw will give you the ability to fine tune the rate of gain. If you have to adjust the screw all the way and it is still too much rate of gain, switch to the next disk.

You will never get an FMU fuel system to work prefect. Its a crude way of adding the needed fuel when boosting an N/A engine, but it works for the most part. The only way to prefect the tuning is to use a programmable engine management system (such as MegaSquirt).

Here is a diagram from my how-to on how the FMU should be plumbed. There are different ways you can plumb the fuel system, but this is the easiest:

Image
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Post by wesker » Sat Nov 01, 2008 4:10 pm

with it in,and looking at my narrow band,when i try to accelerate,it stuters and backfires and leans out badly,so i put my other set-up back on(a 10:1 fmu and an adjustable fpr)and it still does it?did sumthin get f'd up?i opened the fpr and found lil metal shavings?!?what happend to my fuel system?any ideas?

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Post by BlueR/T » Sun Nov 02, 2008 12:27 am

don't know about the metal shavings, did you drill into your tank?


if your car is stumbling as soon as you try to go into boost, then you need a MAP clamp or a missing link, the stock computer freaks out when it sees boost

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