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Discussion Starter #1
As I sit here and plan out my turbo upgrade, I read about the Aeromotive FPR, and feel why not throw it into my list of parts needed. Well, as I searched the web, I found that companys offer the kit with the FP guage and even an install kit including all the SS lines needed for the install. Are there any companys out there that do the same the STi? Anyone know who sells these pieces? Basically I am asking for a complete kit that will install the Aeromotive FPR with the guage (liquid filled) and all the SS lines needed. If anyone has any info or even pics of their setup, post please...thanks:).
 

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i don't think anyone makes a complete kit, chris. i know you can get everything you need for it at summit.

i have a pic of my aeromotive fpr with the n2o2 solenoid in the first post of my thread. i'm using a defi fp gauge. it's a pretty straightforward install.
 

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I've run a rising rate FPR in some other cars but it doesn't seem to be a popular mod on STIs. I know that higher fuel pressure gives better atomization at the injectors but in my experience most of the time they're used to get more fuel flow out stock sized injectors when FI is added. What would be the benefit on a setup that has a properly sized fuel system (besides the better atomization)?
 

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I heard something about the 1:1 ratio of fuel pressure (????) and its easier for the tuner. The guage I was talking about was the one that mounts directly onto the FPR. Its a good thing to get if you have the extra cash, can't see why it would hurt though....
 

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I heard something about the 1:1 ratio of fuel pressure (????) and its easier for the tuner. The guage I was talking about was the one that mounts directly onto the FPR. Its a good thing to get if you have the extra cash, can't see why it would hurt though....
1:1 ratio means that for every PSI manifold pressure increases, fuel pressure is increased 1 PSI over the base pressure.

The stock WRX/STi FPR is a RRFPR. It bases at 43PSI(?), then rises 1PSI for every PSI of boost you are running..
 

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Interesting. I know in the domestic world that when you add a rising rate FPR that the purpose is to finely adjust the fuel mixture and to richen up the mixture as cylender pressures increase. My mustang, when it was running a 10# vortech had a similar setup with a secondary boost a pump to help increase the fuel pressure along with it. But I always thought this was because the old mustang computers were too crappy to tune them electronically. Like swapping a fuel system was a matter of putting in a new MAF tube that corresponded with the injectors you were using and that tricked the ECU to running properly on a higher then stock power level.

I would imagine that a properly sized fuel system on a car like the STI which you can custom tune the ECU would not have any need of a rising rate fuel presure regulator as you can simply add extra fuel to the mixture electronically without the mechanical trickery. The benefit being that you then don't need to run inline fuel pumps and crazy PSI in the fuel system like you did in the old school return fuel system. For that matter, I have no idea if the STi is even a return-line based fuel system that can use such a system.
 

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Interesting. I know in the domestic world that when you add a rising rate FPR that the purpose is to finely adjust the fuel mixture and to richen up the mixture as cylender pressures increase. My mustang, when it was running a 10# vortech had a similar setup with a secondary boost a pump to help increase the fuel pressure along with it. But I always thought this was because the old mustang computers were too crappy to tune them electronically. Like swapping a fuel system was a matter of putting in a new MAF tube that corresponded with the injectors you were using and that tricked the ECU to running properly on a higher then stock power level.

I would imagine that a properly sized fuel system on a car like the STI which you can custom tune the ECU would not have any need of a rising rate fuel presure regulator as you can simply add extra fuel to the mixture electronically without the mechanical trickery. The benefit being that you then don't need to run inline fuel pumps and crazy PSI in the fuel system.
This was my line of thinking coming from gen3 Camaros. My '88 is running a rising rate FPR with a Vortec S-trim. However if there is another purpose for running one on an STI I'm all ears since I'm now tuning my own car and trying to optimize my setup with an FP 18g and DW 740 injectors. I went with the 18g for auto-x and I know the DW 740s are more than enough to feed it but I tune more for spool and torque than hp and if an FPR can have an effect on this I'm game.
 

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I went with the SX Performance Regulator over the Aeromotive regulator. The diaphragm design appears to be better (IMHO). Here are a couple pics of mine (not instsalled yet).





If you are using the stock rails then you'll need to chop out the stock regulator, intercept the fuel return line and run it to your new regulator, and then send it back to the hard fuel line. This is actually fairly easy if you use push-lock (socketless) hose (instead of braided line).

www.bescaredracing.com - /sti/fuel/pressure/regulator/sx_performance/15404/hose/

t
 

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Discussion Starter #9
Wolf...believe there are advantages for this type of system? If so, want to make me a set that will just plug and play:)!?
 

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I went with the Aeromotive unit with a liquid filled gauge, the install was very easy really. Just tap it into the fuel line & run the vacuum hose to the intake manifold.
The stock rails were replaced with Perrin v2's & the stock regulator was removed when I did the engine.

It's a relatively inexpensive upgrade that gives you the ability to monitor & change your FP if need be, another tool to help you tune is not a bad thing.

The only downside I could see, is that it is another thing that can go wrong. But it so simple, I doubt it would.


Wolf - I'm lovin your clean looking setup ^^^
 

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Discussion Starter #11
Thanks Al, I needed to hear that;). Would this work with the APS fuel rails system right? Just like it did with your Perrin setup?
 

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Discussion Starter #12
Wolf,

Do you have the parts list thats needed to do this? I found the Aeromotive guage....what about the fittings, etc? Any reason why Aeromotive didn't make a liquid filled guage....
 

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Using a rising rate FPR in a turbo engine is done to maintain a constant pressure differential between the fuel rail and the intake manifold. Think about how much fuel would flow if the pressure in the intake manifold was equal to the pressure in the fuel rails.
 

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Wolf,

Do you have the parts list thats needed to do this? I found the Aeromotive guage....what about the fittings, etc? Any reason why Aeromotive didn't make a liquid filled guage....
I have a parts list if you go through the pics on my site. However, I haven't installed it yet so there is no gaurantee that hose parts will work 100%. This is just what I am starting off with.

I just went with an aeromotive gauge that I could mount on the AFPR. I wasn't looking for anything fancy because I can easily see later on down the line running a fuel pressure gauge in the cabin.

t
 

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Discussion Starter #16
True, I heard the same with the Perrins, but the APS I heard worse. Either way the manifold is coming out, so it can't be that bad yah know?
 

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If you guys are using an aftermarket regulator, I'd say just go with the Aeromotive rails. DOsent come with likes, FPR adapter block, none of the stuff youre not going to use.

Plus, it has AN inlets and outlets..
 

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If you guys are using an aftermarket regulator, I'd say just go with the Aeromotive rails. DOsent come with likes, FPR adapter block, none of the stuff youre not going to use.

Plus, it has AN inlets and outlets..
I disagree. The aeromotive rails are either fed or returned from the center of the rail. This is not an optimal configuration. You want to feed one side of the rail and return from the other. Using the middle of the rail (like aeromotive) means that you are dead-heading one end of the rail. Yuck. I evaluated these rails before going with the APS rails.

t
 

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Discussion Starter #19
I agree, APS fuel rails are the way to go, unless you go for something way bigger for applications.
 

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guys, a rising rate regulator is almost never used on these cars.

a rising rate regulator will increase fuel pressure at a rate HIGHER than 1:1 while in boost... thus the "rising" rate.

just about every fuel pressure regulator out there has a manifold reference, especially if it is to be used on a forced induction setup. this is because using a manifold reference increases the dynamic range for a given injector size.

all of the commonly used regulators are 1:1, with an adjustable starting pressure--but they're NOT "rising rate."

hth
ken
 
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