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I heard if you put a fuel press reg on a stock mustang and set pressure lower youll gain hp, tru?

How does this work?

Does the fuel press gauge go on the outside of the car or can it be installed on inside?
 

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I dont see how it would add hp, your just increasing/decreasing the amount of fuel. And they have to be mounted outside the car.
 

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they are mounted on the fuel rail. It takes place of your stock non adjustable fuel regulator.
 

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I heard if you put a fuel press reg on a stock mustang and set pressure lower youll gain hp, tru?
False. Likely it will decrease power.

People will tell you all kinds of crap to get you to buy something, won't they?

Many things in the auto business are exaggerated quite a bit, like the power gains from underdrive pulleys or gains from other bolt on parts.

Probably the last thing I would do is change the stock regulator (unless it was bad). I've got a supercharger, aluminum heads, bigger cam, headers, and so on and still have the stock fuel regulator.

Tom
 

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I believe EVERYTHING I read on the internet. :gringreen

The fuel pressure reg is located on the passenger side fuel rail towards the fire wall and has a line coming out of it running to your intake. I would agree with Old man. Its not going to benifit you unless you have the need for more fuel, 300+ hp and you bolt on a bigger fuel pump and injectors.

Who ever told you that you would get 5hp will probally try and sell you the "tornado" for your intake or an electric turbo so run
:ausge446:
 

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I use one, but not to give me HP. I run a Speed Desnity computer. After my mods, I could have left the stock fuel pressure regulator on there and the O2 sensors working with the computers "adaptive" feature would have adjusted the injector "duty cycle" (how long the injectors are turned on each stroke) to make up for the added air ingested from my mods. Since I wanted to avoid increasing duty cycle, I adjusted my pressure from the stock 39# up to 42# to avoid increasing duty cycle. Did I gain HP? - you bet but not just from putting on an AFPR.
 

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Who ever told you that you would get 5hp will probally try and sell you the "tornado" for your intake
:ausge446:
Oh God, we sell those at AutoZone and I ALWAYS try to steer customers away from buying one. Guess they're kind of like the Pet Rock for the 21st Century,LOL. :hihi:
 

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Hey there is nothing wrong with getting an AFPR. I don't have one yet but I would really like to have one so that I can get my pressure at the fuel rail correct. If you have the stock regulator you are at the mercy of it's build. If it is off by 2 or 3 #s then you can do nothing about it. With the AFPR you dial it in so that you are at the exact correct pressure you need for your injectors at the fuel rail.

Sorry this won't give you additional HP.
 

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I disagree. Using an AFPR especially with mods will increase power over a stock unit. More air needs more fuel. More air + more fuel = more power.

The stock FPR is not good for heavily modified engines. It is fine for 19#ers running stock intake, exhaust, and cam.

Power from being able to adjust fuel is nearly as important as being able to adjust ignition timing.
 

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The power you're supposed to get involves being able to fine tune the engine by adjusting the pressure, which is what actually gets you the power... not by just putting on an adjustable regulator and you get power.

Notice I said "supposed to". This is by no means set in stone.

Stock 5.0 engines are around 39 psi stock (give or take a few, either way). A stock 5.0 engine could actually benefit from lowering the pressure a few psi, where a modified engine could use a couple of extra psi. This is where the potential for a few horses comes from.
 

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Yup, stock 5.0 engines can take a few psi less of pressure because 39 psi is a touch too much for stock.

In an ideal engine, the rpm and air/fuel ratio would be 100% linear but it's not. At lower and mid rpms, the air/fuel is usually on the rich side and it leans out above 5000. This is why a couple of psi less will benefit and with a stock engine, you won't be going above 5000 much anyway.
 
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