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Old 02-24-2016, 05:12 PM   #1
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So building a fuel system for the MSM, (EFR 6758 350whp goal) going to put fuel regulator in back of car. Do I need to have a vacuum line on it? It will MS tuned so can you just tune around the fuel boost reference fuel pressure increase or not?

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Old 02-24-2016, 05:19 PM   #2
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Are you converting to return-style? it would be foolish to put in a regulator and convert to return style and not reference it. Really foolish.
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Old 02-24-2016, 05:28 PM   #3
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Are you converting to return-style? it would be foolish to put in a regulator and convert to return style and not reference it. Really foolish.

Yes return style, but regulator in back of car. Foolish, ok. But school me, why?
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Old 02-24-2016, 05:32 PM   #4
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Because as your boost builds you need to build fuel pressure too otherwise you'll run out of fuel for no good reason.
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Old 02-24-2016, 05:50 PM   #5
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Also planning my fuel system for MSM EFR swap and was thinking the rear mount regulator might be a bad idea since the vacuum line would have to be so long if you want it referenced. I'd think that would slow down signal changes even with a very solid vacuum line and a lot more line to possibly get damaged and pretty sure you don't want that if you are using a referenced fuel regulator. In for more info...
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Old 02-24-2016, 06:10 PM   #6
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Because as your boost builds you need to build fuel pressure too otherwise you'll run out of fuel for no good reason.
Lets say your pump is big enough and the base pressure is high enough that is does not dip even with the injectors pulse with 100% what would it matter?

You would tune for a static, lets say 50 PSI of fuel pressure. How would that be bad? Only thing I could imagine is that the manifold pressure is now at 20psi making the fuel pressure effectively 30psi..........maybe your on to something. So base 60? IDK
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Old 02-24-2016, 06:17 PM   #7
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Yes return style, but regulator in back of car. Foolish, ok. But school me, why?
Foolish for a few reasons

In the front, the regulator acts as a damper, and you loose that affect in the back. This is a big thing.

The regulator will be less effective in the back, since it can't correct for the pressure drop after the regulator in the hose between the injectors and the regulator. You just made that hose 10' long instead of 3' long. So you'll get less pressure to the injectors the more you flow.

You need the vacuum reference. It will improve idle, and improve fuel delivery in boost. It keeps the pressure delta between the injectors and the intake manifold constant. Improves flow A LOT when you go in boost vs no regulator.

There's no downsides to putting it up front, so do that.
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Old 02-24-2016, 06:18 PM   #8
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Quote:
Originally Posted by IcantDo55 View Post
Lets say your pump is big enough and the base pressure is high enough that is does not dip even with the injectors pulse with 100% what would it matter?

You would tune for a static, lets say 50 PSI of fuel pressure. How would that be bad? Only thing I could imagine is that the manifold pressure is now at 20psi making the fuel pressure effectively 30psi..........maybe your on to something. So base 60? IDK
That's exactly it. Your effective pressure would drop no matter what cause you're not pressurizing the other side.
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Foolish for a few reasons

In the front, the regulator acts as a damper, and you loose that affect in the back. This is a big thing.

The regulator will be less effective in the back, since it can't correct for the pressure drop after the regulator in the hose between the injectors and the regulator. You just made that hose 10' long instead of 3' long. So you'll get less pressure to the injectors the more you flow.

You need the vacuum reference. It will improve idle, and improve fuel delivery in boost. It keeps the pressure delta between the injectors and the intake manifold constant. Improves flow A LOT when you go in boost vs no regulator.

There's no downsides to putting it up front, so do that.
correct
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