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Discussion Starter #1
Got the new 13134 regulator and made a simple bracket for it and mounted it right in front of the TB .

Couple of questions on the reference line .

How much does vacuum lower base pressure ?

I assume if it lowers pressure its easier on fuel pumps but does an injector rated for 43psi , need 43psi to work ? Is base pressure set with the motor running ?

Can it be referenced at the hat with no issues ?

Sorry about the stupid questions but I've seen it done both ways .

What do you prefer ?


This new regulator is said to be designed for high pressure high volume pumps or duel pumps ......................... i have a Holley 1800 and an A1000 .


The enclosed Aeromotive regulator is designed to be used with high flow, high pressure, electric
fuel pumps similar to Aeromotive’ Eliminator P/N 11104 or larger (bypass flow between 180-300
GPH). Ideal for Dual A1000 systems. Bypass restriction measures 5/16” or 0.313” on the ID.



 

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Typically, base fuel pressure is set with the regulator connected to manifold vacuum/pressure, and the motor running. This is from an OEM perspective. I don't think I'd drop the base pressure below the rated injector flow rating. The injectors don't atomize as well at lower pressures, could cause AFRs to be sporadic.
 

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Yes, on EFI the reference line will get hooked to manifold vacuum, I guess this is since the injector is directly in the port and will be subjected to the same manifold pressures. I seen and heard of it done both ways as for base pressure, line disconnected and line connected. A lot guys run the fuel pressure above the injectors rated pressure, I disconnected my ref. line, and set my base to 50 psi, however, with the line connected, it only drops back to maybe 46-48 psi at idle. When I first built my car, I referenced my fpr before the throttle plates, when looking at the data logs you would be shocked at the fuel pressure spike when the throttle is closed under full boost. At the time I was running 17 psi, had 66 psi fuel pressure, when my TPS went to 0% at the traps fuel pressure spiked to almost 80 psi even though it was only a few tenths of a second. Manifold vacuum would actually pull the fpr damn near full open under sudden decel...
 

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Damn straight!!! Ready to get out to the track again too, and see how much abuse this $100 short block will take. I was testing on the wash pad at the shop a couple Saturdays ago and the Vega yanked the front tires about 6"!! Should cut some better 60's now....
 

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It's only "base pressure" (or injector differential pressure) if you disconnect that hose (or run the pumps with the motor off). Vacuum will drop fuel pressure below that, boost will raise it. Pressure should drop by half of what vacuum is if your gauge is in inches hg. In other words, 43 psi base pressure, 10 inches of vacuum, fuel pressure should be 38 psi if everything is working correctly.
 

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Typically, base fuel pressure is set with the regulator connected to manifold vacuum/pressure, and the motor running. This is from an OEM perspective. I don't think I'd drop the base pressure below the rated injector flow rating. The injectors don't atomize as well at lower pressures, could cause AFRs to be sporadic.
Sorry this is incorrect.
You set base pressure (3 bar/43psi if thats what you want to use) with the regulator unplugged, then when it is plugged in, it will drop the same amount of pressure that the motor pulls for vacuum.

Injector flow rate is based off the pressure differential between above and below the injector, which ends up being the fuel rail and manifold runner, respectively.
the point of using a vacuum reference to the regulator is so that the pressure differential is always the same, so the ecm always assumes the injectors are injecting the same amount.
In the event that you use static pressure(no manifold reference), the ecm will need to correct the injector pulse width to make up for the changing pressure differential.

example: rail is 43psig, manifold vacuum is -5psig so your injectors are actually seeing 48psig of pressure, which will result in extra fuel being injected compared to WOT which would be 0 or more psig in the manifold.
 

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Discussion Starter #8
You set base pressure (3 bar/43psi if thats what you want to use) with the regulator unplugged, then when it is plugged in, it will drop the same amount of pressure that the motor pulls for vacuum.

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yes , Holley says 43psi on the 120lb injectors .
 

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I set mine at 43 lbs unplugged, once it was plugged back in, had about 39lbs. Don't forget to plug the reference line when you set it.
 

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yes , Holley says 43psi on the 120lb injectors .
That is just what they are rated at. Lots of people run 60 or more psi. there are lots of calculators online to figure out the new flow rate at higher pressures. it is not linear.
There can be atomization benefits to running higher fuel pressure
 

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Discussion Starter #11
I'm running 26psi of boost , and I'm not sure how much the A1000 and the Holley 1800 will support at 86 psi .

How would I know if I could benefit from running more base pressure . What do most run with the 120lb injectors
 

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I didn't mean set it with the vacuum connected, just that it needs to be connected to manifold, not hat pressure. After reading it again, I see I should have made that more clear.....
 

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This is a good read, since I'm an efi newb and Ill be setting my holley efi up soon too, after coming off a blowthrough setup.
 

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I'm running 26psi of boost , and I'm not sure how much the A1000 and the Holley 1800 will support at 86 psi .

How would I know if I could benefit from running more base pressure . What do most run with the 120lb injectors
Just set pressure anywhere around 45-50psi which should safely keep your pumps happy and still offer good flow.

It really is not that critical though.

As Trendsetter says, strictly speaking you're aiming to maintain a fixed pressure delta across the injector. But in reality it really doesnt matter that much, unless you're using some strange ecu that requires it, or you to fill in some tables based around this assumption. But any ecu would allow fuel adjustments despite this anyway

If you are using a programmable ecu, as long as fuel pressure behaviour is consistent that's all that matters as you'd be tuning based on this anyway

Whether it's a static high base pressure, a 1:1 boost/vac reference, or a hat reference really isnt important. Consistency is.

Intake setup looks great though !
 

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Lol I just tore out every stitch of old add on shitty wiring out of my car. Ill be building a new relay panel to control fans, w/p, water meth, fuel pump etc...along with my efi system.
Did I mention I HATE wiring, lol
 

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Discussion Starter #18
Lol I just tore out every stitch of old add on shitty wiring out of my car. Ill be building a new relay panel to control fans, w/p, water meth, fuel pump etc...along with my efi system.
Did I mention I HATE wiring, lol

Get a nitrousdave relay board .
 
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