Hey all, I have been wondering if Mounting my Regulator right on the fuel rail might be an issue? As pictured below


I have been noticing most people mount them to the chassis and, have a line off the fuel rail running to them.
Like Tony's car for example pictured below.
Also If anyone knows what that is bolted to the rail above the AEM logo please let me know.

My question is can it cause fuel delivery problems having the Regulator so close to the Injectors? After thinking about it, I think it could? But, I like the look of mine plus the simple location.
Is there a reason why most racers have a length of line after the fuel delivery??? Thanks in Advance for any help given

 

BumB!!! Come on someone has an awesome here?
I really can't dissect this problem. I guess I am just looking for an excuse to keep it were it's at.

 

I'd advise not mounting the regulator directly on the rail as shown in your picture. Unless you are using an OEM configuration regulator, old AEM, B&M, etc that bolts to the rail and seals via flange and o-ring...it's asking for trouble.

An aftermarket regulator should be mounted in a secure and safe location. I have witnessed regulator-to-rail mounting setups simply fail.

What you're asking about on the rail is a fuel sample valve.

 

I have mine on the rail and this is how I set it up:

-8 Feed to Rail


Top View of Rail


Regulator to -6 Return


This is the matching fuel setup to my sig and car in my avatar, which consists of the Full Blown Hanger with dual 255s, -8 feed, and -6 return. I'm only at 50% duty cycle and I believe a base of 40psi.

To OP (ThE HeLLRaZoR), most people don't setup their regulator like you do due to the possibility of breaking the fitting at that end because nothing is supporting the weight. Your setup works but I highly suggest you make a bracket or somehow support that end of the regulator/rail.

 

I do have it supported by a bracket thats not an issue. I am more concerned with low throttle/ Low Engine speed as well WOT. If the Reg being so close to the Injectors could cause Pulsation at cyl#1 (or even entire rail).
I am pretty sure my pump can provide enough Fuel/Pressure to keep that from happening (MP-4302), I just want to be sure!
I suck @ Combining components/Fuel type, to Calculate exact figures to get a definate answer. But, that's were i'm at. I just wish I lived in a bigger city were help is near by lol... From what I have gathered tho... To me the wisest thing would be to move it.

 

If it's supported than it should be fine, my regulator is right above inj #1 and I have no problems. If anything, your setup should be better than mine since the fuel in my setup has to pass through rail, then go up to and through regulator, and then back down to return. Where as your setup the fuel goes straight through rail to regulator, not having to run up and down like mine. You have a more straight flow setup than I do. Theoretically, as long as you have a constant flow without any backing up or clogs then you are fine.

 

In my theory I would think the fuel flowing past the rail then into the regulator would be a better setup versus the regulator being over the one injector. I would think more fuel on both ends would dampen injector pulses and such and provide a more consistent supply to all injectors. Again that is my thoughts on it, plus mounted on the rail has an increase of weight on the aluminum fittings and such. Fuel leak = no good.

 

Agreed, his setup is better than mine because it's more straight flow than mine as I stated.

 

It all has to work before it can be better lol... So I'm thinking am going to mount Reg nxt to the Clutch Res, and run a -6AN 1'5"L line off the rail to it, -8AN return the rest of the way.
I am setting up my fuel system all crazy (my way/hope it works). I will post specifics when I have more free time. I pretty much made it up as I went along lol. I will explain my theory's as to why I did it the way I did. Thanx for feedback It means alot!!

 

why mix -6 with -8?

 

Well on this deal, it's because I have 3' of -6AN line and, the 2 #6 Union fittings (Don't have to spend another $55, on more fitting/line). Also the Rail and, Regulater are designed to accept #6 fittings.
?Could it cause a problem? I would image at low engine speeds- velocity out of Regulator would increase. But, WOT it would increase pressure at the Injectors. To me, an an -8AN would cause the most pressure build up at that area, versus at the injectors.
But, like I said I am making this **** up as I go along (your the only help I have)!

 

I'm trying to follow your train of thought here, but I can't figure it out...
The injectors are the culprit of fuel system pressure fluctuations. And the issue is rectified by volume, not PR valve placement.

Short & sweet:
The pump(s) is flowing 100% of it's capacity 100% of the time. As soon as fuel pressure is greater than the spring pressure in the PR valve, fuel compresses the spring which pulls the ball off the seat in the PRV and allows enough fuel to return back to the tank to maintain your set fuel system pressure, lets say 40 psi for example. When an injector fires, it instantaneausly creates a depression between the pump and PRV, which the PRV has to compensate for by bypassing less fuel to increase the system pressure. So this is where volume comes into play; for the sake of simple math, let's say your fuel rail volume is 1000cc's and your ECU just called for an injector pulse that will deliver 250cc's. The PRV now has to compensate for 25% of your total fuel rail volume by closing down enough for pressure to come back up, then open back up to maintain the set pressure. By that time, the ECU has more than likely called for another injection event and the process repeats, over & over & over creating a pulse frequency. At high RPM, there may not be enough time for the system to replenish itself between injection events and the next injector may fire while the system is still depressed, causing a lean combustion event. Not good.

The way to fix this is to add more volume. This dampens the amplitude of the pulse frequencies and allows the fuel system to recover from depressions quicker allowing for a more stable fuel pressure.

You clould flow through the PRV and plumb it before the fuel rail if you wanted. It functions exactly the same. This is how every returnless system is plumbed (pump flows through the PRV in the tank).