Returnless truck rails and boost referenced regulator. Pics?
 

So it looks like I'll be sticking to the stock truck rails for the time being instead of switching like I had intended.

You guys using returnless rails, how are you setting up/mounting your regulator? I have an Aeromotive 13129 regulator, I planned on putting it in between the pumps and the rail and then returning back to the tank, so it'll be before the injectors, until I eventually switch intakes and rails.

My problem is that the feed fitting on the rail is 4 or less inches from the firewall and the regulator can't be mounted to the firewall or it won't tech in at my local track. How are most of you handling this? Where are you mounting your regulator with returnless truck rails?

put the regulator right at the gas tank, 3ft into the regulator, 3 ft back into the tank and one feed line up to the rail, super easy, save money on line

I've been considering that, but I already have all of the fuel line. I eventually plan on swapping intakes and wanted to make sure I could put the regulator after the rails.

It also has my fuel pressure gauge in it, so there is another issue...


In all honesty, is there anything keeping me from putting this near the tank as far as NHRA regulations go?

Nhra rules stat that the fuel pressure regulator and fuel distribution blocks must be located 6 inches in front of the firewall.

But is that 6 inches in front of the firewall IF theyre in the engine bay?

Lots of OEM regulators are near or in the tank. The corvette style regulators are external and near the tanks.

I think I'm just going to put a 90* fitting straight on the end of the rail, and then solid-mount the regulator to it.

I plan to put the regulator at the tank so I only have one fuel line.

Curious, why everyone doesn't do it this way? Why would you want to have to run another return line??

Is there a benefit I am missing?

Boost referenced FPR's use a return line. It's either a really long vacuum line or a return line. For N/A there is no real benefit. I use a vette FPR/filter in my rx7 but I'm not boosted.

Bit of a random rule that ?

either way, the reg can be mounted anywhere between pump and rails ( or after in a normal system )

IMO closer to the rails is always better. Some regs will be big enough to allow a flow through the main reg body, others you can just tee the reg off the side of the feed line to the rails.
I'd prefer the latter if doing a dead end setup.

Sorry, trying to learn. Why would you need to reference boost for the FPR?


Seems to be a preference to be closer to fuel rail, just not clear why, and what the advantage is.

I am really concerned with a clean clutter free build and would prefer no return line.

I imagine that they want It in front of the firewall so in the event that the flywheel or tranny explode they don't hit the aluminum regulator or distribution block creating a massive fuel leak and a potential fire.

The closer to the rail the regulator is, the quicker the fuel can keep the rails filled and at pressure. Think of the reg as the bottleneck. When you go wot it needs to keep the pressure at the rails stable, and its easier to do so the closer it is. Ideally you have return style rails and put the reg after the rails, but since this is a dead head setup, the closer the better

i didnt have an issue making 700+ tire on 3/8ths hose with the regulator in the back of the car on a returnless ls1 intake

So fuel pressure can increase with boost to maintain a constant pressure across the injector to actually inject fuel.

And it's simple. It gives more accurate/reliable control of pressure at the injector when the regulator is local to the injectors.

Pushing liquid up a pipe takes effort, the longer the pipe the more effort. If you then try and regulate pressure at the source, it leaves lots of room for issues, especially if fuel demand is high.

Then they should regulate not to have such items within a distance of the flywheel or tranny, assuming their location relative to a firewall is a bit daft.

I always post skinnies pic because it's easier to see. But this is how I have mine as well.

https://cimg4.ibsrv.net/gimg/ls1tech...b25144675c.jpg

Mine is mounted on the shock tower now.

https://cimg5.ibsrv.net/gimg/ls1tech...6588944a26.jpg

https://cimg1.ibsrv.net/gimg/ls1tech...8259470cb7.jpg

Using Russell quick connect to an fittings for the rail and old hardline
I have it mounted on the old ac line bracket and haven't had an issue with tech
It's technically not mounted on the firewall, it's mounted on the ac...lol

You need more fuel pressure to overcome boost pressure. Theoretically, if you had 20 PSI of fuel pressure and were running 20 PSI of boost, your fuel wouldn't spray into your intake since the fuel wouldn't be at a higher pressure than the air inside of it. It helps keep duty cycle down under boost as well.

If its not a boost referenced regulator, there isn't much reason to mount it under the hood. My regulator will eventually go after my rails instead of before. It also has my pressure gauge built into it.

Understood, I just assumed you would run your fuel pressure at x+boost pressure all the time. Is there a concern with that?

Sensible. I can see how being closer can give better reaction time and fidelity. Under a quick change, you would have the entire length of tube before the regulator would see the change. It would behave as a buffer.

Is it really that sensitive, though? I was under the impression the flow of regulated fuel was proportionately larger than that of fuel demand at the injectors.

I'm not debating, and I can understand the preference, It's just important to me to have a ultra clean setup. I may want to push the margin a bit on this. Ultimately I could monitor the fuel pressure and A/F ratio at WOT to ensure its getting enough fuel.

Most keep it at the rails because its actually plumbed after the rails, not before. That way no flow is redirected through the return before it hits the injectors, giving 100% unaltered flow from the pump to the injectors. This is how 90% of aftermarket regulators (especially boost referenced) are set up.

Yes, the purpose of a boost referenced regulator is to run Fuel Pressure + Boost pressure. Most of them work on a 1:1 ratio. So if you set base pressure at 40 PSI and are running 20 PSI of boost, it ups your fuel pressure to 60 PSI. Some of them work on a variable, or a rising rate like 4:1. So for every PSI of boost, fuel pressure will go up 4 PSI.