I'm looking to convert to a returnless setup on my car. It is an all motor setup so it shouldn't be a problem converting to returnless. However im not sure if I have the layout right.



Is this a proper setup for a returnless fuel setup? I'm going to use a Aeromotive AFPR.

 

why would u want to go returnless????

i am returnless trying to convert to return because i dont know what FPR to use to bring my fuel pressure down

 

A little more power. I am not going to run boost or nitrous so I can get away with it.

 

what FPR will u be usng???

 

?? your diagram is for return-regulation, not return-less.... kinda... ?? Returnless would have no connection to a return line - just an in-line regulator. Stay with return-regulation. Looks like a 3.0 fuel rail there.

 

IIRC returnless has a return. I think you need some kind of return for the excess fuel to go back to the tank. The AFPR has a return line and 1 input/3 output lines. 2 of them will be capped off obviously.

 

A returnless system does have a return but its in the fuel tank where the fpr is located. My system has the fpr mounted just outside the tank so the return line is about 6" long.

Regardless of how you do it the fuel is still going to be circulating, the variable is the length of the return.

 

+1 to Jime's setup. The primary purpose of "returnless" systems is to avoid having the fuel absorbing heat from the hot-**** engine compartment and fuel rail and going back to the tank. The ideal situation is to do what he did and have the fuel return back to the tank long before the engine bay so it stays cooler.

 

Alright that's what I was thinking.

So do I have the setup drawn out right?

Though I was going to bolt the AFPR to the firewall next to the filter or somewhere in that vicinity.

 

Your diagram is not right. If you eliminate the tee in your picture, then its return style. To make it returnless, there should not be a second fuel rail connection where you show it going into the FP gauge.

 

?? Seems to me that you want the FPR as close to the engine as possible, since regulating the pressure at the tank means that changes in your fuel system (such as a blocked filter, dirty feed line, increased gas flow for more power) can lower the pressure at the engine. If this means a return line, then so be it. By the time the fuel returns to the tank, any extra heat is likely to be removed in the return line. There is a temp sensor in the tank, so the stock ECU will compensate. If you're getting return fuel so hot it has bubbles in it, then a small radiator might take care of it. Anybody actually measured the differences caused by FPR location ??

Personally, I've had too much recent experience with flaky fuel delivery to change away from my FPR setting and holding the pressure correct right at the fuel rail - regardless of changes in fuel load - such as heavy nitrous shots.

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I was speaking in general terms including OEM returnless systems like in the 5.5 gen+ which have in-tank fuel filters. If you realize how hot the fuel rail gets, then there's no way the fuel will cool down before it reaches the tank again; especially if the car's been running for a while and the engine has heat soaked. And it's not just about power either. The hotter fuel gets the faster it evaporates. Now in terms of these "returnless" setups being retro'd into 4th gens there is still a return line involved. It's just that having the fuel return to the tank after passing through the rail is avoided and the OEM return route is shortened. That's all. Nothing to be afraid of.


In any case, I would think that monitoring your fuel pressure is a must whenever altering an OEM fuel pressure system regardless of the setup.

 

Most of my comment was just blathering on, but I have a new respect for where to control the fuel pressure now. My fuel demand will vary widely and flowing more fluid through a 16 ft pipe will cause more pressure drop - if the regulator is at the tank. Note that I regulate pressure going to the rails - I don't flow fuel through them - only the nitrous fuel rail has flow - and the Aeromotive FPR and CNC filter...

Once I raise the bar again with the new engine, the problem will be worse - unless I use a local regulator. It makes me feel better.

 

I'm not understanding?

Regardless of where the regulator is or whether there is a return line or not a 16 ft feed line is a 16 ft feed line, no? Secondly, a "returnless" retro still includes an adjustable regulator that isn't in the tank.

 

To bring the thread back on topic, I would put the fuel pressure gauge between the filter and rail and eliminate the connection between the outlet of the rail and the return line. Then it would be "returnless". You don't want any fuel coming out of the rail.

 

Never mind.....

 

Awww c'mon it was just getting good...

 

Sparring on the forum is fun, but...... I do what works for me.

Putting a pressure regulator at the load end of a pipeline instead of the supply end of the pipe means that the delivered pressure is the same regardless of delivered volume, within the limits of the system.

My A/F is now constant at 12:1 when at WOT at N/A, or spraying a 75-shot or a 175-shot. Constant - at all RPMS to fuel-cut.

[/discussion]

 

Won't argue with what works for you, but I know a remote-mounted AFPR can work just as effectively.

 

Ok would this work?



Now the question, can the 4th gen fuel rail work as a returnless?