Returnless vs Return style fuel

[testorossa1989]

Ive researched enough and havent really found my answer.

I see kits offering upgraded pumps,hats,lines,rails ect for return style. I know a big weaklink in the terminator is the fuel system. I also read that in some warmer days a return style can cause some issues driving wise. Besides being easy to tune, heavy duty pumps, fuel rails.. WHATS REALLY TO GAIN IN RETURN STYLE Is it power? does return yield higher hp through fuel delievery or lower times at the track? or Is it just a apex style fuel system spoken highly of in street/track applications? Does it have any limitations? All i see is a overkilled fuel system (nothing wrong with that) that might give the pumps a break when your not in boost through the whole variable pump psi vs boost psi.

Please school me in this concept, upsides and downsides

 

[Black306]

In a word, simplification. A fuel system basically needs to be able to provide a certain amount fuel consistently and reliably. A return style fuel system does it mechanically with use of a fuel pressure regulator. Typically, pumps are run at maximum voltage supplying as much fuel as they can. The FPR then returns excessive fuel back to the tank. A returnless fuel system does it electronically with a FRPS and FPDM. Since there is no route for excessive fuel to return back to the tank, the amount of fuel sent to the engine needs to be very close to what is required. That is why tuning is very important with a returnless system. Many people have issues with returnless systems working properly and simply dump it for a simplified return system.

Being in a smog Nazi state, unfortunately I have to consider more than just ease of tuning. A conversion to a return style fuel system is actually illegal. I've had more than my fair share of smog related issues and prefer to not go down that road again. Sure, I could probably hide a FPR, but I have a well working returnless system. If it ain't broke, I ain't fixin' it. :lol:

Unless there is an issue with the amount of fuel being delivered, there will not be a power difference between a return and returnless systems.

 

[keith89]

In a word, simplification. A fuel system basically needs to be able to provide a certain amount fuel consistently and reliably. A return style fuel system does it mechanically with use of a fuel pressure regulator. Typically, pumps are run at maximum voltage supplying as much fuel as they can. The FPR then returns excessive fuel back to the tank. A returnless fuel system does it electronically with a FRPS and FPDM. Since there is no route for excessive fuel to return back to the tank, the amount of fuel sent to the engine needs to be very close to what is required. That is why tuning is very important with a returnless system. Many people have issues with returnless systems working properly and simply dump it for a simplified return system.

Being in a smog Nazi state, unfortunately I have to consider more than just ease of tuning. A conversion to a return style fuel system is actually illegal. I've had more than my fair share of smog related issues and prefer to not go down that road again. Sure, I could probably hide a FPR, but I have a well working returnless system. If it ain't broke, I ain't fixin' it. :lol:

Unless there is an issue with the amount of fuel being delivered, there will not be a power difference between a return and returnless systems.

Really? I didn't know it was illegal.:shrug:

 

[bambinov8]

I did return style on my car recently and did not make more HP than when I was returnless . However, the car feels much smoother and mpg went up a bit !

 

[Black306]

Really? I didn't know it was illegal.:shrug:

I'm not sure about the laws in NY. In CA, if it is not a direct replacement part or if it is an aftermarket part without a CARB # then it is illegal. So even upgrading to -8 line and leaving everything else stock is illegal. :fm:

 

[SlowSVT]

A return system can react almost instantaneously to sudden fuel demands due to the fact the pumps are running 100% duty cycle with a mechanical pressure regulator down stream of the rails. A returnless system uses the pumps to regulate the pressure and have to "ramp-up" to meet a sudden fuel demand which will always lag behind a return system.

Almost any modification to an emission controlled car can be construed as "illegal" in most states.

 

[keith89]

I'm not sure about the laws in NY. In CA, if it is not a direct replacement part or if it is an aftermarket part without a CARB # then it is illegal. So even upgrading to -8 line and leaving everything else stock is illegal. :fm:

oh right...CA lol.

 

[UncleSAm]

sorry to kinda jack but on the same topic, which i under stand both and get it, in the 98's whys it "hydrid" system

:burn:

 

[raym5_0]

An issue I have noticed with returnless is when I punch it & let off & hit it again, there is a major hesitation.....which I believe the MOD for PPRV delete fixes, but can lead to rupturing the disc on the FRPS with excessive pressure...supposedly some tuners are able to resolve this in the tune.

On my old foxbody S-trim/FPR/FMU/50lb inj's with a return setup I could get on & off the throttle with no stumble at all...... so I bought the Lethal budget return kit, holding to install for a winter project.

 

[gamebred26]

An issue I have noticed with returnless is when I punch it & let off & hit it again, there is a major hesitation.....which I believe the MOD for PPRV delete fixes, but can lead to rupturing the disc on the FRPS with excessive pressure...supposedly some tuners are able to resolve this in the tune.

On my old foxbody S-trim/FPR/FMU/50lb inj's with a return setup I could get on & off the throttle with no stumble at all...... so I bought the Lethal budget return kit, holding to install for a winter project.

yes i notice if i shift to slow when at wot and not rip the gears fast i get that hestitation too...but im going auto so **** it..staying returnless now..

 

[keith89]

sorry to kinda jack but on the same topic, which i under stand both and get it, in the 98's whys it "hydrid" system

:burn:

i'm not familiar with the 98 setup but i'm assuming when you say hybrid system you're referring to a deadhead return setup. I may convert to a dead head style due to fuel overheating issues from having the fuel constantly running through the hot fuel rails before returning to the tank.

see the second diagram here: Fuel Delivery 101
Not sure if that's what you're referring to.

 

[Casper cobra]

attending the class