Returnless fuel system

[Olav]

I'm building my FI Chevy SB system based around a modified LT1 intake and a LINK fully programable ecm. I also have the PA-4 tank kit with a walbro 255 pump. My engine will be about 400-430 HP. If i use the C5 regulator/ filter is there any drawbacks on this combination. And why? Have posted on several Norwegian forums and peaple say this will not work....but cant tell me why. A lot og newer cars have this system. On a heavily modified engine it will be better with a retur system.

Olav

[Jim Nilsen]

Look into this section and you will find a lot of info. Jody (Camcojob) has done this and so have many others including myself. Other pieces have been use other than the Corvette pieces but the concept is the same and it works. My fuel pressure doesnot fluctuate and the lines are mush easier and less expensive to run. There are also other benefits.

Get back to us if you can't find the info you need to find and don't worry about the people who say it won't work but can't say why, they just are repeating what they have read by others who failed to do it right.

Goodluck

[Olav]

Thanks!

Whats the biggest benefit, other than easier to run lines.

[CarlC]

It's technically not a returnless system. The C5 fuel-filter-regulator does have a return line that must go back to the fuel tank.

To me, there are few drawbacks for engines making less than 600hp when combined with the 255lph pump. Take a look inside the outlet of the pump. The orifices are tiny. The filter is not the restriction or limiting factor.

The advantages are many. Need a filter? Any GM dealer will have one. OE reliabilty? Got that too.

[Olav]

It's technically not a returnless system. The C5 fuel-filter-regulator does have a return line that must go back to the fuel tank.

To me, there are few drawbacks for engines making less than 600hp when combined with the 255lph pump. Take a look inside the outlet of the pump. The orifices are tiny. The filter is not the restriction or limiting factor.

The advantages are many. Need a filter? Any GM dealer will have one. OE reliabilty? Got that too.

I know that it have a return to the tank...I might order a filter/ regulator

Olav

[Jim Nilsen]

Thanks!

Whats the biggest benefit, other than easier to run lines.

The big claim is that you are not heating the fuel up as much going thru the engine bay.

[Bowtie racing]

I have fuel line build going on too. And as well have ricks tank with 225 pump. I did email to aeromotive ( since i have their regulator and filter) about placing the regulator near tank to with single line up front . They did recomend to use return line and mount regulator close to engine.

[TnBlkC230WZ]

I'm not an expert, but this is my underdstanding of the topic.

With a single line going to the fuel rail and the rail is dead headed:

When engine fuel demand suddenly and dramatically increases, pressure on the line will momentarily drop slightly. This is a 1/4 - 1/2 second event and maybe an average of a 5 a psi drop until the pump brings the line pressure back up.

GM has figured out how to size everything to minimize this event. If I were building a system like this, I would want the regulator or return style fuel filter as far away from the engine as possible. The longer fuel line with more pressurized fuel available will minimize the pressure drop and monentary lean condition.

Properly done, the slight lean condition will not be noticable. I wouldn't do it on a turbo or supercharged applicaiton.

Fuel system with the regulator on the return side of the fuel rail:

The fuel pressure will remain constant on the fuel injector side of the fuel system.

[Vegas69]

Everytime I see this topic, I always say it's not a returnless system. It's a very short return. GM has it figured out.

[Jim Nilsen]

According to the accel DFI a dead headed fuel rail is returnless even though some would misconstrue the parts involved but if you read the instructions fully it really comes down to dead head or flow thru.

[Vegas69]

I can see how they could argue it's a dead headed system. The fact of the matter is, the pump can run at full sail and be ready for that wide open throttle blast. In a true dead head system, the pump is bleeding off the pressure similar to an oil pump.