Stock fuel rail modification

[Jerryl]

Has anyone tried to connect the inlet side of the fuel rail to the end side of the rail right before the regulator?

 

[we4Mateo]

Has anyone tried to connect the inlet side of the fuel rail to the end side of the rail right before the regulator?

Like a dual feed? I'm not visioning what you are asking.

 

[gtfrede]

If im understanding everything correctly you would not want to change the feed to the regulator side because you dont want the regulator bypassing fuel to maintain pressure before it reaches all the injectors.

 

[Jerryl]

Like a dual feed? I'm not visioning what you are asking.

Almost.

If im understanding everything correctly you would not want to change the feed to the regulator side because you dont want the regulator bypassing fuel to maintain pressure before it reaches all the injectors.

True. My hypothesis is: The fuel pressure may drop slightly at the last cylinder. Connecting the inlet side of the rail to the end via a small 4AN should reduce pressure drop at #1. I understand that a liquid is incompressible and that delivery volume is not a concern if fuel pressure is constant. It still does not explain #1 going lean on much higher HP applications than I will ever run. You think there is any merit to this?

 

[gtfrede]

I think this boils down to the pressure vs volume argument....the injectors need a constant supply of volume at the proper pressure to achieve the desired results...if you try what you are suggesting the pressure in the rail may remain the same but you would be shooting yourself in the foot taking away the volume of fuel running through the rail because the regulator would be bypassing the fuel flow before it can reach ANY of the injectors....it would just be moving the fuel delivery problem around and not really solving anything.

 

[psycho6cyl]

lean cyls power plate it lol

 

[SIXBANGR]

I did it on my old Stage ll motor several years ago. It worked fine on it. But it was after market rails.

 

[Jerryl]

I think this boils down to the pressure vs volume argument....the injectors need a constant supply of volume at the proper pressure to achieve the desired results...if you try what you are suggesting the pressure in the rail may remain the same but you would be shooting yourself in the foot taking away the volume of fuel running through the rail because the regulator would be bypassing the fuel flow before it can reach ANY of the injectors....it would just be moving the fuel delivery problem around and not really solving anything.

The fpr is what's referred to as a "snap valve" wich can only be truly closed up to xx% of set pressure. A modulating valve would actually work better, and decrease pulsation. My thought is that the extra feed (volume) after injector pulses would at least help. Maybe not.

 

[Jerryl]

lean cyls power plate it lol

Actually, i think . . . It's the opposite. Fronts run rich given same pressure/vol of the fuel system. Rear cyl get more air, and pp redirects to balance air flow.

 

[Jerryl]

I did it on my old Stage ll motor several years ago. It worked fine on it. But it was after market rails.

Thanks for sharing.

 

[SIXBANGR]

I also recall doing it with the stock rail befor I went Stag ll. I cut the end off, drilled it out and put in an AN fitting. I just got rid of that old rail when I moved 7 months ago.

 

[belsie]

As a newbie to these areas I was floored by the fuel coming so far and thru the hottest area as it winds to the rail?? Why not inject fuel into rear of rail with a Y split at rear of rail rather than at the front right entrance feeding the system? Seems like reduction of heat & equal distribution may be an option worth considering!!!!!!!

 

[gtfrede]

I just dont see how it would be of any benifit or could potentially even be detrimental to fueling available for the injectors when they are not recieving the full fuel flow prior to it being diverted away from the rail to keep the pressure where it should be...im sure its because im overthinking it....maybe it makes no difference at all

 

[earlbrown]

The fpr is what's referred to as a "snap valve" wich can only be truly closed up to xx% of set pressure. A modulating valve would actually work better, and decrease pulsation. My thought is that the extra feed (volume) after injector pulses would at least help. Maybe not.

Keep in mind the vac/boost signal going into the FPR is pulsed. Even if you had a diaphragm with 0 mass in a frictionless environment using fuel with 0 mass, it would still be 'pulsey'


With the cross section of the fuel rail ID compared to the flow area of the injector outlet, I can't imagine there's any friction losses in the rail. (ESP when you compare the fuel rail's ID to the choke points ID on the fuel lines themselves) Plus, the fuel is going through the rail faster at idle and cruise than it is at WOT.