I am putting together a new engine setup for this season and will be running a S5 NA intake. I would like to use -6 AN fittings on the fuel rails, I already have fittings that fit the stock S3 fuel rail that came on the motor for the primary but I am looking for something for the secondary rail. I have an S4 NA secondary fuel rail which is aluminum and threaded, the injector bosses are the correct spacing, but the mounting bosses are in completely the wrong place. I guess I can cut off the ends of the S5 rail and weld some fittings on, but I am not entirely sure where I should cut off the end with the regulator, has anyone ever done this? I don't need any regulator just -6 AN fittings on the inlet and outlet.

 

My assumption would be that you can put them between the injector bung and the old outlets..
If you look at the left side of that rail you can cut just after the inlet tube,cutting that piece right off.
The Right side though looks a but trickier as you would need to be pretty well at the edge of where the Outlet tube is..

I have to ask if you have thought about just getting away with taking the regulator off and welding it up?.
That way you retain the IN and OUT on the rail but yet are able to use those ends to go to a hose that has a A/N end.That would hook up to the rest of your modded fuel system.

 

One thing to watch for on the S5 rails is that the mechanism of the regulator and damper is actually somewhat inside the rails, about an inch at each end. If you just cut the ends off you will find them blocked.

S4 rails are a better choice for this as they have metric threads which will directly take AN adapters. Well, I think one side needs to be tapped out but that's easy.

If you do want to use the S5 rails, then you need to cut down almost to the injector bungs and then weld your fittings in that location.

 

Both ends of the S4 rails are already tapped. One end is M14x1.5 and the other end is M12x1.25. The problem is the S4 rail mounting points are totally different.

 

disregard

 

Only primary. The secondary has an o-ring port for the regulator and needs to be tapped out.

The mounting of course is wrong, but some 1/4" spacers take care of that. Or 1/2", I can't remember at this point. It's so long since I've touched stock fuel rails on an FC...

 

the s4 to S5 turbo rails you can do that....are they n/a rails similar?

 

It works turbo-turbo or NA-NA. But putting an NA secondary on a turbo manifold (or vice versa) requires relocating the mounting bosses.