Saturn Sky Forum banner

21 - 28 of 28 Posts

·
Registered
Joined
·
268 Posts
I should also add that some regulators are "boost reference", meaning that they adjust the fuel pressure for boost and vacuum. When you have a set of low pressure injectors in the intake manifold, the air around the bottom of the injector is almost always a different pressure than the fluid in the fuel rail (as well as atmospheric pressure). Fluid always moves from a high pressure to a low pressure, and you want to keep the difference in pressure somewhat constant. If you ran 59 psi of boost, and 59 psi of fuel pressure, then fluid would only "drip" out of the injector due to gravity like someone poked a hole in a bag. This is why some people switch to boost referenced regulator, because it's the difference in pressure that moves the fluid.

A lot of this doesn't apply to direct injection because all you really need to do is deliver the fuel to the front of the car as a feed for the high pressure pump.
 

·
Registered
Joined
·
207 Posts
Discussion Starter #23
His system makes sense. I ran this setup to make it adjustable and keep the same pressure and flow to each injector. It works great for this engine. I do think his setup would work for you if you didn't want to change the rail. There's a lot of cars that are both ways we have listed here. You can always try his and if it doesn't work the way you wanted, you can get a rail or something.
 

·
Super Moderator
Joined
·
11,238 Posts
So to come back to this since it looks like something I'm going to do, the DDM fuel rail makes this a lot easier. The rail has plugs at each end so you could (in theory) easily adapt it into a return fuel system. Now I just need to figure out what I need to do so.
 

·
Super Moderator
Joined
·
11,238 Posts
Just adding

I'm not going to provide part numbers or anything like that for this as this is basically the same build as slvrsky did just with a DDM fuel rail and a different placement of the regulator.

I don't know which layout I'll be going with yet and won't know until the day of the install. The difference in my setup over slvrsky's is no welding is required. You replace the stock fuel rail with the DDM piece and it has ports at each end that allow you to easily convert it to a return system. Remove the plugs from those ports, put one of them in the center feed port, and it's ready to go. You can also leave the center feed in place and tie both end ports together for your return to the fuel pressure regulator but I like the through and through method better because I think it's cleaner.

My plan is to connect to the stock fuel line from the tank in the engine bay to the front of the rail. The Regulator will mount using AN fittings directly to the fuel rail in the back. Here I will have a pressure gage and put the regulator on it's side to clear the cowl at the base of the window. To still be able to access the pressure adjustment, the pressure adjustment screw needs to face the drivers side of the car. This puts the return port on the opposite side of the rail from where the line will route to return to the tank so I use a couple of 90 degree elbows to get the return facing the right direction then use the same style quick connect to connect the return line to the regulator. At the tank, a bulkhead fitting and 90 degree hose fitting will connect the braided line to the tank.

My primary layout:



My (infamous) "Plan B" layout:



And, because this is my first time designing something using AN fittings and I don't know what can go into where...my Plan B's Plan B:



The difference between the two layouts is the extra male to male and female to female fitting between the pressure gauge and the regulator. This connection runs almost DIRECTLY above the oil filter. I want to be able to change my oil filter without removing my fuel rail so if the gauge fitting alone doesn't push the regulator far enough back to have a socket and extension pass down to the oil filter housing, I'll extend it with the male to male and female to female fittings.

For those wondering, yes the regulator does have a port for a fuel pressure gauge but where I'm going to mount it would cause the gauge to face downward and make it completely useless. Thus I use this setup and it spaces the reg away from the rail like I need it as well as letting me see the pressure.

EDIT. Just wanted to add to this post for anyone that runs across it in the future. All the above designs did not work due to clearance issues with the return line fittings. Here is the final layout I recommend. Note that on the fuel inlet side of the rail I used the design above with the 90 degree hose end and a 90 degree male to female fitting because I already had them. In retrospect, I would have replaced those with a 180 degree hose end as shown in the diagram below.

 

Attachments

·
Super Moderator
Joined
·
11,238 Posts
I also think the OP would have been much better off using the stock filter that sits inside of the tank, it's actually fairly big.
I just noticed this and after taking apart my fuel pump assembly to do what the OP did, my question is how would you use the stock in tank filter without using the stock in tank regulator? They look like (from what I can see) tied into one another.

The line from the pump goes out and into a fitting that, I assume, directs it into the filter and the regulator. Then another line comes out of the assembly and heads for the lid to go out to the engine.
 

·
Super Moderator
Joined
·
11,238 Posts
Just got the last parts of this ordered today. Have a lot of it assembled already. Will take some good pics once I start installing to show my version of this build using DDM's rail. Should be a very easy build that anyone who can change the injectors should be able to accomplish.
 

·
Super Moderator
Joined
·
11,238 Posts
21 - 28 of 28 Posts
Top