View Full Version : Feeler: High Flow Fuel Rails

01-02-2011, 08:15 PM
Tonight I was out in my shed having a smoke and somehow ended up with fuel rails in my hands, this got me thinking.

Now I know that a few years ago, as far as I can remember, our stock fuel rails were sufficient for the amount of power that the big dogs were making. Now with some looking to go to E85 and the possibility of more power from these engines then we thought back then, is there the possibility that we may be needing higher flowing fuel rails in the next few years?

Now I know that there is clearance issues to be worked out as well as manufacturing issues but as far as design goes I can work on that in the time that I have available with the input of people like Dave Dalke and others that have significant experience with these engines and their fueling needs up at the higher power levels. I will be using AutoCAD to design these (since I am going to school for computer aided product design) so that will take allot of the expense (for R&D), that we would normally see with new parts, out of the equation.

So, that is my thoughts and my proposal. Let me know what you think.

XR7 Dave
01-02-2011, 09:58 PM
If making a new fuel rail, I suggest designing it for short style injectors because there isn't enough clearance to run a billet rail against one of the big blowers.

Other than that it's pretty simple unless you also want to retain the stock connections and FPR. That makes it a little more complicated.

01-03-2011, 12:24 AM
I agree, they make 60# and 80# short injectors and would allow folks not to have manifold leaks from the injectors as the blower pushes against the rail.


01-03-2011, 01:31 AM
Ok. Well that leaves me needing some more info so I can mock up the heads and intake with a blower case. But I do need to know if these injectors are physically similar to the injectors that Ford used on the V8 SHO's and the Focus. If they are I can just pick up a set at the salvage yard and use them for the mock up.

Also, what interference is being experienced with the blower? Is it do the blower case flexing under high amounts of boost or is it do to limited space? The case that I will be using is just going to be the run of the mill early model so if the side reinforcements the Magnum Powers incorporates into the MPX is an issue I can build up the case with some filler to simulate that. Some pics of that clearance issue would be ideal so I know what I am up against.

Dave, as far as the connections and FPR go I would have to say that the factory stuff would have to go. If I'm not mistaken most, if not all, the high HP SC's are running AFPR's that are remote mounted so I would think the best course of action would be to not consider reusing the stock FPR mount.

Now as far as the line fittings go I know that anyone that has upgraded their lines are more then likely using the appropriate adapters to connect to the factory fuel rail so what I was thinking is using fitings like this http://www.summitracing.com/parts/AEI-15101/ so there would be no changes required to the feed and return lines. A few minor brackets and those could be put in a position similar to the stock location.

01-03-2011, 02:10 AM
Its not the M90s that have fitment issues, Its ARs, Whipples, and other different then stock blowers.

I dont think we need custom rails for M90 based blowers, in terms of flow...Other then the coolness factor and maybe feeding the rail from each bank so there is a more even pressure among all injectors.

I am not sure what applications use shorter injectors, But they plug in and O rings are the same as a stocker or skinny DEKA ones.

01-03-2011, 03:10 AM
Its not the M90s that have fitment issues, Its ARs, Whipples, and other different then stock blowers.

Post some pics so I can see where the issue is. I definitely want to look into this for the non-Eaton's since you say there is a problem and also since they already have a higher potential than the Eaton powered SC's.

maybe feeding the rail from each bank so there is a more even pressure among all injectors.

I think that right there would be a benefit making this worth while. I'm pretty sure that I read that the rear cylinders are naturally lean and I can see how with the way the stock rail is designed. Obviously the guys that have the higher power numbers are the ones the stand to gain most out of something like this.

01-03-2011, 11:43 AM
Consider this. The injectors mount into the heads. The surface the heads present are at an angle so the injectors mount into this hole at an angle where the tops of the injectors are tilted in, towards the center of the V of the motor. the taller the injector, the less clearance there is in the V since the additional height brings you further inward.

With the current height injectors and stock fuel rail there is less than 1/8 of an inch of clearance between the blower housing and the fuel rail mounted on the top of an injector. The stock rail is steel tubing with brazed cups. There isn't enough clearance with the current configuration to have larger diameter tubing for the rail, let alone a billet rail using available blanks. Currently installing the blower with the fuel rail in place puts stress on the injectors as it struggles into place. Tubing any bigger and the blower wouldn't be able to be removed without also removing the rail.

Dropping the injector size may allow for more clearance for the rail against the blower body, but you don't want to forget all the other things you need to clear. On the back side there are the various plenum's that the current rail sneaks under. On the front side there are the accessory brackets, coil pack, and thermostat housing. I had to offset the coil pack mount on my 93 just to clear a -6 AN fitting.

I'd love to see a better fuel rail system, but the effort that will go into build it seems significant. At a minimum you'll need something to fab on.

http://media.motortopia.com/files/cars/album_2009_work/4a946f091fd07/tn_full_fuelrailoverheadjpg_Thumbnail1.jpg (http://www.motortopia.com/photos/446537)
http://media.motortopia.com/files/cars/album_2009_work/4a946fed65083/tn_full_passengersidefuelrailjpg_Thumbnail1.jpg (http://www.motortopia.com/photos/446554)

01-03-2011, 01:26 PM
Awesome Mike, thank you! Those pics definitely put it more into perspective. So I guess that means that when I get the fixture made to hold the heads and intake I need to consider the accessory brackets as well. Good thing I have some spares that I can cut up. Can you get me some measurements on that blower case as well so I can get a "dummy" case welded up so I have something that simulates an AR to work around? I also need to know how the AR is bracketed to the intake so I can mount it.

01-03-2011, 01:43 PM
I think Neibert and I are a couple of the very few that have billet fuel rails. I obviously can't compare mine with the AR/Whipple guys, but Neibert's works well enough. We got ours from Jerrod Imerbthama, but I haven't seen nor heard from him in a long time.

You can choose any of the four ends to feed the rails, but the method is to have a fuel inlet port, one cross-over hose to connect the two rails with fuel, and one outlet port. After the outlet side, you run a hose to a remote style regulator. This ensures that the whole fuel system before the regulator is at the regulated pressure; given that the lines are large enough and consistent in size. They're doing the same thing from the factory with the only difference being the FPR isn't remote mounted. If you want to use the factory FPR, then you may be smoking something hazardous to your health.

01-03-2011, 05:42 PM
Jerrod screwed me over on an order. I sent him money for some rails and he disappeared with my money.

More pictures attached. Case, I can try to take some measurements, but accuracy is tough with it mounted, Perhaps DD has some dimensions for the various housings he has worked with. I assume you'd want to fit the largest.

Other images
http://media.motortopia.com/files/3211/album_2009work/4d2241c234dbd/tn_full_passengersidefrontinjector.jpg (http://www.motortopia.com/photos/591964)
http://media.motortopia.com/files/3211/album_2009work/4d2241cc16b6b/tn_full_PassengerSideRailRoom.jpg (http://www.motortopia.com/photos/591965)
http://media.motortopia.com/files/3211/album_2009work/4d2241cd73825/tn_full_PassengersideMiddleInjector.jpg (http://www.motortopia.com/photos/591966)
http://media.motortopia.com/files/3211/album_2009work/4d2241cfdd029/tn_full_DriversSideRailDistance.jpg (http://www.motortopia.com/photos/591967)
http://media.motortopia.com/files/3211/album_2009work/4d2241d0c3a2d/tn_full_DriversSideFwdInjector.jpg (http://www.motortopia.com/photos/591968)

David Neibert
01-03-2011, 06:21 PM
This post has a few pictures of the fuel rails we installed when doing the 1.7 AR. Still using the same rails with the 2.3 Whipple, but did have to do some clearance grinding on the rail mounting tabs and changed to dual supply lines.



01-04-2011, 11:27 PM
Muscle Motors Performance had the injector tech data on their site so I will get the missing dimensions for the O rings from a stock injector. The only thing I will need then so I can get some mock up injectors made is the connector dimensions and angle so if someone can get me those it would be appreciated.

01-05-2011, 01:25 AM
You could probably make some calculations based on the stock angle vs the stock lenght injectors. With the shorter injector 34.5 MM the rail will drop. the angle will stay the same since it will need to retain that angle for it to slide in the heads. Then you can calculate where the new holes will land on the new rails based on the shorter distance.

On the picture notice the new distance between the injectors, Angle stays the same as stock.

01-05-2011, 10:25 AM
Best thing to do would be fab up one bank. The other bank will work and just need the rail flipped.

Expanding on Ricardo's point, since the injectors angle into the rail, changing the length will change the point at which the injectors intersect with the rail. Consider 2 parallel lines connected by a diagonal line. Getting into basic geometry here. (http://library.thinkquest.org/20991/geo/parallel.html)
Note the change of intersection point as the lines get further or closer together with one end of the line anchored to the same spot (in the head).


Also, you need to keep in mind that while the example above is working with Parallel lines, the stock fuel rail does not run parallel to the heads. The differing angles at the injector ports require different distances from the heads along their length. your best bet (baring a good 3d model of our head) would be to work each injector port individually with math to get it close. Then put it all together in a prototype that you can adjust from there.

01-05-2011, 12:07 PM
This goes out to Dave, I have only been able to find short 60# with ease. The short 80# seems I can only source out of Australia from time to time. They are direct fitment to the Holden VE. Do you have the injectors sourced out from any US distributor? Dont need to tell me who, just want to see if you can get them with ease.

XR7 Dave
01-05-2011, 12:19 PM
There is no problem getting short 80's. Going bigger than that may be an issue though. However, with more and more cars using the short injectors, I think it is only a matter of time before 96's and bigger become available.

01-05-2011, 03:41 PM
So this is where I'm at right now.

I have:

Intake w/elbow
Acc Brackets
Stock fuel rail
Stock style inj.

Pretty much everything for the top end.

This is what I need to do before I can start designing anything:

1) Need to get dimensions of the largest AR currently used on an SC as well as how it is mounted.

2) Get a jig made to mount the "top end" of our engine.

3) Get a set of dummy short injectors made for mock up.

4) Purchase misc. gaskets to ensure proper spacing between heads and intake.

5) Get dummy AR fabbed.

6) Build all parts on AutoCAD.

So I have a long way to go. Looking at a few weeks to maybe a month to get 1-5 on the list completed. Number 6 will take a little longer do to time constraints and class but I should have that done by mid spring.