Continuation of the fuel rail thread
11-06-2013, 02:29 PM
#31
Former Vendor
Jorj7 - thank you for your pictures (post #20 above). I accept your measurements in straight sections.
I agree the ID of your -6 AN fitting is 7.37mm
and the ID of your metric ball flare at the fitting is 7.56mm.
However, as I mentioned several times previously, the crimps in the feeder lines at the end of the fuel rails are the problem.
See pictures below. 1987-1995 fuel rail, before and after cutting.
Because of the manufacturing crimp-and-bend, the steel feeder line becomes ovate. So I measured in both directions, the short side and the long side.
At the minimum, it is 5.36mm. At the maximum, it is 7.24mm. You can do the math to calculate flow through an oval tubing of those ID dimensions. But even at a glance, you can see that it is smaller than the -6 AN line.
So I stand by what our website claims. Our fuel rails, as delivered with -6AN fuel fittings on each end, will out-flow the stock fuel rails.
I agree the ID of your -6 AN fitting is 7.37mm
and the ID of your metric ball flare at the fitting is 7.56mm.
However, as I mentioned several times previously, the crimps in the feeder lines at the end of the fuel rails are the problem.
See pictures below. 1987-1995 fuel rail, before and after cutting.
Because of the manufacturing crimp-and-bend, the steel feeder line becomes ovate. So I measured in both directions, the short side and the long side.
At the minimum, it is 5.36mm. At the maximum, it is 7.24mm. You can do the math to calculate flow through an oval tubing of those ID dimensions. But even at a glance, you can see that it is smaller than the -6 AN line.
So I stand by what our website claims. Our fuel rails, as delivered with -6AN fuel fittings on each end, will out-flow the stock fuel rails.
You think these are the "feeder lines" to the fuel system.
Uhhhh....Wrong end.
Those tighter crimps are on the return side, not the feed side of the system.
They have nothing to do with fuel flow to the injectors.
If they are really restrictive, they would simply raise the fuel pressure.....
11-06-2013, 02:32 PM
#32
Former Vendor
Hacker,
Sounds similiar to what I run, but I've got lot less rwph. Stock fuel rails with -6 AN male ends attached:
(courtesy of Jim M.)
Running two Bosch fuel pumps, 040 and 044, but in parallel. The 044 switches on at 8-9 psi boost. I 'm running 60 psi static fuel pressure and no "boost-a-pump". Pumps ~60 gals/hr with one pump and ~120 with both. More then I need to get the power I'm making, but gives me a nice cushion.
The -6 AN is smaller diameter then the stock 10 mm line:
Stock line
-6 AN to 10 mm adapter I was using before the modified fuel rails.
There are several ways to solve the fuel flow issue, a lot depends on what you're trying to accomplish.
George
90 S4 Grand Prix White (Murf #5)
94 GTS 5-Speed Midnight Blue
06 Cayenne S Havanna/Sand Beige (PASM)
http://928.jorj7.com
Sounds similiar to what I run, but I've got lot less rwph. Stock fuel rails with -6 AN male ends attached:
(courtesy of Jim M.)
Running two Bosch fuel pumps, 040 and 044, but in parallel. The 044 switches on at 8-9 psi boost. I 'm running 60 psi static fuel pressure and no "boost-a-pump". Pumps ~60 gals/hr with one pump and ~120 with both. More then I need to get the power I'm making, but gives me a nice cushion.
The -6 AN is smaller diameter then the stock 10 mm line:
Stock line
-6 AN to 10 mm adapter I was using before the modified fuel rails.
There are several ways to solve the fuel flow issue, a lot depends on what you're trying to accomplish.
George
90 S4 Grand Prix White (Murf #5)
94 GTS 5-Speed Midnight Blue
06 Cayenne S Havanna/Sand Beige (PASM)
http://928.jorj7.com
You need to measure the smallest restriction, which is the swept tube 90 degree hose end that I pictured in the other thread.
AN adaptors are not the problem.
11-06-2013, 02:35 PM
#33
Former Vendor
11-06-2013, 02:40 PM
#34
Former Vendor
Someone in the other thread said a fuel system can only flow as much as the most restricted point.
Cam someone go measure the check valve on the outlet of the fuel pump? The last time I saw one it reminded me of a coffee straw.
I'm on the phone with Todd right now:
The fuel rails on the turbo are 100% stock except for the ends which now have -6 male ends silver soldered on.
Todd noted the -6 line is smaller than the stock hard fuel line it replaced. This was deemed adequate based on many 4-cylinder turbo cars he's been involved with that put down well over 500rwhp with "only" -6 line.
Static fuel pressure is 45-46psi.
The stock hard lines were not replaced on his car to increase flow, the routing simply didn't work with the turbo plumbing, intake etc....
The stock check valves are in both 044 pumps on his car.
The pumps are staged in series, the second one comes on at about 15psi of intake boost. At about 20-21psi a Kenny Bell "boost-a-pump" increases voltage to both fuel pumps to 20+ volts.
Cam someone go measure the check valve on the outlet of the fuel pump? The last time I saw one it reminded me of a coffee straw.
I'm on the phone with Todd right now:
The fuel rails on the turbo are 100% stock except for the ends which now have -6 male ends silver soldered on.
Todd noted the -6 line is smaller than the stock hard fuel line it replaced. This was deemed adequate based on many 4-cylinder turbo cars he's been involved with that put down well over 500rwhp with "only" -6 line.
Static fuel pressure is 45-46psi.
The stock hard lines were not replaced on his car to increase flow, the routing simply didn't work with the turbo plumbing, intake etc....
The stock check valves are in both 044 pumps on his car.
The pumps are staged in series, the second one comes on at about 15psi of intake boost. At about 20-21psi a Kenny Bell "boost-a-pump" increases voltage to both fuel pumps to 20+ volts.
The check valve, in the 044 pump, is the tightest restriction, in either the stock system or a system plumbed in -6.
In my hose business, J2 Precision Hose, we deal with high performance fuel systems that need to support high horsepower engines, on a daily basis. For horsepower outputs in excess of 600hp, we suggest that people remove this check valve and replace it with a higher flow in-line check valve, if they need residual fuel pressure, for their individual application.
11-06-2013, 03:07 PM
#35
Developer
Yes. That particular restriction I measured is on the return side of that fuel rail. There are others.
And as we were discussing "flow through the system" I included it. Its part of the system.
No confusion here.
And as we were discussing "flow through the system" I included it. Its part of the system.
No confusion here.
11-06-2013, 03:17 PM
#36
Administrator - "Tyson"
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Exactly!
The check valve, in the 044 pump, is the tightest restriction, in either the stock system or a system plumbed in -6.
In my hose business, J2 Precision Hose, we deal with high performance fuel systems that need to support high horsepower engines, on a daily basis. For horsepower outputs in excess of 600hp, we suggest that people remove this check valve and replace it with a higher flow in-line check valve, if they need residual fuel pressure, for their individual application.
The check valve, in the 044 pump, is the tightest restriction, in either the stock system or a system plumbed in -6.
In my hose business, J2 Precision Hose, we deal with high performance fuel systems that need to support high horsepower engines, on a daily basis. For horsepower outputs in excess of 600hp, we suggest that people remove this check valve and replace it with a higher flow in-line check valve, if they need residual fuel pressure, for their individual application.
11-06-2013, 04:08 PM
#37
Not that fits the 044 but all the big pump brands have larger check valves. Aero motive has a - 10 one.
11-06-2013, 05:12 PM
#38
Former Vendor
11-06-2013, 05:35 PM
#39
Former Vendor
Whatever you want to rationalize is fine by me.
Anymore discussion on this subject is complete waste of time, for me.
Unless anyone else, besides Carl, doesn't understand that the stock 928 system has more volume and more fuel flow potential than a -6 system, I'm completely done, here.
Let me know if any of you other guys need more explanation.
11-06-2013, 05:57 PM
#40
Nordschleife Master
Thread Starter
pi*7.24mm/2*5.36mm/2 = 30.5 mm^2 is the area of that bend in the return side of the fuel rail. Since there's two of those, they'll together still have cross-sectional area equal to 8.8mm ID line. If one feeds both rails with a single -6AN hose, that's still the bottle neck, since the -6AN hose ID is usually between 7.6mm and 8.7mm. And that ignores the fittings, which are typically tighter.
11-06-2013, 09:15 PM
#41
Developer
Thank you, ptuomov, for crunching the math on that.
But I am referring to the original question - you remember I claimed that the fuel dampener was no longer needed in a larger system, because it is now adequately fluid dampened. That was the original question.
It is easy for GB to point out that this restriction is after the injectors, on the return line. But the fluid dampening effect that we seek (if we are removing our dampeners) is reduced if there is a restriction in the reservoir. The reservoir in this case is the fuel rail, and both feeder lines up to their next restriction (which is usually the fuel pressure regulator on one end and the fuel pump on the other). So it MATTERS that there is a restriction, even though it is in the return line.
We need unimpeded flow and capacity if we are going to use fluid dampening to control the pressure waves, and the restriction in the return line is a problem for that.
Just an FYI: please Google "LS1 Fuel Rails" and see how many dampeners you can find in the illustrations and pictures. They just aren't used any more - everyone has gone to fluid dampening and disposed of them.
But I am referring to the original question - you remember I claimed that the fuel dampener was no longer needed in a larger system, because it is now adequately fluid dampened. That was the original question.
It is easy for GB to point out that this restriction is after the injectors, on the return line. But the fluid dampening effect that we seek (if we are removing our dampeners) is reduced if there is a restriction in the reservoir. The reservoir in this case is the fuel rail, and both feeder lines up to their next restriction (which is usually the fuel pressure regulator on one end and the fuel pump on the other). So it MATTERS that there is a restriction, even though it is in the return line.
We need unimpeded flow and capacity if we are going to use fluid dampening to control the pressure waves, and the restriction in the return line is a problem for that.
Just an FYI: please Google "LS1 Fuel Rails" and see how many dampeners you can find in the illustrations and pictures. They just aren't used any more - everyone has gone to fluid dampening and disposed of them.
11-06-2013, 09:43 PM
#42
Nordschleife Master
Thread Starter
LS1 is a funny example, because by my understanding the factory stock fuel rails still had a fuel damper built in. The pressure regulator and the return circuit are very close to the pump. There's only one line feeding the fuel rail, no return line. The fuel pressure is not manifold referenced, so the ecu tables are calibrated to compensate for manifold vacuum. But those LS1's in Corvettes definitely had a fuel damper.
Or did I look at the wrong engine?
Sequential injection will make dampening less necessary. We have batch fire injection, which often requires dampening. Modern ECU's can compensate for the resonance, making dampening less necessary; we don't have the resolution to do that, so we need fuel dampers.
Or did I look at the wrong engine?
Sequential injection will make dampening less necessary. We have batch fire injection, which often requires dampening. Modern ECU's can compensate for the resonance, making dampening less necessary; we don't have the resolution to do that, so we need fuel dampers.
11-06-2013, 10:24 PM
#43
Former Vendor
If anyone here gets the opportunity to run a fuel system with just the front damper, not the rear damper.....put your hand on the return line from the undampened rail.
We literally just did this very thing, in my shop, with my new intake manifold....wondering if we really needed a rear damper.....thinking for a few minutes that we might be smarter than Porsche.
Not smarter. not even close. Very bad idea.
That return line shakes and vibrates so badly, pulses so badly, I was literally concerned that the hose would be compromised by the shaking.....and I'm running "uber" hose....not generic rubber lined hose.
It's literally unbelievable.
Rob Edwards, Jim Corenman, and I just stood there, each of us grabbing that hose, with complete dumbfounded looks on our faces.
I'm not sure what is happening there, but the harmonics and vibration is absolutely crazy.
I immediately added the second damper and re-plumbed the return side.
I don't know if the dampers are important to the fuel that is present at the injectors....but I can tell you this.....if you are going to not run the dampers, you damn well better have the best fricking fuel lines you can find on those return hoses. I use crimped PTFE on my fuel lines....virtually "bullet proof" to anything you can throw at them. I was still very concerned about the harmonics and the vibration. I can't imagine doing this with generic -6 hose and replaceable fuel hose ends....it would seem to almost be asking for a disaster.
Perhaps Rob Edwards can chime in and tell you what he felt and what he thought.
We literally just did this very thing, in my shop, with my new intake manifold....wondering if we really needed a rear damper.....thinking for a few minutes that we might be smarter than Porsche.
Not smarter. not even close. Very bad idea.
That return line shakes and vibrates so badly, pulses so badly, I was literally concerned that the hose would be compromised by the shaking.....and I'm running "uber" hose....not generic rubber lined hose.
It's literally unbelievable.
Rob Edwards, Jim Corenman, and I just stood there, each of us grabbing that hose, with complete dumbfounded looks on our faces.
I'm not sure what is happening there, but the harmonics and vibration is absolutely crazy.
I immediately added the second damper and re-plumbed the return side.
I don't know if the dampers are important to the fuel that is present at the injectors....but I can tell you this.....if you are going to not run the dampers, you damn well better have the best fricking fuel lines you can find on those return hoses. I use crimped PTFE on my fuel lines....virtually "bullet proof" to anything you can throw at them. I was still very concerned about the harmonics and the vibration. I can't imagine doing this with generic -6 hose and replaceable fuel hose ends....it would seem to almost be asking for a disaster.
Perhaps Rob Edwards can chime in and tell you what he felt and what he thought.
11-06-2013, 10:31 PM
#44
A few of us are running Victors SC kits and the fuel rails are dead headed using the FPR and one Damper. Hans brought a sample of a damper from Bosch that I have been looking at and want to add one to each rail.
Thoughts?
Thoughts?
11-06-2013, 10:42 PM
#45
Nordschleife Master
Thread Starter
If you can find space for them, I would use them. They may prevent a problem and don't see much potential for downside if installed correctly.