New Product: High-Flow Billet Fuel Rails
10-25-2013, 12:54 AM
#61
Rennlist Member
+2 ... Unless you have a fuel rail the volume of the pacific ocean, or which in itself has an ability to absorb shock, you won't see any significant diminution of pressure waves ....think water hammer in copper water supply pipes in a house which have a large system volume, and still hammer when solenoids and mixers slam shut.
The only things that will absorb those pressure waves are hydraulic damper diaphragms, and flexible fuel lines or other flexible components within the pressure circuit, which are capable of absorbing hydraulic shock waves.
The only things that will absorb those pressure waves are hydraulic damper diaphragms, and flexible fuel lines or other flexible components within the pressure circuit, which are capable of absorbing hydraulic shock waves.
10-25-2013, 01:57 AM
#62
Rennlist Member
Carl:
Can you expand on the hardware used in the rear of the 32v application? Does it continue to use the OEM FPR and Rear damper?
Is it asking too much to re-engineer the front plumbing to introduce use of the OEM front damper?
I would consider this, simply because it will make the fuel rails with the intake spacers 'servicable' again.
But..I will keep the dampers.
BUT..I could be convinced some that they are not needed, seeing a sharkplotter output of a street car with an hour of sharktuner logs in it.
The harmonics are easy to see.
Can you expand on the hardware used in the rear of the 32v application? Does it continue to use the OEM FPR and Rear damper?
Is it asking too much to re-engineer the front plumbing to introduce use of the OEM front damper?
I would consider this, simply because it will make the fuel rails with the intake spacers 'servicable' again.
But..I will keep the dampers.
BUT..I could be convinced some that they are not needed, seeing a sharkplotter output of a street car with an hour of sharktuner logs in it.
The harmonics are easy to see.
10-25-2013, 02:59 PM
#64
Developer
Thread Starter
I know from experience that is not true.
But I went to a fuel systems engineering specialist friend of mine to see if he could explain it to me (again) so I could share the explanation with you. He designs fuel systems for Pratt & Whitney, and owns a supercharged 928.
Here is what he just emailed me:
Of course, you can do what you want. I just make the billet fuel rails.
By design, you can plumb them any which-way you like, include dampeners and multiple regulators or just one single regulator like I do.
Whatever you want to do. There is no one right single solution.
But I went to a fuel systems engineering specialist friend of mine to see if he could explain it to me (again) so I could share the explanation with you. He designs fuel systems for Pratt & Whitney, and owns a supercharged 928.
Here is what he just emailed me:
The stock fuel rails held a very small volume of fuel and since the volume that is injected when an injector opens compared to the volume in the rail is a large enough percentage that you will get a pressure ripple that apparently needed a damper.
With your larger fuel rails, they act nearly like an intake plenum. Yes of course fuel is an in-compressible and air is a compressible fluid, but the concept is the same. With a larger volume there is some dampening that comes within the fluid.
Secondly, and I think the most important factor here, is the L/D ratio of the fuel rails and not exactly the volume itself… When the engine is running, there is fuel in those rails starting and stopping, accelerating and decelerating all the time, constantly. In internal flow of tubes, the major factors that determine the resistance to flow are Length/Diameter ratio of the tube and in a smaller scale the surface finish of the tube. Now, imagine with me you have the small diameter fuel rails, and they are super long, imagine the injector on the far end shoots some fluid out. Fluid, in order to fill that spot has to move down to that end, the reaction time of this being able to happen is slow because of it being a super skinny tube with a long length. Since the reaction time of the fuel being able to move is slow, the system sees a full pressure drop to a low point at the injector, and then gets back-filled eventually and comes up to full pressure again. There is always momentum in fluid so if you make the fluid ripple like this, it can find sweet spots where the ripples superposition on top of each other and you have a natural frequency in the fuel rail that might be substantial. I think that is what Porsche was worried about. Now, I don’t know if they were trying to dampen a pressure ripple because they were worried about spiking an o-ring, or if they were worried that the pressure ripple in the fuel rail would make the injection inconsistent. My hunch is the latter. Think of this, at the time they only had 80’s technology computer in the car. They are only opening the injector according to a timed pulse. Nothing else. The pulse width is basic. So, what makes the amount of fuel vary in a set pulse width? Pressure. A pressure ripple in the fuel rail would make the injectors randomly hit low or high pressure ripples when they inject and that would make a slightly less tuned car.
ANYWAYS, what you have done is changed the L/D ratio of the fuel rails such that there is, let’s say, no resistance for the flow to get to the open injector on the end immediately. If you imagine your fuel rail as a large tank…the pressure is the same in the whole tank, when a small injector opens, the low pressure when that injector flows does not reach the whole tank, it stays localized because there is so much more fluid around it.
With your larger fuel rails, they act nearly like an intake plenum. Yes of course fuel is an in-compressible and air is a compressible fluid, but the concept is the same. With a larger volume there is some dampening that comes within the fluid.
Secondly, and I think the most important factor here, is the L/D ratio of the fuel rails and not exactly the volume itself… When the engine is running, there is fuel in those rails starting and stopping, accelerating and decelerating all the time, constantly. In internal flow of tubes, the major factors that determine the resistance to flow are Length/Diameter ratio of the tube and in a smaller scale the surface finish of the tube. Now, imagine with me you have the small diameter fuel rails, and they are super long, imagine the injector on the far end shoots some fluid out. Fluid, in order to fill that spot has to move down to that end, the reaction time of this being able to happen is slow because of it being a super skinny tube with a long length. Since the reaction time of the fuel being able to move is slow, the system sees a full pressure drop to a low point at the injector, and then gets back-filled eventually and comes up to full pressure again. There is always momentum in fluid so if you make the fluid ripple like this, it can find sweet spots where the ripples superposition on top of each other and you have a natural frequency in the fuel rail that might be substantial. I think that is what Porsche was worried about. Now, I don’t know if they were trying to dampen a pressure ripple because they were worried about spiking an o-ring, or if they were worried that the pressure ripple in the fuel rail would make the injection inconsistent. My hunch is the latter. Think of this, at the time they only had 80’s technology computer in the car. They are only opening the injector according to a timed pulse. Nothing else. The pulse width is basic. So, what makes the amount of fuel vary in a set pulse width? Pressure. A pressure ripple in the fuel rail would make the injectors randomly hit low or high pressure ripples when they inject and that would make a slightly less tuned car.
ANYWAYS, what you have done is changed the L/D ratio of the fuel rails such that there is, let’s say, no resistance for the flow to get to the open injector on the end immediately. If you imagine your fuel rail as a large tank…the pressure is the same in the whole tank, when a small injector opens, the low pressure when that injector flows does not reach the whole tank, it stays localized because there is so much more fluid around it.
By design, you can plumb them any which-way you like, include dampeners and multiple regulators or just one single regulator like I do.
Whatever you want to do. There is no one right single solution.
10-25-2013, 03:16 PM
#65
Rennlist Member
"There is no one right single solution."
Yes, there is Carl.
The rail adds a lot of simplicity..and yes, bling, because with the intake spacers it is MUCH more serviceable.
However..the right single solution is to not disrupt the OEM engineering of the dampers.
Period. There is zero debate allowable here. That IS the OEM right simple solution.
There are numerous OTHER ways to do it...after all, your own statement:
"I just make the billet fuel rails"...
Is incorrect, because you are also supplying 'just the rails' with plumbing that removes the OEM fuel control components, which is the "right single solution".
You supply the rails, and an alternative plumbing solution as well.
But like I said, we all know what the OEM system looks like in Sharkplotter with the 'waterfall' effect of 600rpm harmonics centered around 2400rpm from fuel pulses, and we KNOW what a stock system with one damper missing looks like (and it drives like crap on big injectors like that).
It's pretty simple..because we both know your buddy has no financial gain or loss to say anything he likes..but Id probly buy a kit right now if I can see a sharkplotter output with a few hours of city and highway driving to then say "Carl, you were right, the raw data says so".
So, Id buy a kit, provided it was plumbed along the right single solution meeting the OEM damper and FPR requirements.
Yes, there is Carl.
The rail adds a lot of simplicity..and yes, bling, because with the intake spacers it is MUCH more serviceable.
However..the right single solution is to not disrupt the OEM engineering of the dampers.
Period. There is zero debate allowable here. That IS the OEM right simple solution.
There are numerous OTHER ways to do it...after all, your own statement:
"I just make the billet fuel rails"...
Is incorrect, because you are also supplying 'just the rails' with plumbing that removes the OEM fuel control components, which is the "right single solution".
You supply the rails, and an alternative plumbing solution as well.
But like I said, we all know what the OEM system looks like in Sharkplotter with the 'waterfall' effect of 600rpm harmonics centered around 2400rpm from fuel pulses, and we KNOW what a stock system with one damper missing looks like (and it drives like crap on big injectors like that).
It's pretty simple..because we both know your buddy has no financial gain or loss to say anything he likes..but Id probly buy a kit right now if I can see a sharkplotter output with a few hours of city and highway driving to then say "Carl, you were right, the raw data says so".
So, Id buy a kit, provided it was plumbed along the right single solution meeting the OEM damper and FPR requirements.
10-25-2013, 03:27 PM
#66
Developer
Thread Starter
I love that religon. The "One right way" religion. Its my favorite.
You are missing the point: I don't plumb it. You plumb it. I don't sell them with hoses and lines. You plumb it the way it you want to plumb it.
I do hope you notice how old this thread is. These fuel rails are on so many cars and have been dyno'd so many times I cannot even count.
So, Id buy a kit, provided it was plumbed along the right single solution meeting the OEM damper and FPR requirements.
I do hope you notice how old this thread is. These fuel rails are on so many cars and have been dyno'd so many times I cannot even count.
10-25-2013, 04:52 PM
#67
So, don't buy the rails, keep your stock dampers, and motor on in peace
10-25-2013, 06:38 PM
#69
Nordschleife Master
Batch fire systems may resonate so badly that they need a lot of dampening.
Resonant frequency probably changes with bigger rails, but there's no guarantee that it won't be a problem at some rpms.
Slightly modified stock rails with stock or stock-like dampers work in my opinion very well any horsepower level that anyone on this thread has reached.
Resonant frequency probably changes with bigger rails, but there's no guarantee that it won't be a problem at some rpms.
Slightly modified stock rails with stock or stock-like dampers work in my opinion very well any horsepower level that anyone on this thread has reached.
10-25-2013, 06:59 PM
#70
Rennlist Member
I can see a LONGER system changing the timing of the wave, but not a fatter one of the same basic length.
10-25-2013, 06:59 PM
#71
Three Wheelin'
For high horsepower modified cars-
This is from Kinsler: http://www.kinsler.com/page--efi--4.html
"Since EFI injectors turn on and off, the interrupted flow causes pressure waves to bounce around in the fuel rails, especially at wide open throttle where the flows are the highest. In a group fired system you often trigger two or more injectors at a time in a given fuel rail. The simultaneous pluses can reinforce each other at some rpm to give unusually high pressure pulses, sometimes causing poor fuel distribution. It often helps to run a larger diameter fuel rail. Kinsler extruded aluminum fuel rails are .680 inch inside diameter. A large diameter smoothes out the pulses quite well when compared to smaller sizes. Running higher overall system pressure also helps. We often run about 72 psi instead of the more normal 36 to 43. The amplitude of the pressure spikes will remain about the same, but will be relatively smaller based on the percent change in injector flow. We also like the better atomization achieved with the higher pressure and it sometimes gives better power and economy. Be careful about running the fuel pressure too high, as some ECUs don't have enough current to lift the disc or pintle in the injector consistently off the seat against this added pressure, which will result in poor fuel distribution. Be sure your fuel pump is capable of supplying the engine with the volume required at a higher fuel pressure."
Click on "Jim's Bio" on the lower left-
This is from Kinsler: http://www.kinsler.com/page--efi--4.html
"Since EFI injectors turn on and off, the interrupted flow causes pressure waves to bounce around in the fuel rails, especially at wide open throttle where the flows are the highest. In a group fired system you often trigger two or more injectors at a time in a given fuel rail. The simultaneous pluses can reinforce each other at some rpm to give unusually high pressure pulses, sometimes causing poor fuel distribution. It often helps to run a larger diameter fuel rail. Kinsler extruded aluminum fuel rails are .680 inch inside diameter. A large diameter smoothes out the pulses quite well when compared to smaller sizes. Running higher overall system pressure also helps. We often run about 72 psi instead of the more normal 36 to 43. The amplitude of the pressure spikes will remain about the same, but will be relatively smaller based on the percent change in injector flow. We also like the better atomization achieved with the higher pressure and it sometimes gives better power and economy. Be careful about running the fuel pressure too high, as some ECUs don't have enough current to lift the disc or pintle in the injector consistently off the seat against this added pressure, which will result in poor fuel distribution. Be sure your fuel pump is capable of supplying the engine with the volume required at a higher fuel pressure."
Click on "Jim's Bio" on the lower left-
Last edited by Jim Devine; 10-26-2013 at 03:50 PM.
10-25-2013, 07:04 PM
#72
Captain Obvious
Super User
Super User
These rails have no provision for the safety clips that hold the injectors in place in case the rail comes loose. When a bolt holding the rail bracket loosenes, the fuel pressure will push the injector out of the rail and then..........
10-25-2013, 07:20 PM
#73
Rennlist Member
I love that religon. The "One right way" religion. Its my favorite.
You are missing the point: I don't plumb it. You plumb it. I don't sell them with hoses and lines. You plumb it the way it you want to plumb it.
I do hope you notice how old this thread is. These fuel rails are on so many cars and have been dyno'd so many times I cannot even count.
You are missing the point: I don't plumb it. You plumb it. I don't sell them with hoses and lines. You plumb it the way it you want to plumb it.
I do hope you notice how old this thread is. These fuel rails are on so many cars and have been dyno'd so many times I cannot even count.
Remember I was the guy that found the crazy silly engineering problem with this gear after owning a 928 for only a few months back in 2011:
http://www.928motorsports.com/parts/...lerearsway.php
IE:
https://rennlist.com/forums/928-foru...creeeeeak.html
https://rennlist.com/forums/928-foru...reeaakkks.html
..which you had to recall & correct. How old was that product in 2011??
So..the tenure of a product (by anyone), or it's thread, is meaningless. Thing's are learned over time..and that's cool. Don't make it a dirty thing. Besides, if you're upset I'm posting to an old thread, yell at uncre8tv, he breathed life into again, not me.
With many having lived batch-fire resonance issues, it should seem a clear & simple issue to explain the theory (you did) and then say "See, its not there in the AF plot" captured and displayed as suggested.
"I don't plumb it. You plumb it. I don't sell them with hoses and lines"
Really? Lets go to page 1:
https://rennlist.com/forums/attachme...ils-fr32v4.jpg
You seem to replace a lot of THAT..
https://rennlist.com/forums/attachme...ils-fr32v1.jpg
With this.
What part of the plumbing that you show ships, doesn't ship?
I see that there may be a disconnect with the product thread here, and the images/description on the product page itself. If that's so..should be edited here to remove what you dont ship, and noted on your product page that with the rails, you're on your own for plumbing.
But..still, I lived pressure hammering, and would like these rails for the reasons I noted, but would have to retain the OEM dampers and FPR.
An option with plumbing to retain that stuff, would be a positive thing, and creative...because you have the expertise to do that, I do not. That's why money flows from us to you.
10-25-2013, 09:09 PM
#74
Rennlist
Basic Site Sponsor
Basic Site Sponsor
Just as a point of order.....
I'm going to throw out some pure logic to perhaps make the "current debate" perhaps make more sense. I'm not entering into this debate....I use the same rails, bought from the same source that Carl buys them from, on some applications.
I'm only providing background information.
The stock "square" fuel rails have a much larger internal volume than the commonly available aluminum -6 rails....like are pictured.....more than 2X the internal volume! The "stock square rails" actually have a larger volume than a -8 aftermarket rail!
That "aftermarket extruded -6 rail" has an internal bore size of 7/16". I took a picture of a sectioned stock rail and stuck a 7/16" drill into the rail, so that one could easily see that the stock rail has a much larger size than the 7/16" drill sitting inside the stock rail:
[/URL]
I then took a picture of a -6 fuel hose, completely inserted into the inside a sectioned stock rail. The outer braid, the rubber, the entire hose fits inside the square rail....with lots and lots of room to spare:
[/URL]
You can decide which rail has the higher internal volume.....
I'm going to throw out some pure logic to perhaps make the "current debate" perhaps make more sense. I'm not entering into this debate....I use the same rails, bought from the same source that Carl buys them from, on some applications.
I'm only providing background information.
The stock "square" fuel rails have a much larger internal volume than the commonly available aluminum -6 rails....like are pictured.....more than 2X the internal volume! The "stock square rails" actually have a larger volume than a -8 aftermarket rail!
That "aftermarket extruded -6 rail" has an internal bore size of 7/16". I took a picture of a sectioned stock rail and stuck a 7/16" drill into the rail, so that one could easily see that the stock rail has a much larger size than the 7/16" drill sitting inside the stock rail:
[/URL]I then took a picture of a -6 fuel hose, completely inserted into the inside a sectioned stock rail. The outer braid, the rubber, the entire hose fits inside the square rail....with lots and lots of room to spare:
[/URL]You can decide which rail has the higher internal volume.....
__________________
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
10-26-2013, 12:00 AM
#75
Rennlist Member
"The stock fuel rails held a very small volume of fuel"
Wow..ok, someone's 'guy' sucks *****. I never really LOOKED at the rail, but..they are huge...just went out to put own eyes on this.
But maybe its an optical illusion Greg..just sayin'.
Wow..ok, someone's 'guy' sucks *****. I never really LOOKED at the rail, but..they are huge...just went out to put own eyes on this.
But maybe its an optical illusion Greg..just sayin'.