Continuation of the fuel rail thread
11-05-2013, 10:41 PM
#16
Drifting
Greg, I commend you on being quite civil and factual in this thread. My point is that it's not necessary to constantly beat a dead horse until it's a pile pf pulp, it's dead. Point proven.
As far as Carl's snide comments, don't you think there is a small chance that they are in response to one specific group crawling up his butt again and again? If he said that the sky was blue, you guys would challange him as to why and what exact shade with any references listed and how he arrived at that conclusion. I'd be pretty tempted to say that most of his comments are in response to snide comments directed at him either in the referenced post or in prior ones.
I think it brings the whole community down a level to have the snide sniping constantly going on and I for one am tired of it. It's like a bunch of kids, I don't care who started it, it's time to stop. We are all here for roughly the same purpose and that's the preservation and enjoyment of 928's. Carl contributes to this in an admittedly large way so why the witch hunt?
As far as Carl's snide comments, don't you think there is a small chance that they are in response to one specific group crawling up his butt again and again? If he said that the sky was blue, you guys would challange him as to why and what exact shade with any references listed and how he arrived at that conclusion. I'd be pretty tempted to say that most of his comments are in response to snide comments directed at him either in the referenced post or in prior ones.
I think it brings the whole community down a level to have the snide sniping constantly going on and I for one am tired of it. It's like a bunch of kids, I don't care who started it, it's time to stop. We are all here for roughly the same purpose and that's the preservation and enjoyment of 928's. Carl contributes to this in an admittedly large way so why the witch hunt?
11-05-2013, 10:54 PM
#17
Keep up the good work guys.
Last edited by SeanR; 11-06-2013 at 01:45 PM.
11-06-2013, 12:49 AM
#18
Rennlist Member
Just maybe..it's because they're noting flaws and omissions that can be seen and resolved?
But in this case "more, bigger" was discovered to be less, smaller.
No hiding that.
11-06-2013, 01:09 AM
#19
Administrator - "Tyson"
Lifetime Rennlist
Member
Lifetime Rennlist
Member
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.
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.
11-06-2013, 01:52 AM
#20
Addict
Rennlist Member
Rennlist Member
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
11-06-2013, 02:30 AM
#21
Drifting
I never once said that Carl was right about the fuel rail. I personally am producing over 600rwhp with unmodified factory fuel rails. Am I close to the limits of the system? I don't know, it's working just fine. That may change as I reduce the fuel pressure from current levels but as of now, I have no need for Carl's, Greg's or anyone else's fuel rails and I am willing to bet that 600+rwhp (pump gas-auto!) is well into the top 1% of 928 owners. So guys, answer me this...just how many people out there actually need upgraded fuel rails? How many of you actually have a dog in this fight? How many of you are just in this thread to tease another 928 supplier?
I do know a lot of the history as I know most of the players in this little drama. My point is that it's never going to get any better if nobody actually tries. Regardless of history, each thread should be based on the item in the thread and once it's accepted or denied, LET IT GO!
There are a lot of things advertised that I don't approve of and will not buy but I do not go online and rant and rave about how it's not as advertised. The last time I did that was with the owner of Nology Hotwires when he claimed his wires defied physics and produced more power than was supplied. I got him to admit that he was incorrect but it just didn't matter. He did not change any of his advertising and I'm sure it didn't affect his sales other than to me.
As to the moderators, do you really think they are being biased toward Carl or just being more impartial than the attacking crowd? In the couple of "wars" I have been involved in here I have been approached by the mods asking if I wanted to let it roll or shut it down and it was not by my request. I always opted to let it roll but then again, that was my decision. The mods have had to intervene in this drama many times with many people and you know what? It takes at least two to cause a problem and it's usually more than two against Carl. IT'S NOT ALL CARL GUYS!
I'm asking...pleading...but not quite begging that you guys just give it a rest or at least follow Greg's lead and stick to the plain, simple facts to prove a point without trying to drive it into the ground. Do I think Carl was wrong in his advertising of his fuel rails? Yes, I do but BFD! If you guys think you are "protecting" 928 owners then maybe you should be in the off topic/politics area and be cuddling up to big brother. It's up to the individual if the parts he/she is purchasing fulfill their needs or not, not yours. (WOW, Utah is going to kick me out of the state if they heard I said that!) Yes, they deserve opposing views but talk about a dog pile! It seems to me like a concentrated group effort to nullify Carl's sales at all costs and it really disgusts me.
There is my unabridged .02 cents and I know that I am not alone but maybe the only one that will open my mouth to this extent. Guys, how about working in a positive direction? I promise it won't hurt...
I do know a lot of the history as I know most of the players in this little drama. My point is that it's never going to get any better if nobody actually tries. Regardless of history, each thread should be based on the item in the thread and once it's accepted or denied, LET IT GO!
There are a lot of things advertised that I don't approve of and will not buy but I do not go online and rant and rave about how it's not as advertised. The last time I did that was with the owner of Nology Hotwires when he claimed his wires defied physics and produced more power than was supplied. I got him to admit that he was incorrect but it just didn't matter. He did not change any of his advertising and I'm sure it didn't affect his sales other than to me.
As to the moderators, do you really think they are being biased toward Carl or just being more impartial than the attacking crowd? In the couple of "wars" I have been involved in here I have been approached by the mods asking if I wanted to let it roll or shut it down and it was not by my request. I always opted to let it roll but then again, that was my decision. The mods have had to intervene in this drama many times with many people and you know what? It takes at least two to cause a problem and it's usually more than two against Carl. IT'S NOT ALL CARL GUYS!
I'm asking...pleading...but not quite begging that you guys just give it a rest or at least follow Greg's lead and stick to the plain, simple facts to prove a point without trying to drive it into the ground. Do I think Carl was wrong in his advertising of his fuel rails? Yes, I do but BFD! If you guys think you are "protecting" 928 owners then maybe you should be in the off topic/politics area and be cuddling up to big brother. It's up to the individual if the parts he/she is purchasing fulfill their needs or not, not yours. (WOW, Utah is going to kick me out of the state if they heard I said that!) Yes, they deserve opposing views but talk about a dog pile! It seems to me like a concentrated group effort to nullify Carl's sales at all costs and it really disgusts me.
There is my unabridged .02 cents and I know that I am not alone but maybe the only one that will open my mouth to this extent. Guys, how about working in a positive direction? I promise it won't hurt...
11-06-2013, 03:19 AM
#22
Rennlist Member
Gents,
Whereas I am not interested in the politics of the debate, to me the technical part is relatively straight forward. This system is what we call a "spillback loop" and to maintain effective control the fuel pressure in the main rail has to remain constant and thus why there is a cross connection to the vacuum system trying to maintain a constant diffrential pressure relative to the manifold.
Thus the system tries to keep the fuel pressure rail at this constant "differential pressure" in the belief that a constant amount of fuel will be squirted relative to the injector opening time- for this reason the LH [to my knowledge] has no adjustment in the calculation algorithm for absolute manifold pressure- someone correct me if they know differently.
If the pressure drop from the pump to the fuel rail is very small compared to the pressure drop across the injector then that is a good indicator that the system is well designed. Like everything else, as one pushes the system things change and at some point cannot cope. Folks fit bigger injectors to permit more flow per unit pulse. Then some fit 044 pumps to permit more total flow.
In any system of this kind where the hydraulic resistance remains constant, the pressure drop across any two given points is proportional to the square of the flow- so double the flow you quadruple the pressure drop. On a stock system at idle the recycle line takes more or less all the flow given the low number of injector pulses, at high rpms most of the flow will disappear through the injectors. Increase the demand enough, at some point the pump cannot keep up and the pressure in the fuel rail will start to drop. If this happens then you know the system is at its limits and needs upgrading.
If at any point specific cylinders start leaning off that would indeed suggest hydraulic imbalance in the fuel rail part of the delivery system. So the question becomes "is there any sign of this happening?". The obvious candidate for signs will be the cylinder where the injector is furthest away from the source of the pressure and this will only happen if there is any pressure drop of significance across the rail itself. Comparing the cross sectional area of the rail [two of them] compared to the [single] internal diameter of pipe feeding the system and the [miniscule] choking diameter of the injector, I would think the rail itself is not likely to be an issue but that does not mean there is not a problem getting fuel into and out of the rail.
If practical experience in high flow systems suggests otherwise then it would need bebottlenecking. Thus a multi stage process to get more fuel is required wherein:
1. Change the opening times until the injector is saturated.
2. Fit bigger injectors
3. Fit bigger fuel pump
4. Debottleneck the delivery system hydraulics.
If experience suggests step 4 is needed, hydraulic analysis of the plumbing components is needed to tell the designer where to start. At this level of advancement, I would think getting fuel to the rail is more an issue than the rail design itself but if calculation or measurement suggests that pressure drop across the rail [injector to injector] is significant, then indeed it would need revamping.
Beyond that there are other "potential complications". With all the injectors slamming shut in synchronised fashion- that creates shock waves. Thus Porsche felt the need to fit the two dampers in addition to the FP regulator. At some point they will cease to function effectively as we fit bigger injectors and flow more fuel [both in total and per pulse] and if this happens, then chance may impact specific points of injection if resonance pulses happen to fall in the wrong place at the wrong time. We have already seen some sharktuning evidence that this happens in stock systems never mind "quantum change" ones.
I dare say all the above has been written many times over but that is my analysis of the considerations that need to be made.
Every system has limits and the fuel delivery system is no different. When revamping any system one needs to understand the choke points and eliminate them one by one [biggest ones first] until you can get the performance sought.
Regards
Fred
Whereas I am not interested in the politics of the debate, to me the technical part is relatively straight forward. This system is what we call a "spillback loop" and to maintain effective control the fuel pressure in the main rail has to remain constant and thus why there is a cross connection to the vacuum system trying to maintain a constant diffrential pressure relative to the manifold.
Thus the system tries to keep the fuel pressure rail at this constant "differential pressure" in the belief that a constant amount of fuel will be squirted relative to the injector opening time- for this reason the LH [to my knowledge] has no adjustment in the calculation algorithm for absolute manifold pressure- someone correct me if they know differently.
If the pressure drop from the pump to the fuel rail is very small compared to the pressure drop across the injector then that is a good indicator that the system is well designed. Like everything else, as one pushes the system things change and at some point cannot cope. Folks fit bigger injectors to permit more flow per unit pulse. Then some fit 044 pumps to permit more total flow.
In any system of this kind where the hydraulic resistance remains constant, the pressure drop across any two given points is proportional to the square of the flow- so double the flow you quadruple the pressure drop. On a stock system at idle the recycle line takes more or less all the flow given the low number of injector pulses, at high rpms most of the flow will disappear through the injectors. Increase the demand enough, at some point the pump cannot keep up and the pressure in the fuel rail will start to drop. If this happens then you know the system is at its limits and needs upgrading.
If at any point specific cylinders start leaning off that would indeed suggest hydraulic imbalance in the fuel rail part of the delivery system. So the question becomes "is there any sign of this happening?". The obvious candidate for signs will be the cylinder where the injector is furthest away from the source of the pressure and this will only happen if there is any pressure drop of significance across the rail itself. Comparing the cross sectional area of the rail [two of them] compared to the [single] internal diameter of pipe feeding the system and the [miniscule] choking diameter of the injector, I would think the rail itself is not likely to be an issue but that does not mean there is not a problem getting fuel into and out of the rail.
If practical experience in high flow systems suggests otherwise then it would need bebottlenecking. Thus a multi stage process to get more fuel is required wherein:
1. Change the opening times until the injector is saturated.
2. Fit bigger injectors
3. Fit bigger fuel pump
4. Debottleneck the delivery system hydraulics.
If experience suggests step 4 is needed, hydraulic analysis of the plumbing components is needed to tell the designer where to start. At this level of advancement, I would think getting fuel to the rail is more an issue than the rail design itself but if calculation or measurement suggests that pressure drop across the rail [injector to injector] is significant, then indeed it would need revamping.
Beyond that there are other "potential complications". With all the injectors slamming shut in synchronised fashion- that creates shock waves. Thus Porsche felt the need to fit the two dampers in addition to the FP regulator. At some point they will cease to function effectively as we fit bigger injectors and flow more fuel [both in total and per pulse] and if this happens, then chance may impact specific points of injection if resonance pulses happen to fall in the wrong place at the wrong time. We have already seen some sharktuning evidence that this happens in stock systems never mind "quantum change" ones.
I dare say all the above has been written many times over but that is my analysis of the considerations that need to be made.
Every system has limits and the fuel delivery system is no different. When revamping any system one needs to understand the choke points and eliminate them one by one [biggest ones first] until you can get the performance sought.
Regards
Fred
11-06-2013, 03:26 AM
#23
Rennlist Member
Join Date: Oct 2013
Posts: 147
Likes: 0
Received 0 Likes
on
0 Posts
I never once said that Carl was right about the fuel rail. I personally am producing over 600rwhp with unmodified factory fuel rails. Am I close to the limits of the system? I don't know, it's working just fine. That may change as I reduce the fuel pressure from current levels but as of now, I have no need for Carl's, Greg's or anyone else's fuel rails and I am willing to bet that 600+rwhp (pump gas-auto!) is well into the top 1% of 928 owners. So guys, answer me this...just how many people out there actually need upgraded fuel rails? How many of you actually have a dog in this fight? How many of you are just in this thread to tease another 928 supplier? I do know a lot of the history as I know most of the players in this little drama. My point is that it's never going to get any better if nobody actually tries. Regardless of history, each thread should be based on the item in the thread and once it's accepted or denied, LET IT GO! There are a lot of things advertised that I don't approve of and will not buy but I do not go online and rant and rave about how it's not as advertised. The last time I did that was with the owner of Nology Hotwires when he claimed his wires defied physics and produced more power than was supplied. I got him to admit that he was incorrect but it just didn't matter. He did not change any of his advertising and I'm sure it didn't affect his sales other than to me. As to the moderators, do you really think they are being biased toward Carl or just being more impartial than the attacking crowd? In the couple of "wars" I have been involved in here I have been approached by the mods asking if I wanted to let it roll or shut it down and it was not by my request. I always opted to let it roll but then again, that was my decision. The mods have had to intervene in this drama many times with many people and you know what? It takes at least two to cause a problem and it's usually more than two against Carl. IT'S NOT ALL CARL GUYS! I'm asking...pleading...but not quite begging that you guys just give it a rest or at least follow Greg's lead and stick to the plain, simple facts to prove a point without trying to drive it into the ground. Do I think Carl was wrong in his advertising of his fuel rails? Yes, I do but BFD! If you guys think you are "protecting" 928 owners then maybe you should be in the off topic/politics area and be cuddling up to big brother. It's up to the individual if the parts he/she is purchasing fulfill their needs or not, not yours. (WOW, Utah is going to kick me out of the state if they heard I said that!) Yes, they deserve opposing views but talk about a dog pile! It seems to me like a concentrated group effort to nullify Carl's sales at all costs and it really disgusts me. There is my unabridged .02 cents and I know that I am not alone but maybe the only one that will open my mouth to this extent. Guys, how about working in a positive direction? I promise it won't hurt...
1988 s4 Auto ROW black/black West Australia
11-06-2013, 08:30 AM
#24
Nordschleife Master
Thread Starter
Fred --
I run the following fuel system and it appears to be working well. No overheating of fuel and not tell-tale signs of resonance problems in the AFR logs.
Here's the system:
* Custom tank pickup to fit -10AN line
* dual Bosch 044's with the second switched on after both boost and rpm exceed thresholds
* -10AN to the bottom of the engine compartment
* -10AN check valve
* -10AN up to the manifold
* -10AN to dual -6AN Y-block
* two Bosch fuel dampers one per side
* stock fuel rail with minimal modifications
* return side completely stock (can be left stock because the pumps come in at stages to match fuel demand) with a damper and manifold pressure referenced fuel pressure regulator
My personal experience is that fuel dampers are important in a batch fire system, the 928 S4 stock fuel rails have a massive flow capacity and will only need to be modified if it makes connecting lines with different fittings more convenient, and that Bosch fuel pumps are more reliable that aftermarket fuel pumps.
Best, Tuomo
I run the following fuel system and it appears to be working well. No overheating of fuel and not tell-tale signs of resonance problems in the AFR logs.
Here's the system:
* Custom tank pickup to fit -10AN line
* dual Bosch 044's with the second switched on after both boost and rpm exceed thresholds
* -10AN to the bottom of the engine compartment
* -10AN check valve
* -10AN up to the manifold
* -10AN to dual -6AN Y-block
* two Bosch fuel dampers one per side
* stock fuel rail with minimal modifications
* return side completely stock (can be left stock because the pumps come in at stages to match fuel demand) with a damper and manifold pressure referenced fuel pressure regulator
My personal experience is that fuel dampers are important in a batch fire system, the 928 S4 stock fuel rails have a massive flow capacity and will only need to be modified if it makes connecting lines with different fittings more convenient, and that Bosch fuel pumps are more reliable that aftermarket fuel pumps.
Best, Tuomo
Last edited by ptuomov; 11-06-2013 at 08:59 AM.
11-06-2013, 10:32 AM
#25
Spark-plug-girl
Rennlist Member
Rennlist Member
11-06-2013, 11:28 AM
#26
Still plays with cars.
Lifetime Rennlist
Member
Folks, Dave (Lomas) said it nicely. Nothing does a greater disservice community than to see vendors bashing each other. Whether you realize it or not, you are doing yourselves harm while trying to protect others.
Keep it to the facts, period. Said facts should never contain derogatory statements. Seeing a thread like this degenerate into name calling runs counter to everything this community stands for. So back to your neutral corners please else the abyss.
Thanks,
Keep it to the facts, period. Said facts should never contain derogatory statements. Seeing a thread like this degenerate into name calling runs counter to everything this community stands for. So back to your neutral corners please else the abyss.
Thanks,
11-06-2013, 11:39 AM
#27
Developer
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.
11-06-2013, 11:44 AM
#28
Developer
PS: and that's exactly what Jorj7 was fixing when he cut off the feeder line and welded on a steel -6 fitting as he shows in his first picture (post #20 above).
I'm not the only one to have seen these restrictions in the feeder lines and to seek to correct them.
I'm not the only one to have seen these restrictions in the feeder lines and to seek to correct them.
Last edited by Carl Fausett; 11-06-2013 at 12:43 PM.
11-06-2013, 01:02 PM
#29
Basic Sponsor
Rennlist
Site Sponsor
Rennlist
Site Sponsor
In an effort to "get along" I have removed my posts
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
11-06-2013, 01:35 PM
#30
Still plays with cars.
Lifetime Rennlist
Member
Thank you Rog, classy as always!