Fuel Surge under hard cornering
19 June 2002, 12:20 PM
#31
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Actually, it's common practice to weld fuel tanks after they have been used. All you have to do is place a pipe from a cars exhaust into the empty tank and then run it for an hour, this fills the fuel tank with hot carbon monoxide and water vapour and completely cleanses it of any fuel residues.
Been there done that!
What you are talking about there is a surge tube, i made one and installed that into the westie tank, so actually had a swirl pot system, plus a baffled trap door tank and a surge tube. I was pulling very high G's in the fast corners so wanted it to be bullet proof!
A surge tube is basically a bucket, as described above. LOL The lift pump sits inside this tube, which is almost as tall as the tank. In the bottom of the tube you drill 6 x 2mm holes, about 2mm from the bottom, around its perifery. These holes are what the fuel goes through to fill the surge tube. The return from the swirl pot to the tank fills this surge tube also. It's a very simple design, works very well though!
Been there done that!
What you are talking about there is a surge tube, i made one and installed that into the westie tank, so actually had a swirl pot system, plus a baffled trap door tank and a surge tube. I was pulling very high G's in the fast corners so wanted it to be bullet proof!
A surge tube is basically a bucket, as described above. LOL The lift pump sits inside this tube, which is almost as tall as the tank. In the bottom of the tube you drill 6 x 2mm holes, about 2mm from the bottom, around its perifery. These holes are what the fuel goes through to fill the surge tube. The return from the swirl pot to the tank fills this surge tube also. It's a very simple design, works very well though!
19 June 2002, 12:49 PM
#33
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John... Im just saying that joe blogs shouldnt do it...
Maybe im just scared
David
Maybe im just scared
David
20 June 2002, 08:24 AM
#34
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I changed my pump last night - the pickup already sits in a depression at the bottom of tank (like, it's *really* sad, lol!) - on a 5 door anyway.
I reckon it'd be fairly easy to weld a bucket type thing around this area.
John - traditionally these things are totally enclosed except for the small holes I think? Is there any reason not to leave the top open? Only one I can think of is that if I take up yumping then the fuel may still jump out!
Richard
PS: I'll scan photos this morning
[Edited by dowser - 6/20/2002 8:24:56 AM]
I reckon it'd be fairly easy to weld a bucket type thing around this area.
John - traditionally these things are totally enclosed except for the small holes I think? Is there any reason not to leave the top open? Only one I can think of is that if I take up yumping then the fuel may still jump out!
Richard
PS: I'll scan photos this morning
[Edited by dowser - 6/20/2002 8:24:56 AM]
20 June 2002, 10:51 AM
#36
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I'd I've worked it out at then end you know......<clunk><clunk> as I try to refit the pump assembly, lol!
Mind you, the photos I just emailed David shows a fully enclosed in-tank drawing - I guess you're supposed to mount the filter bag inside and the pump outside.....still not very sensible though!
Richard
Mind you, the photos I just emailed David shows a fully enclosed in-tank drawing - I guess you're supposed to mount the filter bag inside and the pump outside.....still not very sensible though!
Richard
20 June 2002, 10:58 AM
#38
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that would require a rather steep angle on the pump assembly and would be dificult to seal properly around where the pickup went through the side of the surge tube.
My design works best if you can achieve it.
My design works best if you can achieve it.
20 June 2002, 11:01 AM
#39
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no sub, there are 6 x 2mm holes drilled 2 mm from the bottom of the tube, this is how the fuel gets inside the surge tube. Laughing at the thought of having to run a full tank just to give 0.5 litres of fuel supply using the weir effect.
20 June 2002, 11:24 AM
#40
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john, completely agree that fuelling should be done with mapping not with rrfprs.
On a nice new car like yours, I would have a word with R19KET (have his number if you want it - mail me offline) and regardless of surge issues, fit a fuel pump. I think it is actually worth every turbo owner fitting one of these as it can only make sure that the injsctor duty cycle mapped into the ecu can deliver exactly whath the cu is expecting and not assume that the fuel is there.
The sti comes with an unprated fuel pump as it is and this is terrible, imagine how bad the normal turbo is!
R19KET used to have a surge tank in his car, he never referred to it as a swirl pot, though it is round. Not sure if he still has it, but I know he doesnt use it now. He had the same problem as you on track, and this cured it without question, it also looks nice, in shiny ally.
Like you did, he uses the uprated in-tank pump to feed the surge tank, and then another pump and filter after the surge tank.
On a nice new car like yours, I would have a word with R19KET (have his number if you want it - mail me offline) and regardless of surge issues, fit a fuel pump. I think it is actually worth every turbo owner fitting one of these as it can only make sure that the injsctor duty cycle mapped into the ecu can deliver exactly whath the cu is expecting and not assume that the fuel is there.
The sti comes with an unprated fuel pump as it is and this is terrible, imagine how bad the normal turbo is!
R19KET used to have a surge tank in his car, he never referred to it as a swirl pot, though it is round. Not sure if he still has it, but I know he doesnt use it now. He had the same problem as you on track, and this cured it without question, it also looks nice, in shiny ally.
Like you did, he uses the uprated in-tank pump to feed the surge tank, and then another pump and filter after the surge tank.
20 June 2002, 11:31 AM
#41
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John,
When you say you don't like adjustable fuel pressure regulators, do you mean all adjustable units, including 1:1 rate ones, or do you meant you dislike rising rate units, such as the "FSE power boost" valve things? Surely it is useful to increase the fuel pressure in order to improve atomisation and flow, as long as the manifold/fuel pressures rise at a 1:1 rate?
[tongue in cheek]
Oh, by the way, have you patented your anti fuel surge system: "My design works best if you can achieve it." ? I know a guy who could help you apply for a patent if you wish to protect your design! You ought to do it fast, as I've seen similar designs in at least a couple of books already.
[/tongue in cheek]
Moray
bbs.22b.com
When you say you don't like adjustable fuel pressure regulators, do you mean all adjustable units, including 1:1 rate ones, or do you meant you dislike rising rate units, such as the "FSE power boost" valve things? Surely it is useful to increase the fuel pressure in order to improve atomisation and flow, as long as the manifold/fuel pressures rise at a 1:1 rate?
[tongue in cheek]
Oh, by the way, have you patented your anti fuel surge system: "My design works best if you can achieve it." ? I know a guy who could help you apply for a patent if you wish to protect your design! You ought to do it fast, as I've seen similar designs in at least a couple of books already.
[/tongue in cheek]
Moray
bbs.22b.com
20 June 2002, 12:29 PM
#42
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If you wanna patent summat, why not patent a centrally mounted fuel pump with a freely rotating pickup arm with a weight on the end? That way the fuel pickup arm will always follow the fuel, thus you don't get fuel surge problems Alternatively, you could just fit an early (say STi II) fuel tank and then you don't get fuel surge problems either The later design just doesn't seem to work as well....
Cheers,
Pat.
Alternatively, you could just fit an early (say STi II) fuel tank and then you don't get fuel surge problems either The later design just doesn't seem to work as well....Cheers,
Pat.
20 June 2002, 12:45 PM
#43
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or you could invent something and then publcially disclose it so that no one can patent it.
Its bad in that now you cant make any money out of it but good in that no one else can stop you from making and selling it.
We like to call it a defensive publication.
Its bad in that now you cant make any money out of it but good in that no one else can stop you from making and selling it.
We like to call it a defensive publication.
20 June 2002, 03:00 PM
#44
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come on guys, lets not mupettise this thread. 
Moray, i mean that rising rate valves are not a good idea. You should map the engine with a known static fuel rail presure as if the presure rises, your injector atomisation changes and you cant control the amount of fuel/pulse rate as well. It's a very dirty way of increasing the fueling.
All presure regulators have fuel rail presure control by feeding the manifold presure to the diaphram. Typically you set the rail to 3 bar with the boost/vacumn pipe disconected, this usually causes the rail to then sit at 3.5Bar on boost. This is the typical setup on a cosworth running a webber FPR. The presure is adjustable by breaking the top seal and moving the allen screw in or out.
I havent played with a Subaru ruel rail FPR but the principle is identical. All injectors are designed with certain preures in mind, if you start screwing around with those presures the atomisation patterns change and although you may think you are increasing fueling, you may actually be causing it to spray in a less atomised way and caue it to burn less eficiently giving a weaker mixture. It's a bit like polishing inlet ports, nice and shiny looks good but in fact it gives less power as the fuel dribbles in rather than staying atomised.
And Moray, i am not saying i invented how to make a working swirl pot and pump system, i am saying this is what i built and it works. This same design is used on the most sucessful Escort Cosworth race car in the world, that of Gareth Lloyd, but using two high presure pumps to the injectors (8 injectors) rather than one. No books i have read have mentioned running a restrictor in the return to the fuel tank from the swirl pot though, that is what presurises the second pump inlet. You go buy a comercially available swirl pot, non of them have this feature yet it makes a big diference in pump life and performance. I am just passing on my knowledge aquired from my race, trackday and rally car construction.
Moray, i mean that rising rate valves are not a good idea. You should map the engine with a known static fuel rail presure as if the presure rises, your injector atomisation changes and you cant control the amount of fuel/pulse rate as well. It's a very dirty way of increasing the fueling.
All presure regulators have fuel rail presure control by feeding the manifold presure to the diaphram. Typically you set the rail to 3 bar with the boost/vacumn pipe disconected, this usually causes the rail to then sit at 3.5Bar on boost. This is the typical setup on a cosworth running a webber FPR. The presure is adjustable by breaking the top seal and moving the allen screw in or out.
I havent played with a Subaru ruel rail FPR but the principle is identical. All injectors are designed with certain preures in mind, if you start screwing around with those presures the atomisation patterns change and although you may think you are increasing fueling, you may actually be causing it to spray in a less atomised way and caue it to burn less eficiently giving a weaker mixture. It's a bit like polishing inlet ports, nice and shiny looks good but in fact it gives less power as the fuel dribbles in rather than staying atomised.
And Moray, i am not saying i invented how to make a working swirl pot and pump system, i am saying this is what i built and it works. This same design is used on the most sucessful Escort Cosworth race car in the world, that of Gareth Lloyd, but using two high presure pumps to the injectors (8 injectors) rather than one. No books i have read have mentioned running a restrictor in the return to the fuel tank from the swirl pot though, that is what presurises the second pump inlet. You go buy a comercially available swirl pot, non of them have this feature yet it makes a big diference in pump life and performance. I am just passing on my knowledge aquired from my race, trackday and rally car construction.
20 June 2002, 03:06 PM
#45
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dirty way... bah humbug... cheap yorkshire way
I learn the hardway when it blows up..
John, I am using 8mm ID hose... is this sufficient?
David
I learn the hardway when it blows up..
John, I am using 8mm ID hose... is this sufficient?
David
20 June 2002, 04:46 PM
#46
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Hello... I have returned only breifly.... got 5 mins free at work.
I thought a swirl pot/tank was used to seperate air and work ?
Surely to eleviate the fuel problem you need a antisurge tank.
The best design is a tall tubular design (G's dont affect the fluid as much), the lift pump (stock pump) feeding into it, The pressure/secondary pump drawing from the base, the fuel rails (via reg) returning to the top, and the surge tank return going to the fuel tank.
It would be quite easy to make one, if you used the tubular design, you wont need to baffle it. Get a decent powered pump for it, and hey presto.
I would suggest the fitting of a high flow fuel filter too.
Do a few sums and calculate how long you expect fuel surge (how long to go around a 180 bend), then how much fuel you will consume a minute/sec... from that you can work out the capacity of the surge tank.
Simple stuff really.
J.
ps - Pat your design sounds like a pump with a piece of 1/2 rubber hose fitted to the end of it, with a brick taped to the other end of the rubber hose
I thought a swirl pot/tank was used to seperate air and work ?
Surely to eleviate the fuel problem you need a antisurge tank.
The best design is a tall tubular design (G's dont affect the fluid as much), the lift pump (stock pump) feeding into it, The pressure/secondary pump drawing from the base, the fuel rails (via reg) returning to the top, and the surge tank return going to the fuel tank.
It would be quite easy to make one, if you used the tubular design, you wont need to baffle it. Get a decent powered pump for it, and hey presto.
I would suggest the fitting of a high flow fuel filter too.
Do a few sums and calculate how long you expect fuel surge (how long to go around a 180 bend), then how much fuel you will consume a minute/sec... from that you can work out the capacity of the surge tank.
Simple stuff really.
J.
ps - Pat your design sounds like a pump with a piece of 1/2 rubber hose fitted to the end of it, with a brick taped to the other end of the rubber hose
20 June 2002, 11:57 PM
#47
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right call me stupid.. ok your stupid..
If the std pump feeds a surge tank / swirlpot.. then return goes back to the tank.. fine.. not a problem..
The std pump cant maintain the flow / pressure? for a turbo... so it goes lean? yes?
Therefore is the uprated fuel pump not going to empty the swirl pot quicker than the std can fill it.. I understand that we arent using all the fuel.. but as it goes lean...
Somebody /anybody..
David
If the std pump feeds a surge tank / swirlpot.. then return goes back to the tank.. fine.. not a problem..
The std pump cant maintain the flow / pressure? for a turbo... so it goes lean? yes?
Therefore is the uprated fuel pump not going to empty the swirl pot quicker than the std can fill it.. I understand that we arent using all the fuel.. but as it goes lean...
Somebody /anybody..
David
20 June 2002, 11:57 PM
#48
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John
I'm not sure how your idea of a restrictor in the return line would work.
At low engine power, there would be a lot of fuel wanting to return to tank. The restrictor would cause a backpressure in the surge tank assisting the main pump as you said. But, at high engine power there will be little, if any, fuel recircing to the tank and therefore no (or less) backpressure in the surge tank.
It would sort of act like a rising rate regulator but in reverse
reducing pressure as load increases 
Andy
I'm not sure how your idea of a restrictor in the return line would work.
At low engine power, there would be a lot of fuel wanting to return to tank. The restrictor would cause a backpressure in the surge tank assisting the main pump as you said. But, at high engine power there will be little, if any, fuel recircing to the tank and therefore no (or less) backpressure in the surge tank.
It would sort of act like a rising rate regulator but in reverse
reducing pressure as load increases Andy
21 June 2002, 05:18 AM
#51
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My car needs at least 1/2 a litre surge tank to stop fuel surge, I still can't picture this device you would put in the tank, and how it would stop fuel surge as effectively. My car would almost suck that thing dry before it could refill again, and going around a corner you have the similar problem where all the fuel ends up on one side of the device.
21 June 2002, 06:30 AM
#52
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Andy,
Your statement;
"But, at high engine power there will be little, if any, fuel recircing to the tank"
The "if any" statement, I assume, only relates to mad buggers like yourself? I, personally, wouldn't like to be in this situation
I guess that the restrictor wouldn't be a problem as long as the it was sized suitably - as you mentioned, it's a flow/pressure thing for the in-tank pump.
J. - good to see you again The photos I sent David included the picture of such a design - tall and thin.
To be honest, this is all theoretical for me at the moment - I've only ever had this problem at less than half tank on the gauge (third of a tank left in reality?). I don't ever go that low on track.
Richard
Your statement;
"But, at high engine power there will be little, if any, fuel recircing to the tank"
The "if any" statement, I assume, only relates to mad buggers like yourself? I, personally, wouldn't like to be in this situation
I guess that the restrictor wouldn't be a problem as long as the it was sized suitably - as you mentioned, it's a flow/pressure thing for the in-tank pump.
J. - good to see you again
The photos I sent David included the picture of such a design - tall and thin.To be honest, this is all theoretical for me at the moment - I've only ever had this problem at less than half tank on the gauge (third of a tank left in reality?). I don't ever go that low on track.
Richard
21 June 2002, 08:28 AM
#53
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John
I know it's an relatively expensive option but I have the PowerStation setup fitted.
Before, I would get starvation through the Esses at Dono with over 1/2 tank left.
As an experiment, I ran right to empty at Bedford with no starvation at all, on slicks, not hanging around. I managed to get 54L in.
So, to me it's worth the money, 'coz I am not as good as you at making custom stuff
I know it's an relatively expensive option but I have the PowerStation setup fitted.
Before, I would get starvation through the Esses at Dono with over 1/2 tank left.
As an experiment, I ran right to empty at Bedford with no starvation at all, on slicks, not hanging around. I managed to get 54L in.
So, to me it's worth the money, 'coz I am not as good as you at making custom stuff
21 June 2002, 09:37 AM
#54
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I got it on about 5/8 of a tank out the Knockhill hairpin last night, and I hardly corner hard. This was with the uprated pump, which I wonder if it seems to suffer more than the original - which only did it on 1/3 or less of a tank. Any others find a difference?
21 June 2002, 09:52 AM
#55
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I've noticed it as well JB...I've had surges on public roads even....
Time to sort it methinks - but as someone said, Powerstations solution is a tad on the expensive side for what U get...
And there are a few more lads way ooop´ norf 'ere that are starting to find this out as well.
Time to sort something together?
/J
Time to sort it methinks - but as someone said, Powerstations solution is a tad on the expensive side for what U get...
And there are a few more lads way ooop´ norf 'ere that are starting to find this out as well.
Time to sort something together?
/J
21 June 2002, 11:20 AM
#56
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Im going to make one... and I dont mind making more than one... I can do these for less than £20 I would have thought... Probably out of steel though... due to cost of aluminium and I should be able to get steel free...
Let me know if you may be interested... it wont be until mid next week though.
David
Let me know if you may be interested... it wont be until mid next week though.
David
21 June 2002, 11:36 AM
#57
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You are forgetting the cost of the pump and hosing david!
Trust me, the design i use works and does not cause any fuel presure changes. This is fully tested on my westfield running 1.8BAR boost and 330BHP with one high presure pump. It is fully tested at well over 580BHP on a full race Escort Cosworth that wins all the time in the fastest saloon car championship in the country using 2 parallel high presure pumps. Both these cars use 2mm restrictors in the return from the swirl pot to the tank and use normal escort cosworth pumps to act as lift pumps.
If it can supply my westie without any problems at 145MPH, flat out throttle for over one minute at the nurburgring, it wont have any problems on a UK circuit.
I really cant be bothered with fabricating a proper race setup and having all the extra kit stashed under my bonnet so i am going to install the STi Anti surge pump assembly and see if that does as good a job as they say it will. I'll let you know the outcome. It's probably no good for massive power scoobs due to the flow rate on the pump used but it should be OK on a standard STi5 with 280BHP. I will test the flow rate of this system prior to running the engine and will see how that compares to the standard STi5 pump currently installed. Hopefully i will have this in the car before Donington.
Trust me, the design i use works and does not cause any fuel presure changes. This is fully tested on my westfield running 1.8BAR boost and 330BHP with one high presure pump. It is fully tested at well over 580BHP on a full race Escort Cosworth that wins all the time in the fastest saloon car championship in the country using 2 parallel high presure pumps. Both these cars use 2mm restrictors in the return from the swirl pot to the tank and use normal escort cosworth pumps to act as lift pumps.
If it can supply my westie without any problems at 145MPH, flat out throttle for over one minute at the nurburgring, it wont have any problems on a UK circuit.
I really cant be bothered with fabricating a proper race setup and having all the extra kit stashed under my bonnet so i am going to install the STi Anti surge pump assembly and see if that does as good a job as they say it will. I'll let you know the outcome. It's probably no good for massive power scoobs due to the flow rate on the pump used but it should be OK on a standard STi5 with 280BHP. I will test the flow rate of this system prior to running the engine and will see how that compares to the standard STi5 pump currently installed. Hopefully i will have this in the car before Donington.
21 June 2002, 01:58 PM
#58
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Im not forgetting the pump... as I have allready bought one off mark... and I can use the std pump to lift... and hose well.. yeah... I was only saying the cost of fabricating the tank...
if anybody would like me to make one then let me know..
David
if anybody would like me to make one then let me know..
David
21 June 2002, 01:59 PM
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John,
I wasn't trying to muppetise the thread.
You said that you thought "variable" fprs were a bad idea, I asked you to clarify this as I was sure that you were actually refering to "Rising Rate" fprs and not adjustable "fixed rate" FPRs and that the post may give the wrong impression to some other readers.
I agree that rising rate units will distort the fuel map, but I also believe that there is some positive benefit to be had from a fixed rate fpr with adjustment on it, such as the webber you mention.
I am a little confused when you write :"Typically you set the rail to 3 bar with the boost/vacumn pipe disconected, this usually causes the rail to then sit at 3.5Bar on boost".
It is my understanding that a fixed rate FPR will maintain the fuel pressure _differential_, call this X, set with the FPR open to atmospheric pressure. So the FPR will raise or lower actual fuel pressure as the manifold pressure raises and lowers, thus the injectors will always have X pressure across them to push fuel from the rail into the manifold. I assume, although I expect I will be wrong on this one, that the injectors efficient working pressure range is based on the differential rather than the system pressure. Have I got this all wrong?
BTW: Is there any problem with fuel heating up as it is constantly recirculated into the pressurised swirl pot? Where does the air "swirled" out of the fuel vent to?
My patent comment was, as clearly stated, made with my tongue firmly in my cheek. No offence was intended.
Moray
bbs.22b.com
Edited as I had miss-quoted one word. ho hum.
[Edited by MorayMackenzie - 6/21/2002 2:25:10 PM]
I wasn't trying to muppetise the thread.
You said that you thought "variable" fprs were a bad idea, I asked you to clarify this as I was sure that you were actually refering to "Rising Rate" fprs and not adjustable "fixed rate" FPRs and that the post may give the wrong impression to some other readers.
I agree that rising rate units will distort the fuel map, but I also believe that there is some positive benefit to be had from a fixed rate fpr with adjustment on it, such as the webber you mention.
I am a little confused when you write :"Typically you set the rail to 3 bar with the boost/vacumn pipe disconected, this usually causes the rail to then sit at 3.5Bar on boost".
It is my understanding that a fixed rate FPR will maintain the fuel pressure _differential_, call this X, set with the FPR open to atmospheric pressure. So the FPR will raise or lower actual fuel pressure as the manifold pressure raises and lowers, thus the injectors will always have X pressure across them to push fuel from the rail into the manifold. I assume, although I expect I will be wrong on this one, that the injectors efficient working pressure range is based on the differential rather than the system pressure. Have I got this all wrong?
BTW: Is there any problem with fuel heating up as it is constantly recirculated into the pressurised swirl pot? Where does the air "swirled" out of the fuel vent to?
My patent comment was, as clearly stated, made with my tongue firmly in my cheek. No offence was intended.
Moray
bbs.22b.com
Edited as I had miss-quoted one word. ho hum.
[Edited by MorayMackenzie - 6/21/2002 2:25:10 PM]
21 June 2002, 02:10 PM
#60
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David
One thing to check out. I'm not sure if these 'internal' pumps can be used 'externally'
I think they may have a relief valve which discharges out the side of the pump. An external pump has this routed back to the suction port.
Not sure but worth a check before it sprays your engine bay with fuel
Andy
One thing to check out. I'm not sure if these 'internal' pumps can be used 'externally'
I think they may have a relief valve which discharges out the side of the pump. An external pump has this routed back to the suction port.
Not sure but worth a check before it sprays your engine bay with fuel
Andy