Now i have the handling all setup on my STi5 i am getting fuel surge once the tank is 1/3 full under fast right hand cornering.

This is down to the fuel tank design, which is poo IMHO.

I believe PE make a swirl pot and pump assembly, is this correct as it's not on their website? Anyone have alternatives?

I could drive always at above 1/3 tank but i dont like the idea of fuel surge ever happening under any circumstances so your info would be apreciated.

cheers
john

 

John, http://www.powerstation.org.uk/News_Page.html, middle of the page.



[Edited by EvilBevel - 6/17/2002 6:24:36 AM]

 

I get this on MY99 aswell, suffered it at the weekend going round a roundabout

Is there not a mod-kit from Subaru to cure this if its a known problem? or is it another "they all do that", added to clutch judder, piston slap, etc etc

 

I thought about making a swirl pot to sort this, but... Ive bought an uprated pump... so do I need 2 uprated pumps... one to keep pot full and one for the rails???

David

 

thanks theo, it's the PS one, not PE. Not cheep really! Then again, if it's a decent fuel pump that can cost £180 alone. I'll check the spec.

You use the standard fuel pump to act as a lift pump to fill the swirl pot. This then feeds the fuel pump that feeds the injector rail.

Thats not really a swirl pot as it's square in design, swirl pots are designed to remove airation as well as provide a resevoir for the pump, that design wont do that. I also have a mod that would force the swirl pot to run presurised, making the high presure rail pump more eficient. I may make my own up. I'll think about it and see if its worth the agro vs cost benefits.

 

John.. any chance of more info as I was thinking about making one..

David

 

I have a drawing from the one i made for the westie at home, i'll pop that here tonight with an explanation of how it works.

 

Cheers.

David

 

http://www.scoobynet.co.uk/bbs/threa...hreadid=104347
CraigH has a swirl pot for sale.

 

was tempted... but for a metal tube with two plates welded either end and possibly a baffle in the middle.. I was going to chance making one instead.

Should cost about £15 to make... god knows what craig would say if I had the cheek to offer that...

David

 

John mail me offline. I might be able to help.

Dan

 

At Bedford - with very hot slicks (track temp 38 deg C) I was getting it with still over half a tank of fuel in the tank! Car was probably pulling over 1g of lateral force in long right handers and ergo - nae fuel!

Looking forward to a solution!

Trout

 

This is the fuel system design i made for the Westfield, you wont ever get fuel surge if you use this.

The intank pump acts as a lift pump to fill the swirl pot. The Swirl pot feeds the fuel tank return when it is full. The return from the fuel presure regulator that normally goes to the tank, now feeds the swirl pot. The pump that feeds the injector rail gets it's feed from the bottom of the swirl pot. Its best to use -8 or -10 hose from the bottom of the swirlpot to the pump inlet and then use -6 hose to the fuel rail if you can.

You should make the internal bore of the outlet from the swirlpot that returns fuel to the fuel tank 2mm rather than 10mm of all the others, this causes the swirl pot to run presurised and feeds the main fuel pump with high presure fuel, this eliminates any chance of getting cavitation on the main pump, which is the main reason for pump failure and inconsistent presure/flow. You should use a high flow fuel filter between the pump outlet and the fuel rail.

This setup, even with the standard intank pump is good for over 580BHP as the intank pump is just topping up the swirl pot as the return from the presure regulator goes back into the swirl pot. You may of course need two main pumps to feed the injectors if you go for 580BHP but the principle is identicle. I ran this setup on my 330BHP using the one main pump, that was capable for over 400BHP on the one pump.



Larger piccie here http://www.btinternet.com/~john.fels...uelsystem1.jpg

You make the swirl pot in a way that the fuel runs around the inner edge of the cylinder, so its spinning as it goes down the pot, this causes all the air to come out of the fuel and by the time it reaches the outlet to the main pump its 100% pure fuel. You should angle the outlet so its fed positevely by the swirl effect of the fuel.

I hope this makes sense.

[Edited by johnfelstead - 6/17/2002 11:13:25 PM]

 

John

I'm curious as to how you are going to keep this car std and original as per previous posts.

You've had the car five minutes and already you've had bump steer, ALK and geometery. You're now looking at AP's and probably bigger wheels if not on 17's already. Now you're after swirl pots and other tweeks. You'll be after a better breathing exhaust next to help the car pick up out of the corners....

Please explain the definition of std and original?

F
PS Thanks for not mentioning that the car is new and an STI (that's original)

PSS Did you not get fuel surge in the Sport? I thought your cornering was legendary in the old motor and matched any turbo for cornering speed

 

I got surge in the sport when it showed on the warning light, never before. It's a diferent fuel tank to the turbo.

The car came with 17" MiM's and SO2PP's.

I dont consider getting the suspension geometries setup/bumpsteer removed as a mod, because it's not, it's just using whats there properly. Maybe my defnition of a mod varies to most. To me mods are where you replace things rather than make them work properly.

I have good brakes now.

The fuel surge issue/swirl pot wont give the car more power, it will just make it less likely to blow up! I didnt think it would be so bad, but getting surge with a tank that must still have 20 litres in it is apauling, thats one seriously crap design!

I wont be touching the engine spec at all, whats the point? I will keep the standard STi exhaust, Standard panel filter etc. The suspension components are staying put too, it's a great compromise, not too low for rough cross country roads, no botoming out yet its firm enough to control the chassis properly. Too many suspension kits are too stiff, they feel fast but they are actually bloody slow as they reduce your grip, especially in the wet. But thats a whole new subject.

 

Leave it with me.. think I may knock one up out of some surplus Large ally tubing.. weld to round flat plates top and bottom then weld some fittings on to this...

Jobs a good un..

David

 

good question re: the use of an uprated fuel pump + swirl pot,
I take it that the second pump will need the same rating as the
first?

 

STi actually sell a part to overcome this problem. It replaces that standard fuel pump assembly:



Full description at:

www.poweraxel.com/sti/news/news2001/sti01004.html

use babelfish.altavista.com to translate.

The results are:


The Subaru Technica international corporation the commodity sets the one for in presser " fuel pump for competition ", we sell the Subaru dealer of entire country, via the STI shop.
" The fuel pump for competition " is the fuel deviation prevention functional equipped fuel pump for the new in presser. There are times when the high G revolution which is continued is done during motor sport having a match of rally, gymkhana, dirt trial and race/lace et cetera, when the fuel remaining amount inside the fuel tank is small, when the fuel has been inclined there are times when the fuel being cut off is caused. In this kind of state, you cannot obtain the kind of acceleration which is thought and become time loss. " The ƒtƒ… for this competition - the l pump " has added the chamber which inserted the divider of the rubber make around the fuel sucking out mouth, 1. By the fact that the fuel approximately of 5 liters is saved the among those, the fuel being cut off at the time of the ƒ��[ƒ^ƒ“ƒN is prevented.
In JAF for the competition part register being completed, as for use to motor sport competition there is no problem, (as for register application only the GDB). In addition we have conformed to safety standards, it is the effective fuel pump to also the person who desires the time rise with the tuning car and the mini- circuit and the like of circuit attack specification.
* This item is a pump ASSY and compatibility of standard, volt/bolt on installing is possible.


< Commodity summary >
Part name Part number Value case Preparation to think
FUEL PUMP ASSY ST420214S000 50,000 Yen Competition


I think the summary of the above is that it has an internal tank which keeps 5 litres of fuel in an internal tank to prevent fuel surge under high-G applications, and it costs 50,000 Yen.

STi also do an uprated fuel pump:

www.poweraxel.com/sti/news/news2001/sti01031.html which flows at 180L/hr. Part number ST420214S000, and costs 42,000 Yen. Plug and play compatible with the standard fuel pump.

John

 

have a word with R19KET (Mark), he can supply a
255ltr/hr pump for £130 delivered.

[Edited by mattski2 - 6/18/2002 10:57:23 AM]

 

the fuel pump wont sort the problem, if there isnt any fuel there to pump up...

Johnfelsted whats your opinion of above?? is it just like an open box with the pickup it?? if so wouldnt this mean that you cant empty the tank fully...

I dont think I quite understand the above...

David

 

I know the pump won't sort it on its own

I reckon a swirl-pot is the best way to go,
although it could end up being quite an
expensive mod if you end up having to get
two uprated pumps, and maybe braided fuel
lines + uprated regulator etc.

What do you guys think of those 'Power Boost'
valve things?

M

 

you only need to buy one pump. Read my explanation again, you use the standard intank pump as a lift pump to fill the swirl pot.

Those Variable FPR are not a good idea IMHO.

As to the STi intank anti surge kit, i dont know enough about it, it's hard to work out what exactly it is doing from that picture. How much is 50,000Yen?

 

do you not like variable fpr's through personal choice.. ie rather get bigger injectors than do it on the cheap?

would like to see some better pics of that sti item..

Will make a swirl pot up... just need to get some scrap ally next week... will post pics up when done...

Havent had fuel surge yet, but dont have much confidence in standard my94uk suspension to go around a corner quick enough!

Edited to add that I have an uprated fuel pressure reg.. Sure someone mentioned cosworth... but couldnt be sure.. made by webber will be adjustable when I punch a hole in the top...


David

[Edited by David_Wallis - 6/18/2002 2:30:26 PM]

 

sounds like a cossie FPR. You should control fuel delivery with mapping, not guesswork or via variable presure regulators.

50,000.00 Japan Yen = 270.875 GBP United Kingdom Pounds
1 JPY = 0.00541751 GBP 1 GBP = 184.587 JPY

I wonder how much i could buy that for in the UK, no doubt tripple. Can you buy direct from STi?

I see how it works now, the feed from the FPR is filling the 0.5litre alloy tank, the tank will probably have some small drillings in the bottom to take its feed from the main tank so it will work more like a surge tube than a swirl pot.

 

I have posted on my site a DIY surge tank, for anyone that is interested. Similar to the other example posted.

http://www.geocities.com/subman2001nz/

 

What about welding and upturned bucket type thing (with a small gap where it joins bottom of tank) directly onto the base of the tank (need to open tank) and having the feed and return pipe going into this?

21st Century Performance suggests this is a good basic solution.....no idea myself

Richard

 

Cannot Weld a fuel tank.... not even once its been washed out...

Just wouldnt dare... you wouldnt believe what happens to an empty fuel tank when it goes up let alone a full one...

You would have to do what sti have done.... which I may look into at the weekend... pics to come soon

David

 

You Wuss, lol

I used to repair (normally brazing up seam splits) and custom-spray old motorcycle fuel tanks. The shop I worked in had a special detergent (?) you cleaned out the tank with first - the whole process took a few days but rendered it safe for this sort of activity.

For sure, don't do anything otherwise

21st Century Performance had some nice photos showing the process of cutting the bottom of tank out and welding in the swirl-pot....but they're Aussies so probably just filled the tank with beer first to clean it out.

Richard

 

Any chance of seeing the photos?

I know it is possible to do.. just meant that joe blogs at home that thinks they can weld with their no-gas 90amp mig, after emptying the tank and washing it out with a bit of water

Besides wouldnt want to weld it as my 230amp mig would probably blow holes through it...

Think it would be safer to do it as said before!

David

 

I'll scan them tomorrow and email.

Richard