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Location:
Sydney
Registered:
September 2004
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surge tanks: a few questions.
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Sun, 06 March 2005 11:18
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Hey all. Been doing a bit of research on this and now have a few questions.
For people who have surgies installed:
1. What capacity is your surge tank?
2. Do you have the fuel return going into the surge or the main tank?
3. Any problems at all with the setups?
If possible, could i get answers to at least 1 & 2 as these are linked. I've read that if a surge tank is too small and the fuel returns to the surge, the fuel can heat up quite a lot. The recommendation was for a surge tank at least 2L large which seems pretty damn big. I also have a few general questions.
4. Why does everyone use a low pressure lift pump from tank to surge? Does it have anything to do with putting too much pressure on the surge tank?
If, for example, I have an efi pump already installed and need greater fuel flow (4agTe  )and decide on a surge tank for peace of mind:
5. Can i use the existing in-tank pump as my lift pump in the above example?
Whoa... long post. Cheers guys!
Eddie.
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Location:
Brisbane, Queensland
Registered:
January 2004
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Re: surge tanks: a few questions.
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Sun, 06 March 2005 11:26
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1. Capacity is usually 1.5L plus, depends on your situation, Mine will be as large as space permits
2. Best idea is to have the fuel return to the surge, and then from the surge have a return to the main tank (when it gets full) although this can cause problems with the fuel heating up. but there are ways around it.
3. space mainly, you obviously need another pump and wire that in, as well as assorted plumbing
4. again this is more related to setup. If you already have an intank pump then use that to fill the surge, under no pressure it would pump lots and lots of fuel.
5. refer above.
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Location:
Sydney
Registered:
September 2004
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Re: surge tanks: a few questions.
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Mon, 07 March 2005 08:40
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I DID use the search and have read all of those + more already. I understand the principles of how surge tanks work and how to go about installing them but was more concerned about the capacity of the surge tanks.
I had only read 1 thread where someone had specified their tank capacity... it was 800ml but made to be very tall and narrow. My concern is that hot fuel can cause the engine to be more prone to detonation.
My questions were aimed at people that ALREADY have surge tanks installed... I thought the questions were quite specific and would allow me to chose an appropriate setup,
ie. either having the return fuel going to tank and having a higher flow from the low pressure pump, OR having an appropriately large sized surge and have the return going to surge, allowing me to keep my current intank pump.
These question about sizing wasn't answered in the previous threads... they stated "as large as physically possible" which doesn't really tell me much in terms of ml.
Anyway... I'm still new to these forums but spend enough time here to realise you guys get REALLY pissed if asked the same question 10 billion times. I ALWAYS search before posting a tech question. I thought my questions were worth another thread. Sorry if they weren't.
Eddie.
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Location:
Melbourne
Registered:
May 2004
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Re: surge tanks: a few questions.
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Mon, 07 March 2005 08:52
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The surge tank i whave to run in the sprinter is a 2l stainless jobby.
I really want to keep this size but i dont want to mount it in the car or the engine bay..... 
Any suggestions.
Jezza
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Location:
Brisbane, Queensland
Registered:
January 2004
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Re: surge tanks: a few questions.
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Mon, 07 March 2005 08:52
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Don't worry about he witzl, he gets cranky sometimes
The only thing i can relate to size, is the larger the better for cooler. Might have something to do with pumping rates as well. Say if you the intank can flow 3L a minute and at full noise your highpresure pump is pumping more then that, you'd want a bit of buffer.
To be honest, i don't know. I do know that ill be making a surge tank to fit the area that i have presently.
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Location:
S.E suberbs, Vic
Registered:
December 2003
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Re: surge tanks: a few questions.
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Thu, 10 March 2005 21:35
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anyone ever thought of welding multiple fins on one to make a crude heatsink out of the outside? because really a tank wouldnt normally need to be bigger than a few hundred cc I would think
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: surge tanks: a few questions.
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Fri, 11 March 2005 00:15
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i dont remember who exactly it was i was speaking to who was witness to some tests performed on the dyno with different fuel temperatures.
Basically the result was that on the street and on the dyno, you will never reach a problem with fuel temperatures that are worthwile considering cooling your fuel supply or changing the design of your fuel system.
Now... i'll be nice  When you have a look at the pimp on the weekend eddie you will see how i have done my fuel system. Visual inspection is much easier to follow, and i have proven this fuel system to work VERY reliably and never surge, have heat issues etc.
I use an old primus gas cylinder with fittings braised onto it. I think volume is around 1-1.5L from memory.... big enough for when fuel levels are low but small enough that fuel is still circulating...
From my fuel tank....it goes
# tank outlet -> carby fuel filter
-> low pressure pump (above diff)
-> factory fuel supply line
-> top of surge tank (in engine bay)
-> Bosch 240 EFi pump
-> 300ZX style inline EFI fuel filter
-> Fuel rail -> Fuel pressure regulator output
-> base of surge tank (refills it, entering at the top would be better)
-> surge tank overflow outlet -> stock fuel return line.
soooo... in answer to your questions directly.
1. 1-1.5 litres
2. Return fuel from fuel rail goes back into my surge tank. This makes sure the surge tank is always full
3. No problems at all. Except when that earth wire came loose... 
4. Low pressure carby pumps are used to supply the surge tank because they can "suck" fuel out of the tank... most EFI pumps lack the ability to suck, they can only push and be fed by gravity. Make sure you use a low pressure HIGH FLOW lift pump.
5. Your existing in tank pump??? By this i guess you are suggesting that you already have an intank EFI fuel pump. If so, then why do you want to use a surge tank? THere is no real need and it would only create more work and extra headaches which are not required. If you think your current intank pump is not up to the job... simple, replace it with an intank 255L Walbro pump from Importbitz at a VERY nice cost. NOWHERE NEAR as much hassle and awesome results.... without all the surge tank ugliness 
That's what i would have done.... but heinsight is a wonderful bitch.
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Location:
Sydney
Registered:
September 2004
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Re: surge tanks: a few questions.
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Fri, 11 March 2005 08:14
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| THE WITZL wrote on Fri, 11 March 2005 11:15 |
Now... i'll be nice When you have a look at the pimp on the weekend eddie you will see how i have done my fuel system.
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Awww... you remembered this time. I feel so wanted now.  Yeah I'll check it out when i see it.
Eddie.
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Location:
Sydney
Registered:
September 2004
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Re: surge tanks: a few questions.
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Fri, 11 March 2005 09:14
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| Sam_Q wrote on Fri, 11 March 2005 08:35 |
anyone ever thought of welding multiple fins on one to make a crude heatsink out of the outside? because really a tank wouldnt normally need to be bigger than a few hundred cc I would think
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Something akin to the older engines that had air instead of water cooling right? You'd need a pretty decent airflow (depending on the tank material and its ability to absorb/lose heat) to get it working properly. From the pics I've seen of surge tanks, usually they mount them in pretty tight spaces, ie between the diff/fuel tank, which means that the airflow is limited to one side as well.
Still... seems like a really good idea in theory. I've seen your conversion Sam_Q and know your pretty handy with a welder. Why not give it a go? On the downside though, it'll probably add a lot of outer width that could have simply been used as extra cc's in the tank.
Eddie.
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Location:
S.E suberbs, Vic
Registered:
December 2003
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Re: surge tanks: a few questions.
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Sun, 13 March 2005 14:37
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I am going to try and avoid using that surge tank I started to make as I will see if I can get my standard tank modified instead, so I only will need one pump and no surge tank at all.
That asside Big T you mention some good points about the airflow and packaging however I am pretty sure this wouldn't effect me. I beleive there would still be a fair bit of airflow because I could drop the fins lower than the tank and theres a fair bit of turbulent air in where I would put it, I wouldn't have an issue with packaging it because I have put the largest pipe in an odd shape hole. The fins can be of any shape so I would come up with something. I will also get it Tig welded on by a friend because my full length welds would add stacks of weight.
For other cars well.. it might be pretty hard to do as you sujest.
All this in mind though it really does come back to who cares? Witzl I beleive it was zoom that did that test and I trust what they do. So I say let it be hot if it doesnt mean anything.
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