Surge Tanks

[Shrike]

So im going to explain this as if no body knows anything about surge tanks (note this is my understanding so correct me if im wrong)

Ok so surge tanks are a tank which is positioned after the fuel tank but before the fuel rail and prevents fuel stavation (surging) by being constantly filled with fuel

Surge tanks are normally between 1-9L depending on application

System goes as so

Fuel tank
Lifter pump
surgetank
feeder pump
fuel rail
return line
surge tank
return line to fuel tank from surge tank
fuel tank

Ok now that we have covered the basics the setup im building includes a custom fuel tank (baffled and with the bottom angled towards the Fittings) in factory positon (under rear seats) modified to be shorter to fit the rear subframe and have a gap for both the driveshaft and the exhaust

So coming off that is the fuel filler pipe, fuel vapour vent pipe, surge tank feeder line (AN-10) and return fuel line (AN-10)

Ok line from the fuel tank connects to a filter and then feeder pump (700hp) (AN-10 in and out) (both fuel pumps and a filter will be in the tyre well along with the surge tank)

Now the issue im having is what size to have the surge tank I was orginally thinking a baffled 10L tank however I just measured up and worked out the space I have and the size I was thinking works out to be almost 40L :S

Of course it will be baffled into 3 sections with the final section having another baffle to make it a 5L section

So if I have this full the car would have roughly 70-80L fuel capacity and 40L at the back of the car so around 30ish kg (which would help me gain more traction with the rear wheels) however im thinking that may be alittle excessive

Thoughts comments?

I may add pics of my paint drawings later haha

(note feeder pump will be rated 1300hP and the whole system will be AN10 apart from the split from AN10 to Dual AN8 into the fuel rail then an8 to the fpr then an10 return)

[Lloyd]

Ok line from the fuel tank connects to a filter and then feeder pump (700hp) (AN-10 in and out) (both fuel pumps and a filter will be in the tyre well along with the surge tank)

Huh?



You need a line from the tank to a lift pump, followed by a filter, which then feeds into the top of a surge tank.

The outlet from the surge tank will go to your main fuel pump followed by filter which will feed the fuel rail. The return from the fuel rail will go back into the top of the surge tank. There will be one more fitting in the top of the surge tank that goes back to the main fuel tank for when the surge is full. Essentially an overflow for the surge tank.

[Shrike]

I didnt word that very well sorry lifter pump will be 700hp

[Crucible]

I didnt word that very well sorry lifter pump will be 700hp

You mean main pump?

[gt4dude]

Why do you need -10?

http://shop.dodsonperformance.co.nz/index.php?product=TS-0401-1007&c=162

is this the fuel reg you're using?

for your 3000hp 7agte?

awesome build though, saw your thread. I like it, wish I had my running gear in a little corolla chassis

[Shrike]

Been looking at

Lifter (fuel tank to surge)
http://fuelab.com/prodigy-fuel-pumps/40 ... -fuel-pump

Feeder (surge to fuel rail)
http://fuelab.com/prodigy-fuel-pumps/41 ... fi-in-line

Fuel pressure reg
http://fuelab.com/fuel-pressure-regulat ... -regulator

Ha 3000hp I think not would need a jet engine for that

Id rather have to much fuel then not enough no one likes a lean engine

[Lloyd]

You don't need/want a high pressure pump for a lift pump. All it has to do is fill a small tank, not pressurise a rail.

[Crucible]

Id rather have to much fuel then not enough no one likes a lean engine

They seem a bit overkill. What are you building?

Twin Turbo Big block?

[gt4dude]

The factory pump should be fine for a lift pump,

I'd have it like this...

-6 pushlock hose clamped to your factory pump, -6 welded bung & fitting for surge tank feed

-6 fpr return welded bung & fitting

-6 return to fuel tank

-8 feed to external fuel pump, -6 braided line from fuel pump to filter, rail, reg & return

[matt dunn]

The shape of the surge tank is what matter as much as the size,

need to keep the diameter of it small, and the height of it tall,
and if it hold more than 10L it is too big.

Too big and it will get surge in the surge tank.

You will need to make sure that the pump that feeds the surge tank
can handle a bit of surge as in air and fuel.
A lot of good HP pumps will overspeed when the suck air,
and the when the fuel returns they are spinning way too fast and snap of the internal drive to the impeller.

It only need to flow the fuel that you plan to use and at very low psi,
compared to an actaul main pressure pump that needs to run at high pressure and flow way more than the injectors use to keep the pressure steady.

A well designed system will run with alomst no surge at all,
and there are ways of doing it with no surge tank too.

May car will not surge until it has less than 250mls in the tank,
and so when it surges, you usually run out of fuel before you complete that lap, even at cruise.( only been caught like that once)

Depends on the application too.

The way you set up a surge setup for sprint races, endurance races,
or the odd track day in a road car will depend in how you design the system.

[Shrike]

Im wanting to gain back some of the fuel capacity I lost from making the factory tank smaller

The space I have will allow me a 540*330*200mm tank which works out to be almost 40L obviously to big (back of the rear tyre well) I want to hide everything there and seal it so max height I can have for a surge tank is 200mm

(I cant run the factory fuel pump as it wont fit due to the modifications to the fuel tank)

Maybe I should run a 2nd fuel tank and 2 lifter pumps

I can go down to smaller pumps but what I was thinking is if Im running full flow then it might not flow fast enough back to the surge tank from the fuel rail

Any thoughts on how much fuel I should be able to run in the car?

[Boost_4_Life]

The shape of the surge tank is what matter as much as the size,

need to keep the diameter of it small, and the height of it tall,
and if it hold more than 10L it is too big..

what Matt said. The idea is to have a height of fuel giving you a buffer so that sloshing does not affect the pickup. If you have a low wide surge tank, you completely go against the whole principle... Dont think I have ever seen a surge tank much more than 4ish? litres in capacity. Cant remember what mine is but its something like 2 or 3L.

[matt dunn]

540*330*200mm tank
max height I can have for a surge tank is 200mm

If the tank is wider than it is tall, it is a create fuel surge tank,
not a stop fuel surge tank.

Think of a a baking tray full of water,
how far sideways do you have to tip it to get one corner dry?

Now think of a yard glass,
How far sideways do you have to tip that to get one corner dry?

[Grrrrrrr!]

Another way to work out if its going to work as a surge tank..

You wont get more than ~1g lateral in anything without wings, so 1g lateral + 1 g vertical gives a resultant 45 degree vector

If you tip the tank to 45 degrees, will the fuel pump pickup be uncovered? If yes, design = fail, try again.

[fangsport]

as Matt said, you can set the system up without a surge pot.

4ag Starlet was done like thus:

facet pump
large inline filter
pressure pump
return line plumbed in between facet pump and filter.

theory being if there was to pressure after the facet pump, it would self-regulate and shut off until required. the decent size of the canister filter acted as a surge pot

only had fuelling isses when there was bugger all in the tank..... or when it was upside down !!

[Shrike]

Ok so Ill get the new fuel tank made

Then run a low pressure high flow fuel pump like used on carbed engines to a 2nd fuel tank in the rear tire well (10-20L capacity) both fuel tanks will be baffled (reason I want a 2nd tank is so I can run the smaller tank on track days and both for long trips/endurance)

Then from the 2nd tank ill run another low pressure pump to a 200x100x100mm high 2L surge tank

All the returns will go to the fuel tank in the tire well and then ill have an overflow from that to the factory fuel tank

I know its over complicated but I think it may be the easiest way to do it to fit my criteria

Will make a diagram later to explain

[MrOizo]

If you're making a custom fuel tank, why not make a tank that incorporates a surge cell inside it? Will save on plumbing and space.

Would a better thought out pick up help here too?

[Shrike]

If you're making a custom fuel tank, why not make a tank that incorporates a surge cell inside it? Will save on plumbing and space.

Would a better thought out pick up help here too?

I have thought of that but the factory tank is being cut down so I may only have a 30L tank instead of 45L so assuming I have high fuel usage it would mean I wouldnt be able to drive a decent distance I have space in the spare tyre well and alittle more weight on the rear end isnt a bad thing with a 4wd system

Sorry custom tank will be alloy but it will be a cut down version of the factory tank with baffles