EFI DIY Serge Tank Idea?

[Buffalobillpatrick]

Thinking about using a 52" length of 1" copper pipe.

I have all the copper on hand & am real good at soldering.

Would hold .7 quarts. Long pipe would help keep bubbles away from the high pressure pump exit port at the bottom end.

Would mount it across frame between engine & my radiator electric fan, high end on passenger side.

3 ports at the top end: low pressure pump supply & return to standard gas tank + EFI pressure regulator return.

It would get air flow across it.

What do you think?

BBP

[Ollie8974]

I am thinking of the same idea, only using a 1 gal fuelcell.

[Buffalobillpatrick]

There is actually almost no pressure inside a surge tank. The low pressure return line to the gas tank fights no back-pressure.

High pressure EFI electric fuel pumps have a habit of going bad. They are very poor at self-priming when gas sloshes around in gas tank. This can kill engine & quickly kills pumps.

Many use a small surge tank as a buffer tank to make sure that the high pressure pump never draws air.

A low pressure/high volume pump is very good at self-priming. It runs constantly with key on & keeps the surge tank full & excess is returned to gas tank.

A surge tank has the high pressure pumps pickup in the bottom. The excess gas from the EFI regulator returns to the top.

BBP

[nullshine]

I am neither a metallurgist/machinist/welder or anyone else who has great experience with metal.

But, with something that long and skinny, in a high vibration environment such as a vehicle, wouldn't it be wise to stay away from copper?

Especially when transmitting such a flammable substance as gasoline near the engine as you are planning to.

[The WidowMaker]

i guess i dont understand the copper or the small diameter long tube. why not use a surge tank that looks like a dry sump oil tank and mounts on the firewall? it would hold more volume, and it would be out of the way of road debris and any front end damage from a crash.

im thinking that you are going for the long tube/copper to get rid of the heat, but its still in the engine compartment. if thats hotter than the fuel, youre actually going to heat it.

Tim

[Buffalobillpatrick]

I have a new stock gas tank & chose not to cut & weld on it to put in a sump & baffles.

Of course, a small diameter external surge tank would not run horizontal. The high pressure pickup port needs to be at the bottom, thus always has fuel above it, and as far away from the top end ports as is reasonable with space constraints.

I have read about a 48" one in some factory sports car, but have lost the link to which car.

My updated plan is to build my own 1.1 quart copper surge tank. 2.5" x 13" Mount it on frame on passenger side of engine. I'm thinking of running the Edelbrock EFI pressure regulator return directly back to the main tank to help dissipate heat & not over heat the surge tank.

For my low pressure / high volume supply pump to the surge tank I'm using a Carter GP4600HP 8#/100GPH, mounted back by the main tank. These re-prime themselves easily without damage as fuel sloshes. The highest port on the surge tank will also return to the main tank.

My high pressure pump is an Edelbrock unit that came with the Pro-Flo system.

BBP

[barraza]

An easy way to make a surge tank is to get an aluminum radiator overflow tank. Mine is about a quart, and is six sided, so it has flat areas to weld to. Get AN weld fittings and weld it up. HP supply out the bottom, return to tank out top, low pressure supply and injector regulator return in near top. I used the stock engine driven mechanical pump as a supply pump, and put a restrictor in it to slow it down. If you don't have a mechanical pump for low pressure, don't get crazy with the low pressure pump. It will be pumping against nothing, ie just filling the tank, so it won't have a problem delivering its rated volume.

Something to remember is that you don't need much volume, a quart will run the engine a long time. A relatively small tank will also make it easy to position, mine is inside the fender, hidden by the battery, hanging off the radiator support on a camaro. Perfect for hanging the fuel pump and filter under the inner fender, where it can be serviced if necessary.

[Buffalobillpatrick]

barraza,

your: "and put a restrictor in it to slow it down" Why?

BBP

[barraza]

Because even a minimal size pump will flow a lot of fuel when it has no restriction and I didn't want to have the low pressure pump pressurize the surge tank. I used a low pressure regulator set between one and two lbs. I never put a gage on the surge tank, but it worked fine. I hate to admit it, but I once hooked the lines up wrong and had no fuel flowing from the main tank. I used the car to take my son to school and made it there and half way back before the car ran out of fuel. It was 11 miles one way!! The thing to remember is that you are not trying to keep the car from running out of fuel, only to keep the HP pump from pulling air. There is a lot of fuel in the lines, pump and filter. If your pressure return line goes back to the surge tank, you should be able to make a wide open run through the gears with minimal fuel. Also remember that as you get up in speed, you won't be accelerating hard enough to keep the fuel in the main tank away from the pickup either.

An interesting idea I heard about once was to bleed pressure off a tank mounted HP pump to make a venturi that would move fuel into an inside the tank sump. Similar to a suction sand blaster. Dont know if the idea worked or not.

[Buffalobillpatrick]

Some of the fuel heating up problem comes from the pumps & gasoline friction in the lines, but most of the heat comes from the fuel rails, headers, time spent in engine compartment.

I just thought of how to determine the amount of heat that the pumps add. Lets say the HP pump uses 9 amps & the LP pump running with almost no back-pressure uses 1 amp. That's 10 amps total.
10 x 13.5V = 135 Watts

135 Watts might raise a 20 gallon tank about 5-10* F (this is a guess)
The temperature would level off at some point where air convection + IR radiation reach a new equilibrium. Painting a shinny metal tank black (some paint is better than others) would greatly increase the IR radiation (emissivity)

BBP

[barraza]

Why worry about temperature? You will never add enough heat to be a problem by pumping it back and forth. Gas boiling points vary by season blend, but even in summer, you should have no problems unless you put the surge tank close to the engine.

[Buffalobillpatrick]

Do some Google searching. Hot gas causes MAJOR problems for some cars in hot weather. Dual Turbos etc. Some run a gas line through a cooler chest filled with ice in the trunk.

[barraza]

Do some Google searching. Hot gas causes MAJOR problems for some cars in hot weather. Dual Turbos etc. Some run a gas line through a cooler chest filled with ice in the trunk.

You're making the whole thing too hard. I built a surge tank like you are planning and have had it working for fifteen years. It's not rocket science.

[Buffalobillpatrick]

I built my surge/swirl tank today. 1.1 qts. 2.5" x 13" pipe.

I would like to mount it back by the main gas tank, but don't see how yet. So maybe I will have to mount it up front where the battery use to be.

My 72 Monte came with a sealed gas cap & EEC system. Fuel tank has 3 vent hoses that go up about 20" to a liquid/vapor separator device.

I'm thinking of running the output from that, (which used to go up front to a carbon canister) into the bottom of my air cleaner.

Gas vapor can be burnt as required & filtered air can be sucked back into main gas tank as fuel is used.

Good or Bad Idea???

BBP

[makoshark]

This is what I`m using:

http://cgi.ebay.com/ebaymotors/Aluminum-Fuel-Surge-Tank-2-Litre-Swirl-Pot-System_W0QQcmdZViewItemQQhashZitem518d0b9cb6QQitem Z350258699446QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fA ccessories

I still haven`t got it installed cause still building the car. I have a Holley Red pump feeding it from the stock tank and then a Walbro 255 feeding the motor from the surge tank. At least thats the plan.

[Buffalobillpatrick]

makoshark, Looks like a nice unit, lots of ports.

I'm not sure about swirling action in a square sided tank?

BBP

[makoshark]

swirling action?

[Buffalobillpatrick]

Read the Ebay listing:

Aluminum Fuel Surge Tank 2 Litre Swirl Pot System

A swirl-pot concentrates the air bubbles in a vortex at the top center for return to the main gas tank.

BBP

[makoshark]

I`ve read it before. I own the tank. I am familiar now with how the system works. It`s more gravity than swirl.