Got an ali tank for my car but unfortunatly it only has one outlet and, as I'm running injection, I need a return line too. Merlin suggested I may be able to epoxy a second one in saving the expense of getting someone to weld the ali for me. Is this a good idea? What should I use? I was thinking of Araldite?

Chris

I don't know of any adhesive suitably reliable to bond alloy and be fuel and vibration resistant. Have you thought of a threaded in line union fitted from the inside and sealed with gaskets / O rings? Would only involve a bit of gynecology through the filler neck which should be reasonably easy if the tank isn't fitted yet.

Mick

Chris,
Another option;
You could also put the return line into the filler neck.
Should be easier welding or soldering a tube into a short length of pipe which could be placed with flexi pipe between tank and filler cap.

Terry

Good idea - why didn't I think of that?

Would still rather fit a 'proper' return tho if at all possible.

Chris

Shouldn't the return line feed the swirl pot? Or have I got it wrong again?

Mick

the metro turbo, that ran an efi pump to a pressurised carb system (!) returned excess fuel into the wall of the filler cap tube. If you took the cap off with the engine running you could se the return jet hitting the side of the tube......


atb

steve

Chris.
How soon do you want to use the tank?
I am happy to weld it for ya, just a matter of getting together sometime to sort it.
Tim.

Be great if we could arrange that mate. I've got no TIG gear tho so I guess you'd have to take it away or I'd have to stop by your place?

Chris

How heavy is it? or can it wait till Donnington?
Can't arrange anything for this weekend as i am at Rockingham Fri till Sunday.
I would need to take it into work as i don't have TIG at home, other option might be if you know anyone coming by this way?

I'll have a think about it and come back to you!

Chris

Chris,
Sorted your tank yet?
Going to Donington?
I could pick it up from you there if you like.
Tim.

but, don't you need a swirl pot?!?!

How about a low pressure pum feeding an external swirl pot, with a pump that feeds the engine?

I've heard of that being done.

Cheers

I was thinking about using a swirl pot as I had one from a Formula 3000 car laying around. Unfortunatly I think I gave it away a few years ago because I can't find it for the life of me now.

Do I need a swirl pot for injection or will it 'be ok'?

Chris

look under the back of a xr3i they have a seperate swirl pot/ fuel return thinggy.

AFAIK you need one. I was told I'd need one when I was going to run injection.

Cheers

That sound good - I'll have a look next time I see one in a car park

Chris

quote:

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Originally posted by timf
look under the back of a xr3i they have a seperate swirl pot/ fuel return thinggy.

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Chris,
when i pick up your tank i should be able to tell you wether or not i can fit a "swirl pot" inside for you..

Or on the bottom???????

You can fit one? Great!!

Chris

quote:

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Originally posted by Viper
Chris,
when i pick up your tank i should be able to tell you wether or not i can fit a "swirl pot" inside for you..

---

On an injection, is a swirl pot needed as an actual swirl pot, or is it just needed purely to prevent starvation?

What about in the tank pumps? Would I still need a separate swirl pot for that or would decent baffling do? I couldn't see anything on the donor, but the tank did have some baffling around the pickup of the pump which is what I'd expect.

[Edited on 4/9/2003 by GO]

my little bit of experience is this.

EFI fuel pumps get very unhappy if starved of fuel as it acts as lubricant. However nuts it sounds, many pumps, inc their electrics, are immersed internally in fuel.

EFI systems recirculate fuel to pressurise the manifold, and draw a fair volume as intake. On my car, using a granada EXTERNAL pump, the inlet hose is about 15mm and the outlet 8mm.

If the fuel sloshes around the tank, the pump will draw in air. this will go into the system and cause misfires and also may damage the pumping internal seals if they run dry too long.

On my car, I made a swirl pot (I understand this to mean a reservoir, and nowt to do with a swirl action) that under the tank.

Basically, I made approx 20mm hole in the tnak bottom, welded 150mm of tube under it, so that the tube fills with fuel from the tank above. The bottom of the tube is closed, and an intake pipe is welded into the side of the 'pot' about 30mm from the bottom (to avoid intake of sediment crap).

So, the theory is that as the fuel sloshes, the 'pot' should have a decent level in it from the tank above, and not starve.

I think my pot is a bit small, but the 35mm tube I had was the best solution at the time. Ideally, you need to know the pump flow rate, in litres, and guestimate a 'slosh period' where you may not have fuel above the 'pot'. From emory my tube holds about 1/4 litre which is a handful of seconds.

The Jag XJ-S has a secondary tank under the main one, that holds a coupe litres, but then under acelleration it shows 3 mpg on the fuel computer!!!!!


A swirl pot isnt esential, but you will get fuel starvation and possible pump damage if it runs dry.

atb

steve

[Edited on 4/9/03 by stephen_gusterson]