Fuel tank

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Midlana1
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Fuel tank

Post by Midlana1 » 04 May 2009, 07:01

The fuel tank is an involved project. I'm "typing out loud" to let you know how the first build goes:

1. While aluminum is an alternative, stainless is the best material.
2. That said, it's a bitch to bend - I had a sheetmetal shop do it.
3. Welding distortion can be a big deal.
4. The internal baffles, great for track-use, may not be worth the hassle for the street. That said, a transverse tank will have a lot of fuel slosh. even normal cornering will cause the pump to suck air when the tank is <30%.

I'll add more as it moves along.

jerelw
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Re: Fuel tank

Post by jerelw » 04 May 2009, 09:43

A baffle near one side of the tank with a one-way swinging gate at the bottom would help. I've seen similar things done with competition oil pans. When the oil sloshes towards the oil pickup, the gate swings open. When it tries to slosh away, the gate swings shut. A small tab or piece of wire keeps the gate from swinging open the other way. It's not perfect, but I think it would go a long way to solving the problem. For street and autocross, I'd do this. Otherwise, a swirl pot fed by 2 electric low-pressure, high-flow pumps (Facet?)(one suction on each side of the fuel tank) would solve it for good. If I was going to do track days, I'd use the latter option.

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Re: Fuel tank

Post by Midlana1 » 04 May 2009, 10:33

Keep in mind that this tank is roughly 43" wide, so there can be a lot of fuel slosh.

In the Mini I used a 10 gallon fuel-cell oriented fore-aft. I could feel fuel slosh as I got off the gas onto the brakes - like a very slight tap from behind. This was apparent even though the cell was a true cell, full of foam (which some people incorrectly think is for fuel slosh prevention.) It had two pickups at opposite side of the tank, two external - and irritatingly loud - Facet pumps feeding an external accumulator, which in turn feed a high pressure pump to the engine. I didn't like all the external plumbing (and hearing the Facet pumps knocking on anything less than a 55% full tank :x )

The Midlana tank plans may be too involved for some builders, but than again, it'll absolutely solve fuel surge problems. It'll be presented along with other possible solutions and buiders can choose.

I'm not sure how much to trust a swival pickup - not in function but for reliability.

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Re: Fuel tank

Post by Jagmandave » 04 May 2009, 11:33

Back in the day, GM tanks had no baffles and when you'd stop your Chevy suddenly your fuel gauge would swing from empty to full and back a few times. Later, either they installed baffles or they dampened the action on the gauge readout! :D

I'd thing some short baffles in the bottom of the tank wouldn't be too hard to weld in, and would stop the slosh. I'll be interested to see what you come up with. My E-type tank has no baffles of any kind, and I don't ever remember it having any slosh noise or causing fuel starvation, but I've never autocrossed the car, and with carbs you have float bowls, so it would take a lot to cause it to starve in a turn.......

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Re: Fuel tank

Post by jerelw » 04 May 2009, 11:42

Just occurred to me you might want good baffling just for weight transfer reasons. Solid plates with rat holes in the corners (3/4" rad., for example) might do.
Didn't know Facets were so loud...

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Re: Fuel tank

Post by mackme » 05 Jun 2009, 20:31

I don't know if this will help with the oil canning problem but it is possible to shrink some of it out by applying dry ice to the low points. Yeah,I know it sounds odd but it has worked for me in the past on smallish areas and its cheap and simple to do. Wear gloves and be patient.

Midlana1
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Re: Fuel tank

Post by Midlana1 » 05 Jun 2009, 23:16

mackme wrote:I don't know if this will help with the oil canning problem but it is possible to shrink some of it out by applying dry ice to the low points. Yeah,I know it sounds odd but it has worked for me in the past on smallish areas and its cheap and simple to do. Wear gloves and be patient.
The problem was me welding in the fuel return fitting before the tank was welded up. Over the length of the tank that single weld bent the entire tank more than an inch! However, it still fits, after I did some metal shrinking using the TIG of all things.

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Re: Fuel tank

Post by vroom » 21 Aug 2009, 06:38

So why can't you rivet your tank together ? Doesn't the bladder contain the liquid ? I know Carroll Smith suggested riveting in the baffles and then TIGing them on the outside to stop leaks. But doesn't the bladder do that. Another welded possibility is to use steel and braze it with your TIG and silicon bronze filler rod.

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Re: Fuel tank

Post by Midlana1 » 21 Aug 2009, 08:56

Most builders can't afford a bladder, so the container is the the tank. I agree about riveting, it's a perfectly viable solution and between rivets and tank sealer it's possible to build the entire tank with little welding. I went with welding because I worry that in a wreck, a seam pop open between ajoining rivets. Also, various fittings still need to be welded so it doesn't avoid it completely, but you bring up a good point. I'll add this info to the book.

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Re: Fuel tank

Post by vroom » 22 Aug 2009, 08:52

Has anybody tried Eagle Fuel cells? They advertise in some of the classic car mags and are FFA approved. Also their web site shows a big autoclave so I guess the are for real. What I really wonder is how their prices are?

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