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Let's discuss fual tank baffling...


Jolane

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I am currently working on designing a fuel tank for my 72. I am keeping the spare tire well. The tank will fit in the stock location, will be made of aluminum, have a GM sending unit, and should be appropriate for EFI. I do not want to put an external surge/header/swirl tank in there. I also don't want a sump like system with the lines coming out the back. I would prefer to have a baffled tank with an internal pump.

 

I see several options, none very inexpensive. I already own a 255 LPM external pump, brand new in box, but don't plan to use this. Anyways, it looks like I can get a "Black Box" with pump from ATL for $400+ with trap doors. Expensive for what it is IMO. Fuel Safe has their version as well, can't remember the exact price, something like $350+. Racetronix has a pump kit for 99+ LS1 camaros as well as a pump upgrade. This uses the stock tank bucket, and does not require tank baffles.

 

Every car on the road has a fuel tank (I think). Every new car is also EFI (I think). I just can't seem to find an pictures of tank baffling for examples. Clifton's site (with pictures of a Supra tank baffle) seems to be down. I know what the 280Z tank looks like (One baffle through the middle of the tank running fore and aft). Anyone have any pictures of baffled tanks and baffle scheme's? Is the baffle in the 280Z tank really sufficient for most applications? Seems very basic to me.

 

I would appreciate any pictures/description/anything concerning new car EFI tank baffling/working baffle retrofit in performance cars/anything. I have searched the MS board as well, and the concensus is to use a swirl pot. Since I am starting from scratch on my tank, I would like to have as much as possible internal, with as little complications as possible. I do realise I would put my surge tank internal, but need a source for a quiet internal carb type pump.

 

Thanks for all help/discussions/pictures...

Joshua

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  • 2 weeks later...

I went through the same thing, did a lot of searching and came up with virtually nothing of use. All I can suggest is that you get hold of an EFI fuel tank or two and cut them open.

 

One peculiar thing is that a 510's fuel tank is very well well baffled in comparison with the S30's which is poor.

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What kind of driving are you planning on? I've done some marginal baffling on my home-designed, shop welded tank and it works fine (1 year + on street driving). It's not meant for extended right-hand turns on low fuel, but for the street, where one would be in and out of a corner fairly quickly, it seems to work fine. I simply surrounded the pick-up with a 3" by 3" square box (no top) about 6" tall, that extends to the bottom of the tank, but are not welded to the bottom of the tank (only welded to the sides. This allows fuel to move through the small slit or space between this box and the bottom of the tank. This flow is more than the engine requires, but slow enough that when I corner to the right (pick-up is on the left side of tank in the corner using no sump), the fuel takes some time to eventually flow out of this box. I followed up with that by bisecting the tank with again the same type of wall from front to back. Then I filled all of this with normal fuel cell foam. The pick-up is in a crease in the bottom of the tank defined by a nearly flat bottom with slight 20º crease to keep fuel flowing toward the pick-up.

 

In this photo, the pick-up is on the far right side up toward the front (cannot see the pick-up hole from this view)

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Drawing of the side profile of the tank.

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You could gut a late 80's/ early 90's camaro tank or look in one with the pump removed to see the factory baffling. Later assemblies are built with the baffle as part of the pump housing. No baffles in the tank itself. That was done in part to allow production of plastic tanks. The problem is fabbing a lock ring assembly to hold the fuel pump housing. A round baffle can be attached to the tank bottom. Spot welding at several places would allow fuel to migrate through small open slots at bottom. Even trap door baffles could be designed to hold fuel in the pickup area whether turning right or left. The idea of foam inserts is excellent. It keeps sloshing to minimum and pretty much guarantees no starvation even with low levels.

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I just can't seem to find an pictures of tank baffling for examples. Clifton's site (with pictures of a Supra tank baffle) seems to be down.

 

Try it again. They shut it down when there is too much use, it's a free site. I can send you some pics if you can't get on there.

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Clifton, I am still getting the same message. If you wouldn't mind posting or sending pictures, that would be great!

 

Thanks for everyone elses help! I looked into the Ford and Camaro pump buckets, but they are seemed too specialized for my needs. Plus, they are expensive.

 

I worked on my tank some more this weekend. Since it is aluminum (.090" 5052), I ordered some aluminum piano hinges from McMaster car. I then built a box (6" x 6") and mounted a 2 1/2" wide hinge to the side, swings towards the inside. The cutout is 2" wide, so the hinge overlaps and cannot swing out. After testing with water, this works GREAT to trap the fuel in the pump pick-up tank. It does not seal perfectly, but definitely acts like a trap door. The fuel will flow in fast, and out VERY slowly. The hinge was ~$6 for 3 feet. I can make ~14 of these.

 

So, now I have a pump tank, very much like the Fuel Safe and ATL units, but instead mine was approximately $10 in material and some welding time (I did this). I am also baffling the tank further both for strength (keep the bottom flat with a full load of fuel) and directional fuel flow control. The baffles are angled so that regardless of car direction (accel in straight, right or left), some fuel will flow towards the trap doors and into the pump box.

 

I know this may be overkill for a street car, but I have experienced issues with low fuel levels in stock cars before in turns on the street, and their pumps are significantly less flow than 255LPM. With such a wide tank, I think the problem only gets worse (fuel is more spread out), so I want to take preventive measures. I also figured out how to mount the pump and level sending unit (Walbro GSS340 and GM sending unit).

 

If anyone wants more details on the hinges I used, let me know. They could always be riveted onto a metal/plastic box to form a pump box for a stock tank...

 

Joshua

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I was gonna order the black Box from ATL, but decided to make my own little setup. I will be empolying an aluminum box with connections for duckbills on two sides running to a Y connector. I hope this and my Porsche fuel pump are sufficient to keep my fuel infected motor fed!

 

Mike

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Thank you Clifton. I have seen your tank before, months ago though, and couldn't remember exactly what the inside looked like.

 

Mike,

That black box from ATL is a little expensive for my tastes. I was seriously considering, and after all, including the pump, it is ~$400. BUT, now that I have a workable solultion for the trap doors, my version will be ~$140 with pump, doing the welding myself. I ordered the pump last night from APEUSA.com. Nice guy to deal with. Not the absolute cheapest, but a wealth of info. I am using the Walbro GSS340 (255 LPM, HP Mustang and Grand National Application).

 

Why are you using duck bills? I am not exactly sure what those are, I assume a valve of some sort. Are you using the stock tank? Just curious about your approach on this.

 

Joshua

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The pump I'm using came with my FI setup about 3 years ago. It's from a Porsche 928/ 911 Turbo according to the numbers on it. Since I have no money in it, I'll use it for now.

 

The duck bill or ducks foot, depending on who you talk to, will fit in the bottom of the cell and act as the pickup for the cell. Using one on each side at the very bottom of the box I'll weld up should insure that we have fuel under cornering on each side of the tank. Of course, the box won't be very large, but large enough to trap the fuel. I expect it to be about 6 wX 6 hX 12l.

 

Mike

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Mike,

I am little confused. So are you going to put baffling internal to the tank, and then inside a baffled area put the duck feet? I got the impression originally that you were going to put the duck feet inside an open tank.

 

Either way, do the duck feet seal shut if fuel is not present, or how do you ensure that air is not sucked in say on the left pickup when in a left hand turn?

 

Thanks,

Joshua

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