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Fuel tank baffling.

25K views 32 replies 23 participants last post by  redranger4.0 
#1 ·
What's the real need for baffling? What are we preventing or helping? Foam sucks, what's the options? Any thing that is in the tank bangs around and pulverizes itself inside the tank and rubs on pumps, filler neck bolts and such. What's best?
 
#3 ·
Basically to limit fuel sloshing around and having the pickup/pump draw air when you still have adequate fuel in the tank. Most of the baffles I've seen have been welded into the tank during construction of it.
 
#4 ·
During a roll/crash (especially at speed, or with large fuel cells) the weight of the fuel itself can smash into the side/top of the tank and cause cracks/leaks etc.

There are lots better options besides foam,

Alltech is making a commercially available product, but you can accomplish the same thing via several other methods.

ex: I used quart oil bottles with the tops and bottoms cut out in a factory toyota fuel tank to keep slosh down.
 
#12 ·
What's the real need for baffling? What are we preventing or helping?
During a roll/crash (especially at speed, or with large fuel cells) the weight of the fuel itself can smash into the side/top of the tank and cause cracks/leaks etc.
^--- this.

fuel usually weighs anywhere from 4-7#'s per gallon. assuming a 30 gallon tank at half full, you're looking at anywhere between 60-105#'s of fuel moving around in the tank.

during a hard roll, that weight slams into the sides of the tanks, stressing the tank and mounts. in a perfect world and in a perfect crash there would be no deformation and we wouldn't have to worry about it. but what happens on the second roll when the rear of the car is already slightly deformed and you have all that fuel slamming into a deteriorated mount? could potentially lead to really bad things. the baffling helps keep that sloshing and fluid hammer to a minimum.
 
#17 · (Edited)
So we are if we are worried about the tank and its mounts why not mount the tank properly? And get away from putting all that crap in the tank. Pretty sure my mounts were tested pretty good at Toolele last year. I can't think baffling makes the fuel weigh any less.
 
#20 ·
I too went with the AllTech baffles. Worked flawlessly in Baja this year. I am also running dual in-tank pumps on the larger 24 bolt plate. I removed the 12-bolt filler neck and installed them through there. There is a reason the OD of the baffles are the size the are- the will fit through a standard 12 bolt fule filler round hole.
 
#16 ·
I have Waynes baffling, it seems as if they are going to be paying much more attention to this in the future. I think Wayne went through extensive testing to get the correct materials with trial and error.
 
#18 ·
I agree Brian on the safety side that I am not sure it is needed/does much. Very solid mounting is more key. We had no foam or baffling of any kind during the badlands wreck and the regular old Jaz 32gal red cell with plastic bladder not only survived the crash (due to proper mounting) but but it also survived a shock shaft that punctured the red steel on the bottom and side but the rotomolded plastic held. If the cell is relatively full it seems like the fuel and cell are moving as somewhat of a "unit" anyway. Meaning you only get significant slosh with inertia separate from the cell itself as you lower the level in the cell.

Had it punctured, whiffle balls or Wayne's system would not have helped. Foam may slow the leak ever so slightly.

The rear firewall and rules around the fuel fill neck seem more important to me than the baffling for safety but perhaps I am missing something.

But if the baffling or foam helps prevent airation or other performance problems in your fuel system that seems like the bigger win. That said even if the safety benefit is nominal its better safe than sorry.
 
#19 ·
^^ I agree with the fuel and the cell moving as a unit when full or near full, at the last leg of fuel (1/4 tank or less) when slosh is at it greatest, there may not be actually enough mass to cause any hammer in the event of a rollover. I agree with the speeds we are reaching safety needs to evolve also. Have we ever had history of any problems or damage relating from no fuel baffling? Or is this a rule "plucked" from another sanctioning body's rulebook? Much like requiring all driveshaft Ujoints to be covered with .040 aluminum, 20 ga steel, 20ga expanded metal, or 1/8 Lexan.
 
#21 · (Edited)
Baffling

as others have said, it's about controling fuel slosh 1st making sure that your pump never sucks air, fluid hammer 2nd. Here is food for thought on the fluid hammer issue, I've seen some guys that race on the circle track use the same or similar tank on a Demolition derby car :shaking: . well one guy learned his lesson last year when he took a hard hit ( didn't have his foam in the tank ) and the resulting "water hammer" cracked the tank open and ruptured the bladder spilling all the methanol on the ground :mad3: 30 min of cleanup later and we were back in buisness with the derby.
also just finished making a tank with my buddy last month for his single seater dune buggy, he's mounting the tank on the side because there is no other room and it makes life simple. any way we made the walls out of 1/4" checkplate and put in .100" thick baffles in this pattern
l_l l_l
l l l l
with 1/2" separtation off the bottom from the lower baffles. I'm betting that the dune buggy is gonna be on its lid in less than an hour :flipoff2:
 
#22 · (Edited)
as others have said, it's about controling fuel slosh 1st making sure that your pump never sucks air, fluid hammer 2nd. Here is food for thought on the fluid hammer issue, I've seen some guys that race on the circle track use the same or similar tank on a Demolition derby car :shaking: . well one guy learned his lesson last year when he took a hard hit ( didn't have his foam in the tank ) and the resulting "water hammer" cracked the tank open and ruptured the bladder spilling all the methanol on the ground :mad3: 30 min of cleanup later and we were back in buisness with the derby.
also just finished making a tank with my buddy last month for his single seater dune buggy, he's mounting the tank on the side because there is no other room and it makes life simple. any way we made the walls out of 1/4" checkplate and put in .100" thick baffles in this pattern
l_l l_l
l l l l
with 1/2" separtation off the bottom from the lower baffles. I'm betting that the dune buggy is gonna be on its lid in less than an hour :flipoff2:
Fuel pumps sucking air is not a safety issue, it's a performance issue, I doubt the rule is in place to make your car run better. The demolition derby car cracking its tank has nothing to do with us, we run either plastic cells in a can or bladders, neither will crack like a homegrown/ welded cell. Cracking in those types of cell come from ridged mounting and ANY chassis flex, been down that road.
 
#23 · (Edited)
HDPE corrugated slotted subsoil drainage pipe. Not sure if it's compatible with gasoline but it's what I will be using in mine because it's fine with diesel.
I'll cut several rolls of the stuff up into 2 inch thick rings and pack the tank full of it.

it's density is between that of the fuel and of water so it doesnt add much weight.
the corrugations make it quite rigid for little volume of plastic which means not much fuel capacity is lost.

the only thing I am worried about is that the fuel pickup may become partially obstructed by the side of one of the rings against the opening, bit the corrugations will prevent a full blockage and the pickup is around 3/4 inch
 
#25 ·
I wrecked a perfectly good off road KTM by putting a 5 gallon tank on it. I wrecked several times when all that went forward on hard braking! Trail braking into a turn? Forget about it. I bought foam but sold the bike before putting it in. Too many stories about foam disintegrating with Kali gas.

I guess there is a reason that MC gas caps are one way vented also!

Things that you don't know that you don't know......yet.
 
#27 ·
No. You need certain HDPE plastics. NOT all of them will work. Look at the bottom of any plastic container to see what it is.

Last week I spoke with an HDPE plastics engineer on this. He consulted other engineers and got back to me.

I was looking at HDPE drain tile at Home Depot so I called the company that makes it to see if it could hold up to full submersion for a long period of time. It wont'
 
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