If its a new tank being fabricated then consider an explosafe filling in stead. Stops slosh and is also safer in the event of something bad happening.
We don't even use baffles on Road Racing Cars. A 2nd electric fuel pump and a surge tank with a return is better. For a road driven vehicle I wouldn't bother at all.
If you are buying a tanks Inc poly plastic tank, the baffle is the central losenge, if you use this and an internal pump you need a tray with a bleeder hole. If using a steel or stainless tank they must be baffled, if shopping for a tank remember the upto 37 filler goes in the rear corner and the 38 to 40 is in the middle
I'm in the no baffle camp. It sounds good in theory, but my experience has been, it just doesn't matter. Studebaker in my avatar has a 32 gallon unbaffled tank. I have driven it about 10,000 miles, and Land Speed raced it a good bit. I'm always running with at least 8 gallons in it, and I've never perceived any weight shift or fuel delivery starvation. Maybe if I was doing a lot of snap transition driving, like Drifting, or SCCA parking lot turns....?
I had a small (13 gal) aluminum tank made that was designed to fit in an unusually shaped place in my truck’s frame. Without asking me the fabricator added one baffle to strengthen the tank because he thought the flat, slab sides might not be strong enough compared to stamped steel tanks with rounded sides. It isn’t a road racer by any means. I figure it can’t hurt and there certainly isn’t any reason to take it out.
So far I’ve yet to see a factory tank in an old car that has baffles in it. My truck has survived 60 some years without them, I didn’t feel the need to add any.
All the Packards I've done had factory baffles. I had a Bronco once with low budget tank, no baffles. With a ¼ to ½ tank, every time I stopped I felt the truck bounce around a little bit, and maybe because it was a short WB and springy 4X4 suspension. Bottom line is they're not a waste of time and effort.
Some tanks will function just fine without baffles.........especially if you never let your tank get very low on fuel. Myself, I'm usually looking for a gas station somewhere between /4 and 1/2 tankful. When we were kids, 2 gallons was plenty for cruising. Depending on the vehicle and the design of its tank, a large tank is going to be worse than a smaller tank when it has only a few gallons in it. If someone is using an intank electric fuel pump, they need cooling or they will wear out faster. The thing about having a baffle is that it may/may not help, but it never hurts anything. I'd use a baffle if possible.
Never seen a reason to have a baffle in a tank. Never seen them in any factory tanks and they get lots of varied driving use without an issue. Never used a baffled tank, even on my cars that see drag race use a lot. The Harwood cell I have in my Austin gasser wasn't built with a baffle, and just has a 2" drop area where the fuel outlets are and works great. My '39 Chev gasser has a fuel cell with the same drop and no baffles either. As for foam cell fillers to keep fuel from sloshing, they're a disaster! None of them will last more than a few years before they begin to breakdown and tiny particles of the foam will plug up fuel filters, and the whole fuel system. If I buy a fuel cell for a project and it's foam filled the first thing I do is remove all that foam and toss it.
The baffle is fixed internally so that the tank straps that wrap around it actually contact where the baffle is to prevent the tank from collapsing when you tighten the straps down. This is the baffle assembly, ready to go into the tank with a perimeter flange going around it. This shows the welded tank, the baffle is inside and the plugs welds are those puckers about 10" in from each end. The baffle width is set by the tank straps, when the straps are clinched down they mate with the baffle perimeter flange with a piece of antisqueek between them. Make sense? Like everything else about a hotrod, its always more complicated than you think.
Many that I have cut apart don't. Had a custom 40 gallon tank under the back of the 79 Elkie that my son had that had several baffles in both directions in it. Paperwork on the tank was in the glove box when I traded for the truck and it had been made in a shop in Arizona. I don't think the 20 gallon aluminum tank that was made as an RV auxillary tank has a baffle in it. You could feel the gas go from one side to another with about a quarter of a tank if you were playing hard in some twisties.
I remember you could hear and sometimes feel the gas sloshing in pickups with behind the seat tanks. My Lincoln has baffles in it from the factory. If you don't think baffles help, try stopping a half loaded smooth bore tanker trailer. The slosh will knock you through a stop sign if you don't prepare for it.
I was about to say that. A panic stop with a food grade tanker will result in the load moving to the front, rebounding and running to the front again. I've seen them shoved halfway through an intersection before coming to a stop. I'm not comparing apple to oranges here. The physics of a moving liquid doesn't change whether it's a tank trailer or an unbaffled automobile tank. Ethanol fuel is 6.58 pounds to the gallon. Eight gallons slamming into the side of a fuel tanks is 52.64 pounds.
I built a tank for my Model A and I put a baffle in the center. It added a lot of stiffness to the tank.
I've has a batch of 60/71 Chevy and GMC trucks over the years and that does hold true. My 48 had the tank under the bed stock so It never had a seat tank. I've cut a lot of tanks open because most scrap yards I have hauled to don't want gas tanks that haven't been cut open.
Foam filled fuel cells is not there to prevent surge, it is there to prevent vaporising of the fuel [there will be a tiny secondary surge benefit] And there are plenty of Road Race cars with standard fuel tanks [spec classes eg: BMW E30 series , and 2K Cup in NZ] Fuel starvation is the issue NOT fuel surge This is true, it doesn't matter whether it is solid or liquid , because mass is mass [there will always be weight transfer with acceleration forces] In fact it would be more beneficial to lower the height of the fuel tank. The best method to prevent fuel starvation is a "surge tank" [basically a dry sump system for fuel] This requires a 2nd pump as a scavenge pump to fill a tall/slim surge tank On my Vintage Road Race Corvette "Surge tanks" were not a period correct modification. [But electric pumps were] So we used a tall Fleetguard fuel filter and added a tank return line to the top of the Adaptor [this was fed by an electric pump] THEN a mechanical fuel pump would draw from the bottom of the filter [these things were 11.5" tall]
So, what you're doing isn't really cheating, it's just a different interpretation of the rules . Sounds like something Smokey Yunick would have done. Wait a minute, I'm pretty sure I saw Smokey do something like this. His rationale was that if it's not in the rulebook, it's legal.
I got the idea from all the vintage SCCA Trans-Am race cars at a Monterey Historic meeting. Understand I was racing a Big Block Corvette amongst a bunch of MG's, Triumph TR's, Morgans, and early 911 Porsches, and they didn't really want American Cars "ruining the spirit of their sport" They treated us like outlaws that were going to "rape their daughters and burn down their church" But revenge was sweet when you pass an MGA doing 100mph at over 170 mph You need to be very careful when reading the rulebook. Most of us usually don't read the Short Title which states "All cars must remain standard ,except for the modifications permitted" [which means if it is not listed, it must remain standard]
And we are now comparing thousands of gallons of liquid sloshing around to 40-50…none of my cars have baffles and none of them try to push me through a stop sign, I’m not saying baffles are bad but I am saying they aren’t required.
"There is a fine line between Innovation and Cheating" The problem with historic racing [even nostalgia drag racing] is 2023 knowledge and "period correct" classification. This even applies here with the pre-65 cut off. Anyway this thread is getting off track! I was merely pointing out how to use a fuel filter as a surge tank for fuel starvation [sloshing isn't a problem] I would be more concerned about passengers being thrown around than fuel surge [especially the wife ]
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