Fuel tank baffles

[///M3 & Z]

Im finally getting around to building my 240z's gas tank. I will be installing the hyper fuel tight fit in tank retrofit kit with 525 lph pump to eventually power e85 on for my rb26 as well as a speed hut fuel float sender. Now that I have the tank cut open I'd like to weld in some baffles. After searching around online there are a lot of different methods being used, Iv came up with a few of my own and would like to get some feedback on them before going ahead if possible.

 

Right around the pickup Im thinking about a maze like this

 

 

and surrounding the maze im thinking the larger sized baffles to help with acceleration and braking as well as one to separate the larger chamber area from the thin area and potentially one more inside of the thin area. I will leave enough room on the side of the baffle for the float sensor. Im also planning to use the Por15 fuel tank sealer kit as its a bit rusty inside. Ironically if the baffles work too well it will make evenly coating it very difficult!

 

[grannyknot]

Since you have the tank all cut open have you considered installing gas tank foam?  A lot less work and lighter.

[seattlejester]

I think it depends on the activity you plan on running. Something interesting to note is that you have to find a decent yield route for the thickness of the material or else it can buckle or you may just have to add thicker material. 

 

Everything I've read say the foam will eventually deteriorate. Unless you build your tank for ease of service I don't think it would be a good idea. Good baffle system to stop big changes and maybe a trap door setup for low gas or a bucket would be preferential.

[///M3 & Z]

Iv also read that the foam deteriorates over time as well, and especially quickly when using e85.

5 hours ago, seattlejester said:

I think it depends on the activity you plan on running. Something interesting to note is that you have to find a decent yield route for the thickness of the material or else it can buckle or you may just have to add thicker material. 

 

Everything I've read say the foam will eventually deteriorate. Unless you build your tank for ease of service I don't think it would be a good idea. Good baffle system to stop big changes and maybe a trap door setup for low gas or a bucket would be preferential.

What do you mean by yield route for the material?

 

 

I made a cardboard template for the maze idea, seems like it may work although im concerned that it may almost be overbaffeling. Ill probably have to put some water in it and slosh around to see what it reacts like.  Was also thinking it would help to sump out the pickup area to make it the lowest point in the tank so fuel naturally pools up there. Maybe its overkill for a car thats going to be 90% street but i like to try making things as good as possible for any scenario i could end up in.

[seattlejester]

Depending on the thickness of the baffle plates and the fact you can't really weld them all the way around without risking warping . If you don't have enough reliefs for the activity you can bend the baffle plate from sudden transitions if the route for the fuel is too convoluted. Based on your thickness and design you may need more yield routes i.e. holes or trap doors.

 

It most likely will be overkill, I went to a couple events with a fuel cell that was just a box and with at least 25% fuel I didn't have any problems other than clogging a fuel filter a couple times. Although it is a bit annoying to see your fuel level change by up to 50% based on if your accelerating, turning, etc.