[TRE Cup]

Thanks to all so far for your suggestions. Great input

the sketches are not final, but ideas we are working on. We want the shape to fit the aesthetic of the 911 trunk dimensions, while allowing space enough for luggage, and perhaps a space saver spare (if located carefully, so it does not hit the underside of the hood)
Also this is not intended to be a ST steel 100 liter replica. We are working separately on that (will be a separate thread once we move forward with it). This is a niche item that offers you extra capacity and options on fender fill, center, left or right fill necks.

Good point on the stock level sender, but here are my thoughts on that: The oe sender does have the "look" but is old tech susceptible to failure with its thin wire design. The modern aftermarket senders are a little bit of a hassle, when it comes to connection and adjustment , BUT it does allow for a taller tank (the whole idea of this tank) and more capacity.

Final finish- To be sure angle bends with welded joints is the least expensive route, and with it comes the "cheaper" look; certainly not as appealing as rolled edges and curved sections. We will do some work on an alternative design that uses a curved upper deck, to see how capacity will be affected. We were thinking to offer a lightly brushed directional finish that would be clear anodized, or black anodized. Polishing would be an option for those wanting maximum bling

Slosh control- internal baffles will control this. Foam filling would not be an option on baffled tanks. If any of you have experimented with liquid flowing thru the fuel cell foam, you will see that the foam serves almost no purpose in controlling slosh.

Bladder ? Bladders are rated between 5-7 years, before sanctioning organizations require replacement. For example, our ST styled composite tank, with bladder, offering it is not cheap $5k plus for a complete set up and replacement bladders take time to make and cost a LOT.

Construction- thick enough , welding by a certified tech, and it will be as impact resistant as it can be. We have to consider a balance on forming the aluminum, weight, and cost of manufacture too

In tank pump option- great suggestion. We will have to see what is available , so a range of engines can be supplied. Carbureted cars can have a return line added from engine to tank, so a standard
(off the shelf EFI) pump can be used. Turbo cars on the other hand require a lot more volume, so there is that to consider in choice of pump manufacturers. In tank pumps have gotten to the point of being very reliable, run cooler (immersed in all that fuel) , and with proper design will use all the gas in the tank. I think to keep costs down, this would have to be an option.

This, and other ideas, adds more complexity to the initial design phase, so our basic shell "fits all". We will have to consider all this in our expected cost. If we go too far up the cost ladder, then you just buy a real race cell, or stay with a rebuilt (or repro) stock tank. If its not appealing enough in features and looks, even if the cost is low, then we don't sell them either

The fiberglass undertray- this is NOT the bottom of the tank, but a filler plate that seals the original hole in the chassis. Our tank would sit further up in the chassis, so there is less likelihood of the fuel tank getting damaged from under side impact. If you look at the way the frame is formed, the original gas tank is the lowest part of the front end ! The fiberglass would be thick enough, and set up a little higher in the opening, to withstand the typical scrapes . It is meant more as a filler piece than protector plate

Lots of details for thought

thank you

FYI- those of you that have installed off the shelf non 911 specific tanks have come to realize, like we did, that it is really labor intensive on doing a clean install. We did a Fuel Safe 911 cell and a Fuel safe rectangular box in a couple 911's years ago, and the end cost was within a few dollars when the tools were finally put away