Custom fuel tank discussion - please comment

[TRE Cup]

We have been giving some thought to the larger capacity gas tanks. Some of you have thirsty motors and asked if we could extend the driving range.

With "correct" replica ST and RS tanks going for over $2k (real ones being either fragile or unobtanium $) , Fuel Safe 911 cells from $2500 and up, we are wondering if there is a market for a well built aluminum fuel tank.

For this particular offering, we are thinking a capacity between 22 and 27 gallons. We are NOT trying to emulate the old school look here, but would offer some filler neck options if you are after the thru hood look.

Specs would include:
drop section for fuel pickup and return- no starvation under cornering or low fuel level loads

baffles to reduce instant side loads from fuel slosh

aluminum construction for no corrosion long life- available in variety of coatings

center or off set fill options- either under or thru hood (using blau 102 mm caps, or monza flip top)

roll over valve for venting and filler neck
aftermarket level sender compatible to oem gas guage

fiberglass "mimic" undertray that seals the bottom opening of oe gas tank . Looks like the oe tank from under the car and keeps the smooth air flow.

Cost estimated in the $1600-1900 range depending on finish and cap options.

This tank would not be legal for track use, where an approved bladder/ foam is required. But would be for DE use in most classes.

What are your comments on this low volume production tank ?

Thank you for your thoughtful input

[TRE Cup]

here are a couple drawings on what it could look like

[turbobrat930]

I think I would have to see a prototype in a car... before I comment on it. I like the idea.. just not digging the looks right now (if in a car, it might be completely different)....

Also offer AN fittings -6 or -8, etc for the modified crowd...

[euro911sc]

Love the idea, but I think it needs to be sub $1000 to get a decent volume. You should also offer a bladder version for those wishing it.

You may also consider modifying existing gas tanks. You could produce the sheet metal and sell it with the modification service or core tank.

Just some thoughts...

-Michael

[mrm930]

I like the idea of custom tanks. However I think, for me anyway, I would like it to fit in the factory location - but a large tank. Through the hood or standard side fill options would be great. Also some kind of hose options with the braided stainless steel and aluminum fittings would also be great - pre-made for specific applications. That would make it easy for the DIYers.

I would be interested - especially if it is high quality and of course the appearance is critical for us detail geeks.

Mark

[sc_rufctr]

I like the idea for a lot of reasons.
Looking at the "drawings" it looks like it would be possible to have a normal fender fill as well. Correct???

Your $1600-1900 range is about right IMO.

[motley911]

Having recently been through a major rebuild, including fitting a fuel cell, I would recommend having an in-tank pump option. Trying to fit a large capacity pump, below the standard fuel tank outlet, after an in-line filter (for pump protection) and routing the larger fuel lines to clear the front suspension cross member was a major problem.

After many attempts at trying to fit the larger capacity fuel supply system I gave up, sold my brand new 044 pumps, removed the standard tank and purchased an Aeromotive fuel cell with an in-tank high capacity pump (A1000). This simplified the install and solved many of the routing / mounting issues. However the rectangular shape of the Aeromotive fuel cell is far from ideal in a 911. The shape of your proposed tank would be awesome.

Additionally, making the height of the tank to suit the standard 911 fuel level sender would also be a nice feature. I ended up having to shorten the 911 sender by ~15mm to get it to fit - a lot of work and a major pain. Using the OEM level sender simplifies the install and for many "street" driven cars is a needed feature.


I hope this helps your product development.
Richard.

[Fishcop]

Dave, would a "spare" still fit in there?

[James Brown]

Safety and liability count for a lot also. Can it be coated with a material that resists impact damage? Maybe a plastic material that is "welded" together (poly tanks) would be a better choice? Baffling inside the tank? Ethanol proof!!

[sc_rufctr]

Originally Posted by Fishcop

Dave, would a "spare" still fit in there?

I would say NO... I wouldn't worry about it. The RUF CTR gets by without one.

[Tom '74 911]

Dave,
As someone who is running the original OEM tank in my '74 911, I think this is a great idea. I did a full fuel tank flush/cleaning a few years ago and found handfulls of crap in my tank. Now a few years down the road, my fuel filter is again looking too dirty - I think due to rust INSIDE my tank. See my comments below.

Originally Posted by TRE Cup

With "correct" replica ST and RS tanks going for over $2k (real ones being either fragile or unobtanium $) , Fuel Safe 911 cells from $2500 and up, we are wondering if there is a market for a well built aluminum fuel tank.

I think there is a market although it is probably small. I have been considering a replacement tank and have looked at fuel cells as an option. My issues w/them for a non-track only car is the price (quite $$) and the lifespan of the foam inside. For a street car, having to replace the foam due to degradation is kind of a pita (plus more $$). I've considered standard (not foam filled) fuel tanks from a place like Summit which would require more effort & some fab work to fit. A more turn key solution would be nice.

For this particular offering, we are thinking a capacity between 22 and 27 gallons. We are NOT trying to emulate the old school look here, but would offer some filler neck options if you are after the thru hood look.

For me personally, I'm not concerned with larger capacity. I don't mind stopping every 3-4 hrs. to pee & fill up. It may be nice to provide a "stock filler connection" option if possible.

Specs would include:
drop section for fuel pickup and return- no starvation under cornering or low fuel level loads

baffles to reduce instant side loads from fuel slosh

Some kind of slosh or swirl pot type arrangement would be important - nice.

aluminum construction for no corrosion long life- available in variety of coatings

Nice, no rust.

center or off set fill options- either under or thru hood (using blau 102 mm caps, or monza flip top)

I know you guys do a lot of thru-the-hood fillers, but as I mentioned above, it may be nice to have a "stock fill connection" option if possible

roll over valve for venting and filler neck
aftermarket level sender compatible to oem gas guage

The sender must be compatible w/the oem gas level gauge

fiberglass "mimic" undertray that seals the bottom opening of oe gas tank . Looks like the oe tank from under the car and keeps the smooth air flow.

I think if you're going to offer a Porsche specific tank like this, the more turn key the better in terms of installation. I know that fiberglass is much easier to mold & work with than aluminum, but how would the durability of a fiberglass bottom be?

Cost estimated in the $1600-1900 range depending on finish and cap options.

This would be the absolute top of my price range. I haven't priced it out, but I imagine you could get a square tank and all the bit you need from a hot rod shop for close to $500? I could be way off and I've never tried to actually make one of these fit so maybe they're a real pita. A buyer will have to weigh the cost of having a turnkey solution for "$X" vs one that will require fitting etc... for less. I realize you have to make $$, but the lower the price, the more you will sell.

This tank would not be legal for track use, where an approved bladder/ foam is required. But would be for DE use in most classes.

I think this is fine. A solution in between OEM and a fuel cell is great.

What are your comments on this low volume production tank ?

A few additional comments: Would a spare tire fit? I WILL NOT mention that I have never used mine because I don't want to jinx myself, but I do carry a spare just in case - as well as a few of those "quick fill" flat cans etc... My last comment is in regard to aesthetics. My car is not stock and I don't really care about using OEM only parts etc... I must say however that the images you posted are not aesthetically pleasing to me - JMHO! One of the things I love about my car is that it's just nice to look at - I love the lines. Anything you can do to compliment that is a bonus I think. I know that curves are FAR more difficult than flat surfaces to work with. For the price range you suggested earlier, I would be MUCH more will to purchase if it was more aesthetically pleasing. CNeilson's (sp?) tank that he built for his most recent ST is at the top of the ladder for me - I think it looks great. I realize something like that is also at the top of the ladder in terms of $$. Maybe there is a good compromise that you could reach?

Thank you for your thoughtful input

[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

[aston@ultrasw.c]

A little off topic, but I think the audience is right.

How long is the stock sender unit: from the flange to the end.

I am thinking about compatible tank heights.

[race911turbo]

Dave,

Rust from fuel tank kill both of my fuel pump, universal fuel tank does not fit well, I made an aluminum fuel tank to replace.