fuel tank dilemma

jimbo · 11-03-06, 10:15 PM

We are to the point with 1149 that I have to seriously think about fuel tanks. It seems to come down to two choices, since I am not going to get race-car type fuel cells for a car that will hardly ever see the track, and that only for "touring" class driving....either aluminum tanks that slide into the sponsons, or FRP tanks using vinylester resin, which is resistant to ethanol. (there have been and continue to be problems in the marine industry with older polyester/fiberglass tanks which are dissolving with ethanol-laced fuels)
So.......has anyone on the Forum made their own tanks, or can they direct me to a reliable maker of custom tanks?

Oh- plastic tanks would be fine, but the cost of custom-rotomolding plastic tanks is very high, the mold manufacturing cost has to be amortized out over many many tanks, which we can't do.

Suggestions carefully read and gratefully appreciated.

Andy · 11-03-06, 11:53 PM

Hi Jimbo,
Ive gone the route of aluminium tanks, that fit through the sponsons.
They have been made, so that they lie on rubber pads stuck to the sponsons.
After consulting someone who has been this route many times before, the following is the advice he gave me.
At the front end, step down the tank, so that the top of the filler spout on the tank, is level with the top of the rest of the tank. This makes it easy then to tighten the hose to the tank, through the sponson end plate.
Use a 3 inch or similar diameter filler spout on the tank, or you will be waiting ages to fill the tank.
Put baffle plates in the tank, one halfway along the tank and the other 6 inches or so from the back end of the tank. Otherwise, youll have problems getting fuel out on hills. The baffle plate at the rear, should ideally be welded to the bottom of the tank, to create a ' dam '.
At the rear end of the tank, extend the pick up tube into the tank, so its adjacent to the rear baffle, ie 6 inches into the tank. That will help with fuel pick up on hills.
Hope that helps.

BenL · 11-04-06, 11:43 AM

Quote:

Originally Posted by Charlie Farley

At the front end, step down the tank, so that the top of the filler spout on the tank, is level with the top of the rest of the tank. This makes it easy then to tighten the hose to the tank, through the sponson end plate.

If you have the bottom of the filler spout lower than the rest of the tank, air will get trapped and prevent you from completely filling the tank. We solved this problem by adding a small S-shaped tube inside the filler that allows the air to escape (you want the top end of the tube pointed down, so you don't get squirted in the face by gas/petrol).

Phil · 11-04-06, 11:01 PM

Jimbo
I made my own tanks...50 series aluminum ..080 thick. I didn't use any baffles, but included an access port in the top of the tank and used foam (Explosafe). For a fuel sender I am using the centroid type which is simply a straight vertical tube with no moving parts. No problems with sloshing, and fuel pickup is good. Follow BenL's advice on the venting as you will have problems with filling. My tanks are 48" long, and essentially a quarter section of an 18" circle...essentially a pie-slice as viewed from the end..I can get approximately 8 1/2 gallons in each tank, and I am satisfied with the performance so far. I didn't anticipate going on any really long trips, so I limited the size of the left side tank,which could have been 60" long, this would have added a few extra gallons, but from a fabricating standpoint, 48" is the width of most sheets, so sizing was done that way. I tested the tanks at 5 psi, and had the usual 3 or 4 leaks, but they are solid now. I always pressure test tanks, but a note here that 4 or 5 psi is about the limit on a larger tank as they will distort, and once bulged are difficult to bring back. If you don't have the means to fab your own tank I would check with someone reputable, and even look at someone that is making tanks for the marine industry as they will be familiar with aluminum work, and most of these guys are careful with testing as the tanks are generally glassed into the hull so no leaks are a must.
Good luck
Phil

jimbo · 11-05-06, 02:29 PM

Thanks to all. There are a number of good marine fabricators here in Annapolis that could make up aluminum tanks. Where did you get the Centroid fuel level senders? I have seen something like this advertised by Isspro. Also, if I use Explosafe does that mean I do not need baffles inside the tank?

with regard to avoiding airlocks during fillups, I would probably run a vent line back to the filler neck, unless this is proscribed for soe reason...

Ian Anderson · 11-05-06, 03:14 PM

Jimbo

The secret is to find senders that will match your gauge

I bought EBS gauges and they sent me matched sender (but I went for the cantilever type anyway.

Ian

Phil · 11-06-06, 12:02 AM

Jimbo
Centroid is located in Florida...just do a Google and you will find them. I believe there are a number of resistance values available to match a number of guages. Also I should have mentioned that I did not baffle the tank, the explosafe foam prevents any sloshing, and although you may get the tank pretty full of the foam it only absorbs a minimal area in regards to capacity. One note, the reason I used the centroid guages is there is no moving float, level is measured through contact with the fuel. The foam would definitely interfere with a float assembly, unless you created a pocket in the tank to isolate it.
Cheers
Phil

Bill Musarra · 11-06-06, 05:59 AM

Jimbo,
There are sweveral catalogue listers that cary the same if not similar senders. I just ordered one from Pegasus. Here is their listing. This one allows you to alter the lenght of the sender to the size of your tank. It also has a provision for a low level warning light to be hooked up which is what I wanted. I use Stewart Warner guages and they listed about 3 or 4 different versions of the same guage with the different electrical values. So matching was easy.

Bill

Lynn · 11-06-06, 11:43 AM

Phil,

I tried to PM you, but your message folder is full.

Regards,
Lynn

jimbo · 11-06-06, 04:17 PM

I appreciate all the help. This will make life a lot easier. I didn't think about this, but of course if you have foam in the tank, you have to use vertical senders, or start removing foam, which is exactly the direction you DON'T want to go in. And if there are baffles, you can't stuff the foam in. So, I understand this now.

I'll have to figure out which senders go with the Smiths gauge that I have. I can read the impedance off the Smiths senders, and hook them up with the gauge on a test setup to make sure that the senders I bought were the right ones. Not that I am going to use them now, but I am sure I am stuck with them.

Thanks to all again. The monocoque is sitting around with the paint curing, and might be delivered back to Safir this week. So, we have reached a new low in our GT40 journey....:

We are actually sitting around watching paint dry. Who says this isn't an action-filled hobby?

Lynn · 11-07-06, 08:12 AM

Jimbo,

My advice is: "do not rely on foam to do the job of baffles!" This is what I tried to PM Phil about.

My tanks are filled with explosafe except for a cylindrical hole for the sender in the normal GT40 location. Despite the foam, my Ford EFI will still snort, sputter and spit with hard braking and long or steep down hills. Several here have had to replace their EFI fuel pumps after experiencing the same as I am about to do. There are solutions talked about here, mainly a header tank (swirlpot) to feed the high pressure pump. Granted the complaints come mainly from those running EFI, but the implications should be interesting to everyone: foam will not prevent air from entering supply lines at low tank levels. This is something no one needs; although its effects may be more or less dramatic dependent on fuel delivery system.

A word to the wise is sufficient,
Lynn

Ian Anderson · 11-07-06, 09:25 AM

Lynn

I'll second that

I am running EFI and have no baffles in the tanks

At 1/3 tank when I brake the "low pressure" Facit pump goes crazy pumping air. The engine runs OK as I have a swirl pot and when on the brakes the engine is not drawing a lot of fuel. (High pressure pump returns to swirl pot.)

I have never done a long down hill road but can believe that would cause problems.

If I was remaking the tanks I would have baffles and in the center sections foam. But I never specified the tanks!

Also to consider is the air escaping when filling the tank - mine have a good system (see under A DAX Build) and Paul's on heis Tornado were terrible with the air rushing our the tank bringing splashes of fuel with it. I believe he sortedit by inserting a pipe inside the filler pipe for the air to escaoe up (higher than where the filler nozzle end is)

Ian