To foam or not to foam...

Hi Guys

Looking to get a set of tanks made and debating whether to get them foam filled or not? What is the general consensus on this would you bother?
They would only be part filled as I am planning on having 4 compartments in the tanks separated by a trap door or baffles.

The tank plan is as follows

from the rear, the first section will be where the fuel out and return will be
using JIC 6 fittings on the top of the tank with a pipe for the fuel out going into the tank, this section shall be separated from section 2 using a trap door arrangement. Section 2 will be foam filled if possible and separated from section 3 with a baffle.
Section 3 will be where the level sender will be located separated from section 4 with a baffle. Section 4 will be foam filled if possible and contain the fuel inlet. Both ends will have a breather outlet/pipe.

My final arrangement will be a pair of tanks each with a pump into a swirl pot then to EFI back to swirl then return to tank via 3 way solenoid valve.

All opinions valued

Thanks in advance

jase
 
If you use oxygenated gas, then the foam will need to be replaced every few years or so but if you plan to race the thing, I suggest you consider it.
 

Doug S.

The protoplasm may be 72, but the spirit is 32!
Lifetime Supporter
The fuel tank in my Cobra was retrofitted with foam "blocks" at some time in the past...I believe it started its life as a drag-racing car. I have a couple of problems with the car that I believe are related to the foam blocks.

First, the fuel gauge does not work well. I have not had the top plates off the tank to find out why, but it NEVER registers above 1/2 full. I believe those foam blocks have moved around inside the tank and are interfering with the action of the float arm (if there is one) and sincerely believe that I can install some sort of ISIS tube-style fuel sensor/sender and have the problem disappear.

Another problem I have regards fuel delivery....I wonder if the pickup is being clogged with crumbs, whatever one would call them, from the foam. If so, it would explain why it runs just fine when started, but at some point there seems to occur a restriction in the fuel flow. I have a Mallory fuel filter installed prior to the Mallory fuel pump (have never changed out the filter, but that is going to happen soon) and have installed an in-line fuel filter in the 3/8" fuel line. I NEVER see any kind of debris in that filter, yet when I proceeded to rebuild the Edelbrock Thunder carb recently there were what I considered excessive deposits of debris in the carb. Most of that seemed to be gritty, but not all of it, so I wonder if it was something that got past the Mallory filter before the in-line filter was installed at the carb.

I believe that the foam blocks are a valuable safety feature, as this car is driven regularly through the city of Houston, TX and we probably all know about the accident prone nature of large cities. I don't want to take them out unless I must, because the possibility of being rear-ended is a huge risk where I drive the car and the front of my gas tank is right at the cockpit's bulkhead...so I would be "toast" if rear-ended...terrifying thought.

Glad somebody else is having questions about the foam blocks, too...will be following this thread to see what others have to say.
 

Pat

Supporter
I believe that the foam blocks are a valuable safety feature, as this car is driven regularly through the city of Houston, TX and we probably all know about the accident prone nature of large cities. I don't want to take them out unless I must, because the possibility of being rear-ended is a huge risk where I drive the car and the front of my gas tank is right at the cockpit's bulkhead...so I would be "toast" if rear-ended...terrifying thought.

Glad somebody else is having questions about the foam blocks, too...will be following this thread to see what others have to say.

Doug, I've replaced the foam in my cells twice so far. It was easy to tell they were starting to go by finding the "crumbs" in my fuel filter. You really don't want to have a stoppage on the road caused by the degrading filter.
In addition to the fire safety, they also control fuel slosh that can affect the handling of the car. Given you cell's placement, you may also wish to consider a fire suppression system. They are not very expensive for the kind of volume to fill the area of a Cobra cockpit.
 

Mike Pass

Supporter
Check out Explosafe. I have it in my tanks. I believe GTD used it in their tanks. It looks a bit like aluminium swarf. It can get in the fuel lines but the filters catch it OK. This place is one that supplies it.
Explosafe

Cheers
Mike
 
Here you are David I goggled it for you

Protex Technologies, Inc.
9205
Town Gate Lane
Bethesda, Maryland 20817
Ph: (240) 499-5745
 
Hi Guys

Looking to get a set of tanks made and debating whether to get them foam filled or not? What is the general consensus on this would you bother?
They would only be part filled as I am planning on having 4 compartments in the tanks separated by a trap door or baffles.

The tank plan is as follows

from the rear, the first section will be where the fuel out and return will be
using JIC 6 fittings on the top of the tank with a pipe for the fuel out going into the tank, this section shall be separated from section 2 using a trap door arrangement. Section 2 will be foam filled if possible and separated from section 3 with a baffle.
Section 3 will be where the level sender will be located separated from section 4 with a baffle. Section 4 will be foam filled if possible and contain the fuel inlet. Both ends will have a breather outlet/pipe.

My final arrangement will be a pair of tanks each with a pump into a swirl pot then to EFI back to swirl then return to tank via 3 way solenoid valve.

All opinions valued

Thanks in advance

jase

Hi Jayson,

I have aircraft spec foams in my GT40 tanks which were produced by ATL at Milton Keynes. For those of you in the USA they are US owned with a UK subsidiary.

Back in 2003 I supplied the tanks and ATL custom cut and installed the foam blocks, as I recall in 2 or 3 separate pieces.

The engine is on Motec managed fuel injection, Bosch fuel filters, Holley low pressure, high volume lift pump feeding a swirl/de-bubbler header tank into a Bosch Motorsport injector pump. The system has run faultlessly.

Last winter I drained and removed the primary and secondary Bosch fuel filters, back flushed them for evidence of foam granules/debris and found nothing. My conclusion is the ATL aircraft tank spec black open cell foam is very long lasting. It also prevents fuel surge and the VDO dip tube style fuel level sensor is very accurate.

I have no tank baffles or traps, no solenoid valve, just a tank return feed off the end of the fuel rail via the pressure regulating valve, a relatively simple but very reliable system.

Let me know if you would like more plumbing details, hose sizes etc. Incidentally, the all aluminium motor capacity is 7.0 litres and produces 530 hp.
 
Hi Chris thanks for your reply (and all the others who posted). I decided against foam in the end and went with just the baffles and trap door although I would be interested in the plumbing details / hoses etc of your installation though.

Cheers

Jayson
 
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