Fuel Tank crossover / equalizer - Page 2

Gary Kadrmas · 01-14-08, 07:13 AM

Ian & Mike,
The above diagram does a good job to identify the components and how the system is constructed per the original cars. I have a question regarding the "swirl pot or swirl tank" which so many forum members are installing on their cars.......and that is it appears that the original cars did not have this fearture, so why are people installing them on their cars now? Are we looking at an improved system design, where the original system was lacking in that area? And if the fuel system (as per the original design) is functioning well on its own, do you really need a swirl pot?

Is this an insurance kind of thing? Just curious.........................,

Ian Anderson · 01-14-08, 11:27 AM

Gary

Easy answer is EFi

With the carbed engines in 1960 you had the amout of fuel in the bowl to allow the engine to run for a while whilst braking / going down hill

With an Efi system you do not have this luxury and the pump continuously circulates the fuel

Now when you brake the fuel sloshes away from the rear pick ups and the pump sucks air and the Efi stops (Most Efi pumps also burn out very quick as the fuel also uubricates and cools the pump)

It is really so much easier to use a carb but with the emission requirements of today EFi needs to be used in some situations

Ian

Russ Noble · 01-14-08, 01:15 PM

FWIW I plan to have no crossover and seperate pumps for each tank.

WRT the long tank issue I will have internally plumbed front and rear pickups and will build a simple inertia valve in the tank to link them to. Under deceleration or down hill it will block off the rear pickup to stop it sucking air and vice versa for acceleration/up hill. Under cruise conditions it will draw from both front and rear pickups.

Gary Kadrmas · 01-14-08, 01:22 PM

Ian,

Thanks for the explaination.

I know Lynn Miner has a swirl pot on his Superformance, and he has Webers. So it must be for the narrow long tanks and the accelerating and decelerating aspect of the construction and function that a swirl pot is used with carb engines in a GT40. Now that you explained it for me, it makes sense. Thanks!

Cheers,

Steve C · 01-14-08, 07:38 PM

Gary,

Frrom what I understand MK1's had individual bladders, seperate fills and no cross connect with 1 elec pump for ea tank.

I know more about MK11's than MK1's ...The MK11's had similar if not same rubber bladders BUT, had only one fuel fill on drivers side and a LARGE cross connect high under the dash connecting both tanks for fueling not tank cross connect carb supply...Ea tank had a baffel plate suspended from the spoonsoon access plate to prevent sloshing BUT, with no hills and rapid shifting/acceleration and deceleration and carb engine with some carb float bowl reserve no starvation problem existed. One pump ea side tank on the mk11 and one reserve pump for get to the pits on I believe the left tanks additional small sump area..

SPF designed the MK1 and MK11 to have SS tanks to preclude galvanic corrosion with the steel mono and not deal with the problems of the rubber bladders..Has 2 fills and a "LOW" crossover at rear bottom of tanks that is large enough to easily allow fuel tank to tank stabilization although all demand is from left tank but, during filling best to fill from one cap while the other cap is open and slow fill....SPF uses a number of baffels per tank and on newer tanks a center left vs rear left tank fuel supply to the pump...Swirl pot is a must (IMHO) for FI and a good idea for carb as well as road cars will see elevation changes ...In my car I have a large Canton fuel filter, a demand Carter low pressure pump and a swirl tank in the left spoonsoon. The spoonsoon Carter pump delivers fuel to the swirl pot that overflows back to the main tank but,has a constant fuel volume that supplies feed to one of 2 Carters that are firewall mounted plummed in parallel..I run one or the other during operation (the 2'nd pump is for redundancy)....Works well.

Steve P2125

Gary Kadrmas · 01-14-08, 09:23 PM

Steve,

I appreciate the explaination about the fuel system. Just another reason why I think the support and help from forum members is fantastic. Thanks again. If you were a little closer, I'd be buying you a beer, but in this case, you will have to settle for an e-mail version........

Cheers

,

Steve C · 01-14-08, 10:03 PM

Gary,

Thanks!...Lynn says you are a stand up guy...guess he's right!....Steve

dennism · 01-15-08, 12:32 AM

Does any body know what was done on the Mk IVs
I'm not familiar with their tankage system
Dennis

Mike Drew · 01-15-08, 01:31 PM

Quote:

Originally Posted by dennism

Does any body know what was done on the Mk IVs
I'm not familiar with their tankage system
Dennis

Jim, the owner of Mk IV J-6, is a very active member of the GT40 forum (over 1500 posts and counting). Here's his profile:

http://www.gt40s.com/forum/members/mk-iv-j6.html

He's a pretty hands-on guy and should be able to explain the fuel system in his car for you.