8 stacks with two tanks

[Lloyd]

Looking into the inglese 8 stack efi with ez computer. the two tanks bring up many issue.
Has anyone split the fuel rails into two separate systems having two tanks, two pumps and to two regulators. This would solve the return line issue. I have an inquiry into inglese with no response.

is this doable or am i going to create issues with possible pressure differences between the two banks

LLoyd

 

[Paul Thompson 'Hooligan']

Two separate systems I think would most definitely complicate matters.

Fuel rail pressures would need to be matched perfectly, otherwise fuelling consistency would suffer.

What about swirl pots? in tank or would you then need two of them too?

Two pumps? - normally a second pump would be included to half the risk of problems due to pump failure, having 2 feed the rails separately will double the risk.

Without a balance pipe arrangement between tanks - both would need to be filled from empty to avoid running on half an engine.

Can of worms springs to my mind but hey, nothing really wrong with thinking 'outside the box' - just doesn't work for me really.

Other opinions may differ so will be interesting to see what evolves.

 

[Bill Musarra]

Lloyd,
I think you are just asking for trouble. You will still need a return line for the fuel lines. There are several issues with what you want to do. Heat, balance in pressure which will cause trouble with fuel delivery and ecconomy, the ECU trying to balance both sides with imput from one(O2 sensor), running 4 pumps all at one time makes for more to break and a lot of power to run them. Then there is the problem of having to have two fuel guages to try and keepup with the fuel levels. In short you will have more headaches than it is worth. Inglese makes a good unit, so go with a good ECU to get the best out of it(lots of choices listed on the forum). For your fuel lines, there are several threads out there for running two tanks with one set of pumps, with and without a change over valve, or with two sets of pumps, and change over valves. Do a search for the method of your choice. Don't tryto reinvent the wheel. These systems are complicated enough.

Bill

 

[Ron Earp]

Wrong forum?

 

[Ron Scarboro]

You can't feed the rails with different fuel systems and two regulators as you couldn't identically match the regulators (one would open at 100th PSI less and always empty to that tank).

The design of the GT40 tanks is not optimal (shallow and long) so w/o a swirl pot you at least need to put a baffle into the tanks.

Easiest solution is to put in a crossover from one tank to the other, but most people don't like fuel crossing through the cabin which is almost unavoidable.

I ran two systems to a surge tank and ran the EFI and return from and to there. It makes for a complicated system requiring 3 fuel pumps and lots of bypass valves and the like. I buried them in the cavity on the drivers side.

 

[Terry Oxandale]

I would think two O2 sensors would help maintain an equal bank-to-bank balance, but after that, you've complicated matters hugely as has been noted in the above posts. On the bright side, you'd basically have two inline four cylinders that if one system failed, the other would get you home (twin versus single mentality).

 

[Ron Earp]

On the bright side, you'd basically have two inline four cylinders that if one system failed, the other would get you home (twin versus single mentality).

Or, as the NTSB reports typically show, get you to the site of the accident quicker.

 

[Lloyd]

gentlemen.
i currently have two of everything running to a "T" connector. two gauges and two switches.
the return line is the issue. I thought if you keep the return line going back to the tank that pressurized it would keep the system simple. treating each rail as its own independent system would keep it simple. The only concern that was raised is the balancing the fuel pressure for each rail. with only one o2 sensor this might be an issue.

the other method i was thinking of is electric shut off valves. that way you could isolate each tank. It would take four valves. i don't believe the fuel pumps would block pressurize fuel from back flowing to the non energized pump. each side would have two normally closed valves so that when the pump is off the valve would be shut
This would increase the reliability of the car with two fuel pump systems each capable of running the entire engine

thanks for the responses
LLoyd

 

[Ian Anderson]

I would think two O2 sensors would help maintain an equal bank-to-bank balance, but after that, you've complicated matters hugely as has been noted in the above posts. On the bright side, you'd basically have two inline four cylinders that if one system failed, the other would get you home (twin versus single mentality).

Not really

Well not with the cross over exhaust as it will "mix" both banks together

I run fuel injection with only 2 pumps - one low pressure feeding a swirl and one HP feeding the rail and one 6 way changeover valve

System goes
Tank - switch over valve (Pollack in my case) - filter to LP pump - swirl
Return from swirl - pollack -tank from which fuel was drawn

Then
Swirl - HP pump - fuel rail - swirl

Both pumps run all the time when ignition is on and engine turning - has a relay cut off if the engine stops for the fuel pumps to stop pumping - in case of accident I don't want fuel to continue spewing out a ruptured pipe

Cheers
Ian

Ian

 

[Seymour Snerd]

Easiest solution is to put in a crossover from one tank to the other....

FWIW SPF join the tanks at the rear with a flexible line along the very bottom of the firewall on the outside i.e. just in front of the oil sump and just above plane of the tub bottom surface.

I have kind of a geneneral question about all this: there seem to be a lot of dual-redundant thinking around here about fuel systems but is the fuel pump + lines + tanks really deserving of that much attention? IOW, once you've got it all hooked up and running with filters, etc., and you haven't made any obvious mistakes like bad wiring, inadequate cooling, mounting too high, etc, is a single fuel pump any more likely to fail than any other part of the car? (BTW I'm thinking carb. here. For obvious reason EFI has two pumps in series but that's not for redundancy and so is a separate issue).

When I think back over the times I've been stranded the vast majority of failures were cooling system (hoses, belts, leaks), batteries, and tires. The only time I've had a fuel system problem was after 100K mi. when the pump simply wore out.

How much of this is because the original cars had multiple fuel pumps? And if it is, were their reasons in the 60's in any way related to solving a problem that we, mostly street driving 40 years, later actually have?

 

[Lloyd]

Gentlemen
Let me also explain my skill level. I'm an assembler not a fabricator. So i need to come up
with off the shelf simple solution. Joining the two tanks is not an option, tanks are plastic fuel cells. Right now i'm leaning toward two systems feeding a "T" connector with electric shutoff valves. does anyone know a source for valves that look decent. the ones i found would have to be hidden.

LLoyd

 

[Ron Scarboro]

Lloyd,
I can't visualize what you're contemplating, but if each pump has a mechanical pressure regulator and they both power the same rail I'm not sure how you balance the regulators so that one doesn't open earlier than the other and feed all the fuel to the tank controlled by the weakest regulator.

I also have the Inglese/FAST system and you may already know, but you CANNOT run lines from both sides of the rail as the distributor is in the way on the firewall side. As such, if either pump grabs air that air can ONLY escape though the injectors (a design flaw versus a TWM system IMHO that could be configured to allow the air to pass through the regulator.

Also, most high pressure pumps must pass fuel all the time or they'll overheat. I'm happy to discuss if you'd like as I probably spent 40 hours contemplating the fuel delivery system on my build. Admittedly I over-engineered by system but included a PDF configuration of a pretty simple surge tank system for EFI that I clipped from another thread.

Finally, if you need a quality return valve, I have another marine valve (see picture 2) that I'd be willing to sell you if you'd like. It was made by Parker Hannifin (Parker Marine Selector Valve Specialized), has one in and two out powered by solenoids, with a manual override (red handle). It is a lot more expensive than the Pollack valves, but are 1/2 NPT so they flow a lot more.

I basically wired it from the respective fuel pump so that fuel is directed back to the pump that is active.

 

[Seymour Snerd]

Joining the two tanks is not an option, tanks are plastic fuel cells.

I don't understand that sentence. Are you saying that because the tanks are plastic fuel cells they cannot be connected directly to each other? If so, why is that? If not, why is "joining" the two tanks not an option?

You say you want an "off the shelf simple solution" but also that "i currently have two of everything running to a "T" connector." Well that's not simple right from the get go, so I'm just not getting what problem you're trying to solve.

 

[Terry Oxandale]

Not really

Well not with the cross over exhaust as it will "mix" both banks together


Ian

Dohhh! Keep forgetting you folks use the 180 design. Thanks for keeping me straight.

 

[Andrew Robertson]

Looking into the inglese 8 stack efi with ez computer. the two tanks bring up many issue.
Has anyone split the fuel rails into two separate systems having two tanks, two pumps and to two regulators. This would solve the return line issue. I have an inquiry into inglese with no response.

is this doable or am i going to create issues with possible pressure differences between the two banks

LLoyd

Hi LLoyd,

I would treat your system as having one overall volume of fuel storage, simply split over two tanks with a 1/2 inch low-level balance line that keeps them both at the same level and allows vehicle corner weights to be relatively equal.

With this approach you then just need to feed and return from one side - two lift pumps (one drawing from front, one rear), feeding a single swirl pot (about 1.5-2 litres), feeding an EFI pump, feeding the rails, returning via regulator to the swirl pot, with the return to the tank also being plumbed into the swirl pot. Swirlpot pump connections are all low on the pot, rail return and tank return are high. 75-100 micron trash screen filters go between tank and lift pumps, 5-10 micron filter between EFI pump and rails. Lift pumps combined open flow rate should be materially above the flow rate of the EFI pump at desired rail pressure.

Hope this helps. Cheers, Andrew

 

[Randy V]

Just a thought...

There are a lot of Drag Racers with HUGE Horsepower that are running dual fuel injection systems as they max out the largest injectors with 6 figure pressures and 100% duty cycles - so they add a second system. IE 8 cylinders, 16 injectors.. 4 fuel rails for a V8 - 2 per bank.

I don't know if any of their fuel system VooDoo would help you or not..

 

[clive]

My Locost clubby ran a Toyota 1ZZ motor. These do not have a return fuel line. The system plumbed in was tank - 'swirl' pot - filter - HP pump - T piece. One side of T fed the engine, other side to a pressure valve mounted beside the pump (at the rear of the car) and bleeding off back to the tank.

Made for a very compact and neat install. Worked beautifully. I will probably use the same setup on the 40, but with selector taps.

Clive

 

[Ian Anderson]

Electric solenoid valves

Jag XJ6 used them as it also had 2 tanks

Ian

 

[Lloyd]

connecting the two tanks is a problem. To connect two tanks you would have to have a common line run from the bottom of each tank to allow one tank to spill into the other as you draw fuel from one tank. I really don't have the skill level or the desire to pierce the bladder of each tank and put a cross over. I now have the ability to draw on either tank now with a carb setup the "T" with two check valves works nicely. i have two fuel pump switches on the dash that supply power to the pumps. if i retain the same concept i would just have to put a solenoid in the return line so the appropriate tank would accept the returning fuel. simply energize the solenoid (utilizing same power source as the pump) on tank that the fuel pump is drawing on and allow the returning fuel back to tank of origin. The more i think about two separate fuel rails systems would be problematic.
two check valves on the pressure side two solenoids on the return side should be a simple solution

Ronald your drawing is very slick

 

[Ron Scarboro]

Please give me no credit for the drawing. I clipped it from another thread.