Fuel surge, scavenging, system layout
Discussion
I'm tyring to decide on my fuel system layout, and wanted to hear the experiences of those here.
In the pictures that I have seen, it appears as though the ports in the tank are raised up perhaps 50-60mm from the bottom of the tank. How much fuel can actually be scavenged from the tank? It seems that there is a significant volume that will not be pulled.
Also, what are your experiences in regards to fuel surge? I know the tanks are foam-filled, does this adequately keep the pickups covered? As my GTR will use EFI (and run hard on the track), maintaining fuel flow is of critical importance. I'm deciding if I wish to fit a surge tank, or if the foam filled tanks are sufficient.
Finally, as to the layout in general, I was thinking of making one tank the feeder for the pressure pump, and then using a transfer pump on the other side to move fuel into the feeder tank. What types of layout have all of you used?
Thanks once again for the insight.
>>> Edited by msv on Monday 16th June 16:31
In the pictures that I have seen, it appears as though the ports in the tank are raised up perhaps 50-60mm from the bottom of the tank. How much fuel can actually be scavenged from the tank? It seems that there is a significant volume that will not be pulled.
Also, what are your experiences in regards to fuel surge? I know the tanks are foam-filled, does this adequately keep the pickups covered? As my GTR will use EFI (and run hard on the track), maintaining fuel flow is of critical importance. I'm deciding if I wish to fit a surge tank, or if the foam filled tanks are sufficient.
Finally, as to the layout in general, I was thinking of making one tank the feeder for the pressure pump, and then using a transfer pump on the other side to move fuel into the feeder tank. What types of layout have all of you used?
Thanks once again for the insight.
>>> Edited by msv on Monday 16th June 16:31
In the pictures that I have seen, it appears as though the ports in the tank are raised up perhaps 50-60mm from the bottom of the tank. How much fuel can actually be scavenged from the tank? It seems that there is a significant volume that will not be pulled.
It's not as bad as it looks. The fuel outlet has a pipe which continues inwards and down to the bottom of the tank. The other outlet on the tank is at the same level as the connection and is used as the EFI return. You can tell between the two by poking a bit of wire into each connection.
[quote
It's not as bad as it looks. The fuel outlet has a pipe which continues inwards and down to the bottom of the tank. The other outlet on the tank is at the same level as the connection and is used as the EFI return. You can tell between the two by poking a bit of wire into each connection.
I thought something like this might be the case. Thanks for clearing that up!
It's not as bad as it looks. The fuel outlet has a pipe which continues inwards and down to the bottom of the tank. The other outlet on the tank is at the same level as the connection and is used as the EFI return. You can tell between the two by poking a bit of wire into each connection.
I thought something like this might be the case. Thanks for clearing that up!
If you're goingto be using it on the track seriously, I'd definitely fit a swirl pot. However good the tanks are, a sustained moderate to high G corner is going to rob the pickup of fuel once the tank begins to empty.
Better safe than sorry, especially when you're looking at fitting something as cheap and easy as a swirl pot. I've always included them in the fuel systems of my race cars.
Better safe than sorry, especially when you're looking at fitting something as cheap and easy as a swirl pot. I've always included them in the fuel systems of my race cars.
If you're goingto be using it on the track seriously, I'd definitely fit a swirl pot. However good the tanks are, a sustained moderate to high G corner is going to rob the pickup of fuel once the tank begins to empty.
Better safe than sorry, especially when you're looking at fitting something as cheap and easy as a swirl pot. I've always included them in the fuel systems of my race cars.
Better safe than sorry, especially when you're looking at fitting something as cheap and easy as a swirl pot. I've always included them in the fuel systems of my race cars.
Although my fuel system is in no way authorized or recommended by Ultima. I have -10 in the bottom of my tanks and crossover lines connecting the 2 tanks, with a tee in the pickup one feeding my EFI fuel pump. My return line goes to the fittings near the top of the tanks. I can fill up very quickly from one side or the other since I have 2) -10 lines crossing over. Only downside is I have no reserve fuel, when the gauge reads empty it's gone.
Jeff Schwartz
USA
Jeff Schwartz
USA
davefiddles said:
The fuel outlet has a pipe which continues inwards and down to the bottom of the tank.
...as I thought it would, but 2 more questions for the owners, please, cuz I saw some others here complaining of their Ultima's engine losing fuel-supply under hard acceleration (and low-fuel):
Does that tube inside the tank go to the *rear* of the tank, so that when the fuel surges there under WOT, the pickup is *also* there to get the last bits? If not, how hard would you assess it to be to add an interior pipe extension toward the rear? Perhaps that, and angling the tanks during installation so the rear is fractionally lower, would let the last drops get picked-up...
Also, a general question: Is a swirl pot affixed to the bottom of the fuel tank?? Sorry, never heard that term for *fuel* tanks; is it somewhat like a sump? :-)
>> Edited by jhr8 on Sunday 22 June 08:41
I've done the same as Jeff, I linked the tanks with -12 then go into a Tee and use a holley blue 'TAP' sorry Top to deliver the fuel through a large bilet filter.
Not had any problems with surge in the tanks despite the track and strip action that the car has done, so I think the pickups are fine and the foam seems to do the job.
Not had any problems with surge in the tanks despite the track and strip action that the car has done, so I think the pickups are fine and the foam seems to do the job.
There would be little chance of modifying the tank pickup, as the tank is foam filled. I think it should stay in the middle, which would better suit all motion conditions. If you are suffering loss of fuel pressure it is time to get out of WOT and limp slowly to the nearest fuel stop.
The swirl pot would be installed up on the bulkhead. A pump would supply the carb/FI from the bottom of the pot. One or more pumps would continually fill and overflow the pot (Return pipe). If the tank(s) suffered fuel surge the swirl pot would start to empty. If it has been sized correctly then it will not empty completely and starve the engine before the pump starts to pick up fuel again.
Steve
The swirl pot would be installed up on the bulkhead. A pump would supply the carb/FI from the bottom of the pot. One or more pumps would continually fill and overflow the pot (Return pipe). If the tank(s) suffered fuel surge the swirl pot would start to empty. If it has been sized correctly then it will not empty completely and starve the engine before the pump starts to pick up fuel again.
Steve
The addition of a surge tank (otherwise called a swirl pot) is the best method of assuring constant fuel supply. The disadvantage is increased system complexity and a weight penalty. In my opinion, however, the advantage outweighs these, as I have experienced fuel starvation before and do not wish to again.
Mark
Mark
Sod’s Law states
“The likelihood of something happening is inversely proportional to it’s desirability”.
This means that fuel starvation will happen just when you have achieved the perfect balance between power, traction, angle of drift, severity of the corner etc. etc.
The result of loosing a vital element of the above equation results in visiting the surrounding scenery.
Steve
“The likelihood of something happening is inversely proportional to it’s desirability”.
This means that fuel starvation will happen just when you have achieved the perfect balance between power, traction, angle of drift, severity of the corner etc. etc.
The result of loosing a vital element of the above equation results in visiting the surrounding scenery.
Steve
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