Is this a dumb idea for a fuel tank?

JJZ28

Veteran Member
Feb 3, 2000
990
Kalamazoo, MI USA
I have an issue with fuel pressure dropping during launch. It will (usually)recover by the end of the run. I am in the process of putting an electric helper pump in the back near the tank to use while I'm racing. I got an idea today while working an a gas powered air compressor. It had a little tank, maybe 2 quarts. Could I mount a tank like this up front? I would tee this line into my mechanical pump with shut offs so I could select either the rear or front tank. Then I could use only the front tank at the track.
What do you think?
 

Marv D

Veteran Member
Lifetime Gold Member
Front mounted fuel cells are the norm in the alcohol crowd. But I don't think a dual cell system is the answer. If your not starving the motor, a fuel pressure drop at launch is nothing to worry about. You have to drain the bowls before there is a problem, and by then the pump has recovered. My Nova has a 250GPH pump, Mallory return regulator vacuum referenced (9psi at idle with vacuum, and 12psi once the throttle plates go WFO and vacuum drops) Data logging I see fuel pressure drop to 1 to 2psi at launch and it recovers to 3-4psi by 2-3,,, sometimes 4 seconds out. By the 1/8th and almost 6 seconds it's still not above 5, and barely makes 6.5 to 7psi at the 1/4. I burn just over a gallon a pass.

NOW, from stupidity I can tell you that if I launch with the fuel pump turned OFF, I go to about the 330 mark on just what fuel is in the bowls. That's with Dominator float bowls, so a 4150 would run dry a little sooner, at the 800HP level.

Still worried about that pesky fuel pressure drop at launch? If you have adaquite line size to support your power level, and have pressure on the top end,, and I mean even 4psi.... your good.
 

PONYEATER

Veteran Member
Lifetime Gold Member
Nov 2, 1999
2,796
Arlington, WA
What size line do you run Marv? Mine doesn't drop nearly as bad as that. I run a a1000 fuel pump and a mallory return style regulator.
 

PONYEATER

Veteran Member
Lifetime Gold Member
Nov 2, 1999
2,796
Arlington, WA
Now I am starting to think the old guy took a little blue pill but the wrong head is swollen :p

Just answer the question. 6-8feet up hill? Give me a break that doesn't last for the whole run. Also you might want to remind the youngins that bigger isn't always better in fuel lines.

Edit: if you would take the training wheels off the damn thing and adjust the suspension you wouldn't be pushing the fuel up hill!
 
Last edited:

Marv D

Veteran Member
Lifetime Gold Member
PONYEATER said:
Now I am starting to think the old guy took a little blue pill but the wrong head is swollen :p

Just answer the question. 6-8feet up hill? Give me a break that doesn't last for the whole run. Also you might want to remind the youngins that bigger isn't always better in fuel lines.

Edit: if you would take the training wheels off the damn thing and adjust the suspension you wouldn't be pushing the fuel up hill!

LMAO.. No blue pills but I did stay at a Holiday Inn Express last week

And RE: Edit,,, now what fun would that be!!!

OK, OK, Answer to your question is an-8 throughout! Nothing bigger, nothing smaller anywhere in the system.

And Aron is dead right. Bigger is better is not always the right move. Engineers can explain the whole deal, but in the end you have to think about VOLUME delivered, not so much psi. A 1" hose with 1psi will deliver a heck of a lot more fuel than a 3/8" hose at 4-5psi. BUT, fuel is heavy. Moving that much fuel (and especially against the g-forces of a hard launch) is a CHORE for even the best of pumps. Larger lines means more fuel (and weight) sitting in the hose. And there is flow lost to friction of the fuel against the wall of the hose. The larger surface area of a larger hose, the more frictional losses. I know just enough about fluid dynamics to be dangerous, but I do know,,, for those few seconds when the fuel pressure is almost nonexistant, a/f readings from the wideband sensor, and EGTs say she isn't going lean. :eek:
 

JJZ28

Veteran Member
Feb 3, 2000
990
Kalamazoo, MI USA
Thanks for the input. For now I'll just go with my helper pump in the back. In hot conditions the car would sometimes fall on its face at around 1/2 track.
The front cell idea was just day dreaming. Probably winter boredom. I might try it someday though.
 




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