Basically I am going to have a high flow, low pressure feed pump in my stock tank. The pump sits inside a baffled bath. I will upgrade the stock pump housing to have a -10 feed and return to my surge tank. Thought -10 would help to keep the surge tank full, and not cause any back pressure issues.

The surge tank is approximately 4-5 litres. The outlet is on the bottom but at the front of the tank. I know this is not good, but i had no other option. Although, the outlet is in a separate compartment from the main tank- with small holes wall to prevent splash back- see diagram and pic.

From the surge tank to the first filter is -10. Then the A1000, then the second filter and then -8 to the 13101 A1000 fuel reg. From the reg to the y block is -8 and then -8 to the rails.

Not sure if needed but was going to have a cross over line at the front of the rails.

Finally, the return from the fuel reg will be -6. Either to the tank or to the surge tank.. whichever is better'¦..

All -10 lines will be braided hose. -8 and -6 are aluminium tubing.

What do you think?? Do I need the crossover at the front of the rails, and where should the return go- to the main tank or surge tank?

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I was reading this guys build before I joined and he runs a surge tank maybe you will find something helpful in his build.

https://www.theturboforums.com/threads/364358-tc78-e85-w-surge-tank-wire-tuck-etc-Bullitt

 

Did you forget to attach the link, or am I still asleep.?

 

Sorry new here as far as posting . lol

 

Love to see what you come up with. 4-5L seems huge, I mean you're talking a solid gallon plus of fuel that you will be replenishing at some point. Throwing some rough math out here (VERY) lets say you have an 8 cylinder engine, running 100lb/hr injectors with an 80% duty cycle. Your use would be 100*.8*8=80*8 or 640gallon/hr. Convert that to gallon/min and with that kind of fuel consumption you could be in it at wide open throttle the better part of a minute before your fuel would run out excluding any fuel being fed into the system. By the way 100s should support about 1400hp with a .45 BSFC (naturally aspirated) and 80% DC.

 

I appreciate your help. I'll confirm the volume of the tank but I'm pretty sure its 4 Litres.

I was told I could keep the stock pump for a feed pump as it will not be under any pressure. Based on your calcs, it seems I should not have any chance of running out of fuel.

Where would you run the return?

 

You circulate fuel on the engine pump back to the swirl pot. I am probably doing one in the lemans eventually because i want to tbi it and dont want the hassle of a return line or a baffled tank. Thinking it will be very small perhaps as small as 4 inches of 3 inch pipe and 2 caps but it is a 250hp engine so why do huge?

 

Whoops 640 lb/hr which is 102.4 gallons per hour or roughly 1.7 gallon/min.

 

I was told that if I run it to the surge tank it will heat the fuel and running it back to the main tank was a better option. I'm just worried about the surge tank filing up and the back pressure on the feed pump....

 

It depends on the feed pump truly, for instance I'm running a carb pump that means I'm getting around 7 PSI total. I could see the bypass working and also your concern about fuel heating. I don't really know if it would make a difference honestly, it would save some labor on the feeding pump for certain if you didn't depend on the bypass for it which is probably a good thing. If you circulate fuel from the swirl pot to the engine and feed back into the tank you'll end up sucking the swirl pot dry because the A1000 can pump faster than the slow pump.

 

What if i got a high volume feed pump and return from the engine into the tank? Surely hi vol pump under no pressure and a decent size swirl pot should keep the injectors spraying?

 

Where ever you return the fuel, you should do it through AT LEAST as large as the supply hose, (which is -8 according to your diagram, from the filter to the rail). This is a lesson I had to learn the HARD WAY, even though I was told to do it that way, I'm looking at all the OEM stuff running 3/8" feed and 5/16 returns, and thinking no way I need the same size or larger return. The result was that I couldn't get the fuel pressure down low enough without a return from the pump's own high pressure bypass, and it caused the whole system to lean out when it opened. Run the same or larger return, it won't hurt anything, and it will allow you to control the system pressure much better. If you return it to the surge tank, I would also run a small return, (1/4"~5/16"?), from the surge tank to the fuel tank from the top of the surge tank, so it will only return fuel to the tank when it gets filled up, and will also allow any trapped gases a way out of the surge tank, other than back through the high pressure part of the system again.