joefish1298

There's a lot of talk about different fuel setups and this isn't a post about which is better or worse.

What I want to understand is how a a particular setup works and delivers the fuel it does. The setup in question, is an in tank pump factory/Walbro feeding a surge tank, which in turn has a Bosch 044 (or other large pump) pumping from the surge tank to the fuel rail.

My question is how does this setup deliver more fuel than the in tank pump itself can deliver? On the street, where you're not always on the gas going WOT I can see how it would work. You wouldn't be using enough fuel for long enough for the Bosch to empty the surge tank with the in tank pump constantly filling it.

However, at the track (circuit) you have much longer periods of WOT and I'm thinking that if you were using enough fuel, for example you're running on E85 and using a lot, that you could empty the surge tank and run dry. If the Bosch is pulling fuel from the surge tank faster than the in tank pump is filling it, surely you have to run out at some point?

Does any of this make sense, or do I completely not understand the setup?

m R g S r

Yes that could happen but you have a safety margin...the margin is the capactlity of the surge tank.

I personally would prefer an oem intank pump feeding the surge tank, then a 1 gallon surge tank, and Bosch 044 inline from there.

rastus

The trick is that the OEM (or smaller) fuel pump is able to keep up with a higher flow rate at a lower pressure.
As such, the tank pump feeds at a higher rate at a low pressure to the surge tank.
The pump in the surge tank, in turn, sends high pressure to the injectors.

Thats how I see it in any case..


--Rastus

crispeed

You got to also take into consideration that the fuel from the regulator in front is returning into the surge tank there by keeping it full. Once the surge tank is full then the excess fuel is returned into the main/factory fuel tank.

Spoolin

Why even use a surge tank?

Whats wrong with just hooking up a second Walbro 255 or Bosch 044 inline externally without the surge tank? If the intank pump should be capable of sustaining fuel to the surge tank while the surge tank pump pulls fuel, wouldnt it also be capable of sustaining enough fuel supply to the second inline external pump without a surge tank?

Doesnt IP do their dual pump setup this way? No surge tank and just a second pump inline externally?

Irishflame27

adding a surge tank is nothing more than a safety feature,

Say you are at the drag strip, and you launch your car from the line, the extreme force that thrusts the car forward is also moving the fuel inside the tank, if the fuel moves away from the pickup for a fraction of a second, you lose fuel pressure and flow. the surge tank is there so during extreme conditions (i.e, hard braking, tight cornering, extreme acceleration) that when the fuel does move in the main tank, that the surge is always full with fuel, feeding a constant flow to the hi pressure pump.....

I am doing a surge setup as Chadd (Spoolin) already knows, i will have pics of it up soon, but it you want to see them now, text me at 623-210-9092 seeings how all i have is cell pics

dsddcd

Same reason people run an oil accumulator on the track. With sustained and varying g-forces on the car if the fuel tank sloshes around and the in tank pump runs dry for a second then the engine will not starve.

For most of us there is NO reason to think about it, I have run a Bosch 044 inline with my factory pumps on many cars and they can take you a LONG way