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Surge Tank / Fuel pump / Fuel line setup

9K views 16 replies 5 participants last post by  Beeble 
#1 ·
So we're looking at getting a surge tank setup on a mate's car, but mine will be following this path sometime so I have a vested interest.
We need a surge tank as we road course race. And drive around roundabouts as fast as we can.

The end point will be a 2.2 with a 3586 or similar, on E85. Currently it's a 2.0 and a Red, soon to be on E85, but we only want to do this once. I guess 600whp is likely? maybe more?

intank is a Walbro 255 in his case, a DW301 in my case.
my questions are :
- will a single inline 044 from the surge tank suffice? or will twin Walbros or twin 044s likely be required?
- what size high pressure line to the fuel rail? will 3/8" cut it?
- I've been reading about using the old high pressure line as the new return line, this sounds sensible :)

Yes, a simple double pumper would be oh-so-easy, but it's not feasible.
And after reading around it seems a bunch of people are having all sorts of fun with their surge tank setups....
 
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#2 ·
A single 044 wouldn't be enough for E85.

My issue was simply the fact I was running both 255s in my setup at the same time. A Hobbs switch will, knock on wood, fix that issue.

Dual 044s seems like overkill, but it'd work as well.

we ran -8AN to the fuel rail. -6AN return line. We modified my stock rail.
 
#3 · (Edited)
^ modified stock rail.. because the fitting is too restrictive?
I have i think 6AN on the return side going to my FPR
so did you put 8AN fitting in the supply side?

The 044 is supposed to be a 600hp pump (engine hp) right? what is a single Walbro 255 rated at as an in-line? presumably more than when it is in-tank where it sucks and blows (could you ever have asked for a better double entendre lead in than this?...) at the same time?


EDIT :
looks like a single 044 inline supports about 680hp on pump at 5bar (3 bar base + 2 bar boost) at 12V. so it will be a bit more.
a single Walbro 255 supports 390hp under the same conditions. so Twin 255s = 780hp.
 
#4 ·
The stock rail fittings are too small, so they just added the correct fittings. An aftermarket fuel rail may provide the same functionality, but I honestly don't know. I don't think the AMS/Boomba rails have, say, -8AN feed and -6AN return, but I didn't look into it.

Yeah, the 044 is rated as 600HP (crank), on what I presume is pump gas. The 255 in line, for example, was rated at 600HP by AMS, back when they sold an in-line 255 kit, which simply went in between the stock in tank pump and the fuel rail. I'm not sure what they're "technically" rated at, but you can do the math on injector size + fuel flow and figure out what IDC % the pump would, theoretically, be good up to. The shop did the math for me, and figured the single 255 off the surge tank would be good for up to 63% IDC on the 1680s.




You can see the -8AN fitting in the center, and on the side the -6AN return.
 
#5 ·
^ yep thanks for that.
I'll have to see what size the stock supply line is
I already have the 6AN return setup so that's all good.

I got pump flow rates from MAP as listed in my post above, for anyone else who's interested :)
 
#6 ·
Jay Racing said:
Q: How does the flow of a Bosch 044 fuel pump compare to a Walbro 255HP?

A: Independent test results show the where the popular Walbro 255HP fuel pump flows 256 LPH at 30 psig fuel pressure, then Bosch 044 flows 290 LPH. This isn't really important though because most cars only see this pressure at idle. Now assume a vehicle running 30psi boost on 45 psi base fuel pressure (75 psi net fuel pressure). At this pressure the Walbro 255HP is flowing 208 LPH and the Bosch 044 is flowing 267 LPH (28% more capacity). Finally, at the top end of the chart (90 psi fuel pressure) the Walbro 255HP flows 156 psi and the Bosch 044 flows 253 LPH, which is 62% more!
This graph illustrates how the Walbo 255HP fuel pump has an exponential decline in flow at higher pressures, where as the Bosch 044 is linear. An interesting fact is that the Bosch 044 at 90 psi is flowing about as much the Walbro 255HP at 30 psi.

Q: How can the Bosch 044 fuel pump, when installed inline in series with an in-tank fuel pump, flow more when it is drawing through a much smaller fuel pump?

A: You have a very good question there. Think of each pump having a low pressure side (inlet) and a high pressure side (outlet). The low pressure side of the in-tank pump is at about zero psi, the high pressure side will only be at a few psi since the Bosch 044 pump is not providing any real restriction. Then, the Bosch 044 pump with the inlet, at a few psi, can push more fuel at higher pressures than it would be able to otherwise. Basically, the "boost" from the in-tank pump shifts the Bosch fuel pump's entire output curve up, especially critical at the higher pressures.
Basically a positive displacement fuel pump creates flow and the fuel pressure regulator causes a "restriction" after the fuel injectors to create pressure. Fuel flow (volume per time) is independant of fuel pressure (force per area).
The in-tank pump is creating low pressure and high volume. Then the Bosch 044 pump would create higher pressure and have to work less to make higher volume. This gives the Bosch 044 pump the capability to create higher flow than it normally would.
Another illustration: Imagine a single intank pump setup. Imagine you've found a way to pressurize the gas tank. This increase in static pressure would push the fuel into (and through) the in-tank fuel pump easier, meaning the in-tank pump would not need to work as hard to create the pressure required by the fuel pressure regulator (it would draw less current that it did before you pressurized the tank). This would give that same pump the ability to create more flow at higher pressures when the output would typically fall off. See this graph to illustrate how a pumps output decreases as pressure increases and how the required current (how hard the pump is working) increases as pressure increases.

 
#8 ·
+1 thanks Clipse.

fuel line size - for a twin 044 or twin Walbro setup with say a 3586 running on E85 - will 3/8" be enough?
does that correlate to 6AN or 8AN? (i think it's 8AN?)
 
#9 ·
It's #/16 inches, where # is the "6" in the 6AN, or "8" in the 8AN.

So 8AN is 8/16, or 1/2 inches.
6 is 6/16, or 3/8 inches.

3/8 or 6AN stuff is pretty small. It LOOKS smallish. But I'm not sure of the math behind it, how much is needed.
 
#10 ·
^ ahh that makes a whole lot of sense.

hrmmm but 8AN (1/2") fuel line is figging HUGE. it's a pipe, not a line :)
yeah fluid dynamics isn't exactly my strength, we need someone like Hollywood to jump in and say "x diameter line with y length and z pressure will flow this much..."

ok thanks for the advice
 
#12 ·
^ if the aforementioned wang came in "pay by the metre" it might come in handy for more of us than just Golden himself :)

ok i just emailed a bunch of flow numbers/pressures/lengths to an engineer friend of mine. He is responsible for getting massive volumes of liquid stuff through huge pipes to far away places, so hopefully this miniature version will be easy for him!
 
#13 ·
ok i just emailed a bunch of flow numbers/pressures/lengths to an engineer friend of mine. He is responsible for getting massive volumes of liquid stuff through huge pipes to far away places, so hopefully this miniature version will be easy for him!
Odd, so am I.
 
#14 ·
^heh, just on opposite sides of the world.
only he's into those Wankel things. He only understands things that go round and round, not up and down.
 
#15 · (Edited)
One more quick question...

Wiring up your 044s/twin setups :
are you running straight off the battery for power, through a new relay.
or straight off battery but tapping the existing fuel relay
or tapping power completely from the existing fuel pump?

We set it up using totally "clean" power from the battery with a new relay hooked up to ignition, and now the front O2 sensor is giving voltage CELs. (P0132 - high voltage)
Tried a different sensor, still the same issue.
Wondering if the two are related?
 
#17 · (Edited)
^which i think is the best way to do it.
Maybe it's just an unfortunate coincidence with the CEL...

I'm trying to think of a way to get a voltage regulated 044 setup - ie at idle and super low load it runs at 9V (like the stock setup). But i think tapping into the stock fuel pump power loom will blow expensive fiddly electrical bits left right and centre.
With twins a Hobbs switch is easy, but with a single this obviously won't work so well
 
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