Albert/ repo/ engine builders. fuel system, help!

[S2central.net]

Drawing it now...

[S2central.net]

Oh I see Repo's scribble now, but here's an attempt at something more clear... How does this look ?

[speeding-g60]

i run fuel cell up front, so i have no need for the swirl pot/ catch tank. you guys who do run in-tank pump to feed external pump inline benefit from that more.

i have two race cars, and both have ~2.25 to 2.5 gal fuel cells. but they are both different after that.

the rabbit has the A-1000 pump, the 13109 Aeromotive FPR after the rail. the cell feeds 100 micron filter then the pump via -8AN about 14" away. out of the pump 10 micron filter to -8AN to fuel rail, rail is 1/2" ID? feeds 4 x 1000 Delphi injectors. -6AN to FPR, and -6AN back to cell. i run 56psi/4BAR static. > 550 WHP from 20vT 4 cyl, GT35R, on C-16 race gas (117 OCT). it hits 36 psi in 4th gear, and 130MPH burnouts are no fun if you are a drag racer .

the CQ chassis, basically the same setup. except twin 044's fed -10AN each. check valve on outlets of 044's, -8AN each to Y-block. -10AN to 10 micron filter, and continued -10AN to rail. same 1/2" ID rail, with 4 x 1600cc Bosch injectors. -6AN out of rail to Fuelab FPR, and then -6AN return to cell. this car is again 20v 4cyl, 10.5k rpm rev range, S366XL turbo. it will run on E85. can go into the 3Bar psi range if i need it to.

both my FPR's have the pressure gauge on them. that is how they are designed.

a couple thoughts:

A: why should you run -12AN to the A-1000 when it is only a -10AN inlet? it is necked down here, so this will be the point of restriction.
B: the bulk of fuel will be used by the rail, so why make the outlet = to the inlet? at idle, my return moves plenty of fuel on the rabbit. the Coupe, it may build a little pressure, but that will help the rail not hinder it. the E85 here is just now decided, i may step up to the -10AN FPR as that is the only choice.
C: the swirl pot or catch tank can be of any size you want, its only purpose is to provide the external pump with fuel in the event the internal one cannot keep up. the larger you make it, the longer you can run before you deplete the catch tank and have no fuel supply.
D: lastly, keep in mind the pumps like 044's and A-1000's, they are pusher pumps, not sucker/puller types. they need to be mounted lower than the fuel supply or they will not last long.

keep in mind these are only my thoughts, its how i am doing mine. the rabbit is proven, it just needs traction. it runs great otherwise.

[S2central.net]

D'Oh yeah - I forgot to add a fuel filter. Probably doesn't matter much but I guess locating it between the primer pump in the tank and the reservoir is best choice... That the way the reervoir always hold clean fuel and the monster pump doesn't get restriction of fuel filter. I've just shown use of 8AN into and out of the fuel rail as I guess they come with those fitments. AN6 return is probably OK though - I see the logic for that.

Anybody know what the fuel flow limit is on stock FPR from Bosch ?

[4WheelDrifter]

I can see this is a good idea for a track or sprint car. But what about a road car? I'd be worried about emptying that 1.5 litre tank quicker than the stock pump could fill it on a long blast. Or am I missing something?

[S2central.net]

Well lets say yu have a ~750bhp S2 that needs 4.5liters per min of fuel at full chat... Even a little 1.5l swirl tank will sustain 20s of maximum flow before it relies on a top up from the feeder pump... Thats roughly two 1/4 mile drag runs - so probably plenty enough.... Outside of a Vmax event or the Mulsanne straight there can't be many places that you need more than 20s worth of full power at ~750bhp.

The purpose of the swirl tank is to keep fuel temperature down AFAIK... On a road car or with more modest power levels its sufficient to run without one using an in-tank fuel pump that is man enough for the job.

[4WheelDrifter]

It's good to see some numbers there. But on the road it isn't that unusual to be flat in top for a couple of miles or more. It would be a PITA to run out of fuel and let a BMW win.

[repo]

Don't miss the fact that intank pump does not need to push against pressure, when it only attempts to keep the catchtank full. Makes it flow waaayyy more than against 3ish bar or so.

Too small catchtank causes the fuel to heat up, if You do not use the aeromotive fuel pump controller. 1.5 liters is plenty enough in capacity wise, but the heatsoak is an issue.

My a1000 has an12 fittings?

[4WheelDrifter]

Don't miss the fact that intank pump does not need to push against pressure, when it only attempts to keep the catchtank full. Makes it flow waaayyy more than against 3ish bar or so.

Ahh. Thanks Jyrki. That'll be the part I was missing.

[speeding-g60]

Don't miss the fact that intank pump does not need to push against pressure, when it only attempts to keep the catchtank full. Makes it flow waaayyy more than against 3ish bar or so.

Too small catchtank causes the fuel to heat up, if You do not use the aeromotive fuel pump controller. 1.5 liters is plenty enough in capacity wise, but the heatsoak is an issue.

My a1000 has an12 fittings?

i agree with the theory on the intank not working so hard while feeding the catch tank. that makes perfect sense.

i cant find an A-1000 with -12AN fittings though, mine only has -10AN....

http://www.aeromotiveinc.com/pdf/11101.pdf

[repo]

My pumps are old. Maybe that is the reason. Or then I just remember wrong, as in latest projects I have eliminators. A first gaze they look completely alike, if forgetting the colour...

But yea, if the pump has AN10, not much reason to go 12, so agree on that.

[S2central.net]

Ahh. Thanks Jyrki. That'll be the part I was missing.

D'oh yeah - I missed that point too. Thanks for that. Is my diagram more or less right then with regards top or bottom location of hoses on the swirl / reservoir ?

I need to add a fuel filter between feeder pump (in-tank) and the reservoir.


Paul

[speeding-g60]

ave a ~750bhp S2 that needs 4.5liters per min of fuel at full chat... Even a little 1.5l swirl tank will sustain 20s of maximum flow before it relies on a top up from the feeder pump... Thats roughly two 1/4 mile drag runs - so probably plenty enough.... Outside of a Vmax event or the Mulsanne straight there can't be many places that you need more than 20s worth of full power at ~750bhp.

The purpose of the swirl tank is to keep fuel temperature down AFAIK... On a road car or with more modest power levels its sufficient to run without one using an in-tank fuel pump that is man enough for the job.

also, Paul, keep in mind this 20 second theory is WITH NO FUEL ADDED TO THE CATCH TANK. the intank pump will still be supplying the catch tank with fuel, so this 20 seconds becomes much longer.... that 1.5L is on demand reserve for the big pump.

[S2central.net]

Totally agreed on that, but it hadn't dawned on me that the in-tank pump would be flowing so nicely into the reservoir - so the nominal 20s scenario above is a bit moot indeed. Never built anything this powerful so its interesting to think about the fuelling strategy... Also crazy to think about big power engines consuming 3 or 4 (or more) liters of fuel per minute at full throttle... Almost makes you want to go outside and hug a tree

[speeding-g60]

not me. this is going to consume quite a bit of fuel..... E85 fed by twin 044's. 40 psi boost. 9 sec 1/4's.... i am looking for ~650+ AWHP out of the 4cyl 20v revving to 10K+. just a plain old Coupe Quattro from over this side of the Pond.... but my goals are lofty. this is the 20v 4cyl 35R rabbit setup, too.