Using an A1000 pump w/o sumping, heres my idea...

[flubyux2]

so, it just came to me, talking to Justin since he asked me if i came up w/ a better idea than just running walbros. since hes paranoid about walbros, i figured id brainstorm with him... heres what i came out with;

Run a regular walbro (or maybe even the stock pump) in the stock location on the hanger. plumb it just like you normally would... except, the feed line wouldnt go up to the motor. wiring up the walbro would be like a full 12v mod, complete w/ a separate on/off switch and relay so that you have to manually turn it on and off.

heres where its gonna get weird...

A1000's arent necessarily self-priming. they arent gearrotor so they cant pick up fuel if its mounted above the level of the fuel in the tank. most people have the idea to sump the rear of the tank (i have a different idea regarding that if one "must" sump the tank). this isnt really an easy solution for a street driven car or any car that turns and stops suddenly. mainly due to fuel starvation and slosh. youd have to fabricate another baffle to make this work.

and now for the twist;

Drill the fuel pump hanger for a -10AN steel bulkhead fitting. braze/tig it for a complete seal. run a -10 soft/hard line down to the bottom of the hanger. this will be your Draw straw, as its called in the Diesel truck world. run the -10an out of the bulkhead, into a -10an three-way tee fitting just before it enters the A1000. use a reducer union on the perpendicular inlet of the tee and take it down to a -6. the walbro should tap into this side of the Tee. With the A1000 on a segregated, manual power switch like the walbro, you can control when to turn on the A1000 so it doesnt turn on by itself when it could potentially be dry.

so, now you could, in theory, give a few psi of fuel pressure and at LEAST 255lph of fuel flow directly into the -10 suction line of the A1000. most of the fuel would cycle back into the tank since its actually wide open inside the tank but its a longer path with at least one 90* fitting which should create a slight resistance.

so flipping the switch on the walbro should manually prime the A1000 with the intank pump. then after a few seconds, you should be able to flip the switch on the A1000 and have it fully primed and build fuel pressure almost instananeously. at that point, you could kill the intank pump and be well on your way without even having to drain your tank, drop it, air it out, cut it, weld it up with a sump that could possibly starve your pump during hard cornering and braking anyways...

discuss/

 

[Doward]

Why shut off the walbro? Let that little bastard feed the big daddy!

 

[bfr1992t]

Someone did this a long time ago (like 8-9 yrs) but with a normal Y block. He had a one-way valve on the "draw straw" too. This was going to be my way until the Walbro 255 become readily available around the time I was building my fuel system (~6 years ago). He used the stock pump for his feed.

You will still have to drop the tank to get to the fuel pump cover. ;-)

Learn something from the rock climber guys and use a longer flex line for the "draw straw" and put a weighted filter on the end. Then it will follow the fuel around.

 

[flubyux2]

doward... thats almost crazy enough to work!

a Y block would also be feasible. but most of them are -6 or 1/2" npt tops... unless you pay top dollar for a big badass ones.

yeah, yours right on that tank dropping... im still used to mkiv's and being able to do it from inside the trunk. the lifter idea isnt too bad either.. assuming the straw will be flexible enough to follow it. Braided hose is wicked stiff, lol

 

[bfr1992t]

Ahh yes, those damned mk4 owners and their easy access fuel pumps.
We've done 87x rwhp and 9.88@144 on two walbro's tho (in a mk4).

I thought there were -8 or -10 Y blocks, or maybe it's -8-10 on the outlet and two -6's for the inlets. Actually I do remember he had two -6's in to the tank. He never turned the stocker off however.

 

[flubyux2]

i know walbros have gone into the 900's but stock TT pumps have been pushed further, into 1000 range iirc.

i know there are blocks configured like you said, either 8 or 10 in, and 6's or 8's out. they are probably aeromotive CNC'd blocks close to $100. the ones i like are the cast aluminum blocks that ahve 1/2" npt on them for $40ish. thats what i had intended to use if i were to do a single feed line on a dual feed rail or staged injectors but employ a second block.

 

[suprabad]

When you consider how useless and rarely used the backseat/cargo area is, (by most Supra owners) and the complexity of accessing and modifying both the in-tank pump and the tank itself, it seems to me that a fuel cell is the way to go. Just gotta find (or make?) the right fuel cell.

Yeah, it's more work initially, (arguably) but in the long run I think it's a better way to go. I let ya know.

 

[Wiisass]

I helped one of my friends put together a pretty nice fuel system for his FC. He's using some aeromotive pump and the stock intank pump, paired with a surge tank.

Here's the surge tank:
http://www.speedmachineperformance.com/product_p/smp fuel surge tank.htm

We just used earl's tube-fit fittings on the stock fuel pump mount, ran the stock feed to one of the 3 top fitting on the surge tank. Ran the stock return to another one of the top 3 fittings and ran the return from the rack to the last of the 3 top fittings. I think all 3 top fittings were -6 and then the bottom fitting was -8 or -10. Then run the bottom fitting to the external pump and then the external pump to the rack. The pump was mounted in the trunk area above the tank and the surge tank was mounted in the same area. So you will always have whatever the surge tank holds in fuel ready to feed the other pump. So no matter what you will never not have fuel to that thing.

I think for the top 3 it was fuel return from the engine on the top, intank fuel pump in the middle and tank return on the bottom. This way it will always be as full as the bottom fitting. I mean you could probably do it with the return to the tank all the way at the top to get a little extra fuel, but I don't think we did it that way and there was a good reason, I just can't remember it now.

I mean you could do something similar with connecting the stock pump directly to the external pump, but then if you have fuel pickup issues during something, you will really notice it. And the draw straw idea could work, but again if there were any fuel pickup issues there during cornering or such, it could allow enough air to get sucked in to mess with the pump. With the surge tank, you will never have to worry about that.

And of course, you have all those nice looking lines all over the place. I wish I could find a picture of the setup, but I can't remember where he posted them or where they might be hosted.

Tim

 

[flubyux2]

surge tanks or air separater tanks for the fuel system are beneficial, but using a stock or upgraded intank pump to transfer fuel into a surge tank doesnt seem like itd work. flow out wont equal flow in. both sides of the equation are not equal. and most surge tanks arent big, like 1 liter usually. a car making 900rwhp can empty that tank in 10 seconds. or, a mk3 making 500rwhp can empty that can in 20 seconds. id be wary of running it dry. but, most people wouldnt have to worry about that... not many people around the country do top-speed runs and run WOT for more than 10-15 seconds at a time, not like people in arizona, texas, florida or other states w/ open roads.

and what makes you think the draw straw wouldnt run to the bottom of the tank? itd run down to the same level as the stock fuel pump pickup or lower if so desired. theres no more chance of sucking air on the draw straw than there would be on a stock intank pump configuration.

 

[Wiisass]

And if it were only the stock pump feeding the surge tank it wouldn't work, but you also have the fuel returned from the rack, unless you think all the fuel delivered to the rack is always used.

But if you really feel that you will be using that much fuel than why not do it right and either spend the money and get a fuel cell or sump the tank.

My concern with the draw straw would be if, for some reason, it comes uncovered. And the fact that there is no positive pressure feed to the pump. Unless you leave the intank pump in but then that wouldn't be enough. It really depends on the pump though, if it's designed to suck as well as blow then the draw straw may be fine. But if it needs a positive feed, then I wouldn't want to trust my motor with just the draw straw.

 

[flubyux2]

as i said before, the straw wouldnt be any more prone to becoming starved than the stock fuel pump... which is virtually never.

a syphon flow will not break either, even if the highest point goes above the level of the fluid its sucking from. i could see it losing the suction if the pump cavitated... but even if this did happen, leaving the transfer pump could keep it primed.

why would i think all the fuel being delivered to the rail is being used? youre not trying to insult me are you? lol

if you are running 90% duty cycle on 550cc injectors, you are putting down close to 500rwhp... which means you are using about 3000cc/min, or three WHOLE liters of fuel every minute, or one liter every 20 seconds... if you Use virtually all of the fuel being delivered to the "rack" then there really wont be much of it returning to the surge tank. it probably wont run dry, but itd get low. that scares me more than the draw straw loosing suction in spite of being fully submersed in the fuel.

fuel cells are inconvenient. 95% of people here want a feasible street car, not a race car to drive on the street. sumping the tank will open up problems of starvation as i mentioned before, unless you build a custom baffel inside... which would become extra costly and thats not the goal of this discussion.

i like the idea of a cost effective alternative to extra fabrication...

 

[Wiisass]

Wait, are we just talking about straight line stuff. Because I've seen many stock pumps get starved during high lateral acceleration. But if we're just talking about going straight, then I guess you don't have to worry about it.

A syphon shouldn't break flow, but I would definitely be worried about the fact that there is no positive constant feed to the pump. So if you leave the intank pump on, then it would probably be alright and keep everything going smooth.

As far as injector duty cycle and all that. If you're running this A1000 pump, that's rated at 600lb/hr at 13.5V and 45 psi. So 600lb/hr is something like 5 liters per minute. So with your example of using 3 liters per minute, that means that there is 2 liters left going back to the tank. So that should keep the surge tank full. And yes, you should deliver fuel to the rack, it makes the motor running more good.

I agree that fuel cells aren't convenient and a lot of people have trouble committing to building a race car. I still think sumping is the proper way to go. But that's not how you want to do it, so we don't need to talk about it. I just like the idea of doing it right versus cutting corners.

But let's get back to that positive pressure feed side for the pump. Based on some quick reading on Aeromotives site, they seem to really want it to be run with some kind of feed to it. And a draw straw isn't the type of feed they're talking about. So have you talked with any of the engineers there about doing something like this with the pump or have you seen this done before.

Now don't get me wrong, I'm all for finding a better, easier way to do things. But I'm not totally convinced that this would be a good idea.

 

[Doward]

The Walbro 255 is rated at 4.25 liters/minute in FREE FLOW. Let the A1000 do the pressurization (remember, flow drops as you increase fuel pressure) and leave the Walbro in a constant free-flow situation.

Would I run the surge tank? No. But then, I wouldn't be running an A1000, unless I'm up around 700rwhp. I'm damn sure not going that route on a 500hp car, it's simply overkill.

The surge tank is a great idea, if you for whatever reason put on a fuel pump that is way bigger than needed, though!

 

[bfr1992t]

Yeah lets be real here guys, on a street car sumps, fuel cells, and surge tanks aren't that feasible. I looked at these options many years ago but decided I prefer to keep the trunk (for targa stow-age), back seats (sure, nobody will ever use them but they look good - always garaged black leather), and don't want fuel lines hanging out the back of my car (to avoid theft/vandalism and maintain a stock/sleeper appearance). Nor do I want to smell gasoline or worry about spilling it while filling a fuel cell through the hatch. Plus in the event that I randomly decide to hit the drag strip I don't want to deal with inspection.

I think a draw straw with a one-way valve and a constant running feeder pump is a viable solution. I'm sure we aren't the first ones to come up with the idea. Worth a call to Aeromotive.

 

[tissimo]

self priming pump?

 

[kwnate]

700whp is very close to maxing out the A1000.

 

[flubyux2]

i like the additional input. Nate has a good point. ive always seen documentation stating A1000's will run out at 800hp on a force induction application, so 700rwhp is right on par with everything ive seen.

also, on a force induction application, dynamic fuel pressures will be FAR greater than 45psi... at LEAST 75psi, possibly more. i personally like to dial down duty cycle and run the injectors at 43psi static just so i can get as close to the advertised/intended fuel delivery as possible, for all intents and purposes.

the check valve, imo, is a great way to reduce priming problems however, i dont know where to find a check valve that is applicable to "high" flow-rates. i mean, i havent looked so theres probably something out there thats fuel-safe and can accomodate 6-10LPM. but itd still require something to prime the line initially, like after removing the lines or a pump or the tank or essentially any process that breaks the seal/syphon of the draw tube. once there is air upstream of the A1000, itll just cavitate.

how bout, the stock pump and a draw tube with a check valve next to it. they run parallel, out of the tank, then the stock fuel pump discharge tees into the draw straw just before the A1000. that seems like itd work as far as priming...

actually, since the A1000 is centrifugal, the gearrotor style of the stock pump can theoretically "blow" thru the A1000 when its unpowered. soooo, what if the A1000 was powered by a relay which is trigged by a boost-sensing switch? as soon as 2psi of manifold pressure is realized, the A1000 will come online to pick up the additional duty required of forced induction. this will reduce the additional wear and tear on the short-lived A1000 during idle, cruise and part throttle conditions while simulataneously contributing to a 700rwhp-possible setup.

 

[kwnate]

the check valve, imo, is a great way to reduce priming problems however, i dont know where to find a check valve that is applicable to "high" flow-rates. i mean, i havent looked so theres probably something out there thats fuel-safe and can accomodate 6-10LPM. but itd still require something to prime the line initially, like after removing the lines or a pump or the tank or essentially any process that breaks the seal/syphon of the draw tube. once there is air upstream of the A1000, itll just cavitate.

http://store.summitracing.com/partdetail.asp?autofilter=1&part=AEI-15107&N=700+115&autoview=sku

Been running that with no flow problems, using the eliminator pump now. Still made 667 on the a1000 though.

 

[flubyux2]

very cool. good find.

are they strictly intended for use on the pressurized side of the the pump or cant the be put on the draw side of it?

 

[Blackfin]

The check valve aside, seems like a lot of work to make an A-1000 work. Why not use a Magnafuel or Weldon pump? Both are self priming and as far as I can tell both are good reliable pumps. The only hiccup is that Weldon recommends their flow controller for street use but so does Aeromotive. It would seem that for pure simplicity of installation a Magafuel Protuner 625 may be the way to go. It delivers all the flow you need, avoids special installation precautions because it is self priming, avoids recommended use of a flow controller and costs no more then the A-1000 plus Walbro setup you are considering.

I mention this only because I am in the same boat. I have a brand new A-1000 ready to install but I am thinking about ditching it for a Magnafuel pump.