Here's an easy to make surge tank

[strotter]

Sure, I don't see why not. Your low-pressure pump will be flowing at its' free-flow rate (in your case 255 liters/hour, or about a gallon a minute), and that's going to be true all the time regardless of the demand from the motor. A similarly rated pump might be pushing about 200 liters/hour against 40 psi.

[Careless]

Made mine yesterday night

 

I'll post picks of it as soon as i wire-wheel or sandblast the unit to remove all the vice marks.

 

I couldn't find a Thread Tap for the damn 3/8 fitting I got.

 

3/8 -16 was not the right size, and 3/8-18 was not available. so I went with a M14x1.5mm metric tap, and loaded on the yellow teflon tape. It seems to be tight as hell, an i think it will work nice.

 

I have a tap at the top of the unit that I have to plug with the same fitting, but a butt-end on it. I had a plug for it already, but the thread differed from the others on the top, and if I plan to run staged injectors I'll be able to run a second return line back to the top of the pump.

 

The only thing that sorta bothered me, but I think it will be ok, is that the single tap at the bottom where the high pressure pump picks up it's fuel from was somewhat thin, i only got about 2 and a half to 3 threads onto it. but i think it's ok, because the differing tap size (metric to imperial) only allowed the top 3 or 4 threads on the barb fitting to thread tightly anyways, because they're tapered.

 

so I just loaded on some more teflon tape there and made it extra tight.

 

 

now, if you plan to use a 240sx receiver dryer from japan or from an s14, BE WARNED, that you will have to pull a metal disc out in small pieces through whatever hole you drill at the bottom.

 

IT IS A PAIN IN THE ASS. It took about an hour to use needle nose pliers to grip that sucker out, and it's a good thing it was perforated with holes so that it could break into smaller pieces, or else it would have stayed in there. There is also a plastic grommet and a pickup tube inside, with a bunch of dessicant and two sponges.

 

make your bottom tap smaller than you need, because the needle nose pliers will crush it to some extent.

 

Happy surgin'

[Careless]

oh, and the next one i'm doing is gonna be made from a toyota sienna unit. the thing is the same width as the civic and 240sx one, just twice as long

[Tony D]

(EFI pump as booster reply is at bottom)

 

I'm going to chime in on complex methods for preventing aeration:

 

There is only one thing that will work: Height. Period.

 

The IMSA #75 Twin Turbo 300ZX car had probably one of the most complex and sophisticated fueling systems in any Nissan Vehicle. It had six pre-pumps sucking from the fuel cel to TWO surge tanks, which then had two main pumps feeding the engine. This could support 1100HP, but during races and due to IMSA Rules imposing 26mm inlet rescrictor orifices on the turbos, it 'only' made 750HP.

 

The fuel cel pumps did suck air and send it on to the surge tanks---they had pickups and several points in the fuel cel and during low fuel conditions and hard cornering, it was inevitable that some of the booster pumps would pump air.

 

The answer they came up with, with millions of dollars of engineering experts and factory technical support was:

Make a Taller Surge Tank.

 

The surge tanks in this vehicle went from the bottom skid plate to literally the roof structure. They were close to 42" tall. The booster pumps fed at roughly 36" in from the bottom, through a deswirl tangential entry sort of arrangement. Fuel return was taken off similarly at the top. Fuel to the main pumps was taken down low right on the bottom of the tanks.

 

I think the chance of 'sucking air' with an open return line is extremely remote---on a racing vehicle pulling 2-3G's and having fueling requirements for top tier motorsports maybe more thought needs to go into it...but at our level, I'm strongly inclined to think we may be overthinking the issue a tad.

 

Like I said, I fed mine for years using the stock 240Z "ticker pump" a Bendix License pump that wouldn't supply the engine with enough fuel in Normally Aspirated form, much less making 350HP to the rear wheels! Sucking from that tank, was a stock Bosch EFI pump, which normally is out of poop by the time you try 250HP...but since I was running Carburetted Blow-Through the lower pressure of the system even at full boost only required 27psi of fuel pressure, and the stock Bosch EFI pump supplied that handily. Matter of fact, due to my jetting I was way rich---that system really overfed me for what I required. Never ever ran lean...

 

When that pump is operating at lower pressures, their flow capability is phenomenal... if you ahve 3psi in your surge tank, you really probably have too large a booster...really!

 

The big thing about the surge tank is to really provide a reservoir for when the unbaffled tank has a pickup uncovered. If you were straight EFI pumping---you loose fuel pressure and the engine burps.

 

If you have a surge tank, or even a swirl pot utilizing the return fuel to augment a 'bulge in the line' when you suck air from the tank it wil ONLY ever make it as far as your surge tank---the bubbles will IMMEDIATELY rise to the top and be carried out with the return line and overflow fuel.

 

If you run a hobbs pressure switch---or even watch a gauge of the pressure level of your surge tank, you will see it is 'dropping' boost pressure regularly if you are running a 240 tank, unbaffled, below 1/4 tank and turning corners at ANY kind of speed. But main fuel pressure will remain unaffected, as when that boost pump regains prime and starts pumping---even though your main pump is sucking down fuel, you still have return fuel coming in to keep the main primed.

 

On the issue of the EFI pump feeding the booster---that will work like you wouldn't believe---as long as you have an EFI tank, running the stock EFI pump will flow like crazy at 1-3psi, and more than adequately fill any surge tank for a larger pump. As long as you have the return line running into the surge tank as well, it should work superbly. Having a surge tank(s) is good insurance when running high-hp EFI setups simply from the fact you won't get that burp---which can cost you pistons! Where'd you dyno the car on Okinawa? Goya?

[BRAAP]

Tony,

Great info as always, thank you.

 

I have a quick stupid question that I should already know the answer to.

 

Being as the OE EFI pump is designed to run under a load, i.e. 30+ PSI, is there an issue with running it at lower pressures say in the 1-3 PSI range for extended periods? My conventional wisdom says the pump should last longer as it isn’t working as hard, i.e. less current draw, building less heat internally, etc, but it will be spinning faster. Could the higher RPM be a long term issue?

 

TIA,

Paul

[Careless]

Tony,

Great info as always, thank you.

 

I have a quick stupid question that I should already know the answer to.

 

Being as the OE EFI pump is designed to run under a load, i.e. 30+ PSI, is there an issue with running it at lower pressures say in the 1-3 PSI range for extended periods? My conventional wisdom says the pump should last longer as it isn’t working as hard, i.e. less current draw, building less heat internally, etc, but it will be spinning faster. Could the higher RPM be a long term issue?

 

TIA,

Paul

 

Hi Paul,

 

Upon taking apart the EFI pump that comes on the 280z, I noticed that the small retainer gear that held the small pump dowels (for lack of technical knowledge on proper nomenclature) in place had a sort of build up on it. I'm not sure if it was just heated gasoline that cause carbon deposits, or if it was actually metal that had been finely ground to a small deposit like consistency. This covered the pump retainer gear and some of the dowels very finely, and I believe it was the cause of it's ultimate demise and seizure.

 

I then replaced the O-ring with one that fit as best as possible on both the top and bottom of the middle gasket plate, after I had cleaned the pre-filter with some brake cleaner and hand polished the dowels and retainers with some 600 wet/dry sandpaper...

 

Put her back in, turned the key a couple of times, and 25 years later, an L28 has its life back.

 

 

What I'm getting at, is that if this build up seem to have happened on a normal pump setup at normal RPM, I'd assume that accelerated pump speed would cause it to wear faster and create film more often, as well as wear out the internal diameter of the middle-gasket plate to the point where it has too large a clearance to pump (but I think the way it's designed doesn't allow for that unless it's run for 25 years, 24 hours a day, 7 days a week.. IF that short of a time span in this case, because the retainer throws the dowels out far enough to reach the ID of the gasket plate, even with large clearances... in fact, it might even pump more if they're further out)

 

And I think as long as it pumps enough gasoline to coat the roller dowels and retainer gear to the point where it will be able to lubricate it somewhat, It should be ok.

 

This is all in reference to the 76 280z pump I have on my car.

BRAAAAAAAAP BRAAAAAAAAAAAAAaaaaapapapapapaapaaaaap

 

TONY D,

 

Nice bit of info there. Do you have pics of said setup? I'd imagine that it was quite hefty in size, and weight quite a bit too, no?

 

My number one reason to do this is so that it doesn't damage my new pistons =)

[Careless]

OK LADIES AND GENTS,

 

Here's my rendition of this fine DIY surge tank. Whether it works as planned, who cares. It was quite fun to make and use my tools again cause I haven't had time to get in the garage to work on anything lately.

 

So i bought a 40 dollar china-special drill press. Used valve spring compressor pivot rod brackets and two bolts to secure the thing so it was as close to plumb-90 as visually possible, (the weld on the bottom sorta made this hard)

 

here's what I came up with.

 

My surge tank is so glam.

 

Close up, for a nice 8x10 glossy.

 

In the preceding photos, I ended up using 3/8 barb fittings with 1/4 hold/thread size, and tapped them using a metric M14x1.5 tap, seeing as no store I went to (not even Home Desperate, where I bought the fittings....GOSH) had the proper tap.

 

The plug is there so that if I plan to run staged injectors, I can use a second return line if I choose not to T off into a main line between both fuel rails. If I do go that route, I'll probably drill two more taps on the diagonal portion so that I can run two fuel lines to the front as well. Not sure how i'd do it now, but that's later stuff anyways.

 

I used yellow gasoline rated teflon tape, which sealed up the threads really nicely. The item used was an S14 JDM receiver dryer.

 

The small holes held on the pressure sensor switch and the lines to the unit, and they are not threaded all the way in. The glass hole in the middle will be good for detecting capacity to some degree. Or not. But I chose not to break it as it's not neccessary.

 

The unit was then taped off with cheap unstretchable electrical tape in traditional yellow colour, to match the gold barb fittings, and then sandblasted to a rough sheen to remove the vice marks and such.

 

Comparing this unit to a Toyota Sienna unit, it's about half the size, and same diameter, so I might end up doing one of those up and giving this to a friend of mine with an AE86, since it's a tad smaller. The volume of this s14 unit is roughly that of a coke can (thinner, but taller, in usable internal space)... so about 320ml of gasoline can probably fit in there.

 

Thanks for posting this small and fun project. I had fun doing it. And I got to bust out my room mates camera to do some photos again. Nothing spectacular, but it was aiiiiiiiiiiiiiiiiiiight.

 

Let me know if you have any questions.

 

Ignore the box that's in the photo. He didn't wanna leave the set of the photoshoot with this sexy collection of nipples that I had fun tapping last night.

 

 

[sweetleaf]

BRAAP, When you talk about the pump running at lower pressure ie 3psi. How do you plan to lower the pressure. If you are talking about less restriction, ie open feed. Than yes it will not harm the pump and will probably prolong the life. Less resistance and more cooling makes for a happy pump ( : ..

[Tony D]

I was just tooling around some JDM websites, and rest assured the DRIFT-BOYS know about using surge tanks on their cars now! I found several very nice (and Expensive) JDM ready made surge tanks that were designed to house various OEM In-Tank pumps, in various capacities. My favorite was a smaller unit of 650CC capacity (when the pump is installed) that is fed off the main tank. That is a nice idea...

 

Anyway, Photos of which setup? The IMSA car... I may actually have them, I just converted about 9,000 exposures from my early Sony Digital Camera---and ran across some photos of the #75 Car with the rear coverings off.

 

The Low-Pressure Application of the EFI Pump was THE way it was done in Japan in the 80's. My $100 (12,000 yen) FPR was set up specifically to take EFI pressures and drop them to Carburetted range, along with the boost-pressure port to keep it 1:1 setpoint above boost. I ran my car for 17 years on a pump that I took out of a junkyard and that was probably 10 years old then. Actually the pump is STILL functional. I think in carburetted blow-through applications the stock EFI pump will probably last longer than most would want it to... LOL

 

The pump most definately was not hot during operation. For a while I was actually running the return into the feed line, and then bleeding off some more to the tank through the dinky 240 Fuel Return Line (what, 4mm? It's small!) and the pump didn't get hot then, either. I KNOW you can't do that on an EFI system as the pump gets hot QUICKLY with recirculation scenarios.

 

There are many Fuel Pressure Regulators (they are all bypass style) that return the fuel to the tank, and have a regulation setpoint between 1 and 10psi. With a spring change I can convert my old Carb unit from 3.5psi pressure to 3Bar! Clever those Japanese. And that FPR is the same age---I see they are STILL selling the same regulator to this day!

 

I don't think 'overspeeding' the pump is an issue operating it at lower pressures---the speed of a DC Motor is pretty much set via voltage---the MSD Boost-A-Pump jumps voltage to get the pump operating at a much higher speed to supply more flow with THAT I could see wear being an issue as you are increasing flow AND pressure. With the setup these Bosch Pumps have (and judging by the pitch of the motor) it really doesn't sound like it speeds up much at all...I think it just doesn't 'slow down as much' as when the fuel pressure loading is on it. I suspect Bosch gives those derated pressure curves because they design for free-flow delivery/speed and then just live with the amperage/flow loss at pressure. They are designed for the flow/pressure curve versus amperage. It's when you add more pressure, speed, AND flow requirements that I would say wear will happen because then you are edceeding the original design.

 

By operating it the way I did, it was on a 'derated curve' ---well within design limits. Remember if the flow is there to be used, flow will raise amperage just as much as a pressure demand will!

[lesd]

Not sure why people are mounting surge tank systems outside of the main fuel tank.

What about this system:

At bottom of main fuel tank , mount a tall 'coffee can 'tower, sealed well at bottom and mostly open on the top. Very simple. Dosn't even have to be 100% leak free, hey it's in the fuel tank anyway...

The low pressure pump sucks from regular fuel tank bottom, and just dumps into the top of the tall coffee can, spilling over the top , a complete mess, but wait, that's right, it's in the fuel tank, so no worries.

The injection pump feeds from a seperate port on the bottom of the 'coffee can' thing. Make the coffee can thing as tall as you can inside the main fuel tank, the taller the less chance of bubbles getting to the bottom of the can.

Plumb the return line from the engine to help fill the can as well.

 

Advantages: no space lost , it's in the tank.

No fancy tank needed . it can even be leaky in there,who cares.

Less hose nightmare.

Disadvantage: Can't point it out to buddies to impress them at get togethers or car shows

 

-Les

[strotter]

Les, I considered just that solution. Problem: getting something with a quart-ish capacity into the tank and fastening it securely. The largest opening in a 240 tank is the fueling inlet, which is, I dunno, about 2"? Doesn't allow much room to maneuver. If you're willing to take a can opener to the tank it's no problem, but that "reassembly via welding" thing is a problem, at least for me.

[Tony D]

"Not sure why people are mounting surge tank systems outside of the main fuel tank. "

 

Bolt on simplicity. No cutting of the tank, mounts easily enough wherever you have space. Easily serviced if you suspect there is a problem. Possibility to make a FAR more efficient scavenging system than if it's in the tank. You can make a better more efficient surge tank externally than possible internally. If they could have made a 42" tall IMSA surge tank internally they would have. Some stuff just works better externally.

 

One other thought, I have the ability to service my fuel pump standing up, over the fender of the vehicle in a vessel that I only have to drain out a couple of liters of fuel from at any given time---no tank draining of couipus gallons required. It also is easier to amke a proper 'in tank' adapter in an external surge tank, than reworking a tank to properly work with, say, a Z32 TT Pump.

 

If you want to drop the tank and cut it apart, more power to ya, but just bolting on a smaller vessel that has better functionality does seem like an easier course in most cases.

 

Besides, nobody can see my surge tank, I---like an idiot---mounted it on the factor holes for the EFI pump behind the axles on the outlet portion of the tank. It's hidden, on other conversions I mounted is for the "Car Show Experience"! LOL

[Careless]

=/ guess my tank ain't upto standards.

[dapiper]

Just pulled my tank for inspection; see my thread on the Bosch 044 hot fuel overkill. Inside is baffel or cylinder where main feed originates up about half way and the return feeds a nozzle near the bottom. This on a '77 280. Not sure what's on the other side of the baffel.

 

OBTW, how can you effectively clean with that obstruction?

 

Shoud I coat tank with POR or something to prevent rusting?

 

On track or in the garage it pumps air below 5 Gal.

[Careless]

OBTW, how can you effectively clean with that obstruction?

 

any sort of cleaning is generally done by sloshing, unless you have them cut it open and re-weld it shut afterwards.

 

I'd just get some type of rust remover and cleaner and slosh it around in there for a good 15 to 20 minutes. then i'd pressure wash the inside, drain it, and then redo it.

 

i'd also do it until i ran out of remover and cleaner.

Hang it by a tree and spin it and twirl it or something to give it a good wash.

 

then repeat the process with a sealer made for this type of chemical (gas)

[Tony D]

To dry mine, and in homage to my Germanic roots, I attached a 'gopher gasser hose' to the tailpipe of the VW, and pumped the tank full of exhaust gas...nice warm exhaust gas (leave out the sender, pump it in through the tank filler, or sender hole). Tank may get some condensation in it if the hose is relatively short and the gas is really hot, but you can't argue that it gets a nice, complete inert-gas purge before any welding repairs are done, and since it heats up nicely any moisture inside is dried out pretty quickly. This is how we did it when I was in Body Class 20+ years ago... Still do it that way today.

[tannji]

Is a hot gas (exhaust) purge considered to be a safe way to prep a take for cutting and welding? I hear horror stories all the time at work about people damaging and losing body parts welding on various fuel tanks... kinda leary of doing it, but a heat treat to remove moisture makes sense to me.... what about purging with argon or nitrogen while heating the tank? My car sucks air pretty badly on left hand turns, but I had resigned myself to an external surge tank or a fuel cell due to the issues with welding tanks. Any more thoughts on this?

[Tony D]

If you purge from nitrogen bottles, there is no reason for heat to be applied, the N2 is superr-dehydrated, and if you cork the fittings and leave only a small pin prick for the N2 to escape (fill through the 1/4" top vent, and off gas through all other openings through small holes) any moisture in the tank, and the pores of the metal will be desiccated through the N2 passing over the metal, and out the vent holes. You can leave the N2 on the tank while welding and the backsides of the weld will look really nice as well!

 

"Inert Gas Purge" is what you really want to do, but most people don't have N2 Available (or didn't) at the time, and the exhaust gas purge was a pretty common thing to to with the old timers. With cars running less than 8% O2 content in the exhaust today after the catalyst, it definately will not support combustion, and the heat helps liberate any solvents from the metal as well.

 

Argon would work, but is much more expensive than N2. Any cryogenically-derived gas will have low/zero moisture content by virtue of the distillation process. This stuff is made a -200 Degrees F and colder, ain't no moisture content there! It went away 232 degrees ago! What you worry about in cryo plants is CO2 plugs as it turns to liquid, and then freezes solid at only -110F, and that can ruin your day trying to cool down a box for N2 or O2...Nothing like taking a rosebud torch into rockwool to 'melt out' a CO2 Ice Plug in an O2 enriched environment! LOL

[tannji]

Good to hear! I get gases at cost, and Nitrogen is not too bad, especially considering I wont have to worry about buying or renting cylinders. I don't think I would weld the tank with the Nitrogen still in the tank... Nitrogen tends to contribute to porosity in the weld, not a good thing, especially in a fuel container = ) I think I might flood nitrogen to desiccate, and then flood Argon while welding.

Hmm, I wonder if I can use the Nitrogen to get rid of the deadening material in the floorboards while I am at it?

[lesd]

Could you just pour some LN into the fuel tank?

 

-Les

 

Good to hear! I get gases at cost, and Nitrogen is not too bad, especially considering I wont have to worry about buying or renting cylinders. I don't think I would weld the tank with the Nitrogen still in the tank... Nitrogen tends to contribute to porosity in the weld, not a good thing, especially in a fuel container = ) I think I might flood nitrogen to desiccate, and then flood Argon while welding.

Hmm, I wonder if I can use the Nitrogen to get rid of the deadening material in the floorboards while I am at it?