What is an External Surge Tank? How does it work?

The 3 rotor is getting close to 1400 hp capable fuel system in preparation for some call outs. Learn about the AI SPR1200 and what a surge tank is useful for.
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[@theguin3apig]

Are you going to run a fuel filter this time?

[@kylekeogh2731]

An external surge tank is to make sure she stays extra wet 😎

[@damonk6289]

RIP altanator trying to run all those pumps lol

[@RobDahm]

That is the worst part haha

[@DjayLSD]

Well, @@RobDahm , Just upgrade it ^^ , believe me, this current hungry surge tank will get rid of your alt in under 2-3 weeks. Upgrade it now, its cheap and will save alot of problems later in the long run ^^ Might seem overkill, but i went with twice the rating, give more headroom and prevent problems with all electronics(ecu act funky when it starve power...)

[@mrjetlife27]

Email mike singer...

[@Legotruck82]

That's why with a newer style ECU, you only run ALL the pumps when the car is up on boost, and needs it. Helps keep fuel temps down too.

[@DjayLSD]

@@Legotruck82 I agree to some point, but' to my experience' the newer the ecu, the more picky on the voltage they get. Old MK1 Pre-OBD ecu could start and run on a mere battery with only 8 volts, and the crap would start no problems... Todays ecu's tend to show sign of problems unders 11volts... They do all sort of funky things, light diming in and out, sensors reading bad range(thus bad engine management), all sort of problem tend to happend. Sometime, a dead batt or alternator can even lead you to think the car got drowned or shorted... Sometime, mostly on GM 's and Pontiac's, the car will start, but light will bedimm, radio will give random weird message, you gonna get the good ole PO420 Cat code, and much more. The car will think everything is fucked up... Change the batt and all is brand new all of a suddent. They does that since about 2005 to be precise ^^ So new or old ecu is not the point, stable current, stable voltage and stable fuel are the 3 keys points of a build.... no matther what you are running and numbers wanted... ;-)

[@wtalk2]

Rob, you are truly entertaining to watch. Please never stop!

[@ZerpsT]

FATHER HAS RETURNED

[@Baksteen_Express]

Not all fuel systems have a return line. Some have a pressure valve in the pump assembly. So they use a return less system

[@ViperDemonWright]

Literally was just gonna say that, glad I scrolled down.

[@patw52pb1]

This surge tank will not work properly on a returnless system.

[@haatch999]

@@patw52pb1 how so? U do a free flow to surge tank so always filled and then use the dead head system to the car works fine

[@patw52pb1]

@@haatch999 Please name a surge tank that the manufacturer specifically states is returnless and will operate properly deadheaded. Without a return line to the main fuel tank how does the system purge air and vapor from the surge tank? In a returnless/deadheaded system any air or fuel vapor would be permanently trapped in the top of the surge canister reducing the effective surge canister volume.

[@haatch999]

@@patw52pb1 the surged tank overfillls then returns the dead head system start with the pumps in the surge tank

[@brianawd]

Both your intank pumps feed the inlet to the surge. Then the surge tank outlet feeds the rails. Your return fuel line goes back to the surge tank return port. The last port is return/overflow to the factory fuel tank!! By not having a return to the factory tank like you talked about the surge tank will pressurize when fuel demand is low!!

[@quartermilefreaks]

Please use somewhat thicker wires to feed those 2 pumps in your tank ( and a thicker ground) you might lose some voltage on the pumps by using that thin gage wire set-up

[@chrrtz_builds2018]

Rob I might be wrong but from what I understand the Overflow port is the one that Should return to the fuel tank, one of the supply/return ports is input from tank and the other one is input from the fuel pressure regulator return line and obviously the last one (the red one ) goes to the fuel rail. From what I understand. Might be wrong.

[@oakfuzz7965]

Hey Rob! Props for uploading on a Sunday. Now my weekend is complete.

[@RadeonMasterRace97]

As always, Down Undah is the home of everything rotary😍😍😍

[@WhatComesAroundTM]

Yay I got an ad 🙂 Probably the only channel I'm happy to see ads on.

[@OxygenGenetics]

Set them up on a hobbs switch and have them come on based on boost?

[@tyjackson6505]

This is a more advanced version of a swirlpot. We used them at Quantum Racing back in 2003. Rob, this will work well. Great investment.

[@moeezahmedshahaab]

Love you Rob

[@rush2489]

This video is such a tease.... I love it

[@TheCarCrazyGuy]

This is just simply dahm.

[@wrighty338]

Thats a nice surge tank setup

[@MikeNolano]

Is there enough flow through an external surge tank to only run that? Rather than two in-tank fuel pumps ?

[@frosty9595]

Should pick up a couple of cheap pressure switches (hob switches?) to trigger relays for multiple stages of fuel. Make it so one in tank and one surge tank pump run at all times. Then set up a 5psi pressure switch to trigger a relay to turn on the other in tank and one more surge pump. Then a 10 or more psi switch to trigger the final pump. Works really well. Then you basically have 3 stages of fuel activated by boost. You have to wire a few relays anyways. Saves you from issues with the fuel pressure regulator getting overwhelmed as well. Can also mix and match and only do one stage.

[@AlexComeau]

@Rob Dahm just keep a single 450 in tank as a free flow lift pump.

[@robrob1596]

Yo Rob I watch all of your recent stuff but sometimes I find some of your classic stuff that's totally relevant. You should find time between your big videos to make these kind of videos again it's a great way to split your time and still produce cool content. You do a great job at describing these components, you took your channel into a new big singularity Direction but I think you could take it in both directions🤘🇺🇲 a little bit of technical informative videos plus crazy awesome rotary videos. Might be surprised the technical informative views might outperform everything else

[@Crashdally007]

Hey rob, I’ve done this style of wiring quite a bit. You may be worried about drawing 5 pumps worth and it being hard on your electrical system, but if you do the correct powers and grounds you won’t have an issue. I can give more insight if you want, I do it for a living😌 more than willing to help with 12 volt electrical

[@ViktorNig]

That into 😂😂 I love it

[@Aseutester]

Holleys Hydromat Technology has been available for years now and much simpler saves the space that an Anti Surge tank takes up! A big bonus is it doubles as a filter too down to an impressive 5 microns!

[@stevenjoubert9923]

Hi Rob

[@reasonAce83]

good content

[@gw3extreme254]

I wish you luck Rob.

[@snape1464]

Can't you switch the 2nd in tank pump along with the 3rd surge tank one? They would only have to run under high load

[@thodorisvlasopoylos3287]

love you rob dahm

[@Hachiae]

had this problem with my stock ae86, a hard right would cut the fuel and would make it stutter until the fuel leveled out again

[@iswinkels]

I highly recommend using a solid state relay to drive the pumps, and use PWM to control the pump speed based on injector duty cycle. I use two walbro 460's intank in a GTR, and the pumps are run in parallel so there is no surge when a second pump starts. It also lowered my fuel temps 15 degrees. At full load the two walbro 460's pumps (which you also have) pull nearly 40 amps. PWM keeps that way down for cruising, but delivers fuel when you need it based on injector duty.

[@iswinkels]

@peter magri Err... No. Just No. In automotive applications PWM is used for the most efficient speed control of DC motors, soft start circuits to reduce the effects of current in-rush, and for precision control of solenoid valves. EG. Pump speed controllers, Fan speed controllers, Boost control solenoids. Link, Motec, Haltech. They all do it. Most modern ECU's will allow you to create a map based on some pre-existing data that the ECU knows about. EG Injector Duty cycle (0-100%), fuel pump running (0/1), boost (0-100% MAP) etc become the axis for a table with which to drive a PWM output.

[@e34boat88]

solid state relay makes no difference in a car aplication.. maybe in something more hightech.. this is and old car.. and there is no point using pwm because these pumps only take so many amps they need. thats how electricity works. pwm is more to control the noice

[@iswinkels]

@@e34boat88 So using your reasoning that the car is old, it should not make use of any new technology right. So no turbine fuel pumps, no E85, no modern turbocharger technology or boost control techniques. Just get by with 1990's technology right... I could go on. Perhaps you missed the whole point of modifying an old car, Most reliable street car fuel systems that deliver over 1000hp of fuel will use some kind of intelligent fuel system control. Those that don't are not reliable. Drag only applications will you find you can get away with running the pumps flat out al the time. The 4 pump fuel system will draw 80 amps at full load. Assume 80-90% pump efficiency that's nearly 200watts of heat put into the fuel. Also running all the pumps at idle delivers way too much fuel. You'd need an AN8 or AN10 sized regulator to keep pressures stable in a bypass/return fuel system. Solid state pump speed control is the only way to properly control this many pumps, and not end up boiling your fuel. Yes it can control pump noise levels, but that's not an issue with the Walbro 460 pump. They are whisper quiet, especially compared to a 1000 hp engine.

[@e34boat88]

@@iswinkels ssd relays are overkill.. e85 is old tech fuel btw

[@iswinkels]

@peter magri Your lack of knowledge and understanding is truly astonishing. But even more amazing is that you clearly have not even googled the use of solid state relays in aftermarket automotive applications. You'll find it discussed everywhere in all the ECU and tuner forms, HP Academy etc. Combined with CAN bus ECU communications, sold state relays are the future of how custom engine management is wired. One power source and ground, programmable power output that is PWM capable. Precision control of anything that runs off DC. Critical applications like boost control above 40psi etc is only possible with PWM. Solid state relays are extremely reliable if you install them properly and use a protection relay when your using an inductive load. I use them in my GTR with dual 460 pumps and a spal thermo that draws up to 60A on start-up. PWM provides soft start to eliminate current surge issues that would happen if I used a normal relay. It also provides near stepper motor levels of motor control. Yes the W460's draw 20A which is 240W of electrical load, but only about 10-15% of that will turn in to heat energy in the form of losses. That heat is put directly into the fuel as the pumps are fuel cooled. So as I said, 4 pumps, 50w/pump = 200w of heat energy being put into the fuel at full load. You still not getting this? Look at all the after market fuel pump manufacturers that produce pumps capable of over 500kw. ALL of them produce their own PWM controllers. So your a "highvoltage plant maintainer". Your in a DC world here. Go back to school. Your not qualified to comment or work on a modern tuned car. Maybe you need to google some answers, because you sure don't have them.

[@Sir.VicsMasher]

Hopefully your electrical system is up to the task of powering these 3 fuel pumps in addition to your 6 GM coil packs during high RPM pulls. Ive noticed a lot of people switching to mechanical pumps after 1,000hp.

[@cesarlopez-zr8fr]

Rob here up with the next video

[@austinrode3974]

If youre having trouble with the fuel pick up why not get the holly fuel mat?

[@NekoStirling]

Rob is the linus tech tips but for cars xD (also drops everything)

[@R26Roman]

Question ❓ say for an rx8 and wanted to improve mpg is there an easy solution to add a second gas tank maybe the size of this surge tank? Something small.

[@lennardthoben9052]

What if you have the second pump in the tank on a switch so when you think you need it you can turn it on manually

[@tscooter22]

Sorry if I missed it, are you using an aftermarket fuel tank? The reason I ask is because FDs come from the factory with a 20 gallon tank.

[@flewis763]

Rob I'd suggest staging the second pump in the tank and 3rd pump in the surge tank together to turn on at a set psi. That will help the electric load while cruising and keep fuel temps down

[@e34boat88]

no need to do that.. all those pumps take so many amps that they need so staging them is just pointless. imagine if 3 pumps take 5 amps each at idle and you remove 1 of them.. now 2 pumps take 7.5 amps each at idle. so its better to run all the pumps at same time so they will all last longer ☺

[@flewis763]

@@e34boat88 well that's not exactly how it works amperage wise. The big thing though is overheating fuel as low load. 5 pump running, fuel temps with go through the roof, especially with no inline cooler. These surge tanks are set up power wise to be easily staged for a reason. Stand alone ecus typically have output just for it as well. Its common practice.

[@flewis763]

Also note for amperage draw, a single walbro 450 as 0 psi takes 14.45 amps to run. 72.5 amps amps up to run fuel pumps at their lowest pressure. Now the 3 in the surge tank when the are is under load I'll most likely go up at 20 amps each. That's huge draw on an electrical system.

[@e34boat88]

@@flewis763 youre right i checked some amp draw maps from walbro. that setup needs atleast an fuel cooler or some sort of staging for the pumps

[@flewis763]

@@e34boat88 yep even on just the twin 450 setup on my porsche I run it staged and a cooler. I'm going up to 525s now though because I'm pushing the limit of the 450s. But ya, they take a ton of amps and so much flow makes tons of heat. Stage helps both even if you don't have a cooler.

[@DeFreshS10]

Why would the pickups be close like that? wouldnt massive sucking power cause turbulence and make the other inlets unstable? Would it be more efficient to have the inlets to the pumps as far apart as possible?

[@abecx]

Would not a fuel pressure sensor and an ECU that can detect a low pressure situation be a much easier and safer solution? I assume this is to keep the engine going instead of cutting power due to lack of fuel more so than a safety solution?

[@beastword7228]

Hi Mr.Dahm

[@antipost]

@Rob Dahm Dude just have 1 of the in tank walbros running at all time then have the second intake wired to a Hobbs switch @ 15 or 20 PSI or like 10-15psi short of peak boost. wired to a relay. So when the hobbs senses Hobbs switch PSI # you choose it then send signal to the relay switching on and powering the 2nd in tank walbro. Problem solved your surge will never be starved.

[@riqtard]

No any update on 4 rotors?

[@S-Kidz]

I like how all the pumps inlets form a triangle lol

[@joeljaipersaud]

Mechman racing alternator and an agm battery should do the trick

[@RecklessRegal]

Overflow from the engine goes back to the surge tank, overflow from the surge tank goes back to the main tank. This way the surge tank is always full and the heated fuel is not reintroduced into the main tank.

[@barrybritcher]

No mesh filter ?

[@mclarenjohnf1]

Are you fitting one of these to the 4 rotor?

[@stevenjoubert9923]

Rob you must send a few rotors towards south africa

[@firestartercanti6636]

so how many 10mm sockets have gone missing from your tools so far?

[@righteousvw]

WOOT!!@ROBDAHM

[@kuromurasaki5273]

the baffled tank in the RX-8 fixes this issue to some extent, yes?

[@capnthepeafarmer]

Why not stick that directly into the tank without the surge tank?

[@austinmyers4420]

why didn't you try holly's new "tanks mats" that can get fuel no matter where in the tank?

[@SoCalSlaughter]

Holly Hydro mat + fuel tank foam. Done.

[@maxrivera2582]

What's up Rob?

[@JAM4382]

You need a Holley HydraMat in your gas tank!

[@DirtDude117]

Make sure you run 3 filters for this system. One going into the engine, one for the return, and one for the surge tank.

[@patw52pb1]

Why 3?

[@jm361]

@@patw52pb1 3 pumps and they had no filters on each pump that why.. You would be surprised whats floating around in fuel and what can kill a pump and or clog an injector, they have filters that filter down to 10 microns.

[@TrojanHorse1959]

Rob, Why not just use a baffled sump & anti-slosh foamed fuel cell to start with?

[@ghettoflyer]

It eludes me why don't you just run a baffled after market fuel tank or fuel cell and just 3 pumps? Is this really that much cheaper/ necessary than paying for an aftermarket fuel tank and buying 2 less pumps?

[@jacobshepherd3997]

not to mention just getting a baffled fuel cell would have a lot fewer components to fail

[@e34boat88]

much easier to use stock fuel cell with couple 450 feed pumps. surge tank is always the best option.. baffled aftermarket tank will always have air bubbles

[@williamstanfield1216]

Why not physically run the fuel system into a bucket to see exactly how much it pumps in a certain time?That would give you a number for static flow rate.

[@patw52pb1]

The flow volume rate is inversely proportional to the operating pressure. So meauring the flow volume at zero pressure is not a valid metric for a system that will need to operate near 100 PSIG. walbrofuelpumps.com/walbro-f90000267-fuel-pump-e85

[@haritzgonzalez516]

This gives you infinit fuel?

[@Bionixx016]

I don't understand why that happened on a dyno. If the car is in one spot how did the original fuel pump not get fuel?

[@pole69ers]

Hey bro what else did it prevent haha lmao

[@John.strong]

Why don't you just stage the pumps with thw ecu Turn them off when not being used At a guess you could get away with running 1 main tank pump and one serge tank all the time Then turn on the last 3 when needed Otherwise thats alot of fuel to heat and cycle the whole time its at idle

[@kbent88]

This is similar to how spacecraft tanks work. without the pump of course. They have to work in micro gravity.

[@93Viggen23]

Not all fuel systems have a return, a lot of modern vehicles us a return-less system.

[@patw52pb1]

Very few modern (

[@sweettee3647]

Why is there no sock on the surge tank fuel pump?

[@GameNerd115]

The surge tank is going to be supplied by the two pumps in the fuel tank which would have socks on them

[@dj4monie]

Holley Hydra Mat = Done. No need for a surge tank, just super expensive for no reason. Good video though.

[@mid.nightrunners8157]

Came for Rob, stayed for the comments

[@Scrrumy]

OUUUUUUUUUU DOCTORRRRR

[@x-hooktowhook3904]

What happened to the 4 rotor coverage!!!

[@jhoffis]

lol that intro

[@Invitingsauce]

If you had to give a time frame....when can we expect to see it on the dyno...

[@aklip]

Not all fuel systems have return lines Wob.

[@vongdong10]

You know you're doing well as a company in Australia when someone from the US wants something you make...

[@Blakelikesfood]

In 5 years this will be considered all a joke: Just place one large fuel pump period....no one uses 2 starters...2 steering pumps...2 alternators...you just use bigger.

[@a456987]

'cmon man, just use all five pumps

[@cobratoxic]

The 3 rotor is going to drink so muxh fuel that is going to be crazy

[@k23turbo80]

Get an extra battery and deal with the amp draw of five pumps

[@oldmanloki]

3:20 is rob a returnless fuel system denier?

[@ndinadis]

all fuel systems on all cars have a return line.... mine doesnt :(

[@patw52pb1]

What year, make, model and what market country?

[@ndinadis]

@@patw52pb1 I dont know if its unique but 05-09 mustang gt for all of north america use a PWM fuel pump and a return-less fuel system

[@bdeep706]

Sure it's not voltage drop to pumps at wot??

[@UpShiftTrackdayVideos]

Please only "Share" when you actually understand how the bloody thing works in the first place!

[@timboslice1984]

All cars have a return line 🧐😳

[@billybobjoe198]

I'm no fuel system expert, but I think lots of cars have "similar" set ups to this from the factory. The Porsche 928 (the only fuel tank I've ever removed) has a small baffled area at the very bottom of the tank where the sock is for the outlet to deal with sloshing fuel. Non M e36's have what I imagine to be a surge tank under their spare tire in the trunk.

[@LAKESHARPER]

its crazy how they over build everything yet break just as much as regular ppl

[@flynndodsworth2693]

Rotary life

[@flynndodsworth2693]

Plus they don't really Rob ran that 3 rotor for a long time before nuking it

[@nagases1572]

that pain tho

[@bgemski]

You’re gonna smash TJ Hunt lol, be nice to the poor ricer

[@CoochieKissKing]

5 pumps. Do it. You need it.

[@padlockbeats151]

Tommyfyeah & Rob Dahm do a "What's in the box?" reference on the same day... Synchronicity or conspiracy???

[@zspec4839]

Daddy rob where is the 4 rotor?

[@velez910]

Well let's make one out of plexy glass and watch it work

[@isitgoodtodo2834]

you should be a teacher

[@twistymcslide2]

meh , Radium USA FTW !!!!

[@kshysztof9649]

Jesus This must feed a lot of fuel

[@athomedetail6512]

And will the vacuum pressure assist the 1 or 2 pumps that are filling the surge tank? Is it completely sealed??

[@malijames12]

Daddy dahm was I first?