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What is a Surge Tank? How Do I Use One in My Fuel System? – Jay’s Tech Tips #36

September 2, 2019

Hi, I’m Jay from Real Street Performance. Today we’re going to talk about what a surge tank is and how it’s used in your fuel system. For a long time high horsepower applications relied on an external fuel pump and an aftermarket sumped fuel cell. The external pumps were bigger and could supply the engine with more fuel. However, they didn’t like pulling fuel out of the factory fuel tank. So you had to sump the tank so the fuel pump would be fed by gravity because most fuel pumps are good at pumping fuel and not great at pulling the fuel to the pump. This is why we used aftermarket rear sump, fuel cells. There are a few reasons why people didn’t want aftermarket fuel cells in their street cars. Filling the fuel cell without the factory filler neck is a hassle. You have crash liability depending on where the aftermarket cell is placed. You have fuel smell in the cabin. And the accurate and available factory fuel gauge was no longer available with your aftermarket tank. This led the people modifying their factory fuel tanks to fit an aftermarket sump. So you would cut the bottom of your factory fuel tank out and weld an aftermarket sump on the bottom of it, leaving your gas gauge intact and your filler neck intact. It wasn’t a bad balance of things. If you had a plastic tank like on a Supra then you would just use a bulkhead fitting on the bottom. Wasn’t a great idea, but it worked ok for the times. But there were some people that didn’t want to do that. They didn’t want the aftermarket fuel cell and they didn’t want to modify their factory tank. This led to the use of the surge tank or multiple in tank fuel pumps. Since we know that the large external fuel pump does not like to pull fuel out of the factory tank, why not use the factory in-tank pump to feed it. Because the large external fuel pump moves more fuel than the factory in tank pump can supply instantaneously, the large external pump would cavitate and lead to the pump’s failure. Cavitation is when the fuel pump is moving air pockets through the pump instead of fuel. The pump will not last long like this. This is where the surge tank comes into play. It’s an external reservoir that fits between the in-tank fuel pump and the large external fuel pump to eliminate the cavitation. The combination of the low pressure high volume in tank pump filling the surge tank and the return line from the regulator filling the surge tank leaves the surge tank full with fuel faster than the external pump can empty it. This eliminates the possibility of the large external fuel pump sucking air and dying from cavitation. While this setup worked extremely well on race cars and track cars, it wasn’t a great option for a street car because people didn’t want to drive around with all the racket associated with a large external fuel pump. This led to people using multiple intake pumps instead of the large external fuel pump. They got the fuel supply they needed without all the noise associated with a large external pump. However, not all vehicles could easily facilitate multiple in tank pumps. Some vehicles have too small of a fuel hat to actually fit more than one pump into the tank. Some vehicles have a split fuel tank that relies on the relationship between the factory fuel pump and the balance tube to equalize the amount of fuel in the tank. Disrupting the relationship between these components can create cavitation and supply issues. Or maybe there are no multi pump hangers available for your application. These two approaches left a void in the market of people that one of the best of both worlds. Companies like Integrated Engineering and Radium Engineering now offer a surge tank that houses multiple in tank fuel pumps inside the surge tank, giving you the best of both worlds. An approach like this makes things easy because you’re only running the hoses and wires. You don’t have to worry about disturbing your factory fuel gauge. You don’t have to worry about getting multiple pumps in the tank or whether or not they’ll fit in the tank. You’re not dealing with an aftermarket fuel cell or a large external noisy pump. So if you’re into the easy way out, something like this works well for you. As vehicles become more advanced products like these will become more popular. Hopefully this video helps you determine whether or not a surge tank is right fit for you. If you have any questions you can post them below in the comments. Please like and follow and I’ll see you next week.


  • Reply Guillermo Rodriguez October 8, 2015 at 4:14 pm

    Legit, so factory lift pump feeds to the surge tank, which holds multiple fuel pumps outside of the stock tank? Which basically keeps the pumps inside of a small surge tank that is not located in the factory gastank. Which keeps the pumps cooler, and takes away the loud fuel pump noise?

  • Reply Andy Nope October 8, 2015 at 7:55 pm

    Greetings, I've got one question. Do Real Street Performance take interns?

  • Reply RocketRaspeed October 16, 2015 at 3:48 am

    I recently put a triple pump hanger in an NA-t supra. I noticed that the NA fuel tank did not have baffles around the pickup area of the tank like a TT tank does. Do you think this will cause issues under acceleration if the fuel level gets too low? What would be an easy fix for this?

  • Reply chad tuggle October 22, 2015 at 2:19 pm

    so if you have a fuel cell and a dual pump surge tank. does 1 pump pull fuel from the cell and the other push fuel to the engine?

  • Reply Steve Snatch October 27, 2015 at 6:06 am

    Are you guys hiring? I would like to be Jay's apprentice. I have automotive experience (work in a dealership) it's getting mundane and I would like to expand my horizon.

  • Reply RAY D March 16, 2016 at 4:28 am

    hey jay, i have a 2000 ford focus zx3. i wanna do a surge tank set up with the stock tank. i have a radium engineering surge tank and a bosch 044 pump. isn't the bosch an external tank pump? you built my short block a few years ago. really u built it for one of your workers and i bought the short block. crower i beam rods, je fsr pistons and billet main caps. ford racing head with extra work and crower cams mccm 10759….duration int/exh durat @ .050 lift 228/228 rr:1/1 gross lift 393/393 lsa 114degrees rpm 1500 to up redline………..custom intake and garrett gt3582r turbo

  • Reply mehrshadvr4 March 27, 2016 at 11:42 pm

    what do you think about mechanical pump? why is it not as popular?

  • Reply NPAC QLD April 2, 2016 at 9:50 am

    my son used one in his modified street R32 gtst fitted a fresh built stage 1 GTR rb26 twin turbo engine,, used a AI duel pump surge tank with single 480 pump and second 480 in the main tank , not to loud , looks trick very tidy , just had heltech installed and first tune on monday on a fresh tank of E85 , ,looking at 485 hp 355kw at the treads at 21psi using stock R34 gtr N1 garrett turbos ,on a safe tune , ,,should be a little rocket ,

  • Reply Jai Xiong May 27, 2016 at 4:37 pm

    Question questions really quick! I have a 2014 evolution gsr, actually tune on e85. With the radium fuel system upgrade. my car was driving just fine for 3 mouths. I was driving on the freeway in 5th gare going 70 miles. I lost acceleration to the car. it starter bogging as I put more gas. could this be a bad fuel pump? I checked all my piping clamps, everything on nice and tight, is this common to happen a lot?

  • Reply Nazeed Allaham July 1, 2016 at 7:25 pm

    Hey im having a problem with my car
    Id be happy if you guys can answer some if my questions

  • Reply TNspeed September 28, 2016 at 4:23 pm

    so how well would a surge tank work on say a 900hp s2000 that's being built as a drag car would it be a good idea to go that route for it

  • Reply john smith October 9, 2016 at 6:27 am

    Even an internal bigger pump can increase the noise considerably let alone an external one

  • Reply Alex Rivers December 2, 2016 at 3:05 am

    how can i get rip of the gas fumes !!
    im getting real sick , actually runing my 240sx s14 V6 on a 2L fuel surge. i was thinking in SS tube lines, but not sure

  • Reply Justin Raymer January 22, 2017 at 12:42 am

    Excellent video, well spoken. Helped a lot clearing the fog for me.

  • Reply Ed DeVoe June 22, 2017 at 1:56 am

    OMFreakingGosh…….. why didnt i see this BEFORE i bought and installed an expensive fuel system that dose not deal w/ fuel sloshing (crying). Just installed last week, build has me broke and I have to keep 1/2 tank + at all times until I can add a surge tank some how.

    I have (2) 460lph fuel pumps IN my stock tank. What is my best option for a surge tank? Can u help me Steve? My build is almost ready for Start Up tune, visit my Facebook profile(Ed DeVoe) and check out my build album. Engine is in this months June, Muscle Mustangs and Fast Fords (torch red 02 NOT MY CAR & ANOTHER STORY). Building a car is an expensive education.

  • Reply PiroFyre July 5, 2017 at 9:30 pm

    I have a legit question about surge tanks. I have a single Walbro 450 I was planning on keeping as an in-tank pump and was wondering if it's a smart idea to route the in-tank to a surge tank with dual Walbro pumps (like the main being 450 and 2nd being 255 or even both being 450s). Or do you think that it'll starve during WOT that is IF the 450 in-tank cannot keep up with with a dual pump surge setup.

  • Reply Buff Production January 6, 2018 at 3:56 am

    anything wrong with installing surge tank in engine bay to utilize the stock fuel lines from the tank?

  • Reply TheDemo714 March 15, 2018 at 12:45 pm

    I gonna be building a 550-650 hp e85 s2000, already have an 450 walbro i was going to drop in but i was leaning towards a surge tank my question is if i do go with a surge tank what pumps/ pump should i be using in tank and in the surge tank?

  • Reply Curly VersaceChoppa April 6, 2018 at 9:51 pm

    Cavitation isn't from air pockets your thinking or aeration

  • Reply stealth418 June 15, 2018 at 12:13 am

    Watch this at 1.25x speed. Thank me later..

  • Reply Vasan Vasanth July 3, 2018 at 2:28 pm

    By installing surge tank.. Is that decreasing the fuel consumption??

  • Reply kasapomashero August 5, 2018 at 7:42 am

    Hi, nice videos! I have a question though. My 340AEM in tank pump overheats in my evo9 relatively easily in hot weather, especially when tank is less than half full. If install a fuel surge tank with an internal pump fix this? Or would the pump in the OEM tank still get hot and eventually failing to fill the surge tank?

  • Reply Cody Koala August 12, 2018 at 2:21 am

    My new fav channel

  • Reply EZoMack1 December 2, 2018 at 12:10 am

    but do these surge tanks run quite in comparison to the external fuel pump, cause my external fuel pump is killing me noise wise. Any input here?

  • Reply Manuqtix Manuqtix December 10, 2018 at 7:20 am

    To convert from returnless to return type. You need an external fuel pump and a fuel surge

  • Reply Jagan PJ April 17, 2019 at 12:55 am

    For which fuel the surge tank will be used???

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