Component Selection & Design for 500 HP Fuel System

Discussion in 'Intake Systems , Fuel Systems and Related' started by Indycars, Oct 11, 2012.

  1. Indycars

    Indycars Administrator Staff Member

    Well I've resigned myself to another summer without driving my TBucket, that's both good and bad. Since I have another five months before it will be warm enough to drive an open car, I want to go thru the component selection and design for a fuel system that will feed the engine that I've built.
    Go here for the engine build thread: viewtopic.php?f=69&t=3814

    I say design because I see this a Systems Design project, I have to select the pieces that will work together as a complete functional fuel system as well as decide:

    1.) What size lines to use including the supply line and return line.
    2.) What materials to use for the metal lines.
    3.) Should I route the metal fuel lines, inside the frame, along side the frame or inside a tube along the frame.
    4.) Do I use barb fittings, NPT (National Pipe Thread), Army/Navy (AN) fittings, SAE O-Ring Boss (ORB)
    5.) Make it ALL CONNECT into one complete system.

    Every project should have goals and these are mine: (Please add your suggestions, so that I might add them to the list)

    1.) Solicit all the help I can!

    2.) Design a fuel system to supply the needs of a 500 HP engine from 50F to 110F.

    3.) System must be compatible with 10% to maybe 15% Ethanol if the new regulations go into effect, as I can't count on always having access to 100% pure gasoline.

    4.) This fuel system will extend from the aluminum fuel tank (Coors Beer Keg) to the carburetor float bowls.

    5.) Budget is $500. This system does not have to be of the caliber of a Pro Stock team that has thousands of dollars on the line if something fails, but I don't want to be stranded on the highway either.

    Every component (Pump, Regulator and filter) can be bought with any of the above types of connections. The preferred connection for me at this time is the ORB, since it does NOT need any sealer like NPT does, but it could always change with budget concerns. If you need to work on the fuel system, just get to work, there will nothing needed to put it back together again. No running to the hardware store for Teflon tape.

    So to kick this off, I'm going to post some information about the SAE O-Ring Boss (ORB) connection from the Aeromotive website.

  2. Indycars

    Indycars Administrator Staff Member


    AN vs. NPT

    Understanding port threads, adapter fittings and line sizes.

    The designation AN stands for Army/Navy and calls out mil/spec (military specifications) for dimensional standards of hydraulic lines, hose-end connectors and port adapter fittings. AN specifications are a popular standard met by all companies that manufacture AN style performance fuel hose and accessories. For many there has been much confusion about the subject of AN lines, NPT and ORB ports, and how all of this works together. Here are the answers for those wanting to know.

    The flare angle used to seal AN connections is required to be SAE, 37 degree, as apposed to the 45 degree flare commonly found on household plumbing adapters. This angle can be found on the male point of the port adapter fitting and on the female inside the hose-end nut. AN port threads are not NPT or “pipe thread” but instead utilize straight threads (like any normal fastener) and SAE O-Ring Boss (ORB) technology for sealing. AN lines, ORB ports and the appropriate port adapter fittings are measured in inch/fractional sizes.

    A dash (–) size in AN “speak” refers to the I.D. of a standard, thin wall, hard line as the basis to construct a comparable flexible hose that may be used in it’s place. A 1/2”, thin wall, hard line measures .500” on the outside diameter (O.D.), has an inside diameter (I.D.) of 0.440”, and a wall thickness of 0.030”. An appropriate, flexible replacement line would be –8 AN, with a minimum 0.440” I.D. Depending on line construction, rubber with stainless steel or nylon braid, or Teflon with stainless steel braid, the line’s wall thickness and O.D. may vary.

    AN line sizes will have a dash (-) preceding the line size. The number after the dash refers to the number of 1/16 of an inch O.D., thin wall, hard line to which the flexible line will compare. For example, calling for a –8 AN line would mean the engineer or system designer requires a flexible line, made of certain materials suitable for the application, that would have the minimum I.D. of an 8/16” (1/2”) O.D. hard line. The actual line construction is dictated by the application with regard to line flexibility, vacuum and pressure capability, abrasion resistance and chemical compatibility, etc. Regardless, the engineer knows a -8 line of any construction will have a minimum I.D. equal to 1/2” hard line (.0440”), and be able to support similar flow rates.

    Here are some of the common army/navy (AN) line and thread specifications:
    -04 AN line = 4/16” = 1/4” hard line. –04 AN Port and Fitting thread is: 7/16” -20 TPI.
    -06 AN line = 6/16” = 3/8” hard line. –06 AN Port and Fitting thread is: 9/16” -18 TPI.
    -08 AN line = 8/16” = 1/2” hard line. –08 AN Port and Fitting thread is: 3/4” -16 TPI.
    -10 AN line = 10/16” = 5/8” hard line. –10 AN Port and Fitting thread is: 7/8” -14 TPI.
    -12 AN line = 12/16” = 3/4” hard line. –12 AN Port and Fitting thread is: 1-1/16”-12 TPI.

    Modern, high performance fuel systems are predominately fitted with safer, better sealing, higher flowing, AN-ORB ports. These ports require a straight thread adapter fitting, with a sealing O-Ring installed over the threads, up to the hex, that disappears into the port when properly installed. No additional thread sealer is required or recommended.

    National Pipe Thread (NPT) ports, AN Ports and port adapter fittings:
    Over the years, in low-pressure hydraulics, NPT has been a popular thread for ports and adapter fittings. When NPT ports are used in a fuel system with AN line, an adapter fitting to convert from NPT to AN is required. NPT was designed for use with thick walled pipe, typically black pipe, used in fixed structures like buildings, to handle distribution of water and natural gas. Black pipe isn’t particularly bendable, flexible or lightweight and hardly desirable for plumbing a high performance fuel system. As a result fittings that adapt NPT ports to AN line are common to allow flexible AN lines to be utilized in performance automotive fuel systems.

    Unlike AN thread, which is straight, NPT ports and fittings are both tapered. NPT male to female adapters start loose, threading easily but get tight and harder to turn well before the hex touches the port. When threaded together, the NPT design creates a wedging effect, binding the thread in order to seal. The use of a thread sealant is common and required with NPT, as it does not consistently create a positive seal on it’s own, like an O-Ring configuration. It’s common to see a number of threads showing on the adapter fitting when NPT is sufficiently tight, making NPT assemblies bulkier and less clean appearing than a similar AN assembly.

    NPT ports are commonly adapted to AN lines, but the NPT size designation is confusing, identifying the pipe I.D. rather than the O.D. Black pipe has a much thicker wall than hard line, so the pipe/port O.D. is much larger than the NPT size would seem to indicate. For example, a 3/8” NPT port will have an outside diameter of 5/8”, allowing for a wall thickness of 1/8” (0.125”). As a result, NPT port sizes allow use of a one step larger AN line than their indicated size would seem to support. As long as the wall of the adapter fitting is not overly thick, the following NPT Port to AN adapters will provide a common I.D. throughhole:

    Maximum AN line for NPT port size:
    1/4” NPT is compatible with up to -6 AN (3/8” hard line)
    3/8” NPT is compatible with up to –8 AN (1/2” hard line)
    1/2” NPT is compatible with up to –10 AN (5/8” hard line)
    3/4” NPT is compatible with up to -16 AN (1” hard line)

    Adapter fittings are available for connecting larger than recommended AN lines to the above NPT ports. Beware, the inside diameter of the adapter fitting will necessarily be smaller on the NPT side, creating a flow restriction that many racers and hotrod enthusiasts overlook. This is a poor practice and should be avoided, but when no alternative is available, consider sourcing a steel NPT to AN adapter from a good hydraulic supplier. Steel adapters will have a thinner wall than aluminum, due to the increase in material strength, leaving a larger I.D. to support higher flow on the too small, NPT side of the adapter.

  3. grumpyvette

    grumpyvette Administrator Staff Member



    viewtopic.php?f=55&t=1939 ... bzyv5ytbP1
    [​IMG] ... uIoAa5RRBs

    for carbs you need consistent fuel flow at 5-6 psi, fuel injection usually requires a 40psi plus fuel pressure, the line size and the fuel pressure regulator will have a big effect on your results, theres some threads and calculators above that will help, generally a 110-150 gph pump and 3/8" / AN#6 lines minimum ,works fine up to about 550- 575hp,with fuel injection systems running 40 psi pumps , but with carbs and lower pressure than above that Id suggest a 1/2 AN#8 line once you get to 500hp and want to go higher
    (Ive always used AN#8 and a 150 GPH rated pump on carb equipped application's for street/strip cars")
    and selecting a fuel pump that can supply at least 50% more flow than the carb or injectors can flow to compensate for the flow restrictions the filter and lines etc. provide.
    keep in mind aluminum fuel lines are far weaker than stainless fuel lines but stainless fittings require a 37 degree flare
    I generally run hard lines for fuel supply and return, but I have run flex lines inside 3/4" emt electrical tubing inside the frame rails ,except for the last 18" between fuel pressure regulator and carb. I buy flex and or hard lines at the local hydraulic supply after I measure very carefully then have them fabricate the lines.. with the correct ends fabricated on the ends of the lines.
    Ive found , running 3/4" EMT tubing which is fairly easy to bend then slipping flex line thru it to be a good system, and yes before you ask youll want to have two because youll have a RETURN LINE , but having two hard lines and skipping the flex inside the protective outer EMT, takes up less room
    Last edited by a moderator: Jun 27, 2018
  4. Indycars

    Indycars Administrator Staff Member

    I thought the AN-ORB connection needed a picture to fully explain why it would be better.

    You can see there is NO teflon sealer needed when you put this connection together.

    AN-ORB Connection02.jpg AN-ORB Connection01.jpg
    Last edited: Jul 9, 2016
  5. Indycars

    Indycars Administrator Staff Member

    I'm not completely sure, but I don't think you can just buy one of these AN-ORB (O-Ring Boss) fittings and screw it into another component unless it is also made to accept the O-Ring. Therefore you have to buy fuel pumps and pressure regulators that are made to specifically accept an ORB fitting.


    Attached Files:

  6. Indycars

    Indycars Administrator Staff Member

    I went thru the calculation to see what size fuel pump I needed. You can go thru the calculation
    or you can use the chart provided to get the flow requirements. The chart shows the flow needed
    at the carburetor, not the free flow that you most often see from the manufactures. The pump
    should be located as close to the fuel tank as possible and therefore there are several restriction
    to the flow long before it gets to the carburetor. It's possible to calculate the pressure drop for
    every type of fitting and line size if you can find it from the manufacture, but good luck.

    There are so many variables involved in the final flow needed in each system that the graph will
    be plenty close to put you in the ball park. Some of the variables are; line size, number and type
    of fittings (30°, 60°, 90° & 180° fittings), even what brand you buy makes a difference because
    not all have the same internal sizes.

    Most of the time I see where they take the calculated flow requirement and then double it, then
    buy the next bigger fuel pump rating using the free flow number.

    Using my example of 500 HP and a BSFC of 0.55 lbs/hphr I would need a pump that puts out
    43.4 gal/hr (GPH). Then double that and you get 86.8 GPH.

    So to be on the safe side I would buy pump rated at 110 GPH or greater.

    Last edited: Jul 9, 2016
  7. grumpyvette

    grumpyvette Administrator Staff Member

    keep in mind that many fuel pumps for carburetors, are rated for flow against ZERO back pressure, youll get a huge reduction in total fuel flow against a 6psi back pressure thats almost standard in a carb equipped application, vs pumping against zero back pressure.this can be tested this is less common with EFI fuel pumps that are generally rated at a set back pressure.
    many problems I see with restricted flow,where its obvious the system goes LEAN, that are not related to simple adjustments like float levels or injector size, are related to the FEED or suction side restrictions of the fuel system , many guys seem to assume a stock fuel system works just fine when you boost power levels significantly, and in some cases they can, but if your adding several hundred horse power its unrealistic to expect the stock system to keep up with the increased demand without serious upgrades
    pressure is a measure of the RESISTANCE to FLOW



    viewtopic.php?f=55&t=733&p=1030&hilit=fuel+cell#p1030 ... est-5.html
    Last edited by a moderator: Dec 11, 2017
  8. Indycars

    Indycars Administrator Staff Member

    Trying to decide if aluminum tubing will work with today's fuels containing Ethanol.
    There is certainly some problem when aluminum and ethanol come in contact with
    each other, but it maybe very small when using 10% - 15% ethanol.

    I can't find a supplier of 1/2" steel fuel line, so if you know of one please post a link.

    I need to run a 1/2" return line and I also thought I would use 1/2" supply line to the
    100 micron pre-filter and then to the pump. After that it goes inside the frame, so
    I was planning on staying with the 3/8" steel line that's already there and inside
    the frame. The frame is constructed from is 2" x 3" square tubing. ... p?t=197352 ... ewall.html


    Attached Files:

    Last edited: Jul 9, 2016
  9. Indycars

    Indycars Administrator Staff Member

    I like the Aeromotive pump since it's connections use the ORB or O-Ring Boss, therefore it
    does not require any kind of sealer on the fuel line connections. But for the price, I could
    use the NPT that the other two pumps use.

    All 3 pumps put out 110 or 140 GPH free flow, so all of them should be able to meet the
    flow requirement of 500 HP.

    Does anyone have any input about the features which would ultimately help me decided
    which pump to purchase. Can I justify spending $114/$144 more for the Aeromotive
    pump over the Summit or Holley?

    Summit ....... $ 97.95
    Holley ......... $ 127.95
    Aeromotive ... $ 241.95

    Aeromotive Fuel Pump 11213.JPG
    Holley Fuel Pump 12-812-1.JPG
    Summit Fuel Pump SUM-G3136-0.JPG
    Last edited: Jul 9, 2016
  10. grumpyvette

    grumpyvette Administrator Staff Member


    heres some related info, keep in mind many parts are imported and quality varies a great deal as do prices, but price does not always indicate the level of quality, ID also point out that steel hydraulic/fuel line has far greater strength than aluminum line, and stainless tubing is far stronger than aluminum, but stainless won,t generally flare to much more than 37 degrees without cracking ... JM-1054KIT ... 42215.html ... 0496542215 ... l-4303.htm
  11. Indycars

    Indycars Administrator Staff Member


    Have you had a chance to use any of these pumps ??? Did you find any of them to
    be so cheap that it would leave you stranded the first week of operation ???

    I've been looking at so many pumps, that I failed to see that Aeromotive has the
    very same pump as the 11213, except that it uses 3/8" NPT connections 11203.
    It costs $52 less.

    BTW, don't believe everything you read on a online retail site. Summit specs the
    Aeromotive 11203 pump at 150 GPH (should be 140 GPH), it's the very same pump
    as the 11213 Aeromotive pump at 140 GPH. If it's critical, it's best to confirm
    ratings on the actual manufactures website.

    NOTE: Prices are prices.


    Attached Files:

  12. bytor

    bytor Well-Known Member

    Im on a fuel pump quest as well. Considering going with an EFI setup for a 383 build I’m working on and have a fuel delivery question. Has anyone had success running an inline fuel pump (Walbro GLS392) with a top feed tank? I have a 78 vette and I'm seeing mixed reviews of gravity feed pumps with the top feed tanks. How big of an issue is this for a street car? I have seen some recommendations to use a "Ford" in line pump because it will suck as well as push. The other recommendation is to use an 82 vette fuel pickup with an intank efi pump. The second option seems easier as I wouldent have to butcher the stock fuel line?
  13. Indycars

    Indycars Administrator Staff Member

    What size are the fuel lines ??? If they are not 3/8", then you would need to replace them anyway.

  14. bytor

    bytor Well-Known Member

    Yep, stock is 3/8 tank to pump and 1/4 return. So I'm thinking run a new 3/8 line for the fuel supply and use the stock 3/8 line for the return.
  15. Indycars

    Indycars Administrator Staff Member


    Attached Files:

  16. bytor

    bytor Well-Known Member

  17. Indycars

    Indycars Administrator Staff Member

  18. bytor

    bytor Well-Known Member

    I'm looking forward to seeing your build fire up for the first time. I'm not too far away. I have a Speed Demon 650 Mech. secondary carb on my current motor that I could use. I'm thinking it might be a lot to bite off doing a new build install, initial start and EFI all at once. Maybe for the initial start use the carb and make sure there are no mechanical issues to deal with. Takes a few unknown variables out of the picture as well. Then focus on the EFI setup. Thanks for the heads up on the link, I corrected it in my origonal post.
  19. Indycars

    Indycars Administrator Staff Member

    Yep when it fires the first time, there will be a grin as wide as the Grand Canyon AND will be there just as long too.

    Makes good sense if you already have a know carb to be at least close to being correct tune.

  20. grumpyvette

    grumpyvette Administrator Staff Member

    while a SBC engine like the one built here for the T-bucket ,can get by with AN#6 LINES (3/8") as your not likely to exceed the potential flow restriction limitations of that size fuel line, and you only need about 100-120 gph pump and about 6 psi, to support the potential 500 hp or a bit more, I'VE ALWAYS PREFERRED THE LARGER AN#8 fuel line size and an ELECTRIC fuel pump that puts out a minimum of 140-160 gph mounted back as close too the fuel cell or fuel tank,and as low as possible and used with a return style regulator.
    my current EFI 383 has a walpro 255 that provides 40 psi but uses 3/8" lines , and it will supply the required fuel to maintain about 500 hp.
    keep in mind Im using an extensively ported stealth ram base with a custom plenum and throttle body and and 36 lb injectors on my 383 SBC
    on my 496 BIG BLOCK I found the larger size fuel lines and larger pump with a fuel cell installed mandatory, as the smaller lines allowed the engine power to drop noticeably by the time I had reached the 100 ft from launch point, swapping to the larger fuel pump helped noticeably, and its generally a good idea if you plan to exceed about 550 hp






    Last edited by a moderator: Dec 11, 2017

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