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Question on requirements using bigger fuel injectors

Discussion in 'New Edge Cobras' started by ATCzMustang, May 22, 2019.

  1. ATCzMustang

    ATCzMustang New Member Established Member

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    I talked with the folks at Comp Cams and I'm thinking about dropping in a bigger cam in the short future. One of the things I need to do is up the fuel injectors from the stock 24# ones to what they recommended which was the 39# ones used in a stock Terminator (i.e. like these FR ones: M-9593-M39). This is a NA 01' Cobra so the fuel compensation is just for the bigger cams.

    I know I'll need a new tune to account for the bigger fuel injectors, but is there anything else I must do as well if switching out the injectors? I'm really only interested in what's required beyond the updated tune and why it needs to be justified as it relates to the fuel system? The air induction and exhaust is already in good shape.
     
  2. blownstang4.6

    blownstang4.6 Active Member Established Member

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    What fuel pump is in it? With custom cams and longtubes you could make around 360rwhp. I have a svt focus 217lph fuel pump with 26k miles on it if you're interested. $70 shipped. Direct drop in.
     
    shurur likes this.
  3. ATCzMustang

    ATCzMustang New Member Established Member

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    So is a larger fuel pump required? I currently have the stock fuel pump on my 01' Cobra. Will it handle the 39# injectors?
     
  4. slo984now

    slo984now AKA 01yellerCobra Established Member

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    The injectors don't affect the pump, to a point. The short answer is yes, the stock pump can handle the 39lb injectors. But the issue is can the stock pump support whatever your power goal is? Usually if you need bigger injectors you also need to upgrade the pump. I honestly don't remember what the stock pump can handle. It's been a long time since I've run one. But it never hurts to have a little extra head room.

    If you haven't bought the injectors yet I have a set of Ford 47lb injectors I'd be willing to let go cheap.
     
  5. scottydsntknow

    scottydsntknow Active Member Established Member

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    I run Cobra #39s in my 00GT with a bone stock 99 Cobra swap. Why? They were $75 and I needed injectors lol. Rebuilt them with a $15 ebay filter/cap/oring kit. Stock pump in the GT. Honestly the 24s are probably fine but I'd talk to your tuner and see what they say. And by tuner I mean actual legit local dyno or remote tuner. If you are running bama or something like that then have fun...
     
  6. shurur

    shurur Well-Known Member Established Member

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    Even with LT and CAMS , I dont the think you will need bigger injectors. Generally they are needed if you add cubes or go power adder route.
    They may also be needed for higher than oem rpm cams, but I doubt it.

    If going with bigger injectors, I would get a bigger pump and even a bigger maf just to take it off the mod list...wth... they kinda go together in a set when you go bigger na cubes than the 4.6.

    I would contact Todd Warren (na svt) about it and inquire about his custom CAMS before pulling the trigger on anything.
    You can pm him from this SVTP site.
    NA SVT Camshafts, Modular Tech Group Public Group | Facebook
     
    Last edited: May 25, 2019
  7. scottydsntknow

    scottydsntknow Active Member Established Member

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    He doesn't need a bigger MAF. Only reason I'd change the MAF out is to go with a slot MAF for easier tuning/accuracy. He doesn't need a bigger pump either tbth if the factory one is in good shape but it is good to futureproof if its older.
     
  8. shurur

    shurur Well-Known Member Established Member

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    He probably doesn't need the bigger injectors either....but again...those should not be needed until going bigger cubes or power adder..or maybe higher rpm...

    I think of the three as a package deal myself once you get to the end of the 4.6 na hp range or go to a power adder.



    Yes,,My FP is intermittent right now..shes 19 years old..so....
    Also oil pan gasket..oil filter gasket...motor mounts...are all crap now..
     
    Last edited: May 26, 2019
  9. ATCzMustang

    ATCzMustang New Member Established Member

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    Yeah so I was planning on the works based on the cam specs, requirements, and talking directly with Comp Cams on the specific one I was looking at (106400) http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=960&sb=2

    Per the requirements for the cam:

    So here's the current plan:
    • Ford 90mm MAF M-12579-L54
    • Accufab Throttle body CTB99-01
    • Ford Racing 39# EV6 Injectors M-9593-M39
    • Walbro Fuel Pump (255LPH) TU229HP
    • Comp Cams 106400
    • Comp Cams Beehive Springs 26123-32
    Notice I added in the fuel pump. After some research, that Walbro is a drop-in 255LPH High Flow pump that's well rated. I even found a thread on this forum talking about it (https://www.svtperformance.com/threads/what-is-the-stock-2001-cobra-fuel-pump-lph.1079906/)

    I really was hoping to run those 39# injectors on the stock fuel pump, but I might run into issues at higher RPMs with the FP Duty Cycle maxing out at starving the engine for gas. If anyone has more feedback on any of the above, feel free to weigh in and I appreciate all the info.
     
  10. blownstang4.6

    blownstang4.6 Active Member Established Member

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    Yes it is a drop in pump. I have an svt focus pump with 26k miles which is also drop in that I'm selling. It supports 400rwhp boosted and is a common upgrade. $70 shipped. PM if interested.
     
  11. Snk-Byet01

    Snk-Byet01 Member Established Member

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    Kenne Bell has some nice tech write ups on pumps, fuel rails and etc. Of course they are trying to sell their BAPs but they put a lot of research and time into their findings. With that said, and what I read, 39# injectors should be fine for your application (with the KB BAP of course). Just my $.02.
     
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