injector question

Discussion in '1996 - 2004 SN95 Mustang -General/Talk-' started by superstang01, Mar 9, 2013.


  1. superstang01

    superstang01 Member

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    will 39lb injectors be enough for my tork tech build on a stock bottom end? Im going for 400-420rwhp

    AND

    Will the MAF from a cobra be a direct swap if i get a jlt CAI for a cobra?
    #1
  2. Three50won

    Three50won Member

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    I would recommend stepping up to 42s. I don't think a Cobra MAF sensor will work. I think the Cobra has the IAT sensor separate from the MAF. The GT IAT sensor is integrated into the MAF. You could just find a MAF calibrated for 42s and you'll be set.
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  3. superstang01

    superstang01 Member

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    Yeah i think im going to do that!

    Thanks
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  4. SRT Handz

    SRT Handz I tripped & fell down and cut myself & got blood

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    I am using 39's and i am at 407... i could still go higher as well
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  5. tank_567

    tank_567 Active Member

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    Made 526 on 39lbs injectors
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  6. superstang01

    superstang01 Member

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    Nice! Would a cobra maf/injectors work for my tork tech build?

    i heard its bad to run cobra injectors on a 2v because they are split spray design?

    and i would need ev1-ev6 connectors, correct?
    #6
  7. SRT Handz

    SRT Handz I tripped & fell down and cut myself & got blood

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    I think most people on forums over-buy on injectors. Same with clutches.
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  8. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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    39 or 42, whatever you find in the classifieds or craiglist
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  9. Three50won

    Three50won Member

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    You guys might have made your stated hp with 39s...but that is def pushing the limit. 42s at an 80% duty cycle for a forced induction engine are around 450 hp at the stock fuel pressure setting...if you do the calculation. And 80-85 percent is the safe zone. Maybe 90% if you're adventurous or have a lot of money or don't really care if you blow your engine. Of course you can up the fuel pressure...but to tell someone you made 526 to the wheels on 39s alone is misleading. Even NA engines with that much hp would be pushing those injectors to their limits big time. Forced induction requires more. You pretty much pushed those injectors and upped the fuel pressure to its limit. And I'm surprised the engine withstood that. A cool day or some bad gas would have blown your engine sky high because there would be no room for error. So yes, you could def make a great amount of hp with any injector. But to make 400-420 rwhp SAFELY at the STOCK fuel pressure would require a bigger injector.
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  10. superstang01

    superstang01 Member

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    so i was just going to buy whatever i could find the better deal on. So this morning i was looking on kijiji and found a 90mm lightning MAF, 42ln injectors and a svt focus pump for 250 and grabbed it!

    seemed like a pretty good deal!
    #10
  11. tank_567

    tank_567 Active Member

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    WTF are you talking about, whos out there running stock fuel pressure on a boosted engine? He's going to upgrade his fuel pump and a turner would adjust his fuel settings. When I made 500+ on the stock engine w/ 39s in, that was done with twin ford GT pumps on stock lines, rails and on a returnless setup.

    Nice!
    #11
  12. Three50won

    Three50won Member

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    WTF are YOU talking about? Like I said, if you push those injectors to their max and upped the fuel pressure, then yes a 39 lb injector can support over 500 hp to the wheels...it wouldn't be a safe combination and probably would last too long but it could be done. But to do it SAFELY with an 80-85% duty cycle and the stock pressure would require a bigger injector. Find a calculator and do the math. So while your set-up may have worked, my contention is that you were maxing those injectors out big time and that your set-up was not entirely safe. Which is why I said your statements are misleading. Because someone will read this and get the wrong idea. And BTW, on a returnless system, the fuel pressure is controlled thru tuning. So regardless of the pumps you had, your fuel pressure was at the stock setting UNLESS it was adjusted through the tune. I know this because I installed twin 255 lph pumps in my GT and monitored and adjusted all the fuel parameters when I tuned it. And another thing, there is absolutely no need to adjust your fuel pressure if you have the correct size injectors. Your pressure was adjusted because your injectors were too small. At 500 to the wheels on a 90% duty cycle for a supercharged V8, you would require at least a 50 lb injector. And a 90% duty cycle is pushing it. 80-85% is as much as I would go.
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  13. 84Ttop

    84Ttop They make new pistons every day, so why worry? SN Certified Technician Mod Dude

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    ^^ What Three50won said.
    90% duty cycle is risky, any more is plain stupid. I had a 2v 4.6 with vortech that made 495 rwhp and had 60lb/hr injectors and a1000 pump. One thing not to skimp on is fuel, you get one shot at running lean!
    #13

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