injector size?

Discussion in 'Fox 5.0 Mustang Tech' started by Mustang88LXKid, Dec 3, 2003.


  1. stangbear427

    stangbear427 Active Member

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    If we're thinking about the same article, that was actually a Ford Performance 333 stroker. Otherwise, it was the 165's, and even that wasn't a normal 302, it was a CHP 306. Even in AFR's add in MM&FF they advertise the 185's on a 393 stroker. Telling ya, get them if you KNOW you are going forced or NOS later (maybe!), but on a NA 302 you'll be dissappointed.
  2. perkys stang

    perkys stang New Member

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    Have you ever done any research? Dyno ? Looked at the duty cycle of a 24lb injector????????

    400 N/A at the crank is a cake walk these days
  3. JJFIVEOH

    JJFIVEOH New Member

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    The 185s need to REV. And if anybody has actually raced, the stock 302 short block can handle 7000 RPMs. In my mind 7000 is pretty high. They only need 24# injectors. It may only put out 350-400, but has anyone actually tried using 24# on a stock motor?
  4. perkys stang

    perkys stang New Member

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    7000 maybe on a factory tach but I wouldn't push a completely stock 302 bottom end to that RPM...

    What does a stock motor and 24's have to do with his combo?
  5. stangbear427

    stangbear427 Active Member

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    It has to do with this is a stock bottom end he's talking about. A mediocre cam, oversized heads and a blower intake on a NA, unstroked motor. Granted, it is always better to err on the side of caution. With injectors, it's better to be a step larger then you need at a lower pressure than a step lower than you need and higher presure b ut either way if 24# er's don't keep up with what's on his list, something else is wrong.
  6. Michael Yount

    Michael Yount Advanced Member

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    If he builds it the to get the reasonable daily driver he said he wanted originally - the 24's will be fine (along with 165's and long-runner intake). If he builds a high-revving "beach" with 185's and spyder intake - I believe I'd go with the 30's; I think that motor will outrun the 24's. But I don't think he'll be happy with that motor.
  7. Mustang88LXKid

    Mustang88LXKid New Member

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    hmm thanks for the advice. But I got the AFR guide and 185's get peak power only a little higher than the 165s. for 185's 1500 RPM's to 6500 RPMs, which isnt really to bad. The 165's get peak at anything to 6000 RPMs. So if this helps any of you. This is the information i have gotten on my own.
  8. Michael Yount

    Michael Yount Advanced Member

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    AFR's generic guide isn't going to be as helpful to you as you think. You've got a lot of folks out here who have a lot of experience with these things which you can take advantage of if you choose to. One way or the other, I'm sure you'll figure it out. Good luck with whatever you decide.
  9. perkys stang

    perkys stang New Member

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    Like I have been saying have you ever datalogged or watched the duty cyle of a 24 lb injector on a motor makeing any kind of power...

    Example... GT40 headed , Zcam motor... 24lb injectors.. enough injector right? Wrong..

    With this combo while tuning the injectors were maxed out before 5500 RPM.. This was with 45lbs of fuel pressure..

    Wanna guess which ones I use?


    I think you can live with the 185's but the spyder has got to go for a street car... Get the RPMII or somehting it will make killer power.. My unported Holley made power to 7200 with no problem and no loss of tq...
  10. JJFIVEOH

    JJFIVEOH New Member

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    I wasnt aware that it was daily driven. Even so, the 185s wont take away that much low end torque and you can still keep the 24#s.....
  11. Michael Yount

    Michael Yount Advanced Member

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    Don't know what to tell you Perks - there are guys out there pushing well over 325-350 crank HP on the 19# injectors at pressures not too much more than stock with a/f ratios where they should be - indicating that the motors not running out of injector. I think part of the problem is that all injectors are not created equal. When flow tested, many 19's actually are capable of 21-22; I suspect the same up-side error occurs with some of the larger injectors too. For street cars I think the smallest injector that will get the job done should be used as the vast majority of the time you're asking the injector to function at the other end of the duty cycle scale - barely open; and the smaller injector does a better job of accurately metering small amounts of fuel than the larger one does. For the incredibly small amount of time my car (most street cars too I believe) actually spends at full throttle, I don't mind asking the injector to work pretty close to it's full duty cycle. I think this is one where we just see it differently. If I had a dedicated racer, yes, I'd go up to the next size injector to be certain; but not on a my daily driver - which is what this fellow said he wanted to build.
  12. stangbear427

    stangbear427 Active Member

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    Yeah, that was pretty much my take on it. I can see where Perk is coming from though- if his avitar is any indication, his injectors probably spend most of their life at WOT. Not necessarily applicable, talking about Z cams and whatnot when Kid specifically said no crazy camming and pretty much minor bolt ons. On the other hand, he still sounds like he's insisting on the 185's- so I have a feeling this project is going to get a lot more serious pretty quick after it's been together awhile, if not sooner...
  13. Mustang88LXKid

    Mustang88LXKid New Member

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    today I called CHP about all of this. They now carry AFR heads, the man I talked to told me he has a 5.0 daily driver and put in 185's and says its fine and he didn't lose and low end power. I also asked him about the spyder, he says that setup is fine and I won't lose any low end power. There's 2 different spyder intake manifolds too, I think some of you are thinking of the Super Spyder, which is for drag (I believe they used the super one in MM & FF). But they have Spyder manifold for the street. I'm now thinking about adding a CHP 331 stroker to the mix (1299.99, forged steel crank and forged steel pistons, all the rest of the kit), if I can get the funds together.....

    I'm not insisting but I've made this combo idea, I just want to see the input you have.
  14. TIMMY2734

    TIMMY2734 Founding Member

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  15. JJFIVEOH

    JJFIVEOH New Member

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    I don't want to say I told you so.............
  16. stangbear427

    stangbear427 Active Member

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    My input is that that's the best idea you've proposed in this thread yet. And for another $.02: I would recommend the 185's with that motor. I never said they wouldn't work on a normal 302, just that it's A LOT of money to spend on something that won't make a bit of difference- when 165's and a FTI cam with a Performer RPM intake would slap you with and extra 100HP+ easily.
  17. JJFIVEOH

    JJFIVEOH New Member

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    If you are investing $$$$ already to buy aluminum heads, why not get the 185s? It's not going to hurt you but it will help you in the long run if you ever make any changes.
  18. NoSloCoupes

    NoSloCoupes "I would do anything for a FREE muffler" Founding Member

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    Perky, you probably making 430-445hp at the crank....isn't that within range of what i hear 24# injectors will support. ;)

    I'm about to pull my 30's and t-rex to go back to 24's so i'll be faster,lol.
  19. Spyderd68

    Spyderd68 Founding Member

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    Call or check X2C Motorsports about a stroker motor, their prices cant be beat. They were very helpful to me when i was looking to buy a stroker motor.

    http://www.x2cmotorsports.com/

    Dave
  20. 86Cobra

    86Cobra Founding Member

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    AFR 185s kill low end torque. Yeah right. More inexperienced internet wisdom at work. :rolleyes:

    BTW, I recently stepped up to 36 lb injectors in my NA 306.

    Also, ditch the spyder. CHP just wants to sell you their crap. You'll be much happier with a Holley or RPM II.

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