Injector questions?

Discussion in '1994 - 1995 Specific Tech' started by GTJake, Jan 8, 2004.

  1. I already have my AFR's sitting in my room and the FTI cam will be on it's way. What do you guys think, 30# or 24# injectors? Would you guys ever buy used injectors? I found a set of 30#'s that looked good, but I don't know about buying used injectors. I figure the tweecer will allow me tune for the 30# if they are a little overkill.

    Here's the pic of the 30#'s....
    [​IMG]

    Thanks

    Jake
     
  2. I would say stick with the 24#'s if you don't plan on doing much else after the heads/cam, however, if your plan for more power go with the 30#'s. I think with a twEECer it can be made to run OK with either. I'd probably buy whatever I could get the best price on. I'd be a little hesitant about buying used injectors, but if they've been capped and not run for a long time, I think they might be OK. I'd just keep yours eyes open on ebay and the classified, I got my 24#'s brand new for $150 about a month ago off the classifieds.
     
  3. Yeah, I was kinda hesitante about buying used injectors, but I don't know, they should be okay with new o-rings and such?

    Jake
     
  4. I would use the 24# injectors. If your going to get into nitrous or boost, your going to need a bigger injector than a 30#, so to optimize your current set-up, I stay stick with the 24's. I also wouldn't buy used injectors. They could be clogged or not flowing properly, and the person selling them might not even know it. I would only buy them if they've been flow tested or whatever it's called when they make sure that all the injectors are working properly. When you get your cam from Ed, I would ask him what he recommends. He might say get the 30's, but I wouldn't think so.

    Joe
     
  5. Trust me go with the 24's all the way. I ran 30's in my car at first and even having a custom chip for them they were way to much. I ended up trading a buddy for his 24's since he was laying lots of nitrous to his car and needed more injector but I was lucky. Go with the 24's they will do you just fine.
     
  6. HP=(Nc X Injector X Dc)/ bsfc

    8cyl x 24lb x 85%(.85) duty cycle/.5 = 326.4 FWHP or 277.44 RWHP

    You should be about 290 rwhp w/ a good afr setup. Check out killercanary's setup on the main FAQ. You will be running the injectors over 85% duty cycle, which severly shortens the injectors life.

    You can get away with it, but I wouldn't want my car down because I decided to save a few bucks on injectors. I know the 30's are a jump in price, so it's your choice.

    btw, 8*30*.85/.5 = 408 FWHP or 346.8 rwhp.

    290rwhp = 60% duty cycle w/ 30's

    JMO
    Scott
     
  7. I was over 300hp with the old motor and almost certain I am about 30hp more with this new one and 24's are working just fine. Just so you know killercanary is also using the same 24's that I do and I think that he will agree that they will be enough for a 302 based street car with bolt on's.
     
  8. The 30#'s and the 24#'s are exactly the same price. I'll ask Ed what he reccomends. I'll probably just buy new because of what Joe said.

    Thanks guys.

    Jake
     
  9. go with the 30's. I had a dyno test and found out actually how lean I was running with an older setup than I have now and with 30's it was just perfect I would go with them by the way I bought mine used no problems.
     
  10. Well, I got an e-mail from Ed today. He said to go with 24#.

    Jake
     
  11. I am in the process of building the same combo as you and have researched this a lot. I've decided that the 24's are the way to go. I am planning on a AFPR, too. I think that the 24's might be a slight bit small, but a bit more pressure will correct for that. Adding pressure makes the injectors perform as if they were bigger. This will also improve atomization of the fuel, which, I believe, is helpful during idle. It's possible that an injector running at very small pulse width's can not have enough 'open' time to develop a good spray pattern. The 30's seem too large. They would make for even smaller pulse widths at idle (to emit the same amount of fuel as 24's), and perhaps poor atomization. I theorize that this helps to cause poor idle quality. Obviously, there are many factors that work with each other to cause problems. Hopefully going with the 24's will help to lessen those factors and work toward a better idle quality.

    Rick
     
  12. It is hit and miss with used ones. I got my 30's used, and they sat too long, and I had to pay to have them reringed and flowed. I since sold them to my friend, and they are fine. I bought my 36's used, and only had them out for about 1 month. Kept them capped and in a air-tight plastic bag.

    RC
     
  13. Scott

    I'm using 30's for the same thought process you have shown here.

    HOWEVER

    Even though 24's are close on the top end you can do the afpr thing and crutch them up a bit as many have done.

    The 30's at idle and at small pw's can be a problem causing a rich condition.

    I use a Tweecer so no fear of lean on the top end or need of afpr or too rich at idle.

    IMHO, If I did not have a tuning device or chip I think 24's & up the pressure would be the way to go.

    Later
    Grady