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injectors 7.4 vortec

This is a discussion on injectors 7.4 vortec within the Technical / Maintenance forums, part of the General Discussion category; I just replaced the leaky stock injectors for the ford 19lb injectors on my 99 7.4 burb. I cannot tell ...

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    Registered User justin302's Avatar
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    injectors 7.4 vortec


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    I just replaced the leaky stock injectors for the ford 19lb injectors on my 99 7.4 burb. I cannot tell a difference in power execpt better response, and easier hot starts, it just starts right up now. I also noticed it idles smooth now. So anyone looking for the alternative to expensive injector replacements look on ebay, I got used ones all 8 cleaned and remaned for 50 bucks!!!!! VS. The cheapest stock ones I could find were on rock auto for 39 a piece.

    All the yellow 19lbs are the same!! some say ford motorsport, it makes no difference. Don't get the small 3rd gen. The ones you need come on 86-2000 v8's 5.0's-4.6's,5.4's.

    If gas mileage changes I'll post. it'll take 2 weeks.
    Last edited by justin302; 08-27-2007 at 12:36 PM.
    1999 Suburban k2500 LT 7.4, magnaflow exhaust, dual batteries, wait4me tune, Bosch style injectors, 33" BFGs AT.

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    Registered User justin302's Avatar
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    Re: injectors 7.4 vortec

    I did a fuel pressure test and it is down to 52psi at idle and 60 with the key on engine off. When it is revved it jumps to 57. It runs ALOT better, I wonder why the fuel pressure is decreased?? Needs less fuel pressure to get same flow???

    It was at 62 psi at idle with the stock injectors. I have a new ac delco fuel pump and new fpr.
    Last edited by justin302; 08-29-2007 at 09:11 AM.
    1999 Suburban k2500 LT 7.4, magnaflow exhaust, dual batteries, wait4me tune, Bosch style injectors, 33" BFGs AT.

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    Registered User justin302's Avatar
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    Re: injectors 7.4 vortec

    bump
    1999 Suburban k2500 LT 7.4, magnaflow exhaust, dual batteries, wait4me tune, Bosch style injectors, 33" BFGs AT.

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    Registered User bradnear's Avatar
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    Re: injectors 7.4 vortec

    All has to do with backpressure(injector size, pretty much) when you have more flow, like with injectors that allow more flow, the pressure will be less as the flow is more momentarily, like when you revved it. Watcha looking for?

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    Re: injectors 7.4 vortec

    What did it take to fit them on. Are the Vortec and ford injection the same? Or did you have to modify the system to fit them on?


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    Re: injectors 7.4 vortec

    Did you tune for the new injectors? if you didn't your constant flow might be off. Ford runs and rate there injectors @ 39psi anything higher will provide more flow then what the injectors are advertised at. with my calculations the ford #19 injectors operating @ 52 psi are actually operating as #22 injectors therefore decreasing the pressure you saw stock.

    The lost in pressure from before to after isnt that great that i wouldn't focus on to much if i were you.
    Last edited by SmokedOutZ28; 08-29-2007 at 02:48 PM.

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    loose nut behind da wheel JeremyB's Avatar
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    Re: injectors 7.4 vortec

    A few people have done this, none have mentioned modifications. What are the factory injectors rated at, I doubt its 19 lb.

    Justin,
    62 pounds at idle is very high, 52 psi- like you have now sounds normal.

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    Re: injectors 7.4 vortec

    Quote Originally Posted by JeremyB
    A few people have done this, none have mentioned modifications. What are the factory injectors rated at, I doubt its 19 lb.

    Justin,
    62 pounds at idle is very high, 52 psi- like you have now sounds normal.
    I doubted it was 19 as well, until i did my own research. The factory injectors are #19

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    Re: injectors 7.4 vortec

    What is involved in the swap? is it just removing the stock poppets and putting in the ford ones or do you change out the CSFI unit and spider?


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    Re: injectors 7.4 vortec

    Thats weird, people on other forums have said that their software says that a 19lb injector can not deliver the HP that the 7.4 is spec'd at. I know that the 5.0 and 5.7 injectors are 19# with the CSFI and MPFI setups. The 4.3 probably uses the same injector

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    Re: injectors 7.4 vortec

    Quote Originally Posted by Koots
    What is involved in the swap? is it just removing the stock poppets and putting in the ford ones or do you change out the CSFI unit and spider?
    Koots
    The 7.4 uses a fuel rail setup similar to the 4.8 and 5.3 GM motors, no stinking spider assembly.

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    Re: injectors 7.4 vortec

    For the 7.4 it took no mods at all to swap out the injectors(4.3 5.7 use a differnt style). I think the stock injectors are rated at 21-22#'s. The fords are rated at 19 @ 3 bars (43 psi). the extra psi of the Chevy fuel pump makes them almost the same. I noticed greater power all the way around (from a stop and on the freeway).

    And the loss if fuel pressure I hope will prolong the life of my pump.
    1999 Suburban k2500 LT 7.4, magnaflow exhaust, dual batteries, wait4me tune, Bosch style injectors, 33" BFGs AT.

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    Re: injectors 7.4 vortec

    you could have opted for a set of 24 pounders then?

    and ford, chevy and I am sure Dodge have used the same high Impedance injectors in cars and trucks for years.
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    Re: injectors 7.4 vortec

    Quote Originally Posted by JeremyB
    Thats weird, people on other forums have said that their software says that a 19lb injector can not deliver the HP that the 7.4 is spec'd at. I know that the 5.0 and 5.7 injectors are 19# with the CSFI and MPFI setups. The 4.3 probably uses the same injector
    Yeah thats what i stated as well in another thread on this forum and was shot down by many people that said they were #19's then did a search on the net and found the same info. The #19's can only up hold like 240hp max on a n/a engine my thinking was that they should at least be 22's or 24's chevy used 22's in the 305 tpi motors starting in the late 80's so why go lower with a 7.4 454 i dunno! I orginally suggested a bigger injector then stock as it wouldn't hurt anything if it was tuned in properly and allowed room to grow with modifications.
    Last edited by SmokedOutZ28; 08-29-2007 at 07:05 PM.

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    Re: injectors 7.4 vortec

    Well I only say that the 7.4 runs WAY stronger now. So who ever says the ford injectors are only good up to 240 hp is mistaken. The stock 7.4 290 hp so....There was a couple of web sites that said the ford injectors are direct replacements, look at http://www.fiveomotorsport.com/Injec...tsGMTrucks.asp

    I also found one other web site that said they replace the stock 7.4 GM multec injectors with bosch injectors, so I called the guy and he said it was the ford (bosch) injectors that they used.
    They also said the 19#ers (bosch) out flowed the GM multec injectors, so it is an upgrade. Now with the lower fuel pressure I hope to get more miles out of my new fuel pump!!!
    1999 Suburban k2500 LT 7.4, magnaflow exhaust, dual batteries, wait4me tune, Bosch style injectors, 33" BFGs AT.

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    Re: injectors 7.4 vortec

    Quote Originally Posted by justin302
    Well I only say that the 7.4 runs WAY stronger now. So who ever says the ford injectors are only good up to 240 hp is mistaken. The stock 7.4 290 hp so....There was a couple of web sites that said the ford injectors are direct replacements, look at http://www.fiveomotorsport.com/Injec...tsGMTrucks.asp

    I also found one other web site that said they replace the stock 7.4 GM multec injectors with bosch injectors, so I called the guy and he said it was the ford (bosch) injectors that they used.
    They also said the 19#ers (bosch) out flowed the GM multec injectors, so it is an upgrade. Now with the lower fuel pressure I hope to get more miles out of my new fuel pump!!!
    Well i didn't specifically say ford injectors but any #19 injector running @ 43.5 fuel pressure are only good to 243.2hp it doesnt matter who make them there still only capable of supporting that much hp without going over the Max recommended 80% duty cycle @ 43.5hp. Now since your truck is designed to run a higher psi it makes the ratings different. Your Ford #19 @ 52 psi are acting like #24 injectors so plugging in the numbers they will support 307.2hp The factory injectors you had being that there #19s with a 62psi fuel pressure was only designed to work at max 290hp if you were to increase the pressure then they would support more but that explains why gm only used a 19lb injector in the 7.4 because of the cranked up rail pressure. Hope that helps and explains things alittle better. Right now your good with the new injectors.
    Last edited by SmokedOutZ28; 08-29-2007 at 09:28 PM.

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    Re: injectors 7.4 vortec

    Just for kicks, what would happen if I were to swap out for 24# injectors??? Waste of fuel??? Or wheelies at every stoplight!!! New calibrated MAF?? I guess I would need better flowing heads and larger cam to create a demand for more fuel??
    1999 Suburban k2500 LT 7.4, magnaflow exhaust, dual batteries, wait4me tune, Bosch style injectors, 33" BFGs AT.

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    Re: injectors 7.4 vortec

    Quote Originally Posted by JeremyB
    Koots
    The 7.4 uses a fuel rail setup similar to the 4.8 and 5.3 GM motors, no stinking spider assembly.
    What a ripoff, how come it coudn't be that way with the other motors? silly GM...


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    Re: injectors 7.4 vortec

    Not always more fuel is better. To much fuel or running rich is no good. More fuel does not always = more power. Sometimes it will choke off the engine giving you less power/performance. More air does equal more power. But to do it in a good way is too build up air under pressure. Such as a turbocharger or a supercharger. You could put injectors in that engine from a semi and not nesscarily gain any performance. As for cost. I would only get a oem injector. Alot of other brands are just not reliable and last very long. And who wants to do that job more then they have too.
    Last edited by justy; 08-30-2007 at 06:00 PM.
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    Registered User justin302's Avatar
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    Re: injectors 7.4 vortec

    What about the marine version of the 5.7 vortec, doesn't that use regular injectors???
    1999 Suburban k2500 LT 7.4, magnaflow exhaust, dual batteries, wait4me tune, Bosch style injectors, 33" BFGs AT.

 

 
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