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fuel injector question

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Old 07-25-2011, 05:21 PM
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Smile fuel injector question

Will ls3 injectors fit the stock ls4 manifold and fuel rail? Are the the same length as the ls4 injectors?
Old 07-25-2011, 05:37 PM
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No they will not, and no they are not. We do share the same style plug with them IIRC.

Can I ask why?
Old 07-25-2011, 07:50 PM
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I was wondering cause I know were to pick up a set really cheap and I was gonna use them in addition with a turbo on my gxp.
Old 08-01-2011, 11:04 AM
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Looks like they use similar injectors.

The LS3 injectors should be a direct replacement (regarding fitment) for your LS4 injectors.

Last edited by deatschwerks; 08-01-2011 at 01:44 PM.
Old 08-01-2011, 01:37 PM
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Originally Posted by deatschwerks
Looks like they use similar injectors.

The LS3 injectors should be a direct replacement for your LS4 injectors.
I doubt they have the same flow rates. I'd like to see some numbers before bolting them on.
Old 08-01-2011, 01:44 PM
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I agree with you there, since the guy is needing them for a turbo project I was assuming he was wanting them because they were bigger.

The LS3/LS7 injectors are ~34# @ 43.5 psi fuel pressure.

...and fixed my post to reflect I was referring to fitment.
Old 08-01-2011, 02:08 PM
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Originally Posted by deatschwerks
I agree with you there, since the guy is needing them for a turbo project I was assuming he was wanting them because they were bigger.

The LS3/LS7 injectors are ~34# @ 43.5 psi fuel pressure.

...and fixed my post to reflect I was referring to fitment.
We are about a 27.8# if I remember correctly so those would probably do well for a turbo car.
Old 08-01-2011, 04:20 PM
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They drop right in and use the same connector. We have a 4 bar (58 psi) returnless fuel system. They flow 41.7 lb/hr @ 4 bar. However, I have noticed some irregularities which I partially attribute to fuel pressure not being measured directly by the ECM. Since the system is only regulated at the self-contained pump, the ECM assumes 58 psi at the fuel rail and uses the MAP sensor to find the actual pressure drop seen by the injector (engine vacuum increases flow). I have some work planned that will systematically get me to the bottom of the irregularity over the next 2 months. What year GXP? What tuning software will you be using?
Old 08-01-2011, 05:49 PM
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Tune is key here. I've seen what happens when people don't get tuned for newer injectors, and if left long enough, it ain't pretty!
Old 08-01-2011, 11:38 PM
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Originally Posted by LS1 Racing
Tune is key here. I've seen what happens when people don't get tuned for newer injectors, and if left long enough, it ain't pretty!
Agreed, although I would assume tuning with the addition of a turbo. I recommend using 08 Vette tables until I work on the issue further.

Here is my thread on the irregularity I was referring to:

https://ls1tech.com/forums/pcm-diagn...frequency.html

The original injectors are going back in the car temporarily for a more careful analysis of the issue, but that won't be for a while yet.



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