Injector recommendation for LT4
Thread Starter
Drifting
Joined: Jul 2001
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From: Largo Florida
Injector recommendation for LT4
I am going to replace the stock ones and I found out that the factory ones are $60 each. What would be a good less expensive replacement? LT4 stock injectors are 28lbs.
Melting Slicks
Joined: Apr 2002
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From: down that one road next to that big tree
Re: Injector recommendation for LT4 (ericcer)
are you completely positive they are 28's? for the life of me i thought they were 24's. 28 is awful large for 330hp. you could use the ford 24 or 30lb injectors for a couple hundred dollars. probably the best bang for your buck
Thread Starter
Drifting
Joined: Jul 2001
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From: Largo Florida
Re: Injector recommendation for LT4 (gtsyellow)
LT1 are 24 lbs and LT4 are 28 lbs. I have heard that the Fords are the better quality ones. Do they fit exactly the same as stock?
Melting Slicks
Joined: Apr 2002
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From: down that one road next to that big tree
Re: Injector recommendation for LT4 (ericcer)
yea they do, they are exactly the same size and impeadence. it's a straight drop in. i just have no idea what you'd want between the 24 and 30. the fords are rated at 39 psi so a 24 would be 25-26lb on stock gm pressure and a 30 would be around 32. probably 24's for a bone stock car and 30's for a modified one and some prom work. i have a feeling the 30's would just be too rich for a stock car. i'm making 410-420hp and using the ford 24's with great success
Thread Starter
Drifting
Joined: Jul 2001
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From: Largo Florida
Re: Injector recommendation for LT4 (gtsyellow)
I would want to stick as close to the stock rating as possible. Looks like the Ford 30 lbs are closer. I have a adjustable fuel pressure regulator so I could adjust a bit. Who has the best prices for these?
Melting Slicks
Joined: Apr 2002
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From: down that one road next to that big tree
Re: Injector recommendation for LT4 (ericcer)
probably summit racing but i seriously think a 30 is too large for your engine. you can try it but you'll probably get better mpg on a 24 with more pressure. running a injector at lower psi reduces the spray pattern and also the power and gas milage. a 24lb injector at 45psi or so will be 26lb or so and your 02 can makeup the rest. running a 30lb at 34psi won't be nearly as efficent. ask around & see what some other people tell you.
[Modified by gtsyellow, 5:49 PM 12/14/2002]
[Modified by gtsyellow, 5:49 PM 12/14/2002]
Burning Brakes
Joined: Nov 2001
Posts: 1,241
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From: Houston TX
Re: Injector recommendation for LT4 (gtsyellow)
they're not exactly the same size. the ford/bosch/hitachi injectors are slightly shorter, from o-ring to o-ring. they'll still fit/work, but you need to pay some attention to how they sit. you can, for instance, slide the injector as far as it will go into the fuel rail, and there results a slight air leak between injector and intake manifold.
also, the injector characteristics, as far as slopes and breakpoints, differ by quite a bit. you'll never get the perfect, across the board fueling like when you use stock injectors, since not all injector parameters are tunable in the commonly available software.
there's probably enough adaption range to compensate, and engines are pretty damn tolerant to fueling uglies, so there's mostly no impact. but on some setups, there will be problems.
that said, since injectors spray better at higher pressures, you're better of using ford 24s at a higher than stock fp, than 30s at a lower than stock fp.
like gtsyellow said, don't forget the fords are rated at a different pressure, so take that into account when setting your pressures to compensate for injector size.
also, the injector characteristics, as far as slopes and breakpoints, differ by quite a bit. you'll never get the perfect, across the board fueling like when you use stock injectors, since not all injector parameters are tunable in the commonly available software.
there's probably enough adaption range to compensate, and engines are pretty damn tolerant to fueling uglies, so there's mostly no impact. but on some setups, there will be problems.
that said, since injectors spray better at higher pressures, you're better of using ford 24s at a higher than stock fp, than 30s at a lower than stock fp.
like gtsyellow said, don't forget the fords are rated at a different pressure, so take that into account when setting your pressures to compensate for injector size.
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Thread Starter
Drifting
Joined: Jul 2001
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From: Largo Florida
Re: Injector recommendation for LT4 (MSR)
actually, i should've asked, why are you replacing them?
Melting Slicks
Joined: Apr 2002
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From: down that one road next to that big tree
Re: Injector recommendation for LT4 (ericcer)
just was reading a few other threads & it jarred my memory about the z06 injectors. nice sets get sold on ebay for $150 and they are a 28lb injector. have you ever dynoed your car to see how much power it's making? also the fords have 2 set ring clips, use the first ones, if you shove the injector all the way in and use the second you'll wind up with a short injector. at least that's the way it was in my case.
also check the other thread where people are talking about injector size, another guy is running a similar setup to you & loves the 28's & is thinking of 30's. might also call around to TPIS and lingenfelter & see what they have to say for exacts
[Modified by gtsyellow, 7:48 PM 12/14/2002]
also check the other thread where people are talking about injector size, another guy is running a similar setup to you & loves the 28's & is thinking of 30's. might also call around to TPIS and lingenfelter & see what they have to say for exacts
[Modified by gtsyellow, 7:48 PM 12/14/2002]
Burning Brakes
Joined: Oct 2002
Posts: 1,152
Likes: 1
From: Wichita KS
Re: Injector recommendation for LT4 (gtsyellow)
Z06 injectors are actually 28.8 Lb/hour @ 58.4 PSI...Stock fuel pressure for the Z06 - $180 brand new on eBay :cool:
[Modified by superlund, 9:52 PM 12/14/2002]
[Modified by superlund, 9:52 PM 12/14/2002]
Burning Brakes
Joined: Jun 2001
Posts: 838
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From: Out by the bridge again, TampaBay
Re: Injector recommendation for LT4 (ericcer)
Eric,
Go with the SVO 30lb injectors. With your cam and other mods they will keep the A/F at the sweet spot. The SVO's are a little shorter but willl work fine. They're cheaper too. Have you been on a dyno with wideband yet?
Go with the SVO 30lb injectors. With your cam and other mods they will keep the A/F at the sweet spot. The SVO's are a little shorter but willl work fine. They're cheaper too. Have you been on a dyno with wideband yet?
Melting Slicks
Joined: Apr 2002
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From: down that one road next to that big tree
Re: Injector recommendation for LT4 (ericcer)
i'm really split on this one, i'm using the 24's and making pretty good power, enough to warrent 30s by a lot of peoples oppinions. TPIS swears 24's are plenty for my combo and even lingenfelter uses a 26-27lb on a 440hp/480tq 383 !! the thing that REALLY made me go 
was suggesting some of us might be near 100% cycle on a 24lb. this is DEFINATLY something i'm going to check into & make sure i'm not going too crazy in duty cycle. there are quite a few benifits to smaller injectors & most of them have been covered in this post. the one thing that's really made me stop my feet was the maxing of the 24lb on a similar engine to my own. i still find it odd i'm running so hard & TPIS and lingenfelter both shy on the smaller side {24/25lb on 350's and 26-28lb on hard 383's}
in short i think eric and i could both benifit from a chassis dyno and injector test while on it.
was suggesting some of us might be near 100% cycle on a 24lb. this is DEFINATLY something i'm going to check into & make sure i'm not going too crazy in duty cycle. there are quite a few benifits to smaller injectors & most of them have been covered in this post. the one thing that's really made me stop my feet was the maxing of the 24lb on a similar engine to my own. i still find it odd i'm running so hard & TPIS and lingenfelter both shy on the smaller side {24/25lb on 350's and 26-28lb on hard 383's} in short i think eric and i could both benifit from a chassis dyno and injector test while on it.
Thread Starter
Drifting
Joined: Jul 2001
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From: Largo Florida
Re: Injector recommendation for LT4 (Half Fast)
Before mods was 297 rwhp. I am waiting to get the car running right before I dyno after the LT headers, hotcam, and electric WP. I should be at 345+ rwhp now. Maybe the aluminum flywheel will show a little HP too.
Half Fast, I am concerned about the SVO 30 lbs actually being higher because of the different psi rating. Your setup can handle that since your heads are worked. Mine are stock. The Z06 ones sound attractive. I don't know if my stock fuel pump can maintain nearly 60 psi nor my adjustable fuel pressure regualtor. Anyone know for sure?
[Modified by ericcer, 9:38 AM 12/15/2002]
Half Fast, I am concerned about the SVO 30 lbs actually being higher because of the different psi rating. Your setup can handle that since your heads are worked. Mine are stock. The Z06 ones sound attractive. I don't know if my stock fuel pump can maintain nearly 60 psi nor my adjustable fuel pressure regualtor. Anyone know for sure?
[Modified by ericcer, 9:38 AM 12/15/2002]
Burning Brakes
Joined: Oct 2002
Posts: 1,152
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From: Wichita KS
Re: Injector recommendation for LT4 (ericcer)
You might squeeze 58 PSI out of the stock pump, never tried it myself though, it’s designed for 44 PSI so?
If in doubt about the Holley AFPR go out and hook up a FP gauge & crank the screw in and see what PSI you can get out of that combo.
I planned to use the Z06 Inj's from the start so I went with a Walbro GSS340 pump W/Hot wire kit & the Aeromotive regulator.
The SVO 30's are cool too; you just won't get the same amount of atomization in the spray pattern that you would get with the Z06 Inj's @ 58 PSI.
:seeya
If in doubt about the Holley AFPR go out and hook up a FP gauge & crank the screw in and see what PSI you can get out of that combo.
I planned to use the Z06 Inj's from the start so I went with a Walbro GSS340 pump W/Hot wire kit & the Aeromotive regulator.
The SVO 30's are cool too; you just won't get the same amount of atomization in the spray pattern that you would get with the Z06 Inj's @ 58 PSI.
:seeya
Thread Starter
Drifting
Joined: Jul 2001
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From: Largo Florida
Re: Injector recommendation for LT4 (superlund)
I found a formula that shows me how the rating changes on the injectors at any given PSI. Here is what I found.
Stock 27.4 lbs running at 42.5 psi gets me 27.08 lbs.
SVO 24 lbs running at 52 PSI gets me 27.66 lbs.
SVO 30 lbs running at 33 PSI gets me 27.54 lbs.
LS6 28.8 lbs running at 53 PSI gets me 27.44 lbs.
I don't like the low pressure needed for the 30 lbs SVO injectors. The LS6 injectors look like the best bet. Also I don't want to re-pregram the PCM. I am concern about using the SVO 24 lbs injectors because of the rwhp I should be putting down. I hear the 24 lbs are good for 400 crank hp and I would be slightly above that if I was making 350 rwhp. So the new question would be - can the stock pump handle 53 PSI? Is the LT4 pump any different than the LT1? Maybe better?
Can anyone point to a link for the LS6 injectors? I have looked twice on Ebay and cannot find them. Maybe they are not selling them anymore?
[Modified by ericcer, 12:36 PM 12/15/2002]
Stock 27.4 lbs running at 42.5 psi gets me 27.08 lbs.
SVO 24 lbs running at 52 PSI gets me 27.66 lbs.
SVO 30 lbs running at 33 PSI gets me 27.54 lbs.
LS6 28.8 lbs running at 53 PSI gets me 27.44 lbs.
I don't like the low pressure needed for the 30 lbs SVO injectors. The LS6 injectors look like the best bet. Also I don't want to re-pregram the PCM. I am concern about using the SVO 24 lbs injectors because of the rwhp I should be putting down. I hear the 24 lbs are good for 400 crank hp and I would be slightly above that if I was making 350 rwhp. So the new question would be - can the stock pump handle 53 PSI? Is the LT4 pump any different than the LT1? Maybe better?
Can anyone point to a link for the LS6 injectors? I have looked twice on Ebay and cannot find them. Maybe they are not selling them anymore?
[Modified by ericcer, 12:36 PM 12/15/2002]
Burning Brakes
Joined: Oct 2002
Posts: 1,152
Likes: 1
From: Wichita KS
Re: Injector recommendation for LT4 (ericcer)
LT1/LT4 pumps are the same, Jack @ Racetronix (supporting vendor) is the fuel pump expert maybe he will chime in on the 53 PSI, or you could give him a call if needed...The LS6 Inj's come & go on eBay but they are consistently on there, I just hopped over to eBay and found these. http://cgi.ebay.com/ebaymotors/ws/eB...tem=1874707373
How's that for service? :D
How's that for service? :D