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What size injectors should I get??

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Old Sep 17, 2010 | 11:55 AM
  #1  
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From: Ganiesville GA
Car: 1992 z28/1992 RS heritage edition
Engine: 350 tpi, 305 tbi
Transmission: 700R4,T5
Axle/Gears: G92
What size injectors should I get??

I need to change the gasket around my intake so I figured I would upgrade my injectors will It will be easier. also putting my throttle body on.


The car is a L98 z28 1992, It has a holley throttle body, aftermarket fuel rails, slp ported runners and plenum,vortec heads and intake, magnaflow cat-back. accel, plugs, wires 8.8mm. etc.

I need to put a fuel regulator on it soon but what size injectors do you feel would be good for this setup. It will also be getting longtubes in a few months.
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Old Sep 17, 2010 | 12:48 PM
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Re: What size injectors should I get??

Those are 22 pound stock. MAking them bigger will not add performance nor will an adjustible fuel pressure regulator.

I will give our a complete set with all the gasket for a great price. Pm me.
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Old Sep 17, 2010 | 01:16 PM
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From: Ganiesville GA
Car: 1992 z28/1992 RS heritage edition
Engine: 350 tpi, 305 tbi
Transmission: 700R4,T5
Axle/Gears: G92
Re: What size injectors should I get??

Originally Posted by InjectorsPlus
Those are 22 pound stock. MAking them bigger will not add performance nor will an adjustible fuel pressure regulator.

I will give our a complete set with all the gasket for a great price. Pm me.
I know but I will be needing more fuel soon. planning on heads and cam and a nitrous shot before the end of the year.
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Old Sep 17, 2010 | 04:53 PM
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Re: What size injectors should I get??

what kind of horsepower are you planning to run?
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Old Sep 17, 2010 | 05:45 PM
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Re: What size injectors should I get??

Originally Posted by david068513
I know but I will be needing more fuel soon. planning on heads and cam and a nitrous shot before the end of the year.
Your original post didn't say that.

See it doesn't work that way, injectors you need now may be different than what you need later. You have to be able to get the car to idle and not run lean on top.

How about you give me a call and we'll run through your plans now and in the future and see what we can do. We can talk mods, time frames, etc....

We'll put an action plan together rather than just guess and run internet calculators. We like to be involved with customer builds, it ensures a better result. Any monkey can run a calculator it takes experience, knowledge, and expertise to get it right.

We like to be involved with our customer builds, our personal technical experience can be useful for you. If we can help you out now, I'll work a deal with you on the next set when you upgrade. Not full price just a token upgrade cost, maybe no charge depending on what you're doing.

My cell number is 201-403-3699 listed here call me anytime now, over the weekend, anytime.

As far as your nitros upgrades, Injectors Plus works with STEVE JOHNSON for nitros design and implementation. Steve is a legened and considered the top NOS guy in the country. I can get him involved with your design and planning. We perfer wet flow as an install, and I have a special for $700 for a complete nitros kit for your motor. (not one of steve's kits) 125 shot.

Let's look at this whole thing as a project rather than a one off put it in and take it out process.

Last edited by InjectorsPlus; Sep 17, 2010 at 05:56 PM.
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Old Sep 17, 2010 | 06:13 PM
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From: WI.
Car: 1987 iroc
Engine: 383 TPIS intake, Dyno Don headers
Transmission: 700R4 w/Pro-built Auto/transgo 2-3
Axle/Gears: 3.27/3.70 borg warner 9 bolt
Re: What size injectors should I get??

Now there's a business I'm going to call when I'm ready for an upgrade!
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Old Sep 17, 2010 | 06:32 PM
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Re: What size injectors should I get??

Originally Posted by red rock
Now there's a business I'm going to call when I'm ready for an upgrade!
I appreciate it. I'm going to work hard to earn your business. FWIW I'm posting from my Droid from a pizza restaurant I'm at with Tue family. I'm always here.
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Old Sep 17, 2010 | 07:45 PM
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Re: What size injectors should I get??

You can "tailor" any application, but you cannot tailor anything without
horsepower.... you size injectors by horsepower.
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Old Sep 17, 2010 | 09:18 PM
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Re: What size injectors should I get??

Yeah, it's a piece of cake. Anyone can slap together a wet flow NOS XXX shot then tune it.

I was just asking my daughter, she's 10, she said she can put it together.

Steve is going to hire her for tech support, it's just a HP number, they're all the same...

(geeze, I typed that with a straight face)
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Old Sep 17, 2010 | 09:21 PM
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Car: 92 T/A 'vert
Engine: Mild .040 over L98 4 bolt mains
Transmission: Mostly stock 700R4, 2600 Vigilante
Axle/Gears: LS1 3.42
Re: What size injectors should I get??

Originally Posted by southbay08
You can "tailor" any application, but you cannot tailor anything without
horsepower.... you size injectors by horsepower.
OK. A (hopefully) 300-325 horse 305. Will stock 19's turned up to say 50 PSI be enough or should I go to 22's? Not trying to hijack but I see a few injector gurus are here right now.
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Old Sep 17, 2010 | 09:22 PM
  #11  
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Re: What size injectors should I get??

To the OP... If you buy the wet kit for $700, I'll throw you $200 toward the injectors.

It's a 125 shot.

Only Caveat is I have to check if I have any left on Monday. If I do, it's yours.
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Old Sep 17, 2010 | 09:26 PM
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Re: What size injectors should I get??

Originally Posted by watajob
OK. A (hopefully) 300-325 horse 305. Will stock 19's turned up to say 50 PSI be enough or should I go to 22's? Not trying to hijack but I see a few injector gurus are here right now.
For safety purposes I'd like to see you in 30s. But that depends on the cam. That is why it's not just a HP number in a calculator.

WHY? you ask?

It is my experience that if you can use a slightly bigger injector, the base calculation is 28, and get it to idle you are far safer on the top end. I just had a customer who melted a piston because the injector wasn't enough at the top although the all mighty calculator said it should be. The calculator is a good guideline but not the end of the story. Much like a flow bench or a dyno.

Better to run a bigger injector at standard 3 bar than a smaller injector at 5 bar.

WHY?

Because you can always compensate by lowering the base fuel pressure to say 39, but you can't make an injector magically bigger.
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Old Sep 17, 2010 | 09:32 PM
  #13  
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From: Location, Location!
Car: 92 T/A 'vert
Engine: Mild .040 over L98 4 bolt mains
Transmission: Mostly stock 700R4, 2600 Vigilante
Axle/Gears: LS1 3.42
Re: What size injectors should I get??

Cam card:
Attached Thumbnails What size injectors should I get??-cam-specs.jpg  
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Old Sep 17, 2010 | 09:33 PM
  #14  
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From: Location, Location!
Car: 92 T/A 'vert
Engine: Mild .040 over L98 4 bolt mains
Transmission: Mostly stock 700R4, 2600 Vigilante
Axle/Gears: LS1 3.42
Re: What size injectors should I get??

Also, Trickflow 175's and a TPIS big mouth/LTR set up.
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Old Sep 17, 2010 | 10:01 PM
  #15  
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Re: What size injectors should I get??

That's not a huge cam. Should be able to use 30s no problem.
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Old Jun 23, 2012 | 09:22 PM
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From: California
Car: 1992 Z28
Engine: 5.7
Transmission: Automatic
Axle/Gears: 3.23
Re: What size injectors should I get??

Hi,

I'm looking to replace my stock injectors in my 1992 Z28 5.7. I want to stay with stock. Are they 22lb injectors?
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Old Jun 23, 2012 | 09:26 PM
  #17  
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Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: What size injectors should I get??

wake up the dead. contact southbayfuel injectors for there bosch 3 22#hr.

http://www.southbayfuelinjectors.com...6&product=2769
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Old Jun 23, 2012 | 09:30 PM
  #18  
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From: California
Car: 1992 Z28
Engine: 5.7
Transmission: Automatic
Axle/Gears: 3.23
Re: What size injectors should I get??

Is the pice I see for 8 injectors? ($165.99/8). Just want to be sure.
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Old Jun 23, 2012 | 09:35 PM
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Axle/Gears: J65 pbr on stock posi 10bolt
Re: What size injectors should I get??

for tgo member there is a 10 percent discount you can pm julie at southbay08 for details.
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Old Jun 23, 2012 | 09:40 PM
  #20  
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Re: What size injectors should I get??

and yes the price listed is for a set of eight.
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Old Jun 25, 2012 | 10:28 AM
  #21  
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Car: 87 IROC Z28
Engine: 355 cid TPI
Transmission: Custom Built 700R4 w/3,500 stall
Axle/Gears: QP fab 9" 3.70 Truetrac
Re: What size injectors should I get??

I make a solid 450HP with 24 lb injectors. I also run them at 70 PSI. Do some research. You need to get away from the general "high performance" aftermarket hype. Injector lb/hr is simply a rating of output at 40 psi. What is really being measured is nozzle size. Raising pressure, to a certain extent, is the same as raising lb/hr rating. Apply more pressure to the fuel at the nozzle, and produce more flow though the nozzle. It also produces better atomization, which is important on our batch fire systems.

The key to choosing injector size is understanding what flow range you can achieve within 40-70 psi and what the tuning limit will be. Injectors can only run reliably up to 80% duty cycle and injector pulse width can only be so small at idle before you run into problems. I can almost guarantee that 30 lb injectors on your 300-325hp 350 are going to create a tuning problem, but what do I know.

Running high pressure requires a beefy fuel system. Your stock pump, or even most in tank upgrades will never hack it.
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