Ok, Getting Confused on Injectors - Boost Forum

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Ok, Getting Confused on Injectors
Tuesday, December 18, 2007 9:37 PM
Ok, I have a 1998 Cavalier with a 2200 engine in it. Its relatively stock, but completly stock on the bottom end. I would like to run around 7psi of boost. I have my copy of HPTuners, and I have also added in an aftermarket fuel pressure regulator that can reach a maximum of 80psi teamed with a Venom fuel pump. My questions are... do I need to change injectors for 7 psi of boost? What about 10psi if i get daring with the engine?

The way I look at it.. if i can up the fuel pressure to, lets say 55psi, my stock injectors should be dumping plenty of fuel in the engine at WOT expecially if I increase fueling tables on HPTuners and decrease them at an idle. I just really want to confirm my thoughts here because I could be very wrong.

The more I searched for the answer, the more I got confused. I would think I would be ok with my setup I have here, but if im not, what injectors do I go for? Some are saying pre-99 Z24 injectors are slightly larger and are perfect fit. I dont know, please anyone give me their oppinion.

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Re: Ok, Getting Confused on Injectors
Tuesday, December 18, 2007 9:58 PM
Your stock injectors are designed for stock fuel pressures on a stock car at a stock power level under stock circumstances. Upgrade them!





Re: Ok, Getting Confused on Injectors
Wednesday, December 19, 2007 4:19 AM
The admiral is absolutely right. That injector setup is put on that car for economy, not power. You will dump more fuel with higher pressures but you will be much better off upgrading your injectors to keep from leaning out.
Re: Ok, Getting Confused on Injectors
Wednesday, December 19, 2007 5:44 AM
Yea, def get bigger injectors. I have a set of lsj 370cc injectors Im trying to get rid of if your interested. Only 3k miles on them, $40 shipped.


Re: Ok, Getting Confused on Injectors
Wednesday, December 19, 2007 10:01 AM
Ok. So what injectors do I use. Iv searched and tfound that ford brown top work good, but i dont know what those are. Iceman, do you know the part numbers on yours?

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Re: Ok, Getting Confused on Injectors
Wednesday, December 19, 2007 9:11 PM
As everyone has stated, yes, you will need to upgrade your injectors.

Secondly, if I remember correctly, you have low impedance injectors, so this is what you will need to replace them with. Again, I believe that 96-98 2.4L, and 98-00 2.2L all run low impedance, and thus, any of these will "fit".

Third, you need to be concerned with duty cycle. I learned this by being an idiot and overlooking the basics. I had 320cc injectors on my fully-built, turbocharged 2.4L, running it at 17 PSI. Yeah, great, my wideband said everything was okay. Well, it wasn't. My car would cut under heavy loads. Why? Because I was overloading, overworking my injectors. You want to ultimately be shooting for a duty cycle of a maximum of 80% (or 0.8). Go HERE to the bottom of the page. That calculator will give a pretty damn good estimate of the size you should be shooting for. You can shove all the pressure in the world onto your injectors, but they won't keep up. Which brings me to my next point...

Get a wideband O2 sensor if you don't already have one. Without it, or at least access to one, you might as well stop what you're doing right now.





Re: Ok, Getting Confused on Injectors
Thursday, December 20, 2007 3:57 AM
He is absolutely right. I had the same problem with my camaro. It was fully built and the injectors I had in it would hit 100% duty cycle and it would fall on its face and sputter.
Re: Ok, Getting Confused on Injectors
Thursday, December 20, 2007 10:04 AM
Well, so what I am seeing is that the Z24 injectors are not going to be big enough. Its showing I need approximatley 350cc on my injectors. Who sells big enough injectors for the 2200? Wow, sounds pricey too. I am getting a wideband kit at the same time I get my turbo so I can attach it into my custom downpipe.

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Re: Ok, Getting Confused on Injectors
Friday, December 21, 2007 1:26 PM
If you are going to turbo, yes it is all going to be pricey.. Save up about $4000-5000 for this project..




My CarDomain!!! --- http://www.cardomain.com/ride/2543660
Re: Ok, Getting Confused on Injectors
Friday, December 21, 2007 7:14 PM
So, as confirmation, do the SS Cobalt injectors work and hook up to the 1998 2200 fuel rail?? I have a chance at buying some, so if they hook up without mods that would work out great. I searched and cant find a answer for my particular engine.

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Re: Ok, Getting Confused on Injectors
Friday, December 21, 2007 9:16 PM
yes they will fit but you have to slightly modify the fuel rail brackets to fit the shorter style injectors




Re: Ok, Getting Confused on Injectors
Saturday, December 22, 2007 1:45 PM
No problem in the end...I had to fab the fuel lines and such to get an adjustable regulator.

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Re: Ok, Getting Confused on Injectors
Saturday, December 22, 2007 1:48 PM
Sorry to repost but I forgot to ask... Has anyone done this?? Is it just a matter of a dremel and a few bits to cut the stock bracket an inch shorter or so?

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Re: Ok, Getting Confused on Injectors
Saturday, December 22, 2007 4:52 PM
i have SS injectors in mine. you just have to oval out the holes in the bracket so the bolt can go through a little higher, that way it pulls the rail a little lower to compensate for the shorter injectors.



Re: Ok, Getting Confused on Injectors
Saturday, December 22, 2007 10:59 PM
what is the cc's or lb/hr of the cobalt ss injectors?

becasue i'd like about 450 hp on mine whenever I get started and the estimated size ill need is 900/ 85 lb/hr... now those are some huge injectors

any tips on the best type to get and where to get them? (peak and hold or saturated?)

'05 sunfire. rksport intake, 2.25" custom dual catback, b&m short throw pacesetter header and high flow cat.
Re: Ok, Getting Confused on Injectors
Sunday, December 23, 2007 10:54 AM
Cobalt SS are not anywhere near that, since they are only 200 some horsepower. They have around 310cc-350cc. I dont know the exact number. Not anywhere close to 400hp flows.

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Re: Ok, Getting Confused on Injectors
Sunday, December 23, 2007 12:00 PM
The lsj injectors are 370cc.

And once again I have a set with only 3k on them for sale


Re: Ok, Getting Confused on Injectors
Sunday, December 23, 2007 12:35 PM
jonathan Jones wrote:what is the cc's or lb/hr of the cobalt ss injectors?

becasue i'd like about 450 hp on mine whenever I get started and the estimated size ill need is 900/ 85 lb/hr... now those are some huge injectors

any tips on the best type to get and where to get them? (peak and hold or saturated?)

Low impedance are the best for performance. Which I believe are called saturated. The best way to tune a motor like that though would be to do staged injection, so that you can have a tolerable idle and cruise as well as still have the available fuel when you are under boost.


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"Youth in Asia"...I don't see anything wrong with that.
Re: Ok, Getting Confused on Injectors
Sunday, December 23, 2007 9:02 PM
Brian Whalen wrote:
jonathan Jones wrote:what is the cc's or lb/hr of the cobalt ss injectors?

becasue i'd like about 450 hp on mine whenever I get started and the estimated size ill need is 900/ 85 lb/hr... now those are some huge injectors

any tips on the best type to get and where to get them? (peak and hold or saturated?)

Low impedance are the best for performance. Which I believe are called saturated. The best way to tune a motor like that though would be to do staged injection, so that you can have a tolerable idle and cruise as well as still have the available fuel when you are under boost.


injectors are basically universal when slightly modified right?ill look at some saturated injectors nd see what i can find. im not sure what you mean by staged injection.

'05 sunfire. rksport intake, 2.25" custom dual catback, b&m short throw pacesetter header and high flow cat.
Re: Ok, Getting Confused on Injectors
Monday, December 24, 2007 9:29 AM
Staged injection is when you use smaller injectors (usually placed in the stock location) which run all the time to tune the engine under light loads, then you have seperate, much larger injectors made to fit on a modified intake manifold (usually along the runners) that are used for tuning under heavy loads. The reason people do that with high HP/liter engines is because using just large injectors is difficult to tune with. You can fine tune better on the low end with a smaller injector rather than a large one. If you were going to do staged injection, you would need a standalone PCM or I believe HPTuners can do it as well (not positive though).


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"Youth in Asia"...I don't see anything wrong with that.
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