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Discussion Starter · #1 ·
Have an 03 tib s/c currently running 3-4 lbs untuned sitting at a perfect 12.1 afr all the way through the rpm band. stock injectors. big walbro fuel pump. also have mafterburner installed. If I were to up the boost to 7psi, and increase fuel pressure, would i HAVE to change the injectors or could i manage a decent AFR with the stocks and a mafterburner tune?
 

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Yes.

Stock injectors are only able to push so much, they are just 190cc's
You should upgrade to at least 290cc if you want to push 7lbs.
Then you need to retune for the new boost level after setting up the new 290cc's
in all you're looking at
(6) 290cc injectors
Pulley
and a bit of time to install and tune. Not difficult, but time consuming to take the manifold off and put it back together.
 

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Discussion Starter · #3 ·
2.8 pulley is on its way, already have some injectors in mind. 290s off a 3.5 kia. mafterburner is already installed and ready to tune. what should i have my fuel pressure at then with the new 290s?

and ill just have to remove the supercharger and the fuel rail bolts right?
 

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i pushed 6psi just fine on my turbo setup while upping the fuel pressure. you should be fine, as long as you can adjust fuel pressure. just becarefull it may want to lean out up top, and pig rich down low. a tuner would make it easier but i think u should beable to get away with it, just dont go above 13.5afr at wot.
 

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I would not listen to promo. I would however listen to people who have boosted before.


What I would do is first figure out the max pressure flow on the stock pump / what the lines can tolerate. I'd say dmdicks is probably the person to talk to on something like that. I know when I personally had 290's and the idle fuel pressure at 45 (for some reason), and stage 2, I was taking away a sh*t load of fuel in open loop. So I'm willing to bet its pretty possible you could cheap the injector system, move the idle pressure up to somewhere in the low 50's, and maybe squeak on by with enough fuel. It'll probably be close though
 

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Discussion Starter · #6 ·
thats what i thought valkare. As you know, my fuel system is a little more original than just a walbro :) i just say that so people dont ask questions. two pumps in the tank. Right now at 4lbs the dyno showed a perfect 12.1 the whole way through. My idle fuel pressure is 52 or so right now. so if i crank fuel pressure a bit more and do a bit of tuning with mafterburner i should be able to stick around 12.5 or so on the stocks at 7psi of boost?
 

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Discussion Starter · #7 ·
oh btw that perfect 12.1 afr i have right now is absolutley no tuning. totally stock maps on mafterburner.
 

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promo has no idea what hes talking about. you should be fine. you might need to up pressure to the 60's
 

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i take it you don't have wideband and thats why your asking
 

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Discussion Starter · #11 ·
well i have an LM-1, just need a new oxygen sensor. besides, the second i get the car on my 2.8 pulley its going straight to the dyno so they will use their wideband, so i guess it doesnt really matter.
 

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Discussion Starter · #12 ·
and to promo - those calculators are ********. Im putting down 240 at the crank on my setup now. guess what size my injectors are? 190s. Guess what your calculator says i need? 250CC!!! whats my afr?? 12.1??? HMMmmmmmm.
 

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Discussion Starter · #16 ·
you set the max duty cycle to 1. its supposed to be at .8 or 80%
 

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Discussion Starter · #17 ·
and you also set the engine horsepower at 203. 203 is my wheel horsepower. i run 240 at the crank. now recalculate.
 

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Discussion Starter · #18 ·
so lets recap. Install 2.8 pulley for 7 psi, Up the fuel pressure to around say 60-62 on stock 190s, pull on dyno, then adjust with mafterburner if necessary?
 

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Yes.

Stock injectors are only able to push so much, they are just 190cc's
You should upgrade to at least 290cc if you want to push 7lbs.
Then you need to retune for the new boost level after setting up the new 290cc's
in all you're looking at
(6) 290cc injectors
Pulley
and a bit of time to install and tune. Not difficult, but time consuming to take the manifold off and put it back together.
I know you guys hate to admit it, but this post is correct. I would not go past a 3.2" pulley without 290's or larger. Can you do it, yes... Are you constantly maxing out your 190's... YES. Get the 290's and rest both easier and assured. If you do plan to run the 190's with a stage 2 let me know how that pans out.
 

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Discussion Starter · #20 ·
well said. uggghghgh. ok fine. ill buy the 290s. i just dont wanna be running crazy rich. i cant seem to get my fuel pressure at idle below 50
 
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