Raptor wrote:Crash wrote:factory 19lb per hour injectors
2.4s are 24lb/hr, aren't they? That's what I've picked up reading this forum, anyway...
Yeah they are, the 2.2's are 19 lb/hr.
Crash wrote:any bigger injector will flood a little bit at idle therefore causing it to be a little rough......reason being is this.....factory 19lb per hour injectors are what the car is programmed for...so lets say the fuel map calls for 30% pulsewidth at 1000RPMs......well then you put in 30lb per hour injectors......30% of 30lbs is a hell of a lot more than 30% of 19lbs....so therfore you are getting more fuel dumped into the engine...so without changing the fuel map.....it will cause a rougher idle with bigger injectors
You're thinking is a bit off, but the theory is the same. Neglecting fuel pressure, which changes with throttle position (and even more if you have a FMU), that works. But since the fuel pressure changes, so does the general size of the injectors. So...
Ford injectors are rated at 43 PSI, you have them at 35 PSI, so effectively at idle you are working with:
F2 = (35 * 30) / 43
24.4lb injectors at 43 PSI. Looks promising, but you have to remember that the 2.4L 24lb/hr injectors are rated at 55psi... so lets say they idle at 40 (I'm not sure what the idle fuel pressure is)
F2 = (40 * 24) / 55
17.4lb/hr.... All at 100% duty cycle. So if you want to figure out what your idle fuel pressure would have to be, to make your 30lb fuel injectors look like 17.4lb/hr fuel injectors (at whatever pulsewidth the ECU wants)...
17.4 = (X * 30) / 43
Solving for X
(17.4 * 43) / 30 = X
X = 25 PSI
Probably way too low for what you want, so the only way to get your 30lb injectors to idle like stock is to adjust the pulsewidth down, using an SAFC, E-Manage, whatever your heart desires that can change pulsewidths.
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well see the problem with the 35lbs are that they are so big that even with trimming them with a fpr they are still over 30lbs @ 35psi so the car cant handle them but i know the car can handle injectors at least around 28-29lbs so what i figure is get a injector thats around 30lbs and reduce idle pressure to around 35psi which will bring it down closer to stock injector size
i know for a fact that the 2.4 can handle 28.5lbs injectors because allot of people use the HO's and they idle fine
so the goal i figure is to find one smaller then the 35's but still larger then the 24 stock ones, the HO's would be awesome if they didn't crap out around 60psi
im not going for crazy psi of boost out of a turbo charger here im running the gm s/c so its say the same cfm so its not like i need 35lbs injectors @ say 80psi lol right now im using them up to 60psi and its still more fuel then what i need for my current setup im just running rich to be safe, i just need something that will support up to say 220-230whp which im sure 30lbs injectors with a fmu can handle, with a larger pump
i just need some idea of injectors
i personally was thinking of the 270cc RC ones. that way it is a little bigger then stock, but can handle the high pressure when need be.
Another thing i am looking into, is having RSM flash my computer/ get ride of the EGR code they say isnt a problem, but they arnt sure about running there s/c reflash on a car with a different power curve/ GM s/c.
But i will keep u updated on any info i find out for sure .
jake i was just gonna email them about the same thing last night lol but i forgot to when my girl called me up on the phone
damn girls they can be a distraction sometimes to what needs to get done lol
ya, i will probably give craig @ rsm a call today on my way to work. Price i think is around 350$ . I will let him know i have another guy interested in the same thing as me. I will keep in touch.
I don't understand why you want to change injectors when you can get a S-AFC for $200 USD and be able to control your ENTIRE fuel curve, including at idle?
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