why cant i just order 220cc or higher injectors from like accel for this thing? wouldnt that increase my fuel input...there is only so much the ecu can lean out the motor....

 

Why would you want to increase injector size?????

The only reason you would do that is when your going with a turbo or supercharger to a certain degree

going to a higher injector size is worthless unless those things are already on your car

 

only way to get any real horsepower outta modding the head..intake...exhaust manifold...and exhaust is to increase the fuel going into the motor....since my apexi afc-ii is useless only other way i can figure to force more fuel into the motor is bigger injector....these motors run way to lean.....
by the way my all motor civic with b18c stroked and bored has 440cc injectors and an afc tuned on dyno for them.....just the better spray pattern from some real injectors increases power....

 

lets see here b18c =170 hp 1nz-fe engine = 108hp.....your giving this engine to high of expectations....if your expecting numbers.....look at a different car.....increasing injector size on this wont gain you anything....this might be a strong motor....just not in the way your wanting

 

the b18c on the civic is bored and stroked not to mention fully built from the ground up....258whp with 12.5:1 compression....daily driven
guess this little scion motor is gonna get a work over......

 

bored everything out and do that and let me know how it turns out im thinking of doing that also but then again im thinking of just buying a crx and slapping a gsr supercharged like i did in my previous 96 hb

 

Ok, here's how injectors work with performance modifications....

The stock injectors will work and feed all the fuel you need until your air flow exceeds the limit of the injectors. For mild modifications the ECU will increase the duty cycle (how long the injector is open) to accomodate the increased air flow. Once your injector duty cycle exceeds 80% or so it can begin to overheat and malfunciton so you need larger capacity injectors so the ECU can use a shorter duty cycle to supply the required fuel. Larger injectors do not mean more HP.... If the injectors are too large and the ECU has to shorten the duty cycle too much to supply the correct fuel it can cause problems too. Kind of like that Goldie Locks & 3 bears thing... Too small, too big....JUST RIGHT.

Sooo, what makes you think these engines run lean?? Have you run a good wide band O2 sensor and seen what really is happening?? I would guess that these engines run JUST RIGHT for what they are stock.

I would bet it will take a better intake and header/exhaust than is currently available for these engines to exceed the stock injectors.

ken

 

i think that before bigger injectors are needed, you could still change the intake, ehxaust, raise the compression, and maybe port the head.

 

Before that, check afr's first.

 

Ok lets just look at it the simple way.

More air + more fuel = more power.

now this is what you want to do.

Nothing + more fuel = ________ (fill in the blank)

i think thats the easiest way to explain it. You need some serious air to upgrade the injectors.

 

Here is what I would do. Some honda had to have found out that 440's work or whatever. I used 720's on my itr because I had to, turbo was starving.

For this car I doubt afr's have been checked or anyone calculated how much injector you need for the hp you are looking for. How are you going to control the injector? Don't just put in 220's!!!

.02

 

running 'lean' makes MORE power. They aren't running leaner than stoich.

 

according to the aem a/f ratio gauge i have and wideband o2 welded in place before cat....hardly ever are in the yellow leds....mostly runs at the edge of the lean and stiotch.....like 3 reds leds and 1 yellow.....very lean....like when i first got my civic si it ran like that.....but on dyno it hurt power..... www.midnightperformance.com does my dyno'n...to lean like that to get the mpg's outta it like they do and it hurts performance....

 

Also remember, the Scions use a returnless EFI system, which is even more finicky as far as injector duty cycle and pulse width is concerned. This is probably the number one reason why you haven't seen too many people put forced induction on these cars... cuz you can't just toss a rising rate fuel pressure regulator on the end of the rail to account for the additional air.

 

you have to look at what an engine will do when it's TOO lean. the ecu takes a calculated value from its fuel maps based on all the inputs its receiving to determine the vehicles operating fuel trims. when the fuel trims are too lean, the engine will reduce its ignition timing advance in order to prevent detonation or other drastic engine failure. manufacturers DO NOT make their cars run too lean such that timing advance is pulled. that would just be a dumb way to make a car. if thats how they made the car, it would prematurely fail and toyota would have a few recalls to do. ive driven a couple of scions, and i can tell you that it doesnt run too lean. you could tell if it was. the car would practically fall on its face from running too lean when you put your foot into it.

bigger injectors with no way to control them would hurt performance. the leaner the car runs without pre-ignition...the more timing advance you get, therefore the more power you get. if you put bigger injectors in that motor (especially friggin 220cc or larger injectors) the mixture would run rich and you wouldnt get as much timing advance, therefore your power output would be far less.

i run 550cc injectors on my talon and 23psi on a turbo that flows 550cfm at 15psi so i find it hard to believe you ran 440's on an all motor, high compression 1.8L engine. first off, i have more displacement and on top of that, i cram tons of air into my engine. even by buddies turbo'd integra runs less than 300's in his.

this motor shouldnt ever need larger injectors until they decide to wrap up some of those FI projects that everyone and their dog seems to be working on.

 

i run 440cc injectors with resistor mod on obd-1 tuned by www.midnightperformance.com no problems at all....even idles ok....so dont know where u think i cant run them....cause i do....oh and i hit 268whp at the last run.....the stock injectors fell off about 7,900rpm i started leaning out.....