Thread: Everything about 02-06 WRX injectors (modifying to 740cc included)

To save u guys the hassle, I notice that the WRX O-rings was too big to fit in the fuel rail and too big to fit in the IM holes. Also if u switch the O-rings from your specv onto the WRX injectors it will still not fit nice and tight. You will need to buy a set of O-rings size 9/16" O.D x 5/16" I.D. You will need 2 per injector, use one for top and bottom of the injector. It fits perfect.

the Base 02-06 WRX injectors are 440cc's, just incase.

If u want more info i can provide it as well, lets just say those 440cc's injectors can also be converted to 740cc's with slight modifications

The Stock Blue 440CC injectors and the STI pink 540s are identical other then the end cap and the color so either injector will work for this mod. There is no advantage to having the Pink STIs once modded so sell them, Make some cash and mod your stock injectors.

There are a few ways to accomplish the mod but what needs to happen is the end cap of the injector needs to be removed. You can grind it off or cut it off. Does not matter really. You can use a band saw or a dremel tool and a vice.

Take your time and cut the silver end cap off where the nozzles (holes) are. Since you are removing the end cap you dont need to send these off to have them matched. What you are doing is removing the flow restrictor (end cap).

Questions:

How much will the injectors flow once modified?
740-750CC

What about the spray pattern?
You end up with a find disk pattern

What about the idle?
Rock solid idle as stock once AFR's are tuned.

What about reliability?
They are stock Denso injectors and you are just removing the end cap containing the sized holes.

Do I need a fuel pump?
Yes, Pressure at the injector is reduces since the injector body can now flow more fuel. You need a fuel pump capable of handing 740CC injectors. Walbro 255lph is fine.

What if I dont have engine management will these work on a stock ECU?
NO, You will nearly double the fuel flow so you will need a safc or other EM to calibrate these injectors.

I am still worried about equal flow. How Can I be sure this works?
You can send the injectors To Venom performance in California or RC engineering for testing once the mod is complete. Venom will even do the mod for you and test each one but the cost is nearly $300.

going boost?

not at all.. other plans.

updated

is that 740cc correct??

yep

oh i got it now lol. getting them opened up i must have missed that part

yea the 440cc's gets to become 740's after u open them up.

bump for nathan

Question...how do you modify them to make it 740cc? What's involved?

Originally Posted by ash

Question...how do you modify them to make it 740cc? What's involved?

Originally Posted by nightrider45

Take your time and cut the silver end cap off where the nozzles (holes) are. Since you are removing the end cap you dont need to send these off to have them matched. What you are doing is removing the flow restrictor (end cap).

...

doh! hahah

Damn that's it? wtfux!