According to Kingpin Performance, we don't need STI injectors. You can modify your stock injectors to flow 740-750. Taken from www.kingpinperformance.com

Its a tough choice on which injector to buy for your WRX. Buy STI Pink injectors? $300-$550 and you get an extra 100cc worth of fuel. PE 650 or 850's? $600-$800 a set and because these are mechanically slow you need tuning or a flash to make them work correctly. Other companies sell an option for $450 and another that requires you to solder in a resistor pack. You can skip all of this and make your own 740CC injectors for free.
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. There will be no adjustment a injector shop can do anyways since they are sealed units. What you are doing is removing the flow restrictor (end cap). The biggest advantage is that the stock ECU is calibrated for the correct opening time compensation for these injectors (dead time). PE's are twice as slow and need more dead time. All of the issues that the PE's bring to the table are absent with these injectors.

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 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 Utec, SAFC, Link, Gems, Flashed ECU 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.

Why are you posting this information and not selling modified injectors?
Because it costs nothing to do this mod and its better to give back to the community. If you do not want to perform this simple mod yourself there are companies out there that will take your $200-$300. Maybe one of the members will try this, report back and offer to mod your injectors for a reasonable price? $50? This way its worth his time to do it and you save a ton of cash in the process by not having to spend $450+ on injectors. Work as a community guys

How many cars have you tuned with these injectors and how long have people been running them?
Kingpin has tuned 7 cars with these modified injectors. All idle smooth, All run fantastic and all have low IDC's One customer has 5000 miles on his set now with out issue.

Hope you guys try this and report back. I would not suggest something that I do not believe it. Some of you can flow test them if you wish and let us know the results. Let the flood gates open!


Thanks

San (I read a lot)

 

great post!
i dont know that much about fuel injectors yet, but it this mod is reliable, you just saved me some cash when i upgrade my turbo.

 

I'll be posting up some new research on this. Going to do this mod, have them flowed, examine the spray pattern with 40 and 53 psi behind it... soon as they are ready... ahem, Nate...

 

This brings me to a question. I am getting the Cobb reflash, stage 1 for now, but when I am ready to upgrade to a different turbo can I use a SAFC to control the extra fuel produced by this mod in conjunction with the reflash? I realize this is not optimal, but with the Cobb reflash, at this point, one is not left with the option of using specific sized injectors with a larger turbo. Maybe this would be a good question for they guys at Cobb.

 

We have 2 sets modified and have started the research into the flow and spray pattern, to be honest it has long been known that the injectors are the same just the holes in the end cap differ but the main concern for us is the pattern no the flow as I am sure they do flow around 720-740cc.

Mike

 

Sounds to good to be true. If this actually works I think there will be alot of ppl selling their STI injectors, and alot more ppl upgrading turbo. both are good for us. For the people that have tested these please inform us of all the goods and bads of doing this mod. Thanks

 

Does anyone think that these injectors flow too much fuel for a vishnu stage 2 unichip?? I was thinking of maybe doing this mod if it works out right. But i think that 740cc is is to much fuel for a P&P VF30??

 

Hey Mario how do you like the P&P job on your VF30? How much better did it spool up I'am thinking of doing it to my VF34

 

I couldn't tell you till this weekend, since i put it on an STi till a friend of mine gets his P&P VF39 back. He gets his turbo tommorrow. I'll Pm you how i like it.

 

damn, i don't suppost that there is any way to limit the flow on the modified injectors is there? i know that there are some of us out there that don't need 740cc injectors, but need more than the stockers. it'd be great to not have to buy STi injectors if i could just modify the stock ones to flow similar ammounts to the STi injectors.

 

EH.... < Tim Allen >MORE POWERRRRR! ARRRRRHHHHhhh < /Tim Allen >

-Ted :banana:

 

damnit, i knew someone was going to say that as soon as i posted.

 

well if your going to be needing that much fuel anyways your gonna alrady have a engine management system, and from what I hear that will control the flow.

 

Exactly, just get some sort of management that controls how much fuel the injectors dump. Utec, reflash, SAFC, emanage, motec...the possibilities are endless.

 

this is being thoroughly discuss on the "other" board. they're waaaay ahead......one word of caution, if you do not need this much fuel, don't do it......or if your enginemanagement cannot trim back the excess, then don't do it

aside for some big turbos, 1820, sr50, etc, you're not going to need this much fuel

but yeah, so far, this seems to be a very legit mod