hot shit injector mod
Thread Starter
"color blind kid"
Joined: Aug 2002
Posts: 902
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hot shit injector mod
http://forums.nasioc.com/forums/show...hreadid=478921
some guy had them flow tested after he did it and got some pretty good numbers click
740CC injectors for free?
some guy had them flow tested after he did it and got some pretty good numbers click
740CC injectors for free?
Originally posted by Kingpin
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
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
Blingo!?!
Joined: Oct 2001
Posts: 1,287
Likes: 0
Im worried what the removal of that screen would actually do to the pattern, if I got ahold of a spare set I wouldn't mind hacking em apart and just log the AFR with the TXS tuner just to be safe. I just question why subaru would restrict the same set of injectors differently (STi and WRX) I would have just run a 740cc injector and pulled the duty cycle to simulate a 440etc and have the extra capability of fueling if an emergency situation arose, unless its just to pair it with a lower fuel pump for price on that
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Thread Starter
"color blind kid"
Joined: Aug 2002
Posts: 902
Likes: 0
Originally posted by M249SAW
Yeah that seems real safe
. I wouldn't trust 5% of the crap on NASIOC.
Yeah that seems real safe
. I wouldn't trust 5% of the crap on NASIOC.
On the second thing I linked the guy had his tested by rc and his spray pattern was excellent and flowed
857
859
862
859
I'm not saying everyones will be the same but if his turned out ok then why not hack some up send them out and save a couple hundred.
sooo...where's the turbo?
Joined: Oct 2002
Posts: 1,624
Likes: 1
Originally posted by M249SAW
Yeah that seems real safe. I wouldn't trust 5% of the crap on NASIOC.
Yeah that seems real safe
. I wouldn't trust 5% of the crap on NASIOC.
nah, i'm just joshin..but they are pretty paranoid on average over there
Thread Starter
"color blind kid"
Joined: Aug 2002
Posts: 902
Likes: 0
Originally posted by M249SAW
I guess its just me. I would rather save a little longer for the part than jerry-rigging my brand-new car (Which will still be under warranty
I guess its just me. I would rather save a little longer for the part than jerry-rigging my brand-new car (Which will still be under warranty
DOUBLE ROLL :o
15 seconds EXHILARATION
Joined: Jun 2002
Posts: 7,801
Likes: 0
I saw that thread. All I have to say is "awesome". You WRX guys needed to get rolling on those free mods, and that one is a biggie. Go buy an AFPR for half the cost of injectors and dial back the fuel pressure if you're not ready for all of that fuel. (I assume the WRX doesn't use one of those returnless systems, right?) It's a shame that DSM use pintle-style injectors, no free upgrades for us or I'd already be sporting the hack-mod injector upgrade. 
