Will Stock STI injectors work?

[KySpeed]

Will the stock 550cc STi Injectors work in out cars? My friend just put 817's in his car and was wonderin if i should go ahead and snag his?

 

[orangezoom]

I think they do.

 

[KySpeed]

Does anyone know forsure?

 

[tekkie]

well they are supposed to be a direct drop in for the WRX, and since the WRX ones are a direct drop into our cars I would say yes

I looked on some subbie boards before the injectors for the WRX and the STI look exactly the same shape. Your best bet to be 100% sure is to post or look on their board to confirm it with them.

 

[bill harvey]

Hi before the mazda i had a 2.5rs turbo and worked in the subaru performance industry for a few years. they will work with no problem at all given you have some sort of fuel management.

 

[tekkie]

he is planning on running emanage, so he has that portion covered

 

[Focus]

The STI injectors will not work. You need the plain jane blue 440cc injectors from the WRX model ( Not the STI )

 

[daedalus]

if you drop the regular 440cc's in with let say a 255lph walbro fuel pump and run engine management capable of handling bigger injectors, then will you be pgb rich at idle, or can you still control the amount of fuel at idle, etc? (The management would be the DSM afc which is capable of controlling larger injectors)

 

[KyRaceFan]

550s are overkill for anything except a much larger turbo than stock. Id try to grab some regular 440s and be happy with those. Throw in a walbro and you'll definately have enough fuel.

 

[speedcicle]

What size are our stock injectors in the msp, and can i upgrade the to something slightly larger with just the unichip piggyback with no fuel managment?

 

[tekkie]

the stock ones are 280cc, they are the same ones as the rest of the 3rd gen proteges

As far as unichip you may need to get it retuned I am not sure on that, but it is capable of handeling them. Your best bet is to contact unichip I would say to get an answer.

 

[speedcicle]

OK well at least i knoiw what size they are now, I dont think i want to go up to 440 i would rather just up it to an injector in the low 3's. Any suggestions?

 

[bill harvey]

why don't you jsut get a rrfpr. or a rising rate fuel pressure regulator. then you can turn up the fuel pressure dependent on boost then you will get the extra fuel you need only when you need it.

 

[KySpeed]

I maxed the 450's out in my dsm on the t25. For a T28 on or around 17lbs you really need 550's.

 

[KyRaceFan]

why don't you jsut get a rrfpr. or a rising rate fuel pressure regulator. then you can turn up the fuel pressure dependent on boost then you will get the extra fuel you need only when you need it.

Running more fuel pressure isnt the best idea. It works, but its the bootleg way to do it. Maxing out your injectors all the time will eventually just **** them up, lock em open(or shut) and can lead to engine melt down. It killed my friends 1.6L miata. He had 240cc injectors running at 140psi of fuel pressure. Sure it lasted a year, but he had a boost spike to 25psi and thats all it took for them to lock close and blow the motor.

 

[BlkZoomZoom]

Our injectors are 280-320cc. Depending on the fuel pressure the pcm gives the regulator.

I bought a set of 577cc stage 1 srt-4 injectors that I plan to try out. Very little modifications had to be made. If I can't get it to run right I will be putting a second fuel rail on.

 

[tracknfield423]

is adding larger injectors better then just adding extra ones or is it really just a preference.

 

[Focus]

is adding larger injectors better then just adding extra ones or is it really just a preference.

The only reason adding injectors may be a prefereable route is because you can keep stock driveability and idle and just add fuel if you run more boost.

Putting bigger injectors may screw up idle, because you have to keep them on for a shorter time and MAY screw up the spray pattern.

 

[tracknfield423]

so if i wanted to keep stock drivability but have more fuel flow i would just add injectors instead of replacing the stock ones with larger ones?

 

[Focus]

That would be the ideal way to do it.