Will STi injectors work?

THAWA · Post by **THAWA** » Thu May 05, 2005 6:45 am

oh right, version 6 sti injectors. As I said sometime within the last 6 years the pressure changed. I don't know when the pressure changed, and for which cars when it changed. It's possible that version 6 sti's were still using 36.3psi, and the change occured with the new generation for the imprezas. I know the legacy changed as early as 99 if not earlier.

I don't think 98's had a higher pressure, but whatever. I've said what I wanted to say. And like you said, it's still an easy fix.

ShaggyGT · Post by **ShaggyGT** » Thu May 05, 2005 12:33 pm

Hmm... Ok so I need a new FPR. I can handle that. But I am not running JDM injectors, I am planning to run the USDM STi type yellow top injectors. The '05 Legacy GT turbo, Forester XT, Outback XT, and STi all run the same yellow top side feed injectors. They are "said" to be rated at 550cc. I can definitely see how a new fuel pressure regulator would be need for that much added flow. Thanks the good information.

-Matt

dzx · Post by **dzx** » Thu May 05, 2005 1:41 pm

So does that mean you should be able to pick up a fpr from a newer subaru?

wrxsubaru · Post by **wrxsubaru** » Thu May 05, 2005 10:14 pm

dzx wrote:So does that mean you should be able to pick up a fpr from a newer subaru?

Ive heard of a SVXer doing this with a I belive 2001 2.5rs FPR.

Quick question does anyknow if the injectors are the smae betweeen the NA legacy and the SVX, and if they are that would mean the 550 STi injectors would be bolt ins?

azn2nr · Post by **azn2nr** » Thu May 05, 2005 10:45 pm

mostly all side feed injectors that are "upgrades" will fit in the na rails

IronMonkeyL255 · Post by **IronMonkeyL255** » Fri May 06, 2005 12:31 am

Oops. I only read the first page before posting. My question was already answered.

gnuman · Post by **gnuman** » Mon May 09, 2005 8:01 am

What THAWA is saying is that the fuel flow is based on stock pressure for that particular injector. If the injector is from a year that uses higher stock pressure than yours, then the fuel flow will be less than rated (pattern may be bad as well), resulting in a net loss of fuel flow at the lower fuel pressure. The higher flowing injectors will not be as much of an increase as you might think, as well.

free5ty1e · Post by **free5ty1e** » Mon May 09, 2005 2:05 pm

So once you go to 92-94 NA fuel rails, the world's your oyster as far as high-flow side-feed Subaru and Nissan injectors go... correct? Are there particular injectors that just won't work or do we just pretty much assume any of 'em will work with the NA rails?

And let's talk about spray pattern:

My assumptions - if the injectors are rated for a lower pressure and ran at a higher pressure, the spray pattern will most likely be intact and proper.

However, if the injectors are rated for a higher pressure than you run them at... the spray pattern may be defunct?

THAWA · Post by **THAWA** » Mon May 09, 2005 4:48 pm

Well there's quite a few different side feed injectors. Obviously any style that is similar to the 90-91 NA AT and 91-94 turbo wont work. I think a few versions of STi's used this style. As well as some 300zx's and a few other nissans. I know denso makes a 550cc/min version of this style as I'm sitting on a set right now. There's a few other side feed styles, like what the supra uses.

An interesting thing to note here though, our NA injectors are supposed to flow 270cc/min right? Well if you look at Joshs flow testing on 92-94 NA injectors they do flow 270cc/min: http://bbs.legacycentral.org/viewtopic. ... 391#119391 at 43psi. Maybe we've been wrong about the static pressure being 36.3 psi? Or maybe we've been wrong about what the NA injectors flow? Anyone care to comment?

IronMonkeyL255 · Post by **IronMonkeyL255** » Mon May 09, 2005 6:01 pm

Also, what fuel pressure to the Nissans run at? They may run a higher pressure as well......

douglas vincent · Post by **douglas vincent** » Mon May 09, 2005 7:12 pm

Who actually has a fuel pressure guage hooked up to their vehicles right now?

My static fuel pressure ranges from 36 to 43, usually at the 43 level though, climbing to 50 on boost.

ShaggyGT · Post by **ShaggyGT** » Wed May 11, 2005 3:01 am

IronMonkeyL255 wrote:Also, what fuel pressure to the Nissans run at? They may run a higher pressure as well......

The fuel pressure of the car does not matter. What does matter is the pressure the injectors are tested at to give said Injector CC's. Take a look at some of the injector flow charts people have posted from RC, you will see they list the pressure used.

-Matt

TheDaveler · Post by **TheDaveler** » Sun May 13, 2007 9:56 pm

Anyone know what injectors fin in 91 Turbo rails? I have a 90 N/A that I could get the rails from as long as the turbo ones could go on, so both cars are still operational... if the 90 n/a ones have more modding potential. Anyone?

kleinkid · Post by **kleinkid** » Mon May 14, 2007 4:09 am

I have just installed the 440 cc grey top fuel injectors into the stock 1991 Legacy Sport Sedan EJ22T rails. I do have a set of 92-94 na rails and the EJ20G 440cc Subaru gray tops do not go in those rails. I obtained and compared a 90-91 na rail with the white(light gray) injectors installed, with my stock '91 EJ22t rails and they are the exact same. Inside the bowls, the dimensions, the lands and sealing areas are the same on both rails. The physical size of the injectors and the soft goods(o-rings, seals etc.) are the same.

TheDaveler · Post by **TheDaveler** » Mon May 14, 2007 7:09 am

I was thinking of going with Nissan SR20 Injectors, anyone know what kind of flow id need for a 30psi boost monster? (cc)

douglas vincent · Post by **douglas vincent** » Mon May 14, 2007 9:50 pm

I am running about 1200 cc at 30 psi. Modded STI sidefeeds (820 now) with a rising rate fuel pressure regulator.

Innovative Tuning · Post by **Innovative Tuning** » Tue May 15, 2007 3:05 am

I've been running US STi injectors in my legacy SS using the 92-94 NA rails for a few months. Worked fine.

91RHDLEGACY · Post by **91RHDLEGACY** » Sun Jun 03, 2007 6:44 am

92 legacy injectors fit in the 91 legacy, I have my right bank fed with 92 injectors, and my left being fed on the stock 91's, they look different, but fit perfect.

Post by **Legacy777** » Mon Jun 04, 2007 6:05 pm

91RHDLEGACY wrote:92 legacy injectors fit in the 91 legacy, I have my right bank fed with 92 injectors, and my left being fed on the stock 91's, they look different, but fit perfect.

Are they n/a or turbo injectors? If this is on a turbo legacy, then yeah, that's fine. If it's on a normally aspirated legacy, the injectors & rails are different and shouldn't work together.

Also, there are some differences in flow, which can lead to the engine running richer or leaner.

pisces_0 · Post by **pisces_0** » Mon Jun 04, 2007 9:10 pm

THAWA wrote:An interesting thing to note here though, our NA injectors are supposed to flow 270cc/min right? Well if you look at Joshs flow testing on 92-94 NA injectors they do flow 270cc/min: http://bbs.legacycentral.org/viewtopic. ... 391#119391 at 43psi. Maybe we've been wrong about the static pressure being 36.3 psi? Or maybe we've been wrong about what the NA injectors flow? Anyone care to comment?

I've been trying to get to the bottom of this myself, and think I've finally found the answer to the static/base fuel pressure question.

Straight from the '92 Service Manual:

Pressure Regulator
By returning fuel so as to balance the above pressure difference and the spring force, the fuel pressure is kept at a constant level 250.1 kPa (2.55 kg/cm3, 36.3 PSI) against the intake manifold pressure

Also, the part number for the fuel pressure regulator is the same between the turbo and N/A fuel systems (#22670AA050). Looks like static/base fuel pressure is, indeed, 36.3 PSI.

91RHDLEGACY · Post by **91RHDLEGACY** » Tue Jun 05, 2007 8:55 am

Legacy777 wrote:
91RHDLEGACY wrote:92 legacy injectors fit in the 91 legacy, I have my right bank fed with 92 injectors, and my left being fed on the stock 91's, they look different, but fit perfect.
Are they n/a or turbo injectors? If this is on a turbo legacy, then yeah, that's fine. If it's on a normally aspirated legacy, the injectors & rails are different and shouldn't work together.

Also, there are some differences in flow, which can lead to the engine running richer or leaner.

the 92's fit in the 91, they are both n/a engines, not turbo. there are no leaks, no power increase or loss. the injectors just physically look different. you can come look at my car, and hear it run if you dont believe me.

Post by **Legacy777** » Tue Jun 05, 2007 5:26 pm

91RHDLEGACY wrote:
Legacy777 wrote:
91RHDLEGACY wrote:92 legacy injectors fit in the 91 legacy, I have my right bank fed with 92 injectors, and my left being fed on the stock 91's, they look different, but fit perfect.
Are they n/a or turbo injectors? If this is on a turbo legacy, then yeah, that's fine. If it's on a normally aspirated legacy, the injectors & rails are different and shouldn't work together.

Also, there are some differences in flow, which can lead to the engine running richer or leaner.
the 92's fit in the 91, they are both n/a engines, not turbo. there are no leaks, no power increase or loss. the injectors just physically look different. you can come look at my car, and hear it run if you dont believe me.

MT or AT?

91RHDLEGACY · Post by **91RHDLEGACY** » Fri Jun 08, 2007 2:07 pm

93Leg-c · Post by **93Leg-c** » Sat Jun 09, 2007 10:42 pm

[quote="Legacy777Also, there are some differences in flow, which can lead to the engine running richer or leaner.[/quote]

Since cylinder #4 in my '93 NA and my '93 ss ran/runs very lean, does this mean that I can fit in an injector with a higher flow rate and possibly solve that lean-cylinder issue?

Arctic Assassian · Post by **Arctic Assassian** » Sun Jun 10, 2007 8:42 am

that is one damn good question. but first, have you had that injector tested or done some form of fuel system cleaner?

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Will STi injectors work?

EJ20G 440cc inj.