Topic: Decapping WRX injectors (Read 78424 times)

caged · « **on:** March 13, 2009, 04:57:23 AM »

I thought I would post up DIY WRX injector hi-flowing. You can use the 01-04 light blue WRX/forestor GT top feed injectors which flow 440cc's or the 01-07 STI pink top feed injectors that flow 565cc's standard. They both end up coming out at about 816cc's each when modified, I used second hand wrx one's which cost me $100NZD which is $50 USD.
The WRX and STI top feed injectors have a strainer on the tip with 12 holes in the end which restrict flow to the desired amount (smaller holes for the wrx).

There are a few different ways to decap these injectors. I put my injectors into my vice with plastic jaws and clamped it lightly with the bottom facing up. I then used a small file around the outside of the strainer tip. The strainer cap is very thin so be careful not to file too deep, after you have filed all the way around the cap will fall off. Give the tip a tidy up with the file and blow the filings away and the hi-flow injector is done. A few people recommend using a dremel but after seeing a few noobs cut the tops off there injectors I decided that the file was safer. I got a mate to put my injectors onto his flow bench and they all came up around the 816cc mark with less than a .5% variance.

The spray pattern is also great. I currently have them in my van and have had no problems.

Decapped injector is on the left.

(Images stolen from OzLiberty forum)

caged · « **Reply #1 on:** March 13, 2009, 05:26:04 AM »

BTW I havent used these on a honda before, but when theres a will theres a way. They have an OBD2 plug and fitted in my mitsubishi L300 fuel rail no probs. They are just a good buget 800+cc injector

caged · « **Reply #2 on:** March 13, 2009, 07:21:17 AM »

On the car Iam running them on atm I have a haltech ECU so I just adjusted the pulse width. I run them on a 2.4L 4cyl with a turbo cam and have a close to stock like idle.

Robb · « **Reply #3 on:** March 13, 2009, 08:55:51 AM »

I wish I had the time/money to actually compare flow differential between separte injectors after 'decapitation' as what the sccobaru dudes claim is the issue is with doing this mod.

Personally, I think that with the capability to trim individual cylinders and keeping the duty cycle in a reasonable range, it wouldnt be a problem.

dive_miguel · « **Reply #4 on:** March 14, 2009, 12:08:35 AM »

Are these high or low impendence?

caged · « **Reply #5 on:** March 14, 2009, 03:15:34 AM »

CSaddict · « **Reply #6 on:** March 14, 2009, 10:45:36 AM »

Im moving this to EM.

TTC · « **Reply #7 on:** March 14, 2009, 12:04:50 PM »

I remember people doing this back when i had my subaru, IIRC tho and i could be wrong but im pretty sure it messes up the spray pattern and creates hotspots.

HiProfile · « **Reply #8 on:** March 14, 2009, 03:43:44 PM »

Quote from: caged on March 13, 2009, 04:57:23 AM

I got a mate to put my injectors onto his flow bench and they all came up around the 816cc mark with less than a .5% variance. The spray pattern is also great. I currently have them in my van and have had no problems.

Given that info, I don't think the inconsistant spray/hotspot rumor is just bullshit from n00bs. Take a look at most subie forums, very few people do much beyond buying bolt-ons. No offense to those that have the ability, you just won't find many people willing to risk a DIY on a car that isn't exactly cheap. I know the motors are cheaper than most Honda's, but most have to PAY someone to put it in...

That said, some people will just enlarge the holes, but you need a very delicate touch, a thorough cleaning, and flow testing if you don't want to be guessing. I just wish they were like the typical OBD1 plug. They will definately be my next injector if I boost my beater's b16, since I already have Deka's in my D16.

SDRAWKCAB · « **Reply #9 on:** March 14, 2009, 06:35:10 PM »

Nice right up.

Robb · « **Reply #10 on:** March 14, 2009, 08:42:29 PM »

I am definitely willing to try this on my 951, I gotta find some of these.

Joseph Davis · « **Reply #11 on:** March 15, 2009, 07:29:33 PM »

STR-4 injectors look to have a variant of the pintle cap, more like a plug.

turbo4life · « **Reply #12 on:** March 22, 2009, 04:02:23 AM »

great write up! no more ricer forums fight over huge difference in flow rate's mis leading other people

chris · « **Reply #13 on:** March 25, 2009, 01:57:49 AM »

height of the injector in mm?

Aero · « **Reply #14 on:** March 25, 2009, 02:14:49 AM »

I remember reading about this a few years ago. I wish more injectors were moddable like this. Nice writeup.

Kain · « **Reply #15 on:** April 02, 2009, 06:26:29 PM »

i highly suggest that you guys do not do this.

Number one, i have tried this on my brotehrs wrx. its an easy and cheap mod.

HOWEVER

flow rates have changed and atomization is almost gone. we sonn replaced them with proper flowing 800cc injectors after they started giving us problems.

caged · « **Reply #16 on:** April 04, 2009, 05:22:04 PM »

Quote from: chris M on March 25, 2009, 01:57:49 AM

height of the injector in mm?

with the injector in the car it is 38-40mm from the injector boss to the fuel rail.

Quote from: Kain on April 02, 2009, 06:26:29 PM

i highly suggest that you guys do not do this.

Number one, i have tried this on my brotehrs wrx. its an easy and cheap mod.

HOWEVER

flow rates have changed and atomization is almost gone. we sonn replaced them with proper flowing 800cc injectors after they started giving us problems.

My atomization is great

. I also have these in my 96 sti with top feed rails and can get it to idle better than the side fed 440cc's. What sort of problems were you getting and what ecu were you running? Ideally you would buy proper 800cc injectors but if i did everything the proper way I wouldn't be on RHMT

.

patsmx5 · « **Reply #17 on:** April 04, 2009, 09:35:15 PM »

Quote from: c0mpl3x on April 04, 2009, 08:41:03 PM

Quote from: Kain on April 02, 2009, 06:26:29 PM
i highly suggest that you guys do not do this.

Number one, i have tried this on my brotehrs wrx. its an easy and cheap mod.

HOWEVER

flow rates have changed and atomization is almost gone. we sonn replaced them with proper flowing 800cc injectors after they started giving us problems.

you also quoted your brothers wrx at 450hp, and it made 300.

drivetrain loss i suppose. i think your middle name is johnny

;D

Joseph Davis · « **Reply #18 on:** April 05, 2009, 11:31:17 PM »

I don't think a WRX driveline could survive a single 450 whp dyno pass.

Kain · « **Reply #19 on:** April 15, 2009, 08:51:03 AM »

Quote from: patsmx5 on April 04, 2009, 09:35:15 PM

Quote from: c0mpl3x on April 04, 2009, 08:41:03 PM
Quote from: Kain on April 02, 2009, 06:26:29 PM
i highly suggest that you guys do not do this.

Number one, i have tried this on my brotehrs wrx. its an easy and cheap mod.

HOWEVER

flow rates have changed and atomization is almost gone. we sonn replaced them with proper flowing 800cc injectors after they started giving us problems.

you also quoted your brothers wrx at 450hp, and it made 300.

drivetrain loss i suppose. i think your middle name is johnny

;D

yah. except, thats not the case.

we threw down 450 whp at around 25 psi of boost with those shitty modified injectors. which i told you

then we swapped em out for some proper 800cc units, and turned the boost down to 19 psi and made 300 whp. which i also told you.

on a 2.5 liter sti block. stock tranny for an 02 wrx. its not liking it one bit. im trying to convnce my brother to go with a haltech e8 and the patch harness to et rid of the shitty subaru ecu and his cobb tuning equipment.

Kain · « **Reply #20 on:** April 27, 2009, 11:03:48 AM »

Quote from: c0mpl3x on April 15, 2009, 03:00:35 PM

get rid of cobb and youll be fine.

and when did you tell me this dyno'd 450hp? you only said you estimated it.

i never held the dyno sheet in my hand or went to that dyno session.

guy at the dyno said it was one of the fastest accelerating wrx he ever saw. i dont know. ive not been in many subarus so i dont know if hes just lieing.

Joseph Davis · « **Reply #21 on:** April 27, 2009, 02:10:49 PM »

450 whp in a WRX is insufficient.

Conceptz-X · « **Reply #22 on:** April 27, 2009, 08:10:50 PM »

Quote from: Kain on April 15, 2009, 08:51:03 AM

im trying to convnce my brother to go with a haltech e8

I wouldn't buy one again!

caged · « **Reply #23 on:** April 28, 2009, 03:01:20 AM »

450 is where it starts to become fun in a classic shape wrx. Unfortunately thats were drive train parts become disposable every drag/circuit meet. :yes:.
We got the RX over here from 1993 and I would say turbo Subaru's are the most fragile engine ever, especially the twin turbo legacy's, they do alot of big end bearing. We haven't had too many problems with the 2001+ engines yet. (I work for a Subaru dealership)

Joseph Davis · « **Reply #24 on:** April 28, 2009, 01:17:33 PM »

I have no 450 whp WRX experience, but since a WRX weighs in like a Mk4 Supra I'm going to say that's slooooooooow after first gear.

caged · « **Reply #25 on:** April 28, 2009, 07:14:42 PM »

Well the version 1 WRX sti RA that iv been playing with weighs in at 1230kgs (2711pounds) standard. It has around 450awhp and does a 11.1 when it doesn't break a shaft or a gear. 1st gear is is a bit average but 3rd gear is where it becomes fun. (last circuit day we wiped all the teeth off a brand new 3rd gear after 2 laps

) I'm waiting for a cage and a dog box's so we can tune again.

Ravage70 · « **Reply #26 on:** May 11, 2009, 07:41:49 PM »

you can do the same thing to type s and si injectors and get 520cc out of them

Joseph Davis · « **Reply #27 on:** September 06, 2009, 01:01:39 PM »

I recently had a chance to tune a KA-T with a set of decapped WRX injectors, it idles just like stock. Flow imbalance or poor atomisation problems would make the idle uneven in the lower rpms, but these worked great.

kgx · « **Reply #28 on:** September 06, 2009, 01:40:26 PM »

i've been running these in my MR2 on E85 for a couple of years now. they idle very well. 750rpm, rock solid. nice thing is if you trim the side tabs off, they plug right into most toyota harnesses and they're highZ so i got to yank the OE resistor box.

they definitely are a bit shorter. i used a camry 5SFE top feed rail, and cut the ends off the stock side feed rail for the injectors to seat into as cups to fit the head. turned out to be a good thing, since they are so short that without the cups, the plug housings were right up against the valve cover. wouldn't have been able to plug them in otherwise.

i can't think of anywhere else you can get ~800cc injectors for ~$100 a set. decapitating them takes all of 5 minutes.

caged · « **Reply #29 on:** September 09, 2009, 01:29:25 AM »

I will try find the pics I took when I installed them in a D series rail/head, It was really easy. I will be running some In my EVO 2 build also.

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Author Topic: Decapping WRX injectors (Read 78424 times)

chris