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Old 09-27-2010, 06:24 PM   #1
Jessekrs123
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Default DIY Intake For Older N/A Subies

Alright, I was asked to do a writeup on how to get a little extra umph out of your older N/A Subies. I am not really sure if this write-up has been done before but, oh well, if so then you got more than one for referencing.
Tools:
- Flathead Screwdriver
- Socket Wrench with Extensions
- 10 mm Socket
- 12 mm Socket
- Hacksaw (Optional)

Items Needed:
- 3 inch Cone Filter
- Adaptor Plate (Optional)
- Heat Shield (Optional)

Disclaimer:
I have done this on 3 of my Subarus. One of them was a 1993 Subaru Legacy Wagon 4EAT, it gave a little more response and a deeper engine noise. Another is my mother's 1996 Legacy Wagon 4EAT, same deal. In the instructions is my 1993 Legacy Sedan 5 Speed, great throttle response, it really wakes up around 4k rpms. I have never had a problem with any of my cars after doing this. This is STRICTLY for OLDER N/A SUBARUS. This will not work on forced induction Subarus. I would not suggest doing this to any Subarus produced after 1997 as the EJ series received changes and I have not tested it on them either. This modification is applicable to any EJ engine produced before 1997.

Instructions
1. This is what your engine looks like with that big air box sitting there.


2. Disconnect the MAF plug from the sensor.


3. Using your socket wrench, 12 mm attachment and the necessary extensions, unbolt the two 12 mm bolts holding down the bracket in which the airbox is mounted.


4. Using your flathead screwdriver, release the clamp holding the MAF to the intake tube and begin to pry the airbox away from the intake tube.


5. There are two tubes that connect into the airbox which are mounted in the fender, just wiggle the airbox away from these before you try yanking the whole thing out.


6. This is what it should look like after you remove the box from the engine bay. I drilled that hole near the fender for increased air flow to my intake, you do not have to do this if you do not want to.


7. Once your airbox has been removed, you must next remove the MAF from the airbox. Using your socket wrench with your 10 mm attachment, remove the four 10 mm bolts holding the MAF onto the airbox.


8. This is what your MAF should look like when you take it out. There is a little rubber ring around the MAF inlet, save this if you ever wish to put the stock airbox back on, but other than that remove the ring so it won't fall into the intake once you get your car all ready.


9. |THIS STEP IS OPTIONAL| Take your removed MAF and using your hacksaw, cut it at the red mark, where the MAF flattens out. If you do not want to cut your MAF apart, you could purchase this adapter http://www.rallysportdirect.com/stat...ate-p-987.html and it should bolt up right to your MAF with the screen still on. Not cutting the MAF is useful if you ever wish to go back to the stock airbox, but after cutting my MAF I just duct taped the cut MAF to the airbox to get through emissions and it worked.


10. Un-cut MAF on the left, cut MAF on the right.
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Old 09-27-2010, 06:24 PM   #2
Jessekrs123
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11. After cutting the MAF.


12. Whether or not you cut the MAF or buy the adaptor plate, the inlet is 3 inches in diameter. Purchase a filter that will fit either or.


13. This is my 3 inch cone. Prep it for installation.


14. Re-install your MAF and make sure it is facing the correct way. Twist it into the intake tube and tighten the clamp.


15. |THIS STEP IS ALSO OPTIONAL| If you want, you could create your own heat shield. My father is a construction worker and he had some sheet metal lying around so I fabricated this and painted it red to match the color scheme.


16. |THIS STEP ONLY APPLIES IF YOU HAVE A HEAT SHIELD| Using the 12 mm bolts that once held down the bracket to the airbox, match the bolt pattern to your heat shield and bolt it into your engine bay.


17. Fit your cone filter onto the MAF. Tighten the clamp down using your flathead screwdriver. Plug the MAF sensor back in.


18. Take some metal wire and wrap it around the intake tube, and tighten it to something because with the airbox gone, your intake will be floating loosely in your engine bay, so tighten it down to something to avoid it from shaking around during operation and making a clanking noise.


That is all it should take. Your car should be more responsive in the lower range and quicker in the higher range. Doing WOT pulls starting under 2,000 rpms, your car might sputter, do not worry about it, it is completely normal, but that doesn’t mean it’s ok to be doing WOT pulls under 2,000 rpms constantly. Have fun with it. It is a nice and cheap mod as opposed to buying those expensive Weapon R intakes. If you have any questions, suggestions or flaming, feel free to leave a post.
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Old 09-27-2010, 06:25 PM   #3
Jessekrs123
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Default

another space saver just incase
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Old 09-27-2010, 09:50 PM   #4
as13070
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Awesome! Great Write up. Ill do this and take some pics. Did you paint the heat shield with anything special? I was thinking of maybe using high temp paint.
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Old 09-27-2010, 10:02 PM   #5
Jessekrs123
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Quote:
Originally Posted by as13070 View Post
Awesome! Great Write up. Ill do this and take some pics. Did you paint the heat shield with anything special? I was thinking of maybe using high temp paint.
I painted it with whatever I had leftover from my intake manifold so high temp works good.
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Old 09-28-2010, 12:32 PM   #6
BE6STI
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This is a great cheap way of getting a little torque bump but part of the reason aftermarket intakes increase power with because they have smooth tubing. The factory intake tube has ribs and whatnot to help reduce noise but disrupt air flow. PVC pipe works well too.
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Old 09-28-2010, 01:32 PM   #7
Jessekrs123
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Quote:
Originally Posted by BE6STI View Post
This is a great cheap way of getting a little torque bump but part of the reason aftermarket intakes increase power with because they have smooth tubing. The factory intake tube has ribs and whatnot to help reduce noise but disrupt air flow. PVC pipe works well too.
You have a valid point, and I had thought of this, but the way I see it, vacuum is vacuum. Slapping on an aftermarket tube with the same diameter without ribs will still see the same amount of air entering the system. Fabricating your own tube would mean you have to add ports for vacuum, so IMO, this is just the easiest, cheapest way to yield more power from your N/A Subaru.
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Old 09-30-2010, 11:03 PM   #8
sol_tegra
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i think this will make your car sound a little better but i dont think you'll make any more power and on the other hand you'll lose power, why do i say that is becuz your sucking in hot air from the engine bay rather then from the air duct or tubing that your stock box is connected to which brings in cool air!!!!
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Old 09-30-2010, 11:14 PM   #9
XanRules
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you'll lose power. Also that hole in the filter isn't doing your MAF any favors, especially with the screen removed. Fail, fail, fail.
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Old 10-01-2010, 12:34 AM   #10
grafton
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by doing this you introduce the maf voltage issue that is in a sticky at the top of this forum, and have issues down low...
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Old 10-01-2010, 12:39 AM   #11
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Quote:
Originally Posted by XanRules View Post
you'll lose power. Also that hole in the filter isn't doing your MAF any favors, especially with the screen removed. Fail, fail, fail.
what hole in the filter? the inner cone?
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Old 10-01-2010, 12:41 AM   #12
rob17san
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I was under the impression that the stock airbox was a sufficent intake?
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Old 10-01-2010, 01:19 AM   #13
XanRules
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Quote:
Originally Posted by mke723 View Post
what hole in the filter? the inner cone?
sorry, it looked transparent from the photo, like there was nothing there

But, dude. That screen is there for a REASON.
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Old 10-01-2010, 01:37 AM   #14
grafton
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Quote:
Originally Posted by rob17san View Post
I was under the impression that the stock airbox was a sufficent intake?
yeah there are small gains by going to the hybrid intake but there's not much power to be made in the intake on our cars
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Old 10-26-2010, 01:30 AM   #15
Jessekrs123
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I am well aware of the factors going into the intake. I understand that there isn't much increase in performance, but there is definitely more throttle response there. This is just for those N/A guys who don't want to spend $200 on a Weapon R Intake. If you don't like the idea of it, don't do it. My car runs fine with this set up. Don't knock it till you've tried it.
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Old 10-26-2010, 02:03 AM   #16
burnout8488
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The fire engine red paint scheme is definitely not working in that engine bay..nor any engine bay i've ever seen really.
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Old 10-26-2010, 02:06 AM   #17
Jessekrs123
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Quote:
Originally Posted by burnout8488 View Post
The fire engine red paint scheme is definitely not working in that engine bay..nor any engine bay i've ever seen really.
Thanks, that is exactly what this thread is about, my red IM, filter, and shield. I would have gone with wrinkle red like the STis, but I didn't have the time to order it on the internet (no parts store had it) and I wanted to get the intake manifold on and get my car running after I dropped the engine in.
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Old 10-26-2010, 02:09 AM   #18
XanRules
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Quote:
Originally Posted by Jessekrs123 View Post
I am well aware of the factors going into the intake. I understand that there isn't much increase in performance, but there is definitely more throttle response there. This is just for those N/A guys who don't want to spend $200 on a Weapon R Intake. If you don't like the idea of it, don't do it. My car runs fine with this set up. Don't knock it till you've tried it.
got datalogs?

You took the ****ing screen off your MAF, dude.
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Old 10-26-2010, 02:32 AM   #19
Jessekrs123
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Quote:
Originally Posted by XanRules View Post
got datalogs?

You took the ****ing screen off your MAF, dude.
No data logs. Find me a datalogger for an OBDI Subaru? Good luck. I did this to an OBDII Legacy and never got a CEL for a rich/lean mixture or abnormal MAF voltage or any CEL in general after this mod. Xan, have you tried this yourself? Or are you just basing your information off a graph and some sticky thread info which was tested on a newer more complex subaru? It states in that thread that he hadn't personally tested it on N/A Legacys and whatnot. Well, now I have tested it on OBDI and an OBDII pre-1997 Legacy and it hasn't given me any trouble, I can definitely feel the increase on the engine load under 1,800 rpms, but I'm not constantly at WOT under 1,800 rpms everytime I drive my car. I don't have logs to back it up, but an absence of any CEL after this mod indicates that the ECU isn't detecting anything irregular that could cause a problem. If the OBDII system doesn't detect a problem then I'm guessing there isn't a problem. I haven't had any issues with the absence of the MAF screen. If someone is worried about this, then buy the adapter which is clearly stated in the write-up above. Keep flaming me, I drive with this set up everyday with no problems. I really don't mean to wage a war, but this set-up works fine for me I've had no problems with it. I'm basing my results off my experience driving with the mod and the lack of any CEL after the mod, not from the sticky about the CAI/SRI problems which was tested on a completely different car from s completely different time. I'm not holding people against their wills to try this out, if they want to do it, fine, do it. If they are afraid to do it because of some sputtering at WOT before 1,800 rpms, then no sweat off my sack.

Last edited by Jessekrs123; 10-26-2010 at 03:03 AM.
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Old 10-28-2010, 07:43 PM   #20
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would this work for a 97 impreza?
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Old 10-28-2010, 07:46 PM   #21
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You have a torque box, not a straight pipe into the throttle body like he has.

You'd also (most likely) have the same MAF problems.

Yes, you could do it.
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Old 10-28-2010, 09:08 PM   #22
Jessekrs123
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Quote:
Originally Posted by sunnyx View Post
would this work for a 97 impreza?
I wouldn't suggest it, I've never tried it on anything newer than a 1997 model. Again, like I said at the beginning of the write-up, it is for older, pre-1997 N/A Subarus. The EJ engines were changed in 1997, so I'm not sure what your results will be.
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Old 10-28-2010, 09:19 PM   #23
Jessekrs123
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Quote:
Originally Posted by XanRules View Post
you'll lose power. Also that hole in the filter isn't doing your MAF any favors, especially with the screen removed. Fail, fail, fail.
Quote:
Originally Posted by sol_tegra View Post
i think this will make your car sound a little better but i dont think you'll make any more power and on the other hand you'll lose power, why do i say that is becuz your sucking in hot air from the engine bay rather then from the air duct or tubing that your stock box is connected to which brings in cool air!!!!
I am definitely making a noticeable, but not much amount of more power. Everyone always says ZOMG it will be sucking in the heat from the engine... 1. I have a heat shield which should dissipate most of the heat and 2. The engine is not constantly blowing it's heat right at the intake. Especially when driving, the engine's heat just blows straight back to the engine side firewall.
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Old 10-28-2010, 09:32 PM   #24
XanRules
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Quote:
Originally Posted by Jessekrs123 View Post
No data logs. Find me a datalogger for an OBDI Subaru? Good luck. I did this to an OBDII Legacy and never got a CEL for a rich/lean mixture or abnormal MAF voltage or any CEL in general after this mod. Xan, have you tried this yourself? Or are you just basing your information off a graph and some sticky thread info which was tested on a newer more complex subaru? It states in that thread that he hadn't personally tested it on N/A Legacys and whatnot. Well, now I have tested it on OBDI and an OBDII pre-1997 Legacy and it hasn't given me any trouble, I can definitely feel the increase on the engine load under 1,800 rpms, but I'm not constantly at WOT under 1,800 rpms everytime I drive my car. I don't have logs to back it up, but an absence of any CEL after this mod indicates that the ECU isn't detecting anything irregular that could cause a problem. If the OBDII system doesn't detect a problem then I'm guessing there isn't a problem. I haven't had any issues with the absence of the MAF screen. If someone is worried about this, then buy the adapter which is clearly stated in the write-up above. Keep flaming me, I drive with this set up everyday with no problems. I really don't mean to wage a war, but this set-up works fine for me I've had no problems with it. I'm basing my results off my experience driving with the mod and the lack of any CEL after the mod, not from the sticky about the CAI/SRI problems which was tested on a completely different car from s completely different time. I'm not holding people against their wills to try this out, if they want to do it, fine, do it. If they are afraid to do it because of some sputtering at WOT before 1,800 rpms, then no sweat off my sack.
there is so much wrong with this statement it frightens me.
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Old 10-28-2010, 10:45 PM   #25
Jessekrs123
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Quote:
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there is so much wrong with this statement it frightens me.
Oh hey Xan, back again huh? What is wrong with my statement, please point out my faults.
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