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ProcessWest intercooler install (LGT fitment)

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I wanted to document the ProcessWest intercooler and hood duct installation in to the Legacy GT. It's a perfect fit and everything is very high quality.


These pictures are taken by cell phone, so forgive me if they are not perfect.


Install time: about 2 hours on one leg and crutches (damn you Achilles!)


Tools needed:


Beer (back in the day I might have referenced some clever microbrew, but these days I take what I can get :))

normal sockets 10, 12, 14, etc

zip ties (not necessary, but I like it clean)

Normal pliers, needlenose, wire cutter (for cutting aforementioned zip ties)

screwdrivers, especially the wee little ones

Drill and various bits


Parts needed:

ProcessWest LGT intercooler kit

'06+ WRX belt cover (optional) - Subaru part # 23774AA030

'06+ WRX alternator bracket for belt cover (optional) - Subaru part # 23791AA002

Really long M5 bolt (optional)



So with that, let's get started:


The supplied ProcessWest installation instructions are great, but I wanted to supplement them and add some things which helped me.







Bye bye engine cover, I'll miss you, we've had some good times together. While I'm keeping the car, you can keep the HVAC tape I sealed you up to the old intercooler with. I'll negotiate joint custody of my intercooler sprayer nozzle with you, maybe I can have it in the summer and you can take the winter?







Bye bye my third factory intercooler, I was hoping you were different than all the rest, but you cracked as well. In the end I realized the problem was me and not my previous intercoolers, whom I always blamed for failing without ever looking at my role in the failures...


I apologize for the lack of instructions removing this one, I felt it was pretty self-explanatory and there are other walk-throughs for it.





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After the intercooler is off, next remove the bracket under the intercooler which holds one of the engine wiring harnesses. There is nothing extremely special about this, except two harnesses tie to that bracket with little tabs, use the aforementioned tiny screwdriver to release those tabs and release the harness.






Here is the new bracket that will be going on, as well as the new flange...





The new mounting bracket goes on with one of the previous bolts and then mounts through a long bell housing bolt, which you'll see my socket is on in the picture.






After the divorce of the bracket and the harness and your subsequent marrying of the new bracket to the car, your harness will now be single. Hook it up with a nearby friend to keep drama on the down low.




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Here is the new turbo flange... Look at the beauty of using the factory o-ring, I wish other vendors would do this...






Also note how nice and thick the flange is...






One tiny thing you'll need to modify is cutting the tab off the factory o-ring as there is no groove in the flange to support it, just use a scissors, sorry I didn't list that in the tools needed...







Here is the factory intercooler for reference so you know what I'm talking about, notice the small tab...







Here is the flange installed... Please note that in this picture I have it BACKWARDS, it should install facing the front of the car. I found that out later and could not get a pic since the intercooler was basically on top of it and I was on one leg...




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Next, I deviated from the instructions and went after the hood duct. I figured that would be easier on one foot and I would save the intercooler itself for when my wife could pick it up and put it on to the car for me. You, in turn, can do it however you want...


First you'll need to remove the underhood insulation. This terrified me as those little pop-its always break and then what do you do? This time I was smarter, I lifted it very gently with the aforementioned tiny screwdriver, and then got a pry bar fully underneath it, not putting any pressure on until it was seated perfect, I didn't break one...





Picture with the insulation off...






Now remove the under hood portion of the scoop itself from the car and bring it all to a workbench... It's 4 self-tapping type screws and one plastic pop-it.




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Separate the plastic duct from the metal portion. At first I used a needle nose pliers, but later I found it much easier to just gently use the aforementioned tiny screwdriver.





The next step is to remove the factory air diverter, the instructions said to drill out 3 spot welds, my car had 5. I had to start with small bits and eventually work up to a 3/4" bit to get it out, making 2 very big holes in the airstream. You'll eventually see I covered those holes with HVAC tape as I'm super anal about that and don't like great air being taken away from where it's supposed to go.





Here is the ProcessWest duct that will be going on to your factory hood scoop.






Here it is mounted to the factory hood scoop with 11 little screws. The PW instructions said I'd need to drill 4 holes, I only needed to do 3. You'll need a tiny allen wrench (not on the tool list I put together above) and a tiny 8 or 9mm wrench (not on the list either) to tighten these up.


A couple things to note here, 1) If I wasn't on one foot I would have put blue loctite on these bolts, they seem to be totally the kind that could come loose and be a pain in the ass later, although the nuts are the biting flanged kind, which will help. 2) There is plenty of room between the scoop and the hood, so position each screw so that only the small beveled head is in the airstream vs the end and nut.


Also, anyone notice those 3 holes on the front of the duct near the 3 screws? Do those look about the size for sprayer nozzles? That would be awesome and some nice engineering if they indeed are!


EDIT: Word from ProcessWest: "The 3 holes in the duct are designed to accept STi water spray nozzles." Awesome!






Once you've put it all together, just put it back on the car, taking note of the tabs on the bottom which hook in to your hood. You'll use those 4 self-tapping type screws again, and that one pop-it...






Then put your underhood insulation back on. You'll need to trim on the bottom, on the rear-facing side of the scoop as the new duct is bigger than the factory one. I actually cut the insulation behind the duct completely off as it was just to difficult to measure up and get precise on crutches. It looks just fine that way and the pop-its hold it well.



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The next thing to do is install the intercooler, which my wife had to help with. For that I apologize that there are no pictures, but I will give some caveats as to things that helped me. This was also the point where I fielded many questions like, "this thing is huge?" and "what exactly does an intercooler do anyway?", "Do only turbos need intercoolers?" And things like that...


1) The ProcessWest instructions say to loosely position the silicon hoses on to the intercooler and drop it in to place. I tried that and found the throttle body side to be awfully frustrating to do in that manner. Since I've had the throttle body hose off no less than a half dozen times, I figured I'd put that end on first and then drop the intercooler on to it, this proved much easier. Have fun tightening the clamp on the throttle body side, if you don't swear a few times doing that one you're a better man than me. No offense to any ladies reading this, but who are we kidding...


2) The passenger side bracket, which sits over the turbo, mounts to a threaded hole on the bottom of the intercooler. This is a very tight fit. It may have been even tighter for me as I've replaced my turbo before and it may be slightly further back than stock, just speculation there. At first I put the silicon hose on the turbo flange and tried to push and pry the bracket and intercooler to get them together, this didn't work. Then I pulled the hose off the turbo flange and installed the bracket to intercooler screw. Once that was in I gently pushed back on the intercooler and pushed the silicon hose on to the flange, it's a very tight fit.


3) My BOV hose was a little short once everything was in place, so I lengthened it. I tapped in to this line for my boost gauge long ago, so that may be because of what I did, vacuum hose is cheap.


4) The kit does not come with t-clamps, but instead worm clamps. Those are probably fine, but I HATE when intercooler hoses blow off and then you have to limp home to take it all apart. For that matter I reused the throttle body side t-bolt clamps I had from before (they're the same size) and then ordered some for the turbo side. The turbo side measures 2 3/8" and 3", I ordered from http://www.frozenboost.com


5) While the intercooler looks huge, and it is, your factory transmission dipstick is now much easier to access.

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The last step of the actual intercooler install is to mount the bracket extender and bolt it to the intercooler so everything is nice and snug. It is as easy as it sounds and looks...




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The optional step here if you purchased a WRX belt cover (on the parts list above) is to install the bracket and install the cover...


The bracket is #4 in the illustration below, #3 is the cover. You remove the long bolt from the alternator mount, remove one washer from the bolt, replace it with the bracket and tighten it all back down. Your existing power steering bracket will be perfect and can stay where it is. You may also look in to the part # for the M5 bolt which ties it as it needs to be rather long and I had none in my bolt bucket, I had to steal one from our Trail70.






Many thanks to fahr_side for the next pic!




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Just FYI the 07 STI alternator/belt cover bolts right on the LGT with no modification or brackets needed at all.





Nice write up and I will be anxious to see how much more power people are able to get out of this intercooler, and if it will be similar to the likes of the STI top mount intercoolers

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Good write-up... parts are really top-notch! I'd be really interested to see some data and / or back-to-back runs against the stock or other TMIC.
Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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VN write-up. Thank you


Vertical thickness-wise, how much bigger is the PW IC than say a Perrin or even an AVO? Also, any clearance issues with the clutch master cylinder reservoir or the clutch slave cylinder banjo bolt?


So where (to what mount) did you re-attach the main electrical connections that you disconnected and removed their mount? In the picture is just looks zip-tied to something. Is there no way to reuse the factory mount?

- Pro amore Dei et patriam et populum -
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^^ The PW bracket for the main electrical connections replaces the factory bracket, I zip-tied the connection to the clutch slave cylinder line (I think). You might be able to make something work the factory bracket, but I didn't... I may do that later when I'm cleared to stand on both feet...


No clearance issues with anything, it is all thought out very well...


Vertical thickness I *think* it's the same as an AVO or Perrin, you just have a longer charge area, nearly double the length, and better endtank designs. My work VPN blocks Australia sites, but the dimensions are on the PW site. He has something about not making it too thick as that's a bad idea when air needs to make a 90deg turn coming in to the hood and through the intercooler.

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Looking at PW's site, it seems like their Y-Pipe (for STI-type turbos) simply slides on to the turbo outlet neck, versus onto a flange like our LGT-fitents. So quite possibly, you'd need a different hose versus a different flange. Dunno how stiff the LGT-fitment hose is so hard to determine whether an STI-type turbo connection is possible given that the outlet is underneath the PW IC and would need to swing up, and then over and into the IC. Sorry if I'm not visualizing that correctly.


And PW's site says that these are 3" (90mm) thick, which is as thick or possibly slightly thinner than the AVO/Perrin TMICs.

- Pro amore Dei et patriam et populum -
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