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4 please, to go.
Ver 7 STi GC, elderly L
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3,623 Posts
Discussion Starter · #1 · (Edited)
I swapped a Version 7 STi engine into my GC recently. The swap is kind of a hodge-podge of parts and is equipped with a USDM STi TMIC. Rather luckily, I found a version 2 splitter on RS25 a few days before I got my swap back. I wanted to jump on this, because they seemed to be a relatively rare piece.

After I got my swap back, I excitedly went out to mount it to my hood. I knew that the actual duct portion was a bit small, but I figured it wouldn't make a huge difference as long as it was greater than 75% of the area of the TMIC surface. Well, it wasn't. It was about 50% of the area and what's more, the rear lip of the duct didn't match up with the back of the intercooler.

I briefly considered reselling it and purchasing a WRX splitter, but i figured, what the hey, and decided to modify it for my IC.

Basically, what I needed to do was widen and shift the duct on the splitter to better line up with and fit my intercooler. My parts list is as follows:

  • 1 - 18x6 piece of sheet aluminum
  • 4 - boxes of sheet metal screws (about 30)
  • 3 ft - fuel line tubing

Tools:
  • pair of tin snips
  • drill with bit that's a bit smaller than the shaft diameter of the sheet metal screws
  • Phillips/Flat head screwdriver (depends on the type of screw you get)
  • (Optional) Vice or pair of vice-grips



Step 1: I measured the intercooler and cut strips of about 1.5" in width (I used the rubber duct that was originally on the splitter as a guide). You'll want to make the actual pieces about .5" shorter than the measured dimension of the IC. This is to allow some fitment tolerance as well as to mediate the fact that when the hood is closing the splitter kind of "scissors" onto the intercooler. If the dimensions are exact, it won't fit over the front lip of the IC due to the geometry of it.




Step 2: I cut about 12 right angle sections of the aluminum for the strapping that will hold the duct together as well as attach it to the splitter plate. This is where the vice comes in handy, since you can just clamp them in the vice and bend them by hand.




Step 3: Once I had the duct fabbed up, I had to remove the old rubber duct and cut the plate, opening its dimensions to match the new duct. In order the find where I needed to cut, I went out to the car and mounted the splitter plate, trying to get some rough measurements on placement. This is the hardest part. The tolerances on the fitment of the duct into the IC are reasonably tight, so it's not something you can just eyeball. A tape measure is a nice thing to have at this stage, but it still doesn't make it a cakewalk. I would have to test fit and fine adjust mine about 4-5 times before i got the fitment right. In the end, it came down to me bringing the hood down until it was nearly closed and eyeballing (yeah I know) how close it was. I really tried to think of a better way to get it finely adjusted, but this is really all i could think of.




Step 4: Once you've gotten the hole lined up, you'll need to attach the duct to it. As I mentioned before, it's quite difficult to get this to line up with the necessary accuracy. In order to make speedy test fits, I initially only screwed in two of the straps to the plate so I could fine tune placement.




Step 5: Now you'll want to use the fuel line on the edge of the duct so it doesn't rattle or cut into the IC. This also helps to make a good seal with the IC. I didn't go all the way around because the tolerances of my duct were too tight on the left and right. If you cut your duct short about .5"-1" you should have no problem going all the way around. I didn't glue my tubing on yet because I wanted to see if it would melt real bad, but it seems to be holding fine. as far as adhesive to use, a little super glue should do the trick

Finished product







Overall I'll really happy with the finished product. There's a couple things i would have done differently, like the short cuts, and maybe rivets instead of screws. It might not be pretty, but it works. Next project DIY IC sprayer. :devil:

One more note: You could make this same splitter much more cheaply if you fabbed your own mounting plate instead of sacrificing an actual splitter. I would have done this if I didn't already have the splitter on hand.

Edit: In case it wasn't clear this DIY will work great for the stock RS backing plate. You'll just need some kind of steel saw to cut your hole.
 

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4 please, to go.
Ver 7 STi GC, elderly L
Joined
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3,623 Posts
Discussion Starter · #2 ·
Anyone gonna try this?
 

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4 please, to go.
Ver 7 STi GC, elderly L
Joined
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3,623 Posts
Discussion Starter · #4 ·
You could probably do this with the original RS backing plate. Or was that your intention for this DIY?
yeah the original backing plate would work great. I basically removed all parts of the original splitter that made it a splitter. Using the original backing plate however, would probably necessitate the use of and angle grinder or steel saw to start the cut. The splitter is pretty thick, and it was a difficult cut with tin snips, even with the original hole from the duct already there.
 

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4 please, to go.
Ver 7 STi GC, elderly L
Joined
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3,623 Posts
Discussion Starter · #6 ·
"Do or do not, there is no try."

That's a quote I heard somewhere, can't remember the guy's name though...he was some short old guy.
 

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4 please, to go.
Ver 7 STi GC, elderly L
Joined
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3,623 Posts
Discussion Starter · #8 ·
i forget:confused:





;)

Hijacking my own thread....have I really sunk this low?
 

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Premium Member
2000 BRP RS-Swapped
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212 Posts
I did this using the 2.5 scoop plug, works great, with a few differences... I cut the metal using tin-snips, that was easy and quick. ...and any final gaps I sealed using a tube of black silicon rubber.
I also make a cardboard version first, (with duct tape of course) to measure, trim & test for fitment.
 

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Registered
01 RS w/ 2.1 stroker ej205
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2,176 Posts
please update thread with photos!!!!!!!!!!!!!

Im currently in the process of doing this. I have a GTSPEC gc8 splitter that i plan to mate up to the USDM GD STi splitter. But seeing this thread will save me time :)

thanks!
 

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Registered
Green 97 OBS
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1,840 Posts
Dunno why I don't have this thing subbed. Now I do. I'll be doing something like this this summer with a sprayer setup. I'll take pics and update here if/when I get the final setup done.
 

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Registered
01 RS w/ 2.1 stroker ej205
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2,176 Posts
This thread is 4 years old. I doubt the OP will be updating the pictures (if he is even still around)
Always worth a try to be optimistic

Dunno why I don't have this thing subbed. Now I do. I'll be doing something like this this summer with a sprayer setup. I'll take pics and update here if/when I get the final setup done.
Greeeat :)

Ill be doing this soon so maybe ill beat u to the punch lol
 

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4 please, to go.
Ver 7 STi GC, elderly L
Joined
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3,623 Posts
Discussion Starter · #18 ·
Hey I re-hosted the pictures just for you guys. An older wiser me would have used high temp foam all around to basically give the air nowhere to go but through the IC. Alas, my RS is now gone so someone else will have to try this.
 
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