I'll be writing up some blurbs about how I got around some of the challenges I made for myself. Here's #1 on the DBW to DBC "adapter" I "made".
I knew going into this that the DBW throttle wouldn't work with the Speeduino and the DBC throttle body wouldn't fit on the DBW manifold. To work around that, I had a plan A and a plan B.
Plan B was to get another N/A phase II intake manifold, move all the necessary wiring over to it and drop it on. That manifold is sitting in my garage right now.
Plan A was to see how hard it would be to make an adapter plate that would bolt into the intake manifold and provide studs to mount a DBC throttle body.. Then I'd just find someplace to put a throttle cable anchor bracket. This was of course easier said than done for my (previously) non-existent fabrication skills.
By all rights I should have gone with plan B, but the same stubborness that got me through this project just wouldn't let me give up on that pretty EJ204 intake manifold and put an ugly EJ222 manifold on.
I'll write up the adapter plate in more detail at some point, but the short version is this:
- The DBW throttle body is much more compact than *any* Subaru DBC throttle body as far as I can tell. This means that the fine folks at Fuji Heavy Industries packed stuff around it in pretty close proximity. Test fitting an EJ18E or EJ22E or EJ222 TB in their intended orientation meant they were running into the fixture for purge control solenoid valve for the evap system, which I'm intending to use. Even if I wasn't though, the throttle cable would have been scraping across the plenum on the EJ204. Because of that, mounting the TB at a 15-45 degree angle only made things worse. Flipping it 180 degrees didn't help either (I can't remember what it was running into).
- Then I found out that if you rotate a DBC TB 90 degrees it will actually *just* bolt into the bolt holes for a DBW throttle body. And in that orientation the throttle cable will *just* clear the top of the plenum.
- So I made a prototype "adapter" plate that just has 4 bolt holes, a hole the same size as the throttle opening and a vertical tab to mount the throttle cable anchor bracket on. That is currently on the car.
- The current prototype "adapter" is made of plastic and the throttle cable anchor bracket is made of angle brackets from the hardware store for mounting shelfs. You can scream now if you want, but it'll be replaced with one made of CNC'ed aluminum before I take it on a roadtrip or idle it in hot weather.
- If anyone working at Lowes is reading this: I would love a sponsorship for this project. Get in touch.
- Just to anticipate one more question: I'm running the car off the MAP sensor, not the MAF so I'm not *as* worried about unmetered air sneaking in around the TB. The stock intake is there temporarily because I had it on hand. See above: I have so much left to do.
If you take a look in this slightly older photo you can get a better view of the visible part of the "adapter". Seems like I didn't take any photos of it outside the car. This is probably iteration 10 or so with the first several mockups made in MDF to gauge fitment and then some prototypes in plastic that didn't quite work out for various reasons.