legacycentral bbs

Just finished a day of Subaru Intercooler Fun...

Take a look at what has been rigged so far... coolant tank will be where the washer tank was, washer tank's getting moved to the trunk until I can find a smaller one or swap back with the battery.





Tomorrow it will be getting finished. Coffee mug mod and MBC also in today - when doing these at the same time you only need to put the two larger hose fittings on the mug, the small one is not needed with the aftermarket boost control.

Lower BOV vaccuum line is run over top of the intake manifold and just left there, it is an atmospheric reference and I just didn't want my new WRX hood scoop to fill it with water by leaving it unrouted. Photos of that to come tomorrow too, hopefully. Why yellow silicone hose? It was pretty much the only way that I had to get the line size I needed that wouldn't disintegrate with vapors (for the canister line from the mug) and it just so happened to come with sizes for the BOV as well. A bit more color than I like under the hood but hey...

With some careful placement, IC has good clearance from the firewall and throttle plate. That's a "2 inch coupler" from home depot that's somehow fitting over the TB and then tapering down to the IC. IC's resting on foam taped to the top of the clutch fluid reservoir. Hood will be spaced up slightly and all will be cleared.

Looks good. That IC-TB coupler wont last long though, I've gone through at least ten of those. AutoZone has a intake adapter thing that works well, try that if you have to replace it.

I used a peice of fuel line to go to my purge canister from the mug.

BAC5.2 wrote:I used a peice of fuel line to go to my purge canister from the mug.

As did I.


Any particular way the couplers were failing? I was wondering if I would have to replace the ones I am going to use later on down the road.....

Lets see a pic of the scoop...

I've had the IC-TB connector blow off a few times (makes me feel like a DSM owner ) but if you really crank it down and make sure it stays tight you shouldn't have a problem. Nice setup, I love the BOV. I think its venting to atmo. right? Are you having any driveability problems?

Heh... drives GREAT... atmospheric BOV = no problems + loud frickin sound

Scoop's black now, got a photo for you as well as the completed coolant tank relocation. ahhh......me rikey vely much

Which adapter from autozone do you mean, they only had 3"-2.5" and 3"-3" couplers, and the tapered one was way too long and wrong size. Part # would be nice - photo?


Scoop was originally red. Lightly sitting on my hood.


Scoop is now black. Mounted properly on my hood. Diverter/air splitter to come.


Overall engine bay shot now


And theres the coolant tank. Screw the washer bottle. Screw it right in its ear.

oh yeah... running 10-12 psi depending on how the MBC spikes. Need to turn my attention to fuel cut defeat next...

Oh - I also fixed up that restrictive intake inside the fender. How do you like my new improved cold air intake?



Also found this rectangle inside a box near the front, looked to be further disturbing air flow. I took that sumbitch out too. Now I'll have some power!

Beware of low-flying birds though. They seem to be attracted right to that thing. I've already had to clean out feathers twice.

Get some whole car pictures so we can see the scoop on the car!

Did you cut the hood? I've been toying with the idea of making a better hood scoop, but time does not permit .

free5ty1e wrote: Which adapter from autozone do you mean, they only had 3"-2.5" and 3"-3" couplers, and the tapered one was way too long and wrong size. Part # would be nice - photo?

You can trim the 2.5-3" down a little and it fits. Oh and don't be afraid to turn up the boost past 11.

Whole car pictures? I think you know what a white Legacy looks like. ...yeah, OK, I suppose I could get one of those sometime soon. Although the scoop's pretty much the only different feature visible from the outside (and the intercooler and BOV from through the scoop).

vrg3's phase II FCD installed today, am no longer afraid of my boost knob Runs 12-14psi like a champ. BOV just keeps sounding better and better. I do feel the lack of the recirculation between shifts, however it's minimal. Car just bucks a bit more if ya don't give it enough gas when letting off the clutch.

Yes, had to cut the hood (quite a few times I might add) and drill new holes and even mount new studs on the scoop but it was worth it. Made sure to put some touch-up paint on all newly-exposed metal to prevent rusting, too. I have some photos of the cutting job, and the scoop studs too. Below.


Scoop hole before


Scoop hole after (holes weren't drilled at this point)


Scoop's new studs (original studs WAY too short) - these are lightly tightened down to the hood and silicone has been dabbed on the end of each stud to prevent the nuts from vibrating off. Getting some weatherstripping from Home Depot to replace the used foam strip around the edge, as it doesn't completely seal right now (don't want to tighten down too hard on the studs until the epoxy really has a chance to fully cure) but thats easily fixed later.

Turbo is louder than ever. Lovin' it. Need me a 16g now.

How much boost do we have enough fuel to compensate for safely? And can even boost be attained in all gears? 1st gear doesnt load up nearly as much as 5th.

(by the way... I dont see how that autozone 3" -> 2.5" coupler would work no matter how much I trim it. Are we talking about the same piece? I do have one here in my hands... are you saying to force the taper over the TB and try to fit a hose clamp over it? Doesn't seem like much clamping room.)

We have enough fuel to compensate for anything the stock turbo can make. At least that's what I found, no knock whatsoever at max boost with 210K miles

For the coupler... put the big part on the TB, then trim it just enough so you can squeeze the IC in there. If it's not thick black rubber than its not the same piece

Anything the stock turbo can make?! As in... 20+ psi? (I thought I'd remembered someone running with the wastegate unplugged resulted in like 21, 22psi...) Whoa. um... at what point does the stock turbo start pumping out superheated plasma and becoming counterproductive??

As for the coupler, maybe you've got a different TB on your '91, but the 3" part is entirely too loose to fit on mine. The 2.5" side is just right for the IC outlet, however. The Autozones I went to had no other couplers but the two I listed. Hmm....

free5ty1e wrote:Anything the stock turbo can make?! As in... 20+ psi? (I thought I'd remembered someone running with the wastegate unplugged resulted in like 21, 22psi...) Whoa. um... at what point does the stock turbo start pumping out superheated plasma and becoming counterproductive??

That was me..lol and no, it was going pretty good.

As for the coupler, maybe you've got a different TB on your '91, but the 3" part is entirely too loose to fit on mine. The 2.5" side is just right for the IC outlet, however. The Autozones I went to had no other couplers but the two I listed. Hmm....

You can squeeze it down with a hose clamp.. it will work.

The hell you say. Well, I guess I'll give it a try this weekend, when I go back over to my friend's place. A garage makes this kind of work a whole lot easier than trying to do something in an apartment complex parking lot. Took about 10 minutes to install that FCD (one of the only things I'd done here in the lot) and by that time I was ready to jump in the pool.

I'm gonna go find a compressor map for the VF-11, and see how much I want to push it. I think I saw one somewheres in one of those PDFs posted in a sticky...

Yeah, there's a compressor map at the end of the engine manual that Josh posted that's allegedly for our stock turbo.

The stock turbo easily pushed 20 psi on my car, and I definitely would not want to let it. I do not believe that the stock fuel system can't safely handle it.

91White-T, what kind of instrumentation did you use to determine that your car was running good on superheated plasma?

vrg3 wrote:91White-T, what kind of instrumentation did you use to determine that your car was running good on superheated plasma?

Butt dyno...lol Seriously though, I've had no problems whatsoever running max boost. I've checked plug #3 pretty often and it doesn't look like its running lean at all...

lol... well I've got problems where I didn't expect them. My BOV's piping is so smooth, that no matter how tight I make the hose clamps, anything above 14psi blows it right out of the tubing. The intercooler gets slammed up against the firewall, and a small gap appears between the BOV and its turbo-side coupler. I'm going to take it off and score the metal up on the outside of the BOV piping so the rubber/hose clamp has a good place to grip something. lol... I also zip-tied the wastegate line to my MBC - that blew off about the same time the BOV blew out of its coupler. So I'm running 11-12psi until I can be sure nothings going to slip apart again

Anyway - I'm trying to read that compressor map and its confusing as all hell. How do you read them things? What I want to know from it is, how hard should I realistically push the stock turbo to be within its efficiency range? I don't like the idea of superheated plasma pumping through my intercooler and engine, so I'd like to limit boost to below that threshold.

And vrg.. you seem to think the fuel system has a problem keeping up with the stock turbo's 20psi, is this due to the extreme heat of the air at that boost level with that turbo or just that the injectors shouldn't be able to keep up without going over 80% duty cycle or something? What's the safe limit for our fuel injectors with the stock turbo?

This will all change once I find me a t3 to hybrid with... then I have no idea how to determine what boost levels would be efficient and/or safe, I'd imagine after that point both the T3 map and the VF-11 map would be incorrect...

Sometimes a little bit of hair spray on a pipe can help keep a hose on it. The Right Way is to have a bead that the clamp can go past, though...

I think that at 20 psi the stock fuel system would be unable to provide enough fuel to properly cool the intake charge, due to both the high pressure and high temperature. Combine that with no means of measuring intake air temperature and you'll get lots of knock and subsequent timing retard.

I don't know that for sure, but I have a hard time believing otherwise.

knock is bad, mmkay?

(did you just call me a retard?)

ohh... "subsequent timing retard"

not "subsequent timing, retard"

HAHAHAH, awesome