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Inside the BBOD


Rosssub
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 Marky']So how does the restrictor pill work different?

hmmm all very interesting hellish stuff that im looking forward to get rid of.

Correct me if im wrong Ross. but from what i understand Vacuum holds it closed, when you start to hit VOD/change over the vacuum is released and the spring opens the IACV. Air has to get into the solenoid "IACV" somehow and the only way is via the vacuum hose. Having the restrictor pill simply restricts the air getting into the solenoid thus slowing down the rate it opens.

[quote name='Rosssub said:

I have a spare B4 TMIC and IACV here, I\'ve been bench testing the opening speed. With a Vac hose connected to the IACV Actuator, applying Vac to close it. Then releasing Vac and timing how fast it opens. Then adding Restrictor Pills to the Vac Hose, to slow it down/restrict it.

IACV opening times:

OEM open 4mm hose - 0.15 seconds

2.0mm Restrictor Pill - 0.35 seconds

0.8mm Restrictor Pill - 0.85 seconds

I think extending the vacuum hose, using larger diameter hose or adding a collector tank would cause more of a VOD delay than anything else. This would cause the VOD/change over to occur slightly higher in the rpm where there might ? be more boost to handle spooling the secondary faster? Creating a similar but yet totally different result than the restrictor pill?

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  • 1 month later...

 Divine said:

Just read entire thread, wow. So 0.8mm restrictor pill in hose #1 and that's it, regardless if you have a BE5 A/B/C/D? My Rev. D is stock standard except a Fujisubo Super R exhaust, would I see any difference?

Rev-D already has this issue sorted via the ECU. Out of interest I did try this a while ago on my Rev-D and iirc it just slightly confuses things and delays the VOD/Change over a little. If you have a spare pill no harm in trying it for yourself though.

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  • 2 weeks later...
 Rosssub said:
Hell yes, no wonder TT boost can take so long to rise. A Restrictor pill in the IACV line to open it slower through VOD could help?

Edit: Need to fix my wiring on the Map Solenoid LED

I was thinking after reading this that if it was opened electronically via a stepper motor or something like that it could then gradually open rather than just opening it. The vac could be used to trigger a pressure switch instead of opening the IACV and that would then tell a small circuit to begin slowly opening over a preset time.

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 Rosssub said:
Well, very interesting so far.

The IACV gets vac at engine start up. Then opens completely (releases vac) at initial VOD, it opens as I start to lose Primary Boost. It stays completely open for Pre-spool, Full TT mode then only closes when back into Single Turbo Mode.

The ECV Duty Solenoid, runs a constant duty cycle (pulses) when in Primary/Single Boost (positive manifold pressure). It also pulses (bleeds) during Initial Primary Mode Deceleration. But when VOD hits, during VOD and in Full TT Mode it does nothing.

I was thinking after reading this that if it was opened electronically via a stepper motor or something like that it could then gradually open rather than just opening it. The vac could be used to trigger a pressure switch instead of opening the IACV and that would then tell a small circuit to begin slowly opening over a preset time.

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  • 4 weeks later...

Well I've got an auto bh5 Rev d and the 0.8mm pill in hose #1 has made a huge difference to the VOD on my car. It's a nice smooth kick from primary to secondary now with almost no lag. And I nabbed the pill from a wrecked bh5 at pick a part for $1 which was even better.

Definitely worth doing!

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  • 7 months later...
  • 1 year later...
  • Admin
On 24/06/2014 at 8:34 PM, B4 I was 250T said:

Hey Ross, ok, so I did the 0.8mm pill today and it's kinda like WTF??!!! This is the most amazing mod ever!! Car feels like it's on a leash and just rearing to go! Can't be sure but pretty sure wheels spun on launch. Dude, you're a genius! Anyone thinking of doing this- DO IT!!! Well worth it, best $13.00 I've ever spent on the car!

You made me excited....

 

 

On 30/12/2014 at 3:25 PM, A_J_T said:

Rev-D already has this issue sorted via the ECU. Out of interest I did try this a while ago on my Rev-D and iirc it just slightly confuses things and delays the VOD/Change over a little. If you have a spare pill no harm in trying it for yourself though.

Do you think I should still be excited?

 

 

Also, IF I do this, worth the time redoing all the lines in the BBOD (and cleaning the solenoids?)

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  • 2 years later...
  • 2 years later...
On 18/01/2014 at 4:16 AM, Rosssub said:

"VOD gone in 24hrs" 😎

Perfection, "ABSOLUTE PERFECTION". 0.8mm Restrictor Pill into Hose #1 at the BBOD (IACV Vac Control Hose)

- Primary Boost Loss throughout the entire VOD is less than 2psi. 😎

- Primary Boost Loss to Full TT Boost is less than one second. 😎

- Completely smooth and powerful transition into Full TT, just more "then more" power. :o

- Stable Boost throughout entire RPM range. 😎

- No Boost Spikes. 😎

- No CEL\'s at all, through entire testing. 😎

I "HIGHLY RECOMMEND" everyone that owns a TT Subaru with a BBOD. Fit a 0.8mm Restrictor Pill into Hose #1.

If you have fitted an \'EBC\' or \'MBC\', then your Primary Waste Gate \'OEM\' Hose contains a 0.8mm Restrictor Pill.

- Push the "OEM Pill" out, with a piece of wire.

- Pull hose # 1 from the top/front port of the BBOD.

- insert the Pill into hose 1, use wire to push it up the hose at least 50mm (2 inches).

- Refit hose 1 onto BBOD.

- GO and enjoy your TT Subaru, the way that Subaru should have built it. :)

If you do not have a 0.8mm Restrictor Pill, the OEM Subaru Part Number is:

0.8mm Pill - 22326AA260

1.0mm Pill - 22326AA010

Subaru Pill Part Number Source:

http://www.perth-wrx.com/vb/mechanicals/48287-restrictor-pill-what-why-you-need.html

Amazing. ;D

 

Sorry I can't let this thread just die but this simply gotta be the quickest and most rewarding mod you can do the twin turbo setup. 

 

Thank you Rosssub! 

 

I did this on my 2001 Rev D 

Auto/Tiptronic and it's made the biggest difference. I've already been running a manual boost controller and luckily I hadn't thrown out the old T piece with the hose which has that restrictor pill in it. Took  me less than 5 minutes to do the hose 1 mod. (Not counting me reading this thread over twice and a bit). 

 

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  • General Member
10 hours ago, Subzero1 said:

can't let this thread just die

 

as long as there are TT's people will join CS to search this info :P

 

that's what old threads are for!

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