Inside the BBOD

[B4 I was 250T]

Hold on!! WTF??!!

[B4 I was 250T]

 Rosssub said:

No ECU tweaks for me, Rev B.

The ECV\'s control/feed (hose 2 in BOD) has a 0.8mm restrictor the same as the Waste Gate control. I changed the "hose 2 pill" from 0.8mm up to 1.0mm. Altering my ECV Duty Cycle.

That could be more your EBC\'s settings (rev d/hks ebc?) Try adjusting/raising your gain

percentage etc.

Edit: Also your Rev D? Tuneable ECU?

So would you recommend replacing hose #2 pill with 1mm pill?

[Rosssub]

 B4 I was 250T said:

So would you recommend replacing hose #2 pill with 1mm pill?

It could have a negative effect if you haven't de-catted and freed up the intake etc. But it's no biggy to swap back if it doesn't help.

[B4 I was 250T]

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!

[Guest]

 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!

Well, what a reply of praise. What exactly is the 'mod'? Place a 0.8mm restrictor pill into hose #1 near the BBOD? B4 I was 250T, can you give me a brief run down on exactly what you did?

Sounds like $13 well spent.

[B4 I was 250T]

 bnneie said:

Well, what a reply of praise. What exactly is the 'mod'? Place a 0.8mm restrictor pill into hose #1 near the BBOD? B4 I was 250T, can you give me a brief run down on exactly what you did?

Sounds like $13 well spent.

I literally pushed a 0.8mm restrictor pill 2 inches up the hose at the BBOD end. That's it! All thanks and praise goes to Ross! Legend!

[Rosssub]

Thanks man, such a massive problem and such a simple fix. Quick recap of what I found after a few days testing the BBOD:

At initial VOD the IACV opens wide, fast. Which is when all primary boost disappears, straight into the spooling secondary turbo.

Putting the 0.8mm restrictor pill into hose #1 between the BBOD and IACV, makes the IACV open much slower as VOD hits.

So the primary turbo/waste gate now have time to react or keep up, as the IACV opens and the secondary turbo spools.

My VOD (initial primary boost loss, to full twin turbo boost), went from 5-7 seconds to 1 second.

[Guest]

Beautiful.

 B4 I was 250T said:

I literally pushed a 0.8mm restrictor pill 2 inches up the hose at the BBOD end. That's it! All thanks and praise goes to Ross! Legend!

Did you get the pill as a genuine one from Subaru?

[Andy_Mac]

they were like $12 bucks from subaru. Took awhile though as they don't usually carry them so had to come all the way from japan

[Guest]

 Andy_Mac said:

they were like $12 bucks from subaru. Took awhile though as they don't usually carry them so had to come all the way from japan

Perfect. Can I order online (can't find it on the Subaru NZ site) or do I request from the dealership?

[Rosssub]

Order by part number through local Subaru, or steal one from an old BBOD (one in hose #2).

0.8mm Pill - 22326AA260

Subaru Pill Part Number Source:

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

[B4 I was 250T]

I went straight to our Subaru dealership (Armstrong Subaru) and ordered it from them :-)

[GorGasmSpecB]

I just pulled a restrictor out of an oldc line labelled 22, I think its 1mm or .8mm. Either way it appears to have made a nice difference. Should be interesting tomorrow after downpipes are fitted!

[GorGasmSpecB]

Did this again last night with something closer to .8mm this time. Previously was a ~1.3mm. Definitely a good improvement, VOD as mentioned by Ross is more of a transition to awesomeness.

I now have my car running really well with downpipes, FMIC, EBC, replaced vacuum lines and the hose 1 restrictor mod.

[legacybe5]

OK. so i got a BBOD from a wrecked legacy and took the restrictor pill (which is suppose to be 0.8mm) from hose #2 in the BBOD. i placed the pill 2 inches into hose #1 (between the BBOD and the IACV).

Transition to twin turbo is SWEEET!!! best ive ever felt from my legacy, the VOD is hardly even noticable. its no longer primary turbo............laaaaaaaggggggggg...............secondary turbo. its now more like primary turbo..secondary turbo.

Though there is one issue ive noticed. From a stand still, if i apply full throttle, im only getting 5 psi max on primary and after change over of the turbo, i get 5 psi max on secondary. If the vehicle is already rolling along at say 30 KMPH and i apply full throttle i get full boost at 15 psi.

any suggestions??

[Rosssub]

Try cleaning out your primary boost solenoid, inside the front passengers guard. Put car into test mode (green and black plugs) then blow some carb cleaner through the solenoid as it pulses open/shut.

Could also be a vac leak (rough idle), or maybe a leaking BOV (can block off to test).

Primary boost solenoid:

[legacybe5]

 Rosssub said:

Try cleaning out your primary boost solenoid, inside the front passengers guard. Put car into test mode (green and black plugs) then blow some carb cleaner through the solenoid as it pulses open/shut.

Could also be a vac leak (rough idle), or maybe a leaking BOV (can block off to test).

Primary boost solenoid:

will try cleaning that today. no rough idle though, car idles great

[legacybe5]

Cleaned the boost solenoid. Tried the restrictor pill again, only 5psi max.

[Rosssub]

Check the diaphragm inside the BOV, secondary relief valve, exhaust control valve actuator and waste gate actuator. (all shown in first few pages).

Check the internal diaphragm by connecting a length of vac hose to the items vac nipple, then suck on it and cover the end of the hose with your tongue. It should hold vacuum permanently. If the vacuum lets go there is a hole in the diaphragm and that item needs replacing.

Make sure there are no splits/holes in the intake pipe, between the air filter and turbo's.

Can do a boost leak test, by blocking the intake at the AFM. Then pump 10-15psi into the manifold with an air compressor. Any boost leaks will be obvious.

Edited August 3, 2014 by Rosssub

[BINKZ]

 Rosssub said:

Thanks man, such a massive problem and such a simple fix. Quick recap of what I found after a few days testing the BBOD:

At initial VOD the IACV opens wide, fast. Which is when all primary boost disappears, straight into the spooling secondary turbo.

Putting the 0.8mm restrictor pill into hose #1 between the BBOD and IACV, makes the IACV open much slower as VOD hits.

So the primary turbo/waste gate now have time to react or keep up, as the IACV opens and the secondary turbo spools.

My VOD (initial primary boost loss, to full twin turbo boost), went from 5-7 seconds to 1 second.

Is there a danger to the engine in doing this? I recently bought a 2002 Rev D GTB (its an auto..) and have been reading around for mods...

[evljat]

We tried it on my rev.d when I was getting it remapped and it didn't make a difference.

[BINKZ]

 evljat said:

We tried it on my rev.d when I was getting it remapped and it didn't make a difference.

Where did you get the remap done?

[Rosssub]

It can be tuned out/adjusted on a REV D, by changing the IACV opening threshold voltage. Telemekas would be the man to ask about that:

 telemekas said:

Excellent work ;D

On reading the post I was surprised how soon the IACV opened.

I always believed the IACV opened when the primary boost and secondary boost where equal.

I assumed the pressure difference would be zero and the output voltage (OV) would be 2.0 as per Subaru literature etc.

See pages 12- 13 on switching to twin charging.

http://www.veloce.pwp.blueyonder.co.uk/Twin%20Turbo%20Operation/ttopprt2.htm

However this is not the reality as you have shown

I have checked the ECU maps on several TTs including the lastest S401.

The IACV opening threshold is set between -7.3psi (0.86 OV) and -1.16psi (1.82 OV) pressure difference.

This can be easily modified in the ECU map (tunable ECU) to get OV of 2.0

[raijin]

 Rosssub said:

It can be tuned out/adjusted on a REV D, by changing the IACV opening threshold voltage. Telemekas would be the man to ask about that:

Actually the effect can be obtained by adjusting the delay values on the ECU for the IACV opening in addition to recalibrating a number of other parameters relating to turbo transition which is what I did with Jag's car when I mapped it (evljat). This does require full definitions for the ROM on the ECU though. This is why the 0.8mm restrictor hack did not provide any additional benefit as the ECU was already producing the desired behaviour via recalibration (I was just curious to see if there was any additional influence)

[BINKZ]

 raijin said:

Actually the effect can be obtained by adjusting the delay values on the ECU for the IACV opening in addition to recalibrating a number of other parameters relating to turbo transition which is what I did with Jag's car when I mapped it (evljat). This does require full definitions for the ROM on the ECU though. This is why the 0.8mm restrictor hack did not provide any additional benefit as the ECU was already producing the desired behaviour via recalibration (I was just curious to see if there was any additional influence)

Have pm'd you haha