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Your Guide To Twin Turbo


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#1 Jimbo

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Posted 11 March 2014 - 08:10 PM

Gents,

Here is a comprehensive guide to TT operation for easy access. Troubleshooting and modification tips follow.

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SOLENOID DUTY AND VALVE OPERATION

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TROUBLESHOOTING TIPS
 


1. Remove intercooler and check the pipes and connections are in good order and that the ICV works
Check your BOV is not leaking/ block it up temporarily. While TMIC is off, inspect the intake pipe for cracks/ leaks and ensure all breather pipework is in the right spot, in good order and the PCV is operating correctly.

2. Remove each and every vacuum line between the BBoD and other components one by one and clean/ check/ replace them as necessary, making sure you replace any restrictor pills.

3.Remove the BBoD and clean all the solenoids, their vents and lines one by one. ( Subaru Upper Engine Cleaner is ideal, link provided for how-to below )
 

4.Reassemble BBoD

5.Remove the boost control lines at the Primary Turbo and plug them up (temporary)

6.Fit a piece of vacuum hose between the compressor outlet nipple and wastegate actuator to give you wastegate pressure boost control (7/9 psi)
 

7.Reset ECU and test the system.

If you still have issues then move down the list here

8.Block up the Secondary BPV. Really it's 99% useless anyway, test.

9.Check operation and adjustment of ECV. It may not be tight enough causing exhaust gas to divert into the secondary at all times. 
you'll eventually get some boost at around 5000rpm if this is stuck open.

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LINK FOR INTERCOOLER REMOVAL http://www.subyclub....l-installation/

LINK FOR GEN3 AFTERMARKET BOV INSTALL http://www.subyclub....oosting-issues/

LINK FOR SOLENOID BOX (BBoD) RESTORATION http://www.uklegacy....urself-cheaply/

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ADJUSTING ECV OPERATION ROD

post-3138-0-62501300-1393463002.jpg 
 

If you look at the rod going from the ECV actuator to the ECV itself (in the Secondary up-pipe) it has two 10mm lock nuts above a LONG flat-sided section.

1.Loosen off the lock nuts

2.Warm up the car and have it idling.
3.Turn the adjuster part (flat sided bit) to lengthen the rod (which opens the ECV) until you hear it rattling,
4.Tighten it again about 2 full turns.
5.Do up the lock nuts and test

This will put enough pre-load on the actuator so that it's held closed, but once the system gets sufficient exhaust flow it will start to creep open slightly and allow the "pre-spool" to begin on the secondary (the whole bypass above is bypassing the pre-spool system which does bugger all)

If it's too loose, it will blow open too early and you'll get erratic boost, too late and it won't open soon enough, making the VoD worse.

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ECV SOLENOID BYPASS MODIFICATION

WARNING: NOT SUITABLE FOR D/E REVISIONS.

 

There are a few other mods you can to do simplify the system.

The ECV has two ports, a top port and a bottom port. You can effectively remove the two solenoids and vacuum lines going to the top-port.

1. Place a T piece into line #22 (Line to DPS) about 5-10cm from the SPV.

2. Cut hose #5 (Positive ECV port) about 10cm from the ECV port and place into the T piece we just put in hose #22.
3. Block up the remainder of hose #5 (From the BBoD)
4. Perform ECV Rod adjustment as described above.

The ECV Duty Solenoid, the line feeding it and the restrictor pill has a tendency to clog up and it blows the ECV open early, resulting in dodgy boosting
It is still pulled and held open by vacuum from the tank, when the ECU tells it to changeover.

post-3138-0-06457300-1393461190_zpse1e04

 

 

Essentially, everything marked in red can be disconnected from the vacuum system. (solenoids need to be connected to ECU or bypassed with resistors)

 

post-3138-0-64224300-1393461730.jpg 


So now with all that junk bypassed and the top port plumbed into the line that feeds the DPS (this line ONLY sees boost once the ECV is open and the Secondary BPV closes) here's your new simplified system.

 

post-3138-0-62567800-1393462430.jpg 

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LINE #1 MOD

(Used without permission courtesy of ClubSubNZ, cheers cubts)

*Figures given may not be accurate or performance gains guaranteed as this is 3rd party untested information.

Outline:

Insert a 0.8mm restrictor pill into line #1 (Intercooler Air Control Valve)

Benefits:

- 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 sequential operation*
- Stable boost throughout entire RPM range*

Instructions:

- 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.

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

0.8mm Pill - 22326AA260
1.0mm Pill - 22326AA010

​Alternatively, a second-hand unused stock boost control line contains an 0.8mm restrictor from the compressor outlet to tee-piece.

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INTAKE MANIFOLD REMOVAL (BH5/BE5)*

*Can vary from Rev A-D but is essentially the same. Some revisions to pipe work/lines.


1. Remove air box and joiner to the intake tract
2. Remove intercooler and BOV (You can find that in the YGTTT thread)
3. Disconnect all the plugs from the manifold harness and the vac line groups from the Black Box (All 3 groups)
4. Using a screw driver, loosen the clamps on the turbo snouts
5. Remove the top breather lines and rubber hoses going to the heads (metal pipes running across the top) and, the brake booster line.
6. Disconnect all coolant lines (You're going to have to lose some coolant, keep some handy for when you finish)
7. Remove coolant header tank
8. Remove Secondary Turbo Bypass Valve
9. Remove throttle cable
10. Remove Alternator (Probably not necessary but makes it much easier to access other wiring plugs)
11. Remove all 3 fuel lines.

12. VERY CAREFULLY check the condition of the breather lines attached to the intake tract before starting the manifold removal process. There's one big one which comes from the block, and goes to an "F" shaped connector. These particular breather lines and plastic connectors are VERY BRITTLE. IF you break one, you're in a world of PAIN. BE VERY CAREFUL removing the breather line which attaches to the intake tract just under the throttle body (it's directly under the line which goes to the ventilation valve in the throttle body). That connector on the intake tract is pretty much guaranteed to break. Unfortunately there's no real easy way to avoid it or do it. You just have to hope it's not in that bad a shape. I would even nearly recommend carefully cutting the breather line in the middle (the easiest thing to replace) and remove the rest of the line off the intake tract once the manifold is out.

13. Undo the 4 bolts at the bottom of each manifold runner. Some of them can be tricky to access (especially around the intake tract) and you'll need an extension for you socket set at least 20cm long. You might have to have some tools that are flexible, too.
14. MAKE SURE the breather lines we spoke about at Step 12 are all freely disconnected. If you try to lift the manifold off and you've forgotten about them, they're toast.
15. Carefully lift the manifold up and towards you and assist the intake tract in becoming free from the turbo snouts if they're a bit sticky. The manifold might take a bit of force to separate from the block it's a bit sticky, patience and a small flat blade screw-driver can help.
16. Before you pull the manifold free, do a quick check to make sure there are no more connectors or lines impeding the removal process. 

Recommendations : 

- It would be wise to grab yourself new manifold gaskets and even a throttle body one if you plan on removing that too.
- Can be a good idea to inspect the injectors and have them cleaned while they're more easily accessible.
- Get yourself some Ultra Blue gasket sealant to aid the re-installation, that way you know it's tight.
- A good opportunity to give the manifold a clean-up and even a lick of paint if you can spare the extra time.
- Get yourself an eBay silicone intake to replace the OEM plastic tract. https://www.ebay.com...zYAAMXQTgZQ9ehi they are expensive and a bit tricky to fit, but it's good insurance in case something breaks, which it will.

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TURBO LISTINGS

PRIMARY(P) SECONDARY(S) SECONDARY W/ WASTEGATE(WG)

VF13P and VF14SWG - 1994 to 1996 Gen2 Legacy GT/RS (AT and MT)
VF18P and VF19S - 1996 to 1998 Gen2 Legacy GTB/RSB (MT)
VF20P and VF21S - 1996 to 1998 Gen2 Legacy GTB/RSB (AT)
VF25P and VF27S - 1998 to 2003 Gen3 Legacy GTB/RSK (AT)
VF26P and VF27S - 1998 to 2003 Gen3 Legacy GTB/RSK (MT)
VF32P and VF33S - 2001 to 2003 Gen3 Legacy B4 S401 & Liberty B4 (MT/AT)

NB: Unsure of VF31 placement, possible AT on JDM Models. Some model years may be incorrect.

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RECOMMENDED MODIFICATIONS

Although it is not recommended to modify a TT system without proper knowledge, here is a rough guide of what is tried and tested.

Intake :

Intake mods are the same as most Subaru's. Due to high temperatures it's best to avoid running an exposed filter in the engine bay. A hand made in guard CAI will net the best results. The stock airbox is more than capable with a higher flowing filter installed. Silicone under manifold intakes are available on Ebay but will only suit the AUDM B4 with the larger VF33 compressor cover.

Exhaust :


For the exhaust, 2.5" dump pipes leading into 3" piping at the dump pipe merge is optimal.  3" dumps are too large and should be avoided. Combine with a high-flow cat. Mufflers are anybody's choice. For the more experienced, manifold and ECV porting is beneficial to the TT process. Replacing the up-pipes with custom pipes is recommended as the stock units break over time and cause sluggish performance, the same can also be done for the crossover pipe. The stock bi-modal muffler has an electronically operated valve which has been known to seize over time.

Vacuum Lines :

Part of the good running and maintenance of the TT system requires at some point for the vac lines to be replaced. For the non-faint-hearted the BBoD can be dismantled and the vac lines within be replaced. Refer to a BBoD line diagram for restrictor pill placement as these are essential. These lines can simply be cleaned with SUEC. All other lines can be replaced by same ID hose readily available at auto stores. About 10 or 15 meters will do the entire engine bay. Be sure to check a diagram for correct fitment. It is also a handy idea to use small labels to re-number your hoses so they don't end up in the wrong place.

Turbo Swaps :

All Subaru TT turbos are interchangeable within their respective positions (Primary or Secondary) , bearing in mind the VF33P has a larger compressor cover and the matching intake tract must be used. All rear exhaust flanges are the same ( Primary and Secondary). Most primary turbos are bush bearing designs and secondary's ball bearing. Hybrid turbos can be made but are for the more advanced modifier. The most common turbos used for maximum performance are the VF26P and VF27S. The AUDM B4 VF33P and VF32S also are great turbos but has above require the intake tract to suit. Do note the earlier VF14S is not interchangeable due to having it's own wastegate and cannot be changed out of early Legacy GT's due to this.

Intercoolers :

FMIC setups are available, notably the kit made by Scarles in NZ. No further information can be given regarding this kit. Larger TMIC's can fit however clearance of the Primary Turbo should be noted. The cast boost pipes to the bottom of the TMIC sit in the same configuration as the single turbo Subaru's.


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1993-1995 Legacy GT/RS (Non-GTB) BBOD Diagram (Secondary Turbo Wastegate Application)

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LGTLines_zpsjtxqakpm.jpg

 

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#2 Jimbo

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Posted 11 March 2014 - 08:16 PM

Rob, i inputted all of your data and how-to's in here and cleaned them up a little. If there's anything you think that should go in here or if anything needs editing, let me know.


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#3 Beckers

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Posted 11 March 2014 - 08:26 PM

Great info, Nice job.



#4 KONG

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Posted 11 March 2014 - 09:19 PM

Awesome Jimbo  ;)

 

Allow me to add some links....

 

 

 

TT intercooler removal and installation.

http://www.subyclub....l-installation/

 

Restrictor pill locations & Aftermarket BOV Vac line plumbing

http://www.subyclub....oosting-issues/

 

Refurbing the BBOD solenoid box

http://www.uklegacy....urself-cheaply/



#5 Jimbo

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Posted 11 March 2014 - 09:27 PM

What i'll do, ill take all this good stuff, keep adding to the original post so it doesn't get lost so it's all in the one place!


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#6 KONG

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Posted 11 March 2014 - 09:29 PM

Great idea.



#7 Mbooma

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Posted 11 March 2014 - 09:34 PM

Amazing .... see now someone like me before todays adventure being a noob this would hav help all being in one thread so great work an ill keep u all updated on my journey of my tt

#8 Jimbo

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Posted 11 March 2014 - 09:44 PM

Your issues and my born again interest in Subaru's convinced me that this needed to be done. There's tonnes of info for the TT out there, but unfortunately it's scattered all over the interwebs. What we are going to do here is compile all this information into the one post so it doesn't get lost in pages and pages of threads. This will be the new one-stop-shop for all your TT needs.


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#9 Hypnotic

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Posted 11 March 2014 - 10:09 PM

Cheers guys, very much appreciated.


As soon as she hands it to you, slowly take of your pants, then, while staring her straight in the eyes rub it against the tip of you penis, while continuing your painfully intense gaze whisper to her;
 
"My eye is watering, this might be a bit hot"

I should just convert to single, right?
 
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#10 Cam.

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Posted 11 March 2014 - 11:15 PM

I think I just spewed.


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#11 Tim.

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Posted 12 March 2014 - 08:23 AM

Haters with hate. But this thread is awesome and much needed. Thanks Jimbo and everyone else for contributing.

#12 allpaw4

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Posted 12 March 2014 - 08:34 AM

This is an amazing thread. I would have used this for sure when I had my TT engine. I haven't read it all yet, but that's what night shift is for. :P

MY02 Blue B4, aka 'The Project' - v8 Spec C engine package and assorted other 'goodies' - Sold, then bought back for parts. In process of stripping.

MY97 Silver RX, aka 'The Track Toy' - All good bits from B4 will find their way into this...
MY03 Holden Commodore - Daily. Because good on fuel.


#13 Dav_fre

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Posted 13 March 2014 - 08:12 AM

A long overdue thread...

No longer will I be scouring through page upon page of different forums thinking "I know
I seen that forking thing here somewhere"!!!




#14 AB501UT!0N

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Posted 24 March 2014 - 11:22 AM

Awesome job mate thank you very much for all the info :D



#15 Jimbo

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Posted 14 April 2014 - 09:22 PM

Some interesting observations i have made with my Rev-A regarding the BOV setup.

I have no idea why it's set up this way but the line from the manifold to the BOV has a restrictor pill in it. This same line, about midway. has a tee which runs a line to a stack which plumbs back into the intake. This same stack also carries the BCS bleed of line.

My question is, why would the factory BOV not have full manifold pressure applied to it to keep it closed? The way the factory setup is, means the BOV would bleed off some boost back to the intake until the pressure equalizes and keeps it closed. I experimented with it and found by running a pill-less line straight from the manifold to the BOV (And blanking off the line which bleeds back to the intake stack) the car felt punchier and more responsive low down. It also took longer to change-over with the factory BOV setup compared to the line i made up.

Looking at the above pill location chart for AUDM B4's, i can't see how this is different and changing the hoses out the way i have done, doesn't have any adverse effects to the way the system operates, only benefits.


STOCK SYSTEM
STOCKBOV_zps284305ce.png

MODIFIED SYSTEM
MODBOV_zps03072740.png


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#16 KONG

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Posted 14 April 2014 - 10:13 PM

Yes Jimbo.  This is the Hose 10 mod & the plumbing needed for people using aftermarket BOV's. It closes the loop in the wastegate control solenoid lines and feeds direct manifold pressure to the BOV without bleeding any off.
I also have 2 x 10c pieces in my GFB and I still think it struggles to hold boost over 16psi.
 
Easy mod ;)

#17 Jimbo

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Posted 14 April 2014 - 10:19 PM

From what i can gather, it seems both the manifold pressure AND part of the BCS bleed off keep the BOV closed. I dare say the pill/s regulate that flow so it's probably more or less the same as total manifold pressure, but i was pretty certain the car felt more responsive with the BOV isolated from the BCS bleed off. I would also say the BCS might respond better without the manifold pushing some (Likely a minuscule amount) positive pressure up its bleed off line.

When i first checked out under the engine bay when i brought it home, it appears some mechanic already put a single line from the manifold to the BOV in place. However the line normally teed off that was supposed to be attached to the BCS/BOV bleed line stack on the tract, but the hose was missing and the connector to the stack was just left open-aired sucking in un-metered air.

Found the lines in the accessory compartment under the rear floor, with the blue t-piece snapped... 


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#18 KONG

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Posted 14 April 2014 - 10:28 PM

WTF!

 

That's so ghetto.



#19 Jimbo

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Posted 14 April 2014 - 10:41 PM

Just did some reading of the link for the "Gen3 Aftermarket BOV" install which covered some info about why the BOV is setup the way it is. Apparently, the BOV is designed to open slightly under boost at cruising speeds to prevent "surging" of the primary. Pretty weird as it's a Gen3 specific thing. The Gen2 setup isn't like this at all, with the BOV fed straight from the manifold. I would say they did it mostly to improve economy and make it less mental then the Gen2.

There was some slight difference in the power band with the BOV setups, with the BOV isolated, it had better response and more boost, however the change-over was slightly more progressive.

Once i get a boost gauge ill do some testing to see the differences, then make an official addition to the main page.

EDIT:

Can someone confirm something with me, the line that goes from the BOV line tee to the stack on the tract, does it have a pill in it? According to the diagram above, there should be one in there. Which probably explains why mine felt like crap when i put the lines back to stock configuration. 


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#20 KONG

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Posted 14 April 2014 - 10:42 PM

And pics & build thread cubt!?






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