looking at adjusting my Twin Turbo boost levels

[Guest]

so I understand on a single turbo you attach the manual boost controller on the turbo to waste gate vacuum line but what do you do on a twin turbo because there is two boost levels to adjust primary and secondary e.g. 14 psi and 16 psi can you turn both up or down?

[Joker]

ya dont basically

ony two options are Apexi-AVCr or Greedy Spec II (that not the right name but its close)

both these EBC's allow you to set RPM based boost levels ie 15/18 psi at different points in the rev range

never really got mine set up proper or figured out how to use it

and beware apparently you need a cert for a EBC these days too

[Guest]

having a cert for a boost controller is ridiculous what's the place coming to, ebc would be quite expensive right?

[telemekas]

Due to the more complex nature of the TT boost control (switching between boost control solenoids and the sometimes overlay of control between them). The system needs to be kept intact and then you can try and manipulate around that.

Try this:

MBC in line to the primary turbo wastegate actuator after the T junction.Therefore adjusting only how much boost/+ve pressure the actuator gets (similar effect to a stronger actuator spring but variable) this should control 2nd boost

MBC in line No:5 to the top port of the large ECV actuator.This again will adjust the boost/+ve pressure the actuator gets.This should control single turbo/dual spin up boost

See how it goes.

[Joker]

cert chatter : http://www.clubsub.org.nz/forum/index.php/topic,31659.0.html

and yea bout $400 for one of them ebc's i mentione

"Greedy Profec Spec II" was the name of the other one

[Marky]

I'll throw in a quick "What" here

All 4 of my GTB's I've done the same way - whipping the factory boost control out outright, running a bleed valve or relief valve inline from primary turbo boost-signal point to the WG itself, done - that is all, treat it like any other turbo car just with a weirdo flat spot in the middle.

On all 4 is has had the same result of XX psi on primary and the same on secondary.

The internet might say different - I've seen some creative setups before - but for me, this has worked 100% fine every time.

My BH right now I am using a super high tech plastic bleed valve, it makes 15psi by 2200 in 4th, does not spike over that, and then holds it rock steady on secondary to the red bits on the tacho. I was going to muck around with a relief valve or an electronic boost sensing switch but haven't seen any need for it, this is working as well as I'd need it to.

Not trying to stir or anything - more just my experience with them, I'm sure others have had different.

[Joker]

which shapes Marky? sounds like your way is good (II have no clue/don't fiddle with mine BG5c)

we might need to clarify methods per Model, thou I doubt they will be hugely different

[Marky]

Two of them have been BH's - like early (rev A?) - other two were both BG GTB facelift, one auto, one manual.

Just drove the current one (It's a novelty for me as wife has it all week) and the 2200rpm is a bit optimistic - it'll do it if I load it on the brakes a touch or do it in 5th - but anyway, they're nothing complicated.

Disclaimer: I could well be wrong with this but I see a lot of stuff online I know is waaaaaay off the mark

The way I look at things is to break it down a bit - the stuff in and around the secondary turbo on the drivers side is all soley about the switchover onto secondary. The regulation of exhaust gas to control boost is all done by the wastegate on the primary turbo. It's no different to (for arguments sake) a single wastegate on a TT inline motor. It's not done often but works just fine. The secondary WG on an early TT as I understand is purely an emergency overboost sort of thing and not actually functional(?).

Out of the box most people find they run (ish) 11 and 14psi, or whatever your model does. Open the exhaust up or put a pod filter on or whatever, and you get (for arguments sake) 12 and 15.

Now that's not what the system does by itself - the factory boost control solenoid / ecu is running making you higher psi in "twin" mode on purpose. The more you free up the breathing, the more boost you run. As the ECU isn't doing this in a closed loop fashion, it isn't saying "I am meant to run 15psi and will try to" - it's just saying "I am at full throttle and therefore will pulse this fast" and the guys who set this up knew that "Pulse this fast = make this much boost".

So....

If you take the factory setup out of the loop, just run a hose from the little pipe on the turbo, to the wastegate, you will get actuator pressure - in the case of my car, that means 9psi primary, 9psi secondary, and being overtaken by hondas.

If you introduce a bleed valve here, I have never experienced any spiking, overboosting, or discrepancy in what I ask for. On some cars, for sure, but I've never had a problem with a TT legacy at least. No noticable difference between hot or cold weather - that said I don't have it turned up to the point the car is on the ragged edge of "safe" to start with. I can ask it for 12psi on both, 20psi on both, or if I used something RPM triggered I could ask for 9psi on one and 20psi on both - or vice versa.

The key thing I think is that half the problem stems from people trying to use a bleed valve in conjunction with the factory boost control system, it's never going to work quite right, same goes for basically any turbo car with an electronic boost control solenoid.

If you want electronic boost control so be it - chuck the solenoid for it in the same place, but as has been said it can be a mission (but do-able) to set it up right as closed-loop systems will throw a wobbly at the switchover point, and open loop (non-feedback) electronic controllers are in my opinion at least a waste of cash. I have had wicked results from using a pneumatic relief valve (like a valve which blocks pressure to the wastegate until it "pops" open at given PSI) and also from using a boost activated switch attached to a factory boost control solenoid, basically an in-cabin version of the relief valve.

Like I said - I might be wrong about it, but it has always worked just fine for me - I think a lot of the time the TT setup just gets put in the "too hard" basket and I've seen some retarded advice online which muddies the water even more. End of the day the boost control system in these cars is absolutely nothing different to any other. The switchover side of things and the dead spot don't help things - but if you leave them out of the picture, it becomes a lot simpler to look at.

[Guest]

wow great info man! so just to clarify if I buy a gfb mbc I remove the restrictor pill in the turbo to waste gate line and join the mbc after the tee?

[twinturboboy]

Tell you what why dont you just leave your car standard, the more you piss around with boost levels and things like that the more prone the TT Legacys are to giving trouble - this is why people always moan about having trouble with their cars - because they root them by putting pod filters in and playing with the boost and things like that

No hard feelings m8 but just a thought aye!

[Guest]

well there shitty and gutless any way so modding only makes them better that's the way i see it

[Stoffa]

 twinturboboy said:

Tell you what why dont you just leave your car standard, the more you piss around with boost levels and things like that the more prone the TT Legacys are to giving trouble - this is why people always moan about having trouble with their cars - because they root them by putting pod filters in and playing with the boost and things like that

No hard feelings m8 but just a thought aye!

+1000000

Wise words

or ditch the twin turbo and go single

[Eight_dollar]

set them up properly - not many know how ! twins arent simple

and for what its worth boost is controled by the primary wastegate (during primary and sec boost)

To modifiy a twin without desent knowledge of the system is usually the start of no return to a single

Heard stories from someone in the know, that so many twin get changed because people cant work them out - or mod them to there BEB coffin

[twinturboboy]

Interesting that you say they're s***ty and gutless - I wouln't call 190+ KW gutless

[Joker]

I had 180kw at the wheels at one stage OEM

[Guest]

yeah well it seems like you can't do anything on them with out something going wrong like a pod filter for example most cars go better with a decent pod with a cold air box . . . and as for me saying they are gutless that's just my opinion maybe its just my car . . . not having a go at any body but I can now see why people always say "buy a nissan" LOL

[Joker]

most cars pre 95~ went good with a pod : post that Manufacturers figured out fuel efficiency was good and filters/air boxes were better designed

[Guest]

Someone has a pod fetish...

[Guest]

funny guy . . .

[Guest]

Not you...

[Prodrivebugeye]

From what i've read in this thread and others, successfully using a ebc on a tt legacy setup requires rpm dependant boost correct? Would any ebc that has rpm dependant boost settings fit the bill? I know people say that the profec spec b 2 and avc-r are the ones to use, but if another controller has that would it work?

[Joker]

 JoKer said:

ya dont basically

ony two options are Apexi-AVCr or Greedy Spec II (that not the right name but its close)

both these EBC's allow you to set RPM based boost levels ie 15/18 psi at different points in the rev range

never really got mine set up proper or figured out how to use it

and beware apparently you need a cert for a EBC these days too

[Jambun]

I have most of a AVC-R (minus pressure sensor) if you want it. 2hundy!

[kamineko]

 SilverRsk said:

From what i've read in this thread and others, successfully using a ebc on a tt legacy setup requires rpm dependant boost correct? Would any ebc that has rpm dependant boost settings fit the bill? I know people say that the profec spec b 2 and avc-r are the ones to use, but if another controller has that would it work?

not going to comment (much) on modifying your car for cheap gains then complaining when its not easy

however just FYI the profec 2b does not have a rev input

[Prodrivebugeye]

Oh ok so the profec isn't suitable, cheers for the info. Not to sure about the easy part of your post, but i appreciate the advice.