External Wastegate Legacy GT Setup

[Elan]

Hi guys,

I have had a bit of a look around, but can't seem to find the information I need on installing an external wastegate.

My questions are:

Is it possible to run twin turbo off an external wastegate?

If yes, does anyone know where the pressure hoses go, or where I could find a digram demonstrating this?

When I got my car it had an external wastegate, and I recall it boosted quite nicely. I since connected it back to the internal, and now 8 months later I can't remember where the hoses went! (I am not sure if hoses is the right word.. suction piping or whatever..)

I don't recall the car screaming so it is possible that the last owners had it set up wrong anyway.

If anyone knows that would be great!

Thanks

[kamineko]

inb4 'people around here don't like the external wastegate screamers much'

don't get me wrong - external wastegates have their place, when you have backpressure problems on a serious engine/turbo setup

otherwise, the likes of koom will just suggest removing the secondary downpipe if your just after the noise

and what model TT do you have. some don't run and secondary internal wastegate to begin with

[Elan]

Hey fair enough, I realised I may have sounded like that after posting. I am not doing it for the noise. I want to try it out and see if it fixes my boost problems.

I figured since the wielding has already been done there is nothing to lose.

If it did fix the problems then I would probably get it plumbed back as my car is loud enough. (Fails wofs for being too loud most places (except one place I found which is completely legit but they are just quite lenient with exhaust noise.))

[Elan]

And haha actually I think I found that post at some point when I was researching saying about the secondary downpipe..

BG5 station wagon 94.

As I understand it the turbos only run off one internal wastegate anyway?

[WRXONP]

What's the "boost problem" to start with ???

External on twin turbo = waste of time

[mattapo]

wow a twin turbo with a boost problem, thats a first......

[Elan]

Hahahaha. I just don't remember it having boost problems when I test drove the car with an external.

pretty simple. I put my foot down by 80% and it boosts smooth and high. I floor it and it boosts and then cuts out/the car shutters and sometimes backfires.

[Timmah]

 Elan said:

Hahahaha. I just don't remember it having boost problems when I test drove the car with an external.

pretty simple. I put my foot down by 80% and it boosts smooth and high. I floor it and it boosts and then cuts out/the car shutters and sometimes backfires.

Car idles okay? No CEL's?

I have a friend with a TT b4, and has the a problem that you're describing close to perfectly. He has a bung o2 sensor and a vac leak.

[Stoffa]

I would be checking coil packs on a car that old, good place to start, change the plugs while you've got the coils out

[WRXONP]

You say it boosts high ??? How high ? Could be as simple as spark blow out or could be hitting fuel cut

[Elan]

Yeah idles completely fine. My boost gauge measures in bars but it seems to get up to 1.2 bars in secondary turbo, which i think equates to something like 17psi.

I have heard these subys can't go past 18psi on stock ecu, so perhaps this is what is happening. I just wouldn't expect boost cut to completely cut the whole car out. I know this is way too high for stock turbos but i have actually had a lot of trouble bringing the car back to stock boost since I took the external off =P Even if I wind the boost controller really low it does not seem to effect the boost very much.

Could be spark but I am pretty sure it would idle weirdly and run rough if that were the case. (And aside from the cut out she runs real nice)

[WRXONP]

If it's cutting right out - that's boost cut which is the ecu saying wooooooow fella calm down so it turns injectors off (fuel cut) to stop you blowing it up -

So u have some form of boost controller on it ? If you hook the factory hoses up how they should be you will find it won't over boost and cut out on ya

[Elan]

Okay that sounds legit, how do I put it on stock?

My friend did it once but I don't think he was 100% sure if he was doing it right and it still cut iirc.

Yeah I have one those typical boost controllers, can't remember the brand atm cause I'm at work but I think you can get them pretty cheap at scarles.

[Pappu1]

look up a legacy wiring diagram and plumb it like that first..

yea as said above could ewasily be boost cut

[WRXONP]

Vacuum diagram not wiring haha

Check all hoses are plumbed as per diagram and it should boost without cutting

[Elan]

Sweet thanks I'll have a look and let you know what happens when I factorise it.

[Koom]

 kamineko said:

otherwise, the likes of koom will just suggest removing the secondary downpipe if your just after the noise

In this case I'd suggest finding the source of the problem (as WRXONP has eluded to already) rather than just removing the downpipe off the external as it'll still cut. So there

Sounds more like one of the internal wastegates isn't working properly or somethings bung with the vacuum/boost hose setup but I hate TT's so have never tried to trouble shoot them, so I am no help here whatsoever ;D

[Elan]

Haha yeah there is only one internal but if that were the problem then properly installing the external would fix it I know there must be a way seeing as the last guy had the section wielded into the exhaust for the external.

I thought twin turbos were strange but then I found out that when the second turbo comes in both turbos are actually running paralel, which is kinda cool.

Gonna try this factory boost when I get a change though, probably tomorrow.