how do you control boost on vnt´s?

[carrizog60]

hello

right now my boost is at 1 bar give it or take,so if i want to increase the boost would be better to adjust the vanes rod or keeping how it is and add a mbc before wastegate can?

the engine is a 1.9td,the turbo is a vnt2052v with a k03 wastegate controlling the geometry.

i feel a lot diference in pull and noise as soon as boost hits 1 bar and vanes move position,can this be reduced?
if i close the vanes for more peak boost wont this cloged feel be more present?
but adding just a mbc the turbo might loose rpm as vanes move because the engine might not produce enought drive pressure to sustain boost at the level i want...

never ride on a converted vnt car so dont know if this is normal.

[carrizog60]

on another side,i have a friend that has a ibiza and i love the sound of that exhaust...
we can hear a very blown noise and when moving almost looks like it has a dump valve.
my previous golf gtd with the k24 also did this pfiuuuuu(lol) sound,(altough only when revving hard and the ibiza doesent need to rev)is this harmfull to the engine/turbo?

why wont mine do that sound? vnt,with a 60mm straigh exhaust with only a empty silencer at the back...


edit:sound like zagarus when it let gas off(sorry for using as reference)
http://www.youtube.com/watch?v=8Z_HE2kl-uY&feature=relmfu

[wdkingery]

edit:sound like zagarus when it let gas off(sorry for using as reference)
http://www.youtube.com/watch?v=8Z_HE2kl-uY&feature=relmfu

i wanted mine to sound like that too..

[carrizog60]

my k24 sounded like that...
the turbo and engine still runs,and make that sound.

[Fredrikkk]

The sound you hear is the wastegate letting the pressure go through the exhaust! Most likely since you have a VNT albeit with a wastegate, it won't sound like that because the vanes block the sound. Maybe...

[carrizog60]

the ibiza of my friend its a stock tdi with vnt and does that sound...plus a exhaust note that is like forced air

[rodpaslow]

I have a vnt 17 on a 1.6 and it will make a quiet sound when you back off the throttle.  Mine is relatively new and the old 15 I had you could hear at idle with the  control off at idle.  I think after a period of time they get a bit of exhaust stuck to the vanes and then maybe make a bit more noise? Not sure about that one.

My control works for now - it's run by a cable and a reversed vacuum can (made for boost now) that backs off the cable.  But I've found with the 17, even with the control backed right off, it will climb a second time up to and over 20 psi with no problem; no time at all.  I'm going to add a wastegate so it can never go over 18 psi as that is the max I want to run.  I think I will remove my control as well and just run it at maybe a bit over 1/2 way and see what it does.

there's a few posts in FAQ you should read if you haven't already got something in mind for control...there's a few there to reference.

[R.O.R-2.0]

I have a vnt 17 on a 1.6 and it will make a quiet sound when you back off the throttle.  Mine is relatively new and the old 15 I had you could hear at idle with the  control off at idle.  I think after a period of time they get a bit of exhaust stuck to the vanes and then maybe make a bit more noise? Not sure about that one.

My control works for now - it's run by a cable and a reversed vacuum can (made for boost now) that backs off the cable.  But I've found with the 17, even with the control backed right off, it will climb a second time up to and over 20 psi with no problem; no time at all.  I'm going to add a wastegate so it can never go over 18 psi as that is the max I want to run.  I think I will remove my control as well and just run it at maybe a bit over 1/2 way and see what it does.

there's a few posts in FAQ you should read if you haven't already got something in mind for control...there's a few there to reference.

even with the vanes WIDE OPEN, and moderate fueling, the turbo will make more than 18psi.. you are going to have to lessen your fuel to keep it under 18psi.

whats up with 18psi? is it a magic number? is 20psi too much?

[libbydiesel]

R.O.R., that is only true if fueled significantly above stock.  At stock fueling with a VNT15 with vanes wide open on a 1.6TD, it will max out at 7-8 psi run to the rev limit.   

[rodpaslow]

18 psi is no majic number, I just figure it gives me a bit of leeway before hitting 20.  I want to see what happens once I install the wastegate, if it controls it well, meaning no overshoot like it currently does with a Giles pump, then I will likely have it set to 20.

But you are correct, I have found with this vnt 17, with the vanes wide open and this Giles pump, It will easily hit 25 and climb exceedingly fast.  That is why I want to add the wastegate and see if I can stop it from going over 18 at first, and will likely turn up the boost more once I see it working perfectly.

[carrizog60]

i only get 1 bar right now,so i could close the vanes for more boost.
but wont that also plugs the exhaust?

[rodpaslow]

I've found that closing the vanes will close the exhaust to a point.  But you will also find at a point in the rev range you will have to back off or risk boost going easily 30 psi and over.  Mine at 3/4 throttle, at about 3200-3500 I'm easily at 20 psi and in a second or two I peg my boost gauge at 30, but I usually back off before then - my boost control/boost can has already backed off the lever to full open and it still keeps rising quickly.

If you don't have some sort of control to back it off/open the vanes I'd keep it at least half way open and test until it's doing what you want.  But your are correct about drive pressure.  I had a vnt 15 that I kept the vanes fully closed and gave it full throttle and blew up the turbo at about 25 psi.  It was used so I don't know how good/bad the internals of the turbo were.  my $.02

Drive pressure is certainly and issue with the turbine side of this turbo as others I'm sure will attest to.

[carrizog60]

i controll the vanes with a wastegate.
maybe they are very open so boost will not rise enough.

problem is torque on low rpm...

i dont want massive torque down low for engine protection,that´s why i choose vnt20 but righ now it spools faster than a k24.

if i close the vanes for more boost boost will come earlier...

[libbydiesel]

Low-end torque is the reason for installing a VNT.  If you don't want the low-end, then install a wastegated turbo.  Your VNT 20 will flow at least 20 psi without impeding exhaust flow. 

[keaton]

my sig has a link to a standalone VNT controller