VNT died, K24 swap now..

[catlin_cava]

2001 TDI - stock application, no mods, Turbo would spike past 25psi on accelarations but would never hold a steady boost.
1999 TDI - at first on stock the vanes kept sticking, after 216s and Malone stage 2 at 17PsI I ha less issues, when the Turbo failed due to a run dry it's now out of range of boost.
2006 TDI - stock, well treated always well maintained by PO and me(full service record) I went from blowing smoke and over boosting to under boosting and loosing boost while driving

[8v-of-fury]

Other than the one loosing oil, did you have them checked out as to what the problem actually was?

If not then a VNT failure cannot be claimed. That would be false information.

[catlin_cava]

The 01 is still kicking lol
The 06 was a vanes failure, dealer confirmed me the turbo was ***ed

[libbydiesel]

How were the vanes failed?  I have seen them melted from excessive EGTs, but again, that's an engine management failure not a turbo failure.

[Newschooldiesel]

should we say FACK VNT's kev and just dual turbo mine? 

[maxfax]

Just go without the turbo... Problem solved.. 

[theman53]

Were any of catlins turbos measured with a boost gauge or just vag com? I have heard vag com reads absolute pressure which would be about 14.7psi higher than manifold pressure. Either way they had issues, but I was just wondering.

ROR, sucks, but it will work out soon.

Why was I thinking the top end of the vnt 15 was around 15psi? I don't know if it is or not, but I seem to remember hearing that somewhere, maybe streettoys old site? Then the 17 was good to almost 20psi and then the 22 was good to 25psi??? Just numbers off the top of my head, but wondering what it should be if those are off.

[catlin_cava]

I dont know the exact cause of failure on the 2006 on the vanes, I'll I know the turbo was pooched so we bough a new car,

My 2001 was on a boost gauge its how I knew about the killer spikes. If I drove 120kph for more then 1 hour straight and slow down and accelarate again the turbo would spike past 30 and hold till the car would go into limp mode

[srgtlord]

no turbo= less  ***t to break

[R.O.R-2.0]

If the vanes stick at all then they can easily spike.  Again, that's an control/engine management issue and not the fault of the design of the VNT turbo itself.  I agree that the stock vane control stinks and causes almost all of the issues.

What about them do you feel is junk?  Do you think they should be designed to withstand ingesting something without breaking fins.  LOL!

i never said mine ingested anything.. and my vanes were stuck OPEN. like wide open. least boost and back pressure possible..

and i dont expect a turbo to be able to eat a ball bearing and continue making boost..

im basing my "VNTS are JUNK" response to all my other observations of failures on other vehicles.. i mean hell, its RARE to have the original VNT on a car that has over 200k on it now..

[Luckypabst]

its almost like the turbo ate something.. i thought it ingested the compressor nut, but it was there.. i havent had it off to look yet, but i can feel blades MISSING.. it has atleast 2 blades missing on one side, a long blade, and a short one..

idk how it could have ingested something tho.. i have a decent air filter, and ZERO holes in my turbo intake.. something bounced around the turbo inlet, and messed up the compressor wheel bad.. maybe i will find whatever it was in my intercooler when i drain and clean it..

Not speaking for Libby, but this leads me to believe that you claim your turbo ingested something.

Chris

[fatmobile]

I've put 2 VNTs on Rabbits.
 Other than vanes sticking I have had no problems.
 I use boost to back mine off but there is also a knob on the dash to adjust where the turbo is sitting.
 I shove the knob in and floor it, to smoke out the Cummins diesel in the truck behind me, then pull it out and leave them in the cloud.

 I have a friend with a TDI that has gone through a couple. Says they both went at low boost while cruising but he hasn't done an autopsy.
 Same car 2 good turbos maybe it's the car. Oil supply or something.

 I'd put another one on.

[R.O.R-2.0]

its almost like the turbo ate something.. i thought it ingested the compressor nut, but it was there.. i havent had it off to look yet, but i can feel blades MISSING.. it has atleast 2 blades missing on one side, a long blade, and a short one..

idk how it could have ingested something tho.. i have a decent air filter, and ZERO holes in my turbo intake.. something bounced around the turbo inlet, and messed up the compressor wheel bad.. maybe i will find whatever it was in my intercooler when i drain and clean it..

Not speaking for Libby, but this leads me to believe that you claim your turbo ingested something.

Chris

i dont understand how it could have ingested something.. i have an air filter in place, and working.. i checked for chunks that would have caused damage, and found none..

i still havent even taken the turbo off yet.. dunno how bad it is, or even if theres a turbo left anymore..

[R.O.R-2.0]

i still think it ingested something.. there were 4 broken blades on the compressor, not to mention it was ALL F#CK#D up..

bearings, what bearings?

the shaft was about broken, the second i went to twist the nut off the shaft, it snapped.. then once i got the nut loose, that end of the shaft snapped too..

after seeing the size of the shaft in these things, im never going to be running one again.. (VNT15)

yes, shaft snapped in 2 PLACES AS I WAS DISASSEMBLING IT!!!

im gonna say that VNTs are FINE for stock/low performance engines.. but i would avoid them on performance engines.. the LARGER VNTs may be better tho, but its still hard to say..

[libbydiesel]

The shafts are definitely strong enough to withstand removal and installation of the compressor wheel.  Something very wrong happened to your turbo to significantly overstress the shaft.  The VNT 15 shaft is intentionally small to reduce mass and spool time but as such I would still feel comfortable using the VNT15 up to about 15-18 psi (I think even at that pressure a VNT17 would be a better choice, but I wouldn't be concerned about failure).  The VNT 17 has a shaft that does not have the step in it like the shaft of the VNT 15.  It is much stronger and will interchange with the VNT15, but the added mass extends spool time slightly.  The compressor wheel on the VNT 17 is also larger and so at max boost it is less labored.    

My brand new zero mile VNT15 on my 1.9 mTDI AHU will not produce more than 6-7 psi with the vanes fully open and enough fuel for the EGTs to reach 1400° pre-turbine.  I find it unlikely that you were hitting 20 psi with the vanes fully open unless you had extreme EGTs.  Probably your vanes were stuck in a semi-open state.

I would never recommend operating a VNT without controlling the vanes.  There's no point.  There is no advantage to a VNT with stationary vanes as over an appropriately sized wastegated turbo.  However, the performance advantage of properly controlled VNT turbo over the performance of a wastegated turbo is almost as significant as the performance advantage of a wastegated turbo over operating without a turbo at all.