Catastrophic VNT 17 failure

red16vdub · Sep 8, 2016

IndigoBlueWagon said:
Unless I'm mistaken (which I am often) 2620 bar less one atmosphere is 23.7 PSI, give or take. I've always understood that the safe boost limit for a VNT-17 is 22-24 PSI. Both turbos mentioned here were running more than that.

26psi was recommended for what my mods were at that time. I have egt/boost gauges and certainly didn't exceed or reach what the car was tune for. The turbo blew out the exhaust along with 80% or so of the oil, luckily for me zero engine damage. I cut my losses and dug deep into the piggy bank for a 17/56

Bajan

red16vdub · Sep 8, 2016

Pics of the grenade vnt 17

The turbine went out the 3" exhaust .

Bajan

turbovan+tdi · Sep 8, 2016

First turbo plate looks legit. To me anyhow.

red16vdub · Sep 9, 2016

turbovan+tdi said:
First turbo plate looks legit. To me anyhow.

Yes it does

Bajan

Drivbiwire · Sep 9, 2016

HelenaTDI said:
This is what is left of my compressor. I flushed out my IC with a gallon of acetone today. Cleaned all the intake piping as well. Air cleaner looked fine.
Do I trust using the IC or get a new one? I used compressed air to blow anything out afterwards.
Had a cup or so of oil pour out the IC. Where did the other 1qt or so of oil go? Tried running a magnet down my down pipe as far as I could go. Couldn't retrieve the exhaust turbine and shaft. Not sure if it blew out the tail pipe. I shouldn't have any interferences so maybe it's out.

Compressor stall at the Exducer, tips are all missing....

Drivbiwire · Sep 9, 2016

red16vdub said:
26psi was recommended for what my mods were at that time. I have egt/boost gauges and certainly didn't exceed or reach what the car was tune for. The turbo blew out the exhaust along with 80% or so of the oil, luckily for me zero engine damage. I cut my losses and dug deep into the piggy bank for a 17/56

Bajan

Stop focusing on the 26psi, were you flowing enough volume at 26psi to prevent surge/stall of the compressor?

a bigger turbos isn't going to necessarily solve it if you haven't improved the volumetric ability of the engine to allow the increased capability to pass thru it.

Drivbiwire · Sep 9, 2016

Centrifugal compressor stall patterns..

Drivbiwire · Sep 9, 2016

Here's the map, 1749.

Its that dashed line on the front end of the map that blew that turbo...

red16vdub · Sep 9, 2016

Drivbiwire said:
Stop focusing on the 26psi, were you flowing enough volume at 26psi to prevent surge/stall of the compressor?

a bigger turbos isn't going to necessarily solve it if you haven't improved the volumetric ability of the engine to allow the increased capability to pass thru it.

I'm not quite sure how to answer that , but will say the only changes made was different turbo and retuned.

Bajan

Nevada_TDI · Sep 9, 2016

Honestly, I am confused myself; how could a turbo be making that much boost and have an issue with stall? I could maybe understand a gasser with a bad b.o.v., but our diesels don't have throttle bodies.

turbovan+tdi · Sep 10, 2016

Tips are missing because they were machined off by the compressor housing.

Can't see how it would stall as well.

AnotherPerson · Sep 10, 2016

Kinda related here. I have a vnt17 stock tune. I won't have any stall issues will I? I don't do hard launches

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Nevada_TDI · Sep 10, 2016

Not likely with a stock tune .

AnotherPerson · Sep 10, 2016

Thx. Just making sure since it may be after new years for the tune now.

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mrchill · Sep 11, 2016

That turbo was defective. Pure and simple. I have run 17 turbos way outside their intended tolerance with ZERO failure. The setup was a typical strong but not overdone hardware profile. The tune was typical for the setup. No failures. Til that one. As a point of interest. Long ago, when we were first running 17's, I had one in my green car. All the testing I did with pumps, nozzles, really edgy tuns and other hardware was done with that 17. Ultimately, when I was doing a new hardware profile along with special nozzles, I ultimately ran that turbo at 47 psi during testing (didnt know it would do that...surprise). It never did fail. I later had it converted to a 1752...where it still lives on. All the conjecture in the world will not change the fact that the turbo I saw, had a fatal flaw from the factory.

HelenaTDI · Sep 12, 2016

mrchill said:
That turbo was defective. Pure and simple. I have run 17 turbos way outside their intended tolerance with ZERO failure. The setup was a typical strong but not overdone hardware profile. The tune was typical for the setup. No failures. Til that one. As a point of interest. Long ago, when we were first running 17's, I had one in my green car. All the testing I did with pumps, nozzles, really edgy tuns and other hardware was done with that 17. Ultimately, when I was doing a new hardware profile along with special nozzles, I ultimately ran that turbo at 47 psi during testing (didnt know it would do that...surprise). It never did fail. I later had it converted to a 1752...where it still lives on. All the conjecture in the world will not change the fact that the turbo I saw, had a fatal flaw from the factory.

Yeah I was surprised my 1st VNT 17 failed with some momentary boost spikes of 28-30psi on a WOT.
New VNT 17 was installed over the weekend. It did have a label glued on it over some engraving as the previous one did. Bought from a different very reputable vendor.
Sent my logs from group 1,3,10 and 1,4,8 together to my tuner. Also group 11. They say everything looks great. Yet I had a boost spike of 24-25psi which was on an uphill pull fairly heavy acceleration but not a WOT. Doesn't help my confidence much as I'm already on the max boost of this turbo without doing a WOT.
I think quality control has gone down hill in my opinion on these VNT 17's. Just my .02. Hope I'm wrong.

Nevada_TDI · Sep 12, 2016

If your boost is maxed out at less than WOT, I suggest you to talk to your tuner.
You mention the "spike" how long did it last and what PSI did the turbo settle into on the rest of the hill?

HelenaTDI · Sep 12, 2016

Yeah only lasted a second or so then dropped down to low 20's. Didn't expect to see a spike of 24-25psi.
My logs all checked out by my tuner. I will log a few 3rd gear WOT runs from 1500-4000 on a gradual uphill climb.

ryanp · Sep 13, 2016

The actuator rods are very short on these from the factory, especially cupra turbo's. They need to be much longer.

I doubt the spikes kill them, upper RPM creep will, boost needs to drop a lot after peak power to prevent overspeed.

A lot of customers and tuners miss this when checking logs!

HelenaTDI · Sep 13, 2016

Checked prior to install. My actuator rod was 3inHg when it starts to move and 18inHg at full travel at the stop. Setup was identical to my last one that grenaded.

ryanp · Sep 13, 2016

if thats long enough for you then OK.

JFettig · Sep 13, 2016

You are exactly right Ryan.

The only setting that I have found to repeat success is lifting at 4in-hg, not 3, not 5, not any sort of stop reading. 4in-hg lift.

HelenaTDI · Sep 13, 2016

It was set that way from the vendor. They set them all up prior to shipping. Can't imagine 4inHg has much of a difference.
Prolly be kicking myself for not running a 17/22. I run them on two other Jetta's with zero issues.

JFettig · Sep 13, 2016

Most vendors don't set them up, they just ship them as they receive them. 4in-hg makes a HUGE difference on a tuned car.

HelenaTDI · Sep 13, 2016

That may be. But this vendor set it up before being shipped. I called them and asked about it.
The range I'm told is 3-5inHg when the rod starts to move and 18-20inHg at full travel at the stop.

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Ruairí · Sep 13, 2016

I have overboost on my vnt17 at wot 4000rpm in 4th and 5th. Duty cycle hitting 94.4%. Car has hflox 240s from Ryan. Stock tune. Actuator starts to move at 3 and hits stop at 18. I started a thread and received mixed advice, 2 posters said leave actuator alone as it's probably excess fuel which should be sorted by mapping, 2 other posters said to lengthen actuator by half or full turn before mapping. I decided to leave it alone.

Reading the last few posts here I might lengthen the actuator so it lifts off at 4. I didn't really pay much attention to when the actuator started to move as research pointed to hitting the stop at 18 as being the magical number. I rebuilt the 17 with new melett core and garett actuator and had it flow tested on a proper bench. That's why I was reluctant to adjust actuator.

JFettig · Sep 13, 2016

That is the problem with forums, so many people repeat the wrong information you don't know who to trust.

zuks90idi · Sep 13, 2016

OP, I would be concerned about parts going back through the exhaust manifold and getting ate by pistons.

Yes it can happen, up stream past valves only to be beat to hell by a piston.

I have a short block sitting here that suffered this same failure. I'll see if I can get some pics.

HelenaTDI · Sep 13, 2016

zuks90idi said:
OP, I would be concerned about parts going back through the exhaust manifold and getting ate by pistons.

Yes it can happen, up stream past valves only to be beat to hell by a piston.

I have a short block sitting here that suffered this same failure. I'll see if I can get some pics.

Yeah was a concern that's why I spent a lot of time cleaning/inspecting everything. Compression check was good. Wasn't about to pull my head.
Spent a lot of time with the IC, air box, Intake, piping as most likely any shrapnel will accumulate in the IC. The exhaust turbine wheel that sheared off most likely shot out my 2.5" exhaust. I don't have any interferences with it. Everything else looked great. Yeah maybe I rolled the dice not pulling the head to inspect further. But I didn't think it was necessary.

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VWDAVID · Sep 14, 2016

HelenaTDI said:
Checked prior to install. My actuator rod was 3inHg when it starts to move and 18inHg at full travel at the stop. Setup was identical to my last one that grenaded.

You really need to be looking at boost not just where the rod starts and stops. I have seen some that had to be set to start at 5 to make them act correctly. Others at 3. I feel 3 is too short and that's prob what help blow both turbos either than or its your tune. There is a big difference between 3 and 4 as previously said. I ran vnt17 at 28 psi for years and it never blew.

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