VNT died, K24 swap now..

[R.O.R-2.0]

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.  
  

dude, ill tell you again..

VANES FULLY OPEN! do you want a picture of how far open they were? ill go snap one real quick.. turbos disassembled on my bench.

the vanes were pointing directly at the shaft of the turbine.. they could open no further.. they are all stuck in the position that i ran them in for almost 50k miles..

my VNT was an anomaly.. it still spooled quick, and performed great for a long time.. ive never heard anyone retain the quick spool/high boost that i had, without operating the vanes.. my VNT still built boost by 18-1900 revs, and still made 18-22psi clear to redline.. all with no vane control.. go figure..

anyways, its completely pointless to argue about this.. im almost positive that my turbo ate something. no turbo will survive eating something..

my VNT was used, with an unknown history.. it was SEIZED when i got it. im VERY surprised i got 50k miles out of it honestly.

in the grand scheme of things, this turbo actually performed AWESOME, but i DONT think i will be installing another..

im out for BIGGER and BETTER things now.. ive had my eye on compounds for quite some time, but never wanted to make the jump because my VNT still worked soo good. but, now its dead, so i have no other options rather than a conventional turbo or 2..

the other idea i been throwing around is SUPERCHARGING it.. M62 driven off the cam or something like that..

[libbydiesel]

No picture is necessary on my account.

I wasn't aware of any arguing.  Were you arguing about something?

I wish you the best on your endeavors. 

[R.O.R-2.0]

No picture is necessary on my account.

I wasn't aware of any arguing.  Were you arguing about something?

I wish you the best on your endeavors. 

i was arguing about nothing.. but you and others have said many times before that VNTs wont make over 10psi with the vanes fully open..

ive called BS every time that subject is brought up. my turbo has its vanes open, like tips of vanes pointing directly at the turbine shaft.. to me, that is as open as the turbo gets.

anyways, no, i wasnt arguing. but if you could only get 6-7psi out of your open VNT, then you must have not nearly as much fuel as i do.. i was worried about driving my car home with no boost to be completely honest.. every time i hit more than 1/4 throttle, it would just start pouring coals.. i know i was running it hot.

anyways, still, seems like this turbo ingested something. there was too much damage to the compressor wheel for it to have just lost the bearings.. there were also pock marks all over the turbo intake, also leading me to believe that something bounced around on the face of the compressor wheel, breaking blades off as it was bouncing around..

i really dont see what could have saved this turbo.. if it ingested something, then its my own damn fault for not checking my air filter and intake tubing more carefully. i still need to pull the intercooler, drain it, and try to fish the chunks of compressor wheel, and the foreign object that destroyed my turbo..

some time this week, im going to be bolting on my K24 turbo, and fabbing up all new oil lines, and charge piping..

[410]

So how about some pictures?  Lets see what it looks like.   Or maybe we should just keep talking about it!

[R.O.R-2.0]

So how about some pictures?  Lets see what it looks like.  Or maybe we should just keep talking about it!

all i have, are DIRTY pieces of it.. that need washed off..

and i broke the compressor housing off it while i was removing it.. it broke off way too easy, so im thinking it cracked the backing plate when whatever it ate went thru.. then the shaft broke.. theres still some shaft in the turbo cartridge also, as well as some TRASHED bearings..

too late for pics tonight tho..

[R.O.R-2.0]

well, i put a K24 on my car today.. its sorta mid mounted. directly under my gasser intake manifold.. LIKE DIRECTLY UNDER IT..

and the K24 is HUGE compared to the VNT.. i used to have turbo scream at idle, now you cant even tell its turbo charged till you bring the engine up in the RPMs..

now, it reminds me of a tractor puller, sitting at the line spooling the turbo.. hold the engine at about 3000 revs and the turbo starts spooling nicely..

[RabbitJockey]

How much boost?  How do they compare power wise

[R.O.R-2.0]

How much boost?  How do they compare power wise

i havent driven the car, just started it, and revved it a little.. i can already tell without even driving it, that its gonna be a laggy MOFO..

i need to build a downpipe, finish my oil line, and finalize the install..

it will be done soon enough tho. might be able to drive it tomorrow..

[MJF]

do you want a picture of how far open they were?

Yes, please.

[R.O.R-2.0]

i feel stupid now 

the K24 performs better than the VNT.

i think it even spools as quick, or maybe even quicker..

wastegate unhooked, and i peak 20psi in every gear..

its got compressor surge like a mofo tho.. like every time you shift, the turbo barks.. what gives?

[81 vw pu]

i feel stupid now 

the K24 performs better than the VNT.

i think it even spools as quick, or maybe even quicker..

wastegate unhooked, and i peak 20psi in every gear..

its got compressor surge like a mofo tho.. like every time you shift, the turbo barks.. what gives?

Sounds like you got the same results as I did? I'm happy as hell with the K24.
 I have the same bark, most noticable about 15 psi and higher, as soon as I lift and push the clutch to shift.
Out on the freeway yesterday 5-6psi at steady 65-70mph cruise, cob the throttle and boost climbs past 15 fairly fast.

[R.O.R-2.0]

i feel stupid now 

the K24 performs better than the VNT.

i think it even spools as quick, or maybe even quicker..

wastegate unhooked, and i peak 20psi in every gear..

its got compressor surge like a mofo tho.. like every time you shift, the turbo barks.. what gives?

Sounds like you got the same results as I did? I'm happy as hell with the K24.
 I have the same bark, most noticable about 15 psi and higher, as soon as I lift and push the clutch to shift.
Out on the freeway yesterday 5-6psi at steady 65-70mph cruise, cob the throttle and boost climbs past 15 fairly fast.

glad our results are the same.. i was REALLY worried about the turbo bark, because its VERY loud.. yep, boost up past 15psi, then throw the clutch in, and BAAAAAAARRRRRKKKK, shift a gear, boost up, clutch in, BAAAAAAARRRRRKKKK..

i havent had much time to play yet, because i just got it driveable earlier. and only drove it about 2 miles..

anyways, i thought i was going to have a laggy power band, but the K24 spools basically just as quick as the VNT did.. im pleasantly surprised! and im also making almost 25 psi now.. i was making ~ 15psi with the VNT.. i just left the wastegate un hooked..

ive read about the MAGIC WASTEGATE on the K24 many times, so i figured i might as well just leave it un hooked, and see how it goes.. and it regulates boost pretty much perfectly, and exactly where i want it. you can still hear the waste gate blowing open when boost picks up tho, so its still functioning, but from drive pressure blowing it open, not boost pressure against the diaphragm..

[81 vw pu]

I hooked up the wastegate like stock for kicks (no MBC) and could only get 8-9 psi.
I kinda like the turbo-bark, sounds like a premature tire chirp
And egt's at 65-70mph with 5-6 psi boost= 750-800F lowest its ever been!!!

[R.O.R-2.0]

I hooked up the wastegate like stock for kicks (no MBC) and could only get 8-9 psi.
I kinda like the turbo-bark, sounds like a premature tire chirp
And egt's at 65-70mph with 5-6 psi boost= 750-800F lowest its ever been!!!

yea, i was getting the waste gate to open in neutral, without even using full throttle, when i had it hooked up to a boost signal..

stock boost levels are JUST NOT ENOUGH!

and i get both tire chirp, and turbo bark now..  

[RabbitJockey]

thats interesting the big vnt advocate has had a change of opinion 

but to be fair to the vnt your vanes were not operational.