bebbetufs

I seem to be cursed. Seems that no matter what, my turbos are destined to blow up.
So far I've had:
1. Foreign element in intake, possibly from PO = compressor wheel toast
2. Epic DIY rebuild fail = completely wasted turbo
3. Shop refurbished turbo tossed the nut after 1000 miles = lots of arguing...

Now the shop is claiming something is wrong with my car which caused the turbo to toss the nut. They claim any failures that do not happen within 2 minutes of the first WOT run is the customers fault

I'm struggling to understand what could be wrong on my side to cause this. Please list reasons you can think of that can cause the turbo to toss the nut so I can get a better understanding of what I'm up against.
TIA

Darwantae951

Improper assembly

Paulyy

id blame the shop who rebuilt the turbo

bebbetufs

I already do but what can they counter with? What could be wrong on my side?

Paulyy

compressor surge is all that will loosen a nut. or possibly over the rpm limit on the turbo (trying to boost on a huge boost leak)

bebbetufs

Thanks. I'll read up on compressor surges.

Paulyy

i doubt that would of happened to you with a stock turbo.

theres a few different ways a compressor can surge.

the by pass valve is blocked or deleted which will cause air to go thought the turbo backwards causing a flutter noise and may cause it to spin backwards.

another way is if the compressor wheel is moving more air then the engine can take on boost will cause compressor surge also as the air cannot go through the by pass valve and force its way though the compressor.

a way to prevent this is a ported shroud housing. like the one i have in my sig.

bebbetufs

Thanks for helping me understand this.

Blow off is new and tested ok.
I have not tested the WG but will get a pump with a manometer and test at what point it opens. Could overboosting a stock turbo cause surging, or is the compressor wheel simply not big enough?
Anything else I should consider?

I don't know what to look for in the sig for the ported housing. Can you help me spot it?

Paulyy

not necessarily over boosting, but trying to make boost where the turbo cannot. the k26/6 cannot make 15 psi at redline no matter what you do. if you push it to 18 psi it will still fall off to around 12 psi, this causes the turbo to spin more and over spinning the turbo which isn't good.
The compressor wheel is just to small and cannot flow that much air.

On the left is my GTX3076R (ported shroud housing) the right is a stock 26/6.
on the left you will see it looks like there's 4 holes (ports) around the compressor wheel. which the other turbo hasn't. That's a ported shroud. what it does is when the air tries to go back though the compressor blades, the air will miss the blades and go through the ports.

http://www.turbobygarrett.com/turbob...o_tech103.html
There's a few images in there to show you how it works. and it'll explain it also.. better then i just did.

bebbetufs

Thanks for the link. Very interesting.
The stock turbo on my car is the k26/8. I suspect it will take even more to make that surge.
I've left the dual port at minimum boost, but I guess the stronger spring results in higher than stock boost. I'll find out when I check it later.

Paulyy

the stock turbo wont surge under it's own power. the only time it will surge if the air cannot escape though the by pass valve. you have nothing to worry about.

the only reason i can think of that the nut would come off the turbo is the nut who put the turbo together.

bebbetufs

Should there be Loctite on the nut (itself)?

Paulyy

I'm not sure, hopefully someone else can answer that for you. on mine it didn't look like there was any.

lart951

You loctite the the thread on the shaft

bebbetufs

Ok. Should that be Loctite red or green? I see some traces of green on the threads of the shaft