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4.0TT Turbo Failure Thread - S6 S7 RS7 A8 S8

A8 / S8 (D4 Platform) Discussion Discussion Forum for the D4 Audi A8 Produced from 2010-2017 Audi S8 produced from 2012-2017
View Poll Results: 4.0TT Have your turbos blown yet?
2013 - NO
31
26.27%
2013 - YES
13
11.02%
2014 - NO
15
12.71%
2014 - YES
7
5.93%
2015 - NO
22
18.64%
2015 - YES
3
2.54%
2016 - NO
14
11.86%
2016 - YES
2
1.69%
2017 - NO
8
6.78%
2017 - YES
3
2.54%
Voters: 118. You may not vote on this poll

4.0TT Turbo Failure Thread - S6 S7 RS7 A8 S8

 
Old 02-06-2019, 02:52 PM
  #31  
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Just got off the phone with those guys. Very knowledgeable. As we know the RS7 turbo is the S8 turbo. They have those out of the box ready to go for replacement. Probably the easiest route(3k). No change or upgrade to performance. They offer 2 other types that are ball busters putting them at 825 whp. But you need all their other components to get there. Intake, fuel system, hpfp, custom tune beyond APR's stage 2. Spending closer to 12k. They make them in house. Said the sold over 200 pairs last year and had 2 failures. As the earlier post stated, 3k is not a big deal in the big picture. No need to think your out of the car. Good to know there is a 3k solution to these when they **** the bed. And a monster out there if I wanna spend the $.
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Old 02-07-2019, 03:32 AM
  #32  
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Originally Posted by chris355 View Post
I get it and I'm with you: a $10k repair bill keeps me awake at night. $3k I can live with - maybe even jump in and do it as preventative maintenance. But I'll have to learn more about what the aftermarket options are before making my decision.
My feelings exactly. At 34k with 9 months left of CPO I can still get nearly all my $ out of the car I've put in to it, so I'm The Clash: Should I Stay Or Should I Go?

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Old 02-07-2019, 05:15 AM
  #33  
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2013 audi S8

60000km and both turbos failed. oil filter screen I believe was the issue. Has anyone replaced or even more so REMOVED them completely? Also curious if anyone has replaced their S8 turbos with RS7 turbos??? I'm in the process of getting mine rebuilt or popping on RS7 rebuilt turbos but not sure how that will affect my unitronic tune.
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Old 02-07-2019, 10:49 AM
  #34  
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Originally Posted by twinturbo_tommy View Post
2013 audi S8

60000km and both turbos failed. oil filter screen I believe was the issue. Has anyone replaced or even more so REMOVED them completely? Also curious if anyone has replaced their S8 turbos with RS7 turbos??? I'm in the process of getting mine rebuilt or popping on RS7 rebuilt turbos but not sure how that will affect my unitronic tune.
If you look up the part numbers you will find almost the same part number for the S8 & RS7 turbos.

2013/2014 S8
Part Number: 079145722A turbocharger 4.0 LITER, w/S8 Right
Part Number: 079145721A turbocharger 4.0 LITER, w/S8 Left

2014 RS7
Part Number: 079145722B turbocharger 4.0 LITER, w/RS7 Right
Part Number: 079145721B turbocharger 4.0 LITER, w/RS7 Left

I would not run without the oil screen, but the new one (rev G) will not clog as easily.

Also more info:



From Reference: Königstedt, J.; Aßmann, M.; Brinkmann, C.; Eiser, A.; Grob, A.; Jablonski, J.; Müller, R.: The new 4.0l V8 TFSI engines from Audi. 33rd Vienna International Engine Symposium, 2012

The S8 & RS7 have a larger 67mm main bearing journal than the S6/S7/A8, 65mm.
The material used for the V8 TFSI is C38 mod. with 65 mm main bearing diameter;
for the higher-powered variant (S8/RS7) the material is 42CrMoS4 with 67 mm main bearing diameter.

The static compression ratio of the S8 & RS7 are lower, 9.3 : 1, compared to the S6/S7/A8 of 10.1 : 1,
so different pistons.

Engine Block (infers that the S8 & RS7 blocks have extra T6 heat treating)
The engine block is made as a homogeneous low-pressure gravity die-cast block
from the hypereutectic aluminium-silicon alloy ALSi17Cu4Mg. Owing to the increased specific power output
and the associated increase in thermal and mechanical loading, the 382 kW variant is additionally heat-treated
by the T6 process.

The cylinder heads for all performance versions of the engine are laid out identically.
The only difference consists in different valve timing (lift event lengths for the camshafts)
in the engine variants with more than 420 hp (309 kW).

The cooling systems for the A8 and S8 are identical with the exception of the ATF heating/cooing

Airflow in the S6, S7, and A8
All engines in the C7 series and the A8 with the 420hp (309 kW) engine variant have
their air intake on one side. The intake air is taken through only one air filter module.

The Audi S8 has a dual-branch air intake. Each cylinder bank has its own air filter
module on the respective side of the vehicle.

All engines in the S6, S7 and A8 with the 420 hp (309 kW) engine variant have
their air intake on one side. The intake air is taken through only one air filter module.

On engines with a power output of 520 hp (382 kW) the compressor wheels are
larger, providing for the greater air requirements of the engine.

An additional oil cooler is installed on the S8 version of the engine. It is an air-to-oil cooler
mounted at the front of the vehicle. Oil does not flow through this cooler continuously.
Flow through the additional oil cooler is regulated by a thermostat. The thermostat is located
in the oil passage of the upper part of the oil pan and opens at an oil temperature of 230 F (110°C).

The only difference in the turbocharger module between the 309 and 382 kW engines (S8/RS7) is that the
variant with higher power output has a larger compressor wheel diameter, and so the machining
in the compressor housing is adapted accordingly.

Last edited by m444; 02-07-2019 at 10:57 AM.
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Old 02-07-2019, 12:06 PM
  #35  
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My extended warranty is covering my turbo replacement. Will only cost me $350. Only another year of the warranty before I get stage 1 DT performance tune. Very glad they blew up while in warranty lmao. Dealership told me that the screen won’t be a problem anymore with the updated turbos.
The guy who is going to put in my tune told me it’s not the screen that’s the problem, but the valve that’s under it.
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Old 02-07-2019, 12:13 PM
  #36  
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The only difference in the turbocharger module between the 309 and 382 kW engines (S8/RS7) is that the
variant with higher power output has a larger compressor wheel diameter, and so the machining
in the compressor housing is adapted accordingly.
[/QUOTE]
Good work M444.
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Old 02-07-2019, 04:21 PM
  #37  
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Originally Posted by chris355 View Post
So here's my question...

If the 'Optimized' oil strainer ($15) and check valve ($50) fixes the problem, why wouldn't AOA just issue a recall? Does it make sense to just do this at my next service visit?
This is exactly what I would like to know also. And what does the check valve do (or not do) that is supposedly the cause of the turbo failures?

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Old 02-07-2019, 09:03 PM
  #38  
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Originally Posted by Verybumpy View Post
This is exactly what I would like to know also. And what does the check valve do (or not do) that is supposedly the cause of the turbo failures?
The check valve keeps oil primed at the turbo, so it does not start dry.
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Old 02-08-2019, 11:10 AM
  #39  
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Originally Posted by m444 View Post
The check valve keeps oil primed at the turbo, so it does not start dry.
otherwise when you shut the car off the oil would drain with gravity's help back into the oil pan and the bearings would start up (essentially) dry until oil from the sump was pumped back up to the turbos...
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Old 02-10-2019, 07:41 AM
  #40  
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Well my car is currently at the dealer. 2013 S6 with 63000 miles on it. All services completed by the dealer and at recommended intervals. Both turbos are blown. Received a quote of about 13K to repair the turbos and the breather assembly repair, Im assuming thats the oil separator issue. I have contacted Audi of America to see if they can do anything. If they cant then I have to see which route to go.
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