RS7 Turbos vs S6 Turbos

[Vol 4.0T]

s6

[CanuckRS]

For such a knowledgeable, honest, and valued forum member like yourself, I'm not surprised you didn't already know this.

[S4Per]

The question is (and what the video doesn't answer) : how can both the turbine diameter be increased and larger compressor wheels be used if the housings are the same?

[CanuckRS]

The question is (and what the video doesn't answer) : how can both the turbine diameter be increased and larger compressor wheels be used if the housings are the same?

You could also ask how come an RS7 is faster than an A7 since the body is the same. That would be your answer.

[CanuckRS]

Wow, I think technical discussions like this tend to go way over your head.

haha, says the troll who doesn't even own an S6.

you know, one day you'll learn that more words don't make you any more correct about something. maybe someone else can spoon feed you the answer.

[HyperM3]

Just because the housing is the same doesnt mean the internal diameter cant be bored out a little more. Many parts are bored out to make things breath easier while the exterior doesnt change; Manifolds, Throttle Bodies, Turbo's. Did you measure the inlets on both? From just looking, the fan blades even look different.

[hodrosS42001]

Just because the housing is the same doesnt mean the internal diameter cant be bored out a little more. Many parts are bored out to make things breath easier while the exterior doesnt change; Manifolds, Throttle Bodies, Turbo's. Did you measure the inlets on both? From just looking, the fan blades even look different.

This is how 'hybrids' are made and spot on. The housing can be machined even more for bigger compressor wheels.. Aka TTE hybrids.

[RAF_S7]

The part number for the turbo units are the same across all 4.0T variants, however there is a different suffix between the S & RS versions, meaning there is an upgrade/modification between the units.

Regular S model turbos have Part # 079145704P (Left hand unit parts quoted)

RS model turbos have Part # 079145704S

If the turbos were identical between the RS and S models, the full part number would also be identical (including suffix)

Oh, and the RS Plus models use the same turbos Part #'s as the regular RS's....

[bhvrdr]

This is how 'hybrids' are made and spot on. The housing can be machined even more for bigger compressor wheels.. Aka TTE hybrids.

Absolutely. Back in the 1.8t days (too many years ago, lol) we used to swap our K03 turbos for K04 turbos. It was a really stealthy upgrade because the housings are the same. A dealer would have no idea if you swapped the plaques on them.


From Audi:

Twin-Scroll Turbocharger
Rationale
A twin-scroll turbocharging design was developed
for the 4.0L V8 TFSI engine because more common
designs and methods of turbocharging posed
limitations for gasoline engines. For example, Variable
Turbine Geometry (VTG), which is already standard in
turbocharged diesel engines, proved unacceptable
because of the higher exhaust temperatures found in
gasoline engines.

Turbine housing design also presented limitations.
In passenger cars with twin turbochargers, turbine
housings are predominantly single-branch designs,
where the intake cross-section into the turbine has no
divider in the center. As a result, the impulse energy of
one branch could interfere with the adjacent branch
over this common entry area.
The new dual branch design of the 4.0L V8 enabled
separation of the two exhaust manifold tracts until
right before the turbine housing intake.

Differences for the Individual Engine
Variants
No differences can be seen from its outside
appearance. The exhaust manifold, the material of
the turbocharger, and the turbine are the same on
all performance versions. 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.

Twin-Scroll Design
Exhaust passages from two cylinders at a time run
separately from each other in the exhaust manifold
and turbocharger housing. They are joined just before
the turbine, preventing reciprocal interference of
exhaust fl ows. This guarantees a rapid buildup of
torque and outstanding response

Torque builds up quickly from idle speed. The 4.0L V8
TSFI engine develops approximately 295 lb ft (400 Nm)
of torque as early as 1000 rpm.
The high output version of this engine makes its
maximum 479.4 lb ft (650 Nm) of torque available fulltime
from 1750 to 5000 rpm.

[bhvrdr]

gotcha. silly translations. My bypass valve is a "compressor regulating flap" according to vcds ;)

Mike

[HyperM3]

I can report that by "increasing the turbine diameter" they were referring to machining out the housing to accept the larger compressor wheels.

So, basically what I said.

[F16HTON]

What I would like to know is the differences between the actual design of the compressor wheels. Inducer, exducer, blade pitch, material, weight. More than likely the community will see more turbo upgrade options in the future.

Companies such as Xona Rotor & Alpha Performance must be working on something. TTE and Loba already have made and released upgrades.

[S4Per]

Companies such as Xona Rotor & Alpha Performance must be working on something.

I have zero doubt we will see something here in the next 6 months or so (and focusing on the tranny limits again).

[F16HTON]

Quattro GmbH just says they made the compressor wheels larger and changed the compressor wheel geometry. Wonder if the specs could be obtained from IHI.

As for aftermarket turbo options stateside, I doubt you'll see anything anytime soon. There's just not a very big market for it. Take a look around the forum and you'll see far more interest in painting brake calipers, emblems, wheels, etc. Those with S6s or S7s are more inclined to just go the tried and true OEM RS Turbo route. It's kind of like how the B5 S4 crowd used to go with the OEM RS4 bolt on turbos. Going with anything bigger would put them in uncharted waters with regards to engine tuning and engine/transmission reliability.

I would not necessarily say that. Contrary to the belief of those who post, the world is much larger than the forums. The the technology for the turbo manufacturers already exists Xona Rotor (formerly known as Forced Performance) has been making OEM based hybrid turbos for some time. The market for bolt on OEM replacement turbos is much larger than it used to be. The technology for making compressor and turbine wheels has improved greatly with the ability to CNC wheels rather quickly.

The OEM RS6/7 turbo route did not take off due to the shear const of obtaining new OEM parts. I'm pretty sure APR anticipated this and only chose to calibrate for the turbos because of this. They may or may not pursue their own Stage III hardware kit in the future but reselling OEM parts will not cover the cost of keeping them on the shelf.

Although the cost may be similar (at retail) for the S6 and RS7 turbos, there is much less margin at the dealer because Quattro GmBH parts are not as discounted from Audi (the dealer makes a pretty small margin and has no room to pass it on).

[S4Per]

I'm with you, 500.

6-8 months, and they'll be here.
It'll be a niche market, and APR won't play, but some other tuners with established custom tuning records will lead the way via partnerships with the likes of Xona. It's going to be fun :)