Audi has officially unveiled its newly redesigned B10 generation S5! The S5 is Audi's performance ICE sedan, replacing what previously was the S4 and S5. Utilizing a new naming strategy, odd model numbers are designated for cars using internal combustion engines and even model numbers for electric vehicles. The A4/S4 is here to stay but on a dedicated EV platform.

034Motorsport has been the leader in producing performance hardware and software for the previous generations of the S4 for over two decades, and we're excited about all the new changes to the now S5.

In this write-up, we're going to focus on some deeper technical info that we managed to get our hands on that goes into more detail about what mechanically is different in the B10 over the B9.

First we'll discuss the big changes to the Engine and Drivetrain, starting with the new EA839evo 3.0T engine:

The B10 S5 is equipped with an updated generation of the EA839 3.0T Single Turbo V6, dubbed the EA839evo. 

This engine has a whole host of enhancements over the outgoing model, such as a 48-volt generator to power the E-Motor found within the DSG gearbox, a Dual High-Pressure Fuel Pump system over the single HPFP configuration currently seen, a Variable Geometry Turbocharger, Water to Air cooling built directly into the intake plenum, and much more.

Starting with the Hybrid System, this diagram outlines a separate low temperature coolant loop separate from the engine coolant loop that is used to not only cool the E-Motor on the transmission, but also passes coolant through the Turbocharger compressor cover itself to keep the turbocharger cool.

This coolant loop is also used for the Water-To-Air intercoolers found in the upper intake manifold.

The EA839evo ditches the Air-To-Air style charge air cooling system found in the previous generation B9 S5 in favor of twin Water-To-Air intercoolers. Audi is no stranger to using Water to Air intercoolers, like on the previous generation B9 RS5 which also uses a Water-To-Air intercooler before the Throttle Body. The EA839evo in the B10 takes Water-To-Air a step further by integrating two charge-air coolers (one for each bank of the engine) directly into the upper intake manifold, after the throttle body. 

Since there is no large front mount intercooler to route the charge air to, the turbocharged air immediately exits to the throttle body and through the Left and Right bank charge-air coolers and down into the engine. This shorter charge air system should provide faster throttle response as there is less total volume to fill over a standard Air-To-Air system. The integration of the charge-air cooler into the intake manifold is something that has been commonly found on S55/S58 BMW engines, and should offer solid performance in a compact form factor.

Moving onto the Turbocharger, instead of a conventional turbocharger system like what is found on the EA839, the EA839evo uses a Variable Geometry (also known as Variable Vane) Turbocharger. In the exhaust turbine side of the turbocharger, there are sets of vanes that can rotate to direct more or less air at the turbine wheel depending on what is desired. This system aims to provide the best of both worlds between a small quick-spooling turbocharger and a large high-flow turbocharger. 

Closing the vanes directs more air quickly to the turbine, providing very fast spool-up when you are at lower RPM and there is less exhaust gas moving. As the RPM increases, the vanes can then open to bypass excess exhaust gasses around the turbine (similar to a wastegate) but most importantly, reduce backpressure between the engine and the turbocharger as more exhaust gas is produced. This uncorks the turbocharger to a degree, allowing it to flow and perform efficiently in higher RPMs. The effect of closing and opening the vanes within the turbo effectively allows the turbo to have an adjustable A/R (see this article for a deeper explanation of A/R). Closing the vanes creates a smaller A/R with faster overall exhaust gas velocity but limits overall exhaust flow, whereas opening them up creates a very large A/R and flow area, with the cross-sectional flow area across the turbine increased significantly to allow higher exhaust flow. This technology truly allows you to optimize the power delivery for every part of the powerband.

In the documents we have seen, Audi has found the integration of the Variable Geometry Turbocharger to reduce knock tendency by it being more efficient in allowing all exhaust gas to exit the combustion chamber, and achieve an overall lower exhaust gas temperature, which helps the car run more efficiently on less fuel.

Variable Geometry Turbochargers have been commonly used in Diesel engines for decades, and in select Porsche 911s since the 997 Generation. We for one are incredibly excited to see this tech trickle down to Audi, and for the potential this system provides to future tuning of the factory turbocharger for more performance!

Lastly, as the graphic depicts, you can see the coolant ports in the cutaway of the compressor cover, highlighting where the turbocharger is water cooled to reduce overall temperatures.

The Variable Geometry Turbocharger also implements additional sensor provisions for even more refined control of fueling. As depicted in this graphic, it incorporates 2 additional Lambda sensors, one for each bank of the engine before the turbocharger itself, allowing the ECU to have better bank-specific control of fueling and air/fuel ratios. On the outgoing EA839 in the B9 S5, there is only one sensor within the turbocharger to read data combined from both banks, so the addition of Pre-Turbo Bank-Specific Lambda sensors on the EA839evo will allow for even more safe control of fueling within the ECU.

This is critical data that the ECU needs, given Audi has announced something new (and potentially contentious amongst the internet-tuning community). More on that shortly.

Along with turbocharging upgrades, the Direct Injection fueling system receives enhancements on the EA839evo over the outgoing model. Unlike the single 250 Bar HPFP system previously used, the EA839evo has Two High-Pressure Fuel Pumps in the system capable of reaching 350 Bar of fuel pressure, ensuring stable and consistent fuel flow to both banks of the engine. This pressure increase allows for a shorter injection timing window to get the desired amount of fuel sprayed, and helps accommodate the higher compression of the EA839evo and further avoid predetonation. This should also provide a significant step-up in fueling when it comes time to further improve performance through Dynamic+ tuning. 

The Fuel Injectors and Cylinder head also see changes over the previous generation, with adjustments to the top profile of the cylinder head, and changes in the spray pattern of the direct injectors both in spray size and distance between each injection. These changes likely aim to improve fuel atomization in the chamber, resulting in better fuel efficiency and less emissions per combustion event. These changes in the cylinder head profile along with other changes has resulted in the compression of the engine increasing from 11.2:1 to 12:1 as well.

On the topic of the combustion process, along with the changes made to the fuel system, injection system, and exhaust gas monitoring systems, Audi notes that they are now targeting a 1.0 Lambda for air/fuel mixture throughout the entire operating range of the engine via their factory ECU tuning. Regardless of the RPM, the ECU will be targeting a 1.0 Lambda to reduce fuel consumption and emissions while still achieving their power output of 362HP and 405Ft-Lbs. On the previous EA839, Audi targeted 1.0 Lambda in most driving conditions, but have made improvements to the fuel atomization and injection strategy to expand that operating range.

While this may be concerning to some, this is likely well within the safe operating range of these systems. Unlike older generation port-injected engines, the incredibly advanced technology behind Direct Fuel Injection and how that fuel atomizes in the cylinder means that less fuel is needed to have a safe combustion event. HP Academy has a great blog excerpt that goes over how a leaner Lambda value can still be safe within a Direct-Injected engine. Check that out here. 

To offer a crude summary, the Lambda values measured after the cylinder (via the Lambda probes now found on both banks of the turbocharger), don’t usually reflect the air/fuel mixture that is actually found in the cylinder. That’s due to a variety of variables like the injection method and spray pattern of the injectors themselves.

Bear with us as we get a little nerdy here. If you’re not interested in the nitty gritty, keep on scrolling for more fun facts about the rest of the B10 drivetrain. 

Audi has provided a graph denoting the type of injection methods they employ in their factory mapping. Single injection is what most people think of when they think of a fuel injector spraying fuel. The injector opens, sprays a pulse of fuel, closes, and the combustion process takes place. This is used under lighter load conditions where little fuel is needed. 

As you can see in the graph above, Audi utilizes a different injection method in higher load and higher RPM combustion events, called Split Injection. Lower in the RPM but higher in load, the fuel injector sprays fuel into the cylinder at Four different times throughout the intake and compression stroke. This allows for incredibly precise atomization of fuel throughout the air as it is being sucked into the cylinder and compressed in preparation for igntion. As the RPM rises, this drops to a Twin injection method, where fuel is injected twice during the intake/compression stroke. 

The amount of time the injector can open is largely down to the time a combustion cycle takes place at, and at a lower RPM, the combustion cycle is slower overall, resulting in more time for the injector to best atomize and inject fuel. As RPMs rise, the cycle speeds up, resulting in less overall time. This does not mean less fuel is injected as RPMs rise, as the total desired fuel amount is split across the injection sequences. 

034Motorsport ECU tuning already employs Split Injection strategies for many of its software offerings, often finding that Split Injection not only leads to a cleaner combustion event, but results in more power due to better fuel atomization compared to a Single Injection. 

The changes to the fueling strategies as noted above, along with implementation of 2 additional Catalytic Converts with Gasoline Particulate Filters integrated in, overall emissions are significantly reduced on the EA839evo over the previous generation, particularly in Carbon Oxide and Hydrocarbon emissions (Not the THC that you’re thinking about).

With all of these changes, Audi has increased the overall Horsepower and Torque Output across the entire powerband to 362 HP and 405 Ft-Lbs of Torque

Moving onto the Drivetrain and Chassis, it appears that Audi has positioned a 48-Volt battery pack and power inverter in the trunk of the S5, likely under the floor. This too is water cooled with the Low-Temperature coolant loop that is cooling the turbocharger, charge air, E-Generator, and E-Motor. 

One of the largest changes between the B9 and B10 generation is the switch from the ZF8 Automatic Transmission back to a 7-Speed DSG Dual Clutch Automatic, with an integrated 48-Volt electric motor. This is not the first time the S4 has came with a DSG Automatic (B8 & B8.5 with the DL501), nor is it the first time an EA839 has been provided with a DSG, as the C8 A6 and A7 are only available with the DL382+ 7-Speed DSG currently. Audi does not note which model transmission they are implementing in the B10, but our theory is that it is an updated variation of the DL382+. In one leaked Audi technical document, it is called the DL552M, but we’ll need to wait and see as more information becomes available. It has not been seen how this transmission handles higher horsepower beyond factory tuning, whereas the ZF8 has proven itself quite robust with higher horsepower, so our fingers are crossed that these perform well!

The E-Motor built into the 7-Speed DSG is capable of adding an additional 24hp and 174ft-lbs of torque, putting the total combined power at 386 HP and a whopping 579 FT-Lbs of Torque, making this one of the most powerful S5s out of the box! It also allows the S5 to be briefly driven in an EV-Only mode, though this range has not been confirmed yet. We’re very excited to see how we can utilize this E-Motor within our ECU tuning, as well as what could be done to potentially improve its performance!

While there was some speculation that Audi was switching to Quattro Ultra for the B10 S5, we now can confirm based on updated information from Audi that it will indeed retain the conventional Torsen Quattro All-Wheel Drive system found in the B9 generation, along with the performance Rear Sport Differential.

Like in previous generations of Torsen Quattro, the additional Rear Sport Differential allows for the entirety of torque that is sent to the rear to be vectored to one wheel or another, depending on the handling needs. This most notably can allow the outside wheel to be driven more than the inside when cornering, helping improve rotation and reduce understeer (and potentially assist with some fun powerslides).

On the Front Axle, Audi has noted they have stiffened some components in the steering and suspension, likely the rubber bushings found on the control arms, for better handling and steering feedback. In the graphic, we can also see that brake cooling ducts are now added to the lower control arm to help cool the Front Brakes, which appear to no longer be the 6-Piston Akebono fixed caliper found on the B9/B9.5, but a Single-Piston Floating Caliper. 

Generally speaking, we’ve found Audi’s tend to need more braking performance, not less, but the S5 does now have Regenerative Braking through the E-Motor in the drivetrain, so it is possible that the load on the conventional braking system is reduced enough that a lighter caliper package is still suitable. 

That is everything we know about the B10 Audi S5 so far! What are your thoughts? Are you interested in one? We’re excited to get our hands on one and begin to see where the Dynamic+ philosophy can be applied to enhance its performance!