Type turbo Audi S4 into a search bar and you will find two very different conversations. One is about the 2018+ B9 and B9.5 S4, which left the factory with a turbocharged EA839 3.0T V6 and responds brilliantly to more boost. The other is about bolting a turbo onto a supercharged B8, which sounds great in a forum thread and far less great on an invoice. This guide covers both honestly, starting with the part every high-boost B9 needs first: 4 bar MAP sensors for the Audi S4 EA839.
How the S4 Became a Turbo Audi S4 Again
The S4 has been boosted, unboosted, and boosted again. The B5 S4 used a 2.7-liter twin-turbo V6. The B6 and B7 switched to a naturally aspirated 4.2 V8. The B8 and B8.5 (2010-2016) went supercharged with the EA837 3.0T. Then the B9 brought turbos back with the EA839 3.0 TFSI, a new V6 with a single twin-scroll turbocharger mounted inside the vee, rated at 354 hp and 369 lb-ft in US trim and paired with an 8-speed automatic in US cars.
That hot vee layout keeps the path from exhaust ports to turbine short, so response is quick for a turbo engine. It also packs a lot of heat into the top of the engine, which is why cooling, ignition, and sensor accuracy matter so much once you raise boost.
What the Factory EA839 Turbo Gives You
On software alone, the stock turbo has meaningful headroom, which is why tuning is the first and biggest step on a B9. Where does it run out? As boost targets climb, three things start to limit you:
- Boost measurement: the factory MAP sensors are 3 bar units. Push boost high enough and the ECU literally cannot read what the turbo is doing.
- Ignition: more cylinder pressure makes weak coils show up as misfires under load.
- Heat: higher boost means hotter charge air and a harder-working cooling system, so power fades on repeated pulls.
Only after those are handled does the turbo itself become the limit.
Turbo Upgrade Paths for the B9 S4
Stage 1 and 2: software and supporting parts
Most B9 owners get the biggest improvement per dollar here: ECU software (and transmission software for sharper shifts), plus intake, charge-air cooling, and exhaust flow. Our Audi S4 B9 exhaust guide covers the exhaust side.
Upgraded turbo replacements
Several upgraded turbochargers are made to replace the factory EA839 unit in its factory location, using larger or improved compressor and turbine wheels. They make more top-end power, but they demand more fuel, more calibration work, better cooling, and a transmission and driveline that can handle the torque. This is where MAP sensor range becomes non-negotiable.
Big turbo conversions
Fully custom larger-frame setups exist, but they involve fabrication, fuel system rework, and extensive tuning. They are project cars, not weekend upgrades.
What to Look For Before You Add Boost
- ✅ Sensor range: 4 bar MAP sensors so the ECU can see and control higher boost.
- ✅ Spark: coils that deliver strong, consistent energy under load.
- ✅ Drivetrain control: a firmer transmission mount to reduce slop and wheel hop.
- ✅ Braking: brakes that match the new speed, especially at the rear.
- ✅ Data: logging of boost, timing, and intake temperatures after every change.
Vorsprung vs Typical Name-Brand vs Dealer
The dealer has one answer for a high-boost B9: stock parts. Typical name-brand support parts work, but many are premium-priced alternatives for the same basic components. Our EA839 4 bar MAP sensor kit includes two precision-calibrated sensors that plug into the factory harness for $99.99, and it cross-references OEM part 04E906051J.
| Vorsprung 4 Bar MAP Sensors | Typical name-brand option | Dealer/OEM | |
|---|---|---|---|
| Sensor range | 4 bar | Varies | 3 bar (stock) |
| Sensors per kit | Two | Varies | Sold individually |
| Connection | Factory harness, plug-and-play | Varies | Factory |
| Supports higher boost tunes | Yes | Yes | No |
✅ Plug-and-play EA839 fitment ✅ B9 fitment help from real Audi owners ✅ Fast US shipping
Shop the EA839 4 Bar MAP Sensors, $99.99
Recommended Parts for a Turbo Audi S4 (B9/B9.5)
- ✅ 4 Bar MAP Sensors, B9 EA839 ($99.99): covers EA839 2.9T and 3.0T, installs like the factory sensors using the charge pipe retention clips.
- ✅ Zeus Ignition Coil Upgrade Kit, EA839 ($199.99): direct plug-and-play coils for the B9/B9.5 S4, S5, and SQ5.
- ✅ Haken Street Rear Big Brake Kit ($1,599.99-$1,649.99): fits B8 through B9.5 and retains an electronic parking brake caliper.
- ✅ TruShift Transmission Upgrade Mount ($19.99): 65 durometer rubber for B8 through B9.5, less drivetrain movement under load.
- ✅ Velocity rotors ($574.99-$1,399.99) when you are ready to upgrade rotors.
Browse more in our tuning solutions collection.
What About Turbocharging a B8 or B8.5 S4?
Here is the realistic answer. Turning a supercharged B8 into a turbo Audi S4 means removing the supercharger and its intercooler setup, then adding custom exhaust manifolds or turbo mounting, oil and coolant lines, a new intercooler and charge piping, fuel system upgrades, and a custom calibration. There is no factory turbo version of the EA837 to borrow parts from, so almost everything is one-off.
Can it make big power? Yes. Is it the best use of money on a B8? Rarely. The supercharged 3.0T already makes instant boost, and its upgrade path is proven: the TruDrive crank pulley ($249.99-$329.99), the Artus-Sturm ported supercharger service ($749.99-$1,599.99), and the GP Ice heat exchanger ($449.99). Our Audi S4 mods roadmap lays out that path step by step, and performance parts for Audi S4 sorts it by budget.
Install Notes
- MAP sensors and coils are driveway jobs with basic hand tools; disconnect the battery and take your time with brittle clips.
- Install sensors before the tune that needs them, and confirm with a log that boost readings look sane.
- The TruShift mount is a quick bolt-on insert; expect slightly more vibration than stock.
- Rear big brake kits need a lift or solid stands, fresh fluid, and a proper bleed.
Turbo Audi S4 FAQ
Is the B9 Audi S4 turbocharged?
Yes. The 2018+ B9 and B9.5 S4 use the EA839 3.0 TFSI V6 with a single twin-scroll turbo mounted in the vee. That makes the B9 a factory turbo Audi S4.
Can you put a bigger turbo on a B9 S4?
Yes. Upgraded turbos made to replace the factory EA839 unit exist, but they require supporting fuel, sensor, cooling, calibration, and drivetrain work to be reliable.
Why do I need 4 bar MAP sensors on a turbo Audi S4?
The factory EA839 MAP sensors are 3 bar units. Tunes that target higher boost need sensors with more range so the ECU can measure and control boost accurately.
Is the B8 S4 turbo or supercharged?
The 2010-2016 B8 and B8.5 S4 are supercharged with the EA837 3.0T. Only the B5 (twin-turbo) and the B9 onward are factory turbocharged S4s among recent generations.
Is a turbo swap on a B8 S4 worth it?
Usually not. It requires custom fabrication, fueling, and calibration. Most B8 owners get more reliable power per dollar from a crank pulley, ported supercharger, and better cooling.
Do Zeus coils fit the B9 S4?
The EA839 version of the Zeus coil kit fits the B9 and B9.5 S4, S5, and SQ5. The EA837 version is for the older supercharged cars.
What brakes should I get for a tuned B9 S4?
A rear big brake kit like the Haken Street kit, which fits B8 through B9.5 and keeps an electronic parking brake, is a strong upgrade alongside quality rotors and fluid.
Bottom Line on the Turbo Audi S4
A turbo Audi S4 build lives or dies on supporting parts. On a B9 or B9.5, measure boost correctly with Vorsprung 4 bar MAP sensors for the EA839, give it stronger spark, then plan the drivetrain and brakes before chasing a bigger turbo. On a B8, skip the swap fantasy and let the supercharger do what it does best.
Shop the 4 Bar MAP Sensors, $99.99
Drive the difference. Drive Vorsprung.
Prices checked September 25, 2026 and subject to change.
