Supercharger Swap: What Actually Happens When You Put a Roots Kit on the CEBB Engine
The 2019 Audi S4 comes with the 3.0T CEBB engine. It makes about 354 horsepower and 369 pound-feet of torque from the factory. That is decent for a daily driver, but it is not fast enough for people who spend time on canyon roads or quarter-mile strips. The most common upgrade path involves a Roots-style supercharger kit. You will find several options on the market from vendors like AC Schnitzer, VRSF, and some European tuners. Each kit routes differently, uses different pulleys, and changes the sound character of the engine in ways that matter more than the dyno numbers. Here is what the process actually looks like when you sit down to do this. Most kits follow a similar pattern. You remove the intake tract, drop the supercharger unit onto the intake manifold using the supplied hardware, connect the drive belt, and run the intercooler piping from the compressor outlet to the throttle body. The intercooler is mandatory because the CEBB engine's cooling system was never designed to handle the heat rejection of a supercharger. Running hot charge temps will cause the ECU to pull timing, and you will end up slower than stock after three or four hard passes. The real work starts with tuning. This is where most people mess up. You cannot simply bolt on the hardware and expect the car to run safely. The stock ECU maps are built for turbo boost pressure curves, not supercharger boost. You need a custom tune that adjusts fuel enrichment, spark timing, and boost targeting. I had a situation where a customer installed a kit and ran the manufacturer's off-the-shelf tune without any individual adjustments. The AFRs leaned out around 4000 RPM under wide-open throttle because the fuel injector duty cycle hit a ceiling the tune did not account for. The fix was a custom map that backed off boost slightly at high RPM and added fuel trims across the board. I used a Live Data tool to monitor AFRs in real time, and once the tune stabilized around 12.8 to 13.0 AFR at peak boost, the car ran cleanly.
What Numbers to Expect
A properly installed and tuned supercharger kit will typically push the CEBB engine to between 450 and 500 wheel horsepower, depending on the boost level and supporting modifications. The torque curve is where the real difference shows. Stock torque peaks around 1350 RPM and stays flat through 4500 RPM. With a supercharger, torque starts climbing almost immediately and keeps building. You can expect roughly 450 to 520 pound-feet at the wheels. That changes how the car drives completely. Launch traction becomes a management problem rather than a question of power availability. Supporting mods matter more than people realize. If your car still has the stock intercooler, you should replace it with an aftermarket unit. Stock setups cannot dissipate heat fast enough when you are generating additional thermal load from forced induction. Upgrading to larger fuel injectors or a high-flow fuel pump is also wise if you plan to run boost levels above 8 PSI consistently. The factory fuel system handles moderate boost fine, but there is a threshold where you will run lean.
Common Problems and How to Fix Them
I have seen the same issues pop up repeatedly across different kits and installations. The most frequent one is belt noise after the first few thousand miles. The CEBB engine has a long accessory belt routing that puts tension on the supercharger drive pulley. If the idler pulleys are not replaced or adjusted during installation, you will get a chirping sound that gets worse when the engine is cold. The workaround is replacing all idler and tensioner pulleys with aftermarket units and torquing everything to spec on the first install. Do not skip this step. Another issue is boost lag at part throttle. The Roots supercharger does not produce boost until it spins fast enough to move air. Below 2000 RPM, you will notice very little difference from stock. Some drivers describe this as feeling sluggish off the line. The solution is a smaller drive pulley that increases blower spin ratio at low RPM. It trades some top-end boost for more low-end response. I usually recommend this for cars that see mostly street driving rather than track use.
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Installation Difficulty and Time Estimate
If you have basic mechanical skills and a decent tool set, expect the installation to take between 6 and 10 hours for a first-timer. An experienced mechanic with the right lift and tools can do it in about 4 hours. The hardest part is usually routing the intercooler piping in tight spaces behind the front bumper. You will need to remove the lower fascia in most cases. Some kits include a custom bypass valve that vents blow-off pressure through the intake, which keeps things simple. Other kits require you to fabricate or buy a separate blow-off valve for the compressor outlet. I prefer the bypass valve approach because it is cleaner and less prone to boil-over issues. A complete supercharger kit for the 2019 S4 runs between 3000 and 5500 dollars depending on the brand and what is included. Tune costs vary widely. A basic off-the-shelf tune from the kit manufacturer might run 500 to 800 dollars. A fully custom dyno tune from a reputable shop will set you back between 1000 and 1800 dollars. Supporting modifications like an upgraded intercooler and pulleys add another 800 to 1500 dollars on top. Total project cost typically lands between 5000 and 7500 dollars when done correctly. There are cases where this upgrade is not worth the money. If your primary goal is just slightly quicker acceleration for highway merging, a quality ECU flash tune that adds 30 to 50 horsepower might be more cost-effective. The supercharger is overkill for casual driving. It also increases long-term maintenance costs because you are adding a mechanical component that wears over time. Belt replacements, pulley inspections, and potential compressor rebuilds are real expenses down the line. The CEBB engine is already robust, but adding forced induction means you should stay on top of maintenance intervals rather than stretching them.
