Tuning Your Audi S4, S5, A6, A7, or Q5 3.0T at Altitude
With every IE part, we put in your hands our objective is for you to enjoy it and have fun. So, we decided to write a little piece explaining the effects of altitude on the gains found from tuning your Audi 3.0T Supercharged engine found in B8/B8.5 S4 & S5, C7 A6 & A7, and Q5/SQ5 chassis. This will hopefully allow you to make a better decision about flashing Stage 1 vs going to a Stage 2 pulley upgrade and beyond.
Audi 3.0T Supercharger Boost Explained
The engine on your Audi 3.0T uses a fairly small but efficient Eaton TVS 1320 supercharger. The supercharger output can be increased by changing pulleys and making it spin faster, but in the context of a stage 1 software tune, its maximum output is fixed. In stock form, boost is controlled by a small electronic bypass valve called the RFP which is located in the back of the supercharger. This allows some airflow to be looped around the supercharger and limits the boost pressure downstream. At sea level, impressive gains are available by asking the ECU to deliver more boost, until the bypass valve is fully closed at full throttle. Of course, the rest of the calibration must be adjusted to deal with this extra flow. At nearly every altitude, up to about 6000 feet or so, the boost pressure obtained on the stock tune is the same - so power remains relatively constant. This can be dyno-checked by noticing that the "uncorrected" stock baselines are basically the same at any reasonable altitude. As altitude increases and the air becomes increasingly thin you will be able to see that this bypass valve (RFP) is closed further, even on the stock tune. This means that as you go up in altitude, the margin for boost increase between stock and Stage 1 tuned is increasingly thin. At very high altitudes, in some cases the only place it's possible to get more boost than OEM is at high RPM levels from 5000 RPM or higher, where the OEM calibration really cuts back power. In some cases, the difference from sea level may be 20% or higher! For this reason, gains over stock are much less at very high altitudes than at sea level. The cars still deliver – on par dyno results using the SAE correction method, which adjusts power readings for air density. However, the OEM numbers will show as quite high.
High Altitudes vs. Sea Level Power Gains
If you're at a higher altitude, we suggest going at least directly to Stage 2 with a supercharger pulley upgrade. This will give you the modifications you want and really put a smile on your face. For customers at sea level, we suggest hitting stage 1 first for a bit, enjoy that, and then go stage 2 when you get bored of the extra power.