Audi's 4.0 TFSI Twin Turbo V8 showing its tuning potential - Already over 600 wheel horsepower tune only (APR)

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The German turbo V8 era sure is getting fun with Mercedes-Benz, BMW, Audi, and Porsche all going back and forth in a turbocharged V8 power war. Audi has the motor with the smallest displacement of the bunch but it is hardly giving up much of anything to its larger V8 competition. Proof? How about over 600 horsepower at the wheels with just a tune? APR was able to get exactly that with their Stage I ECU upgrade and 100 octane race fuel in the new S8 hitting 610 horsepower at all four wheels.

We all saw last week that the Audi S8 is already in the 10's in the 1/4 mile tune only courtesy of APR. Below you have dynographs for the Audi S8 stock on 91 octane, Stage I on 91 octane, Stage I on 93 octane, and Stage I on 100 octane race fuel. The S8 puts down an impressive 485 all wheel horsepower completely stock on 91 octane showing it is slightly underrated to begin with.

This all begs the question as to how the 4.0 TSFI V8 differs in various applications. This same basic V8 is used in the S6 and S7 tuned to 420 horsepower. In the S8 this output rises to 520 horsepower. In the RS6/RS7 this output rises to 560 horsepower. It is safe to assume the S8 has different turbos on the 4.0 than the S6/S7. Does the RS6 and RS7 then have different turbos than the S8? What exactly are the differences between the 4.0 TFSI in all the models it is used in at different horsepower levels? AudiBoost hopes to find out. What is certain is that this motor is capable of serious power with only mild modifications.

Audi S8 Dynographs below.

91 Octane:

93 Octane:

100 Octane:

Performance Figures: