The 4.0 TFSI is a pretty awesome motor. From the OEM, there are a couple different configurations and different outputs depending on model. Here’s what the factory rates them at in Metric HP (PS) and lb-ft of Torque:
S6/S7
Horsepower (@ rpm) - 420 @ 5,500-6,400
Torque (lb-ft @ rpm) - 406 @ 1,400-5,200
A8
Horsepower (@ rpm) - 420 @ 5,000
Torque (lb-ft @ rpm) - 444 @ 1,500
S8
Horsepower (@ rpm) - 520 @ 6,000
Torque (lb-ft @ rpm) - 481 @ 5,500
RS6/RS7
Horsepower (@ rpm) - 560 @ 5,700-6,600
Torque (lb-ft @ rpm) - 516 @ 1,750-5,500
Depending on model they have different transmissions too. The S6/S7 gets the DSG while the A8/S8/RS6/RS7 all get a tiptronic.
We strapped our S7 and S8 to our Dynapack All wheel hub dyno and got some pretty interesting results out of the motors both stock and modified. The figures were were putting down to the hubs was very close to what Audi rated the vehicles at the crank. We’re wondering if Audi downplayed the output of these engines. We went ahead and figured a drivetrain loss that seemed reasonable for our marketing figures, but the results were higher than what Audi stated.
Here’s some interesting data at the wheels:
NOTE - Due to image size, you’ll need to scroll right to see the HP graphs
S7 vs S8, 93 octane, all 4 wheels, stock:
http://www.goapr.com/includes/img/products/dyno/40tfsi_d4_s8/s8-oem-93-vs-s7-oem-93.png
Next up we compared the S7 with APR software to the S8, stock with 93 octane
http://www.goapr.com/includes/img/products/dyno/40tfsi_d4_s8/s8-oem-93-vs-s7-apr-93.png
Now here’s a comparison of the S8 stock and the S8 with APR software on 93 octane
http://www.goapr.com/includes/img/products/dyno/40tfsi_d4_s8/s8-oem-93-vs-s8-apr-93.png
And finally, the S7 with APR software and the S8 with APR software, both on 93 octane
http://www.goapr.com/includes/img/products/dyno/40tfsi_d4_s8/s8-apr-93-vs-s7-apr-93.png
On both cars, the S7 and the S8, there’s room for more torque on 93 octane, but we didn’t want to push it too far on stage 1, so we capped torque around 525 AWFT-LBS of torque and 625 AWFT-LBS of torque respectively. The S8 has all of 700+ AWFT-LBS of torque in it if you go really hard!
Now I don’t have good back to back acceleration data, but here’s what the S8 put down with APR 93 octane stage 1 and with stock software. The gains are pretty impressive and this thing really throws you back in your seat!
http://www.goapr.com/includes/img/products/dyno/40tfsi_d4_s8/40tfsi_d4_s8_s0_vs_s1_93_0-130.png
http://www.goapr.com/news/wp-content/uploads/2013/10/s8acceleration.png