[My5ABaby]

Stock Turbo Information (S4)

The stock turbo on an S4 features an 11-blade turbine measuring 64mm (2.52 in). The scroll's smallest area is 6.00 sq. cm (0.93 sq. in) primary path, and a 9.48 sq. cm (1.47 sq. in) secondary path. The distance between turbine shaft center and the center of area was 59.4 mm (2.34 in) for the primary path and 60.4 mm (2.38 in) for the secondary path. The compressor is a 12-blade design, with a 63 mm (2.48 in) diameter. The maximum turbine speed is 110,000 rpm.

The S4 FC featured a unique twin-scroll design that virtually eliminated turbo lag. At low speed, exhaust gas enters the turbo via the primary path. When the engine reaches 2500 rpm, the secondary path is opened.

Maximum Boost Levels

* 2000-5000 rpm: 320 mm mercury (0.42 bar/6.2 psi)
* 5000+ rpm: 280 mm mercury (0.36 bar/5.4 psi)
* Fuel Cut: 400+ mm boost

Edit: I guess I should of read Roen's post more carefully because this is on there too. Oh well...