7 . 0   mm ▁/ ▁ 3 5 . 4   mm ▁ 6 ▁+ ▁ 6 ▁bla de ▁compress or . ▁At ▁idle , ▁the ▁tur bo ▁sp ins ▁at ▁around ▁ 2 0 , 0 0 0 ▁r pm ▁and ▁it ▁can ▁go ▁on ▁to ▁a ▁maximum ▁speed ▁of ▁ 1 9 0 , 0 0 0 ▁r pm . ▁It ▁has ▁a ▁ 1 7   mm ▁diameter ▁waste gate ▁opening ▁to ▁by pass ▁excess ▁exhaust ▁gas . ▁The ▁secondary ▁tur bo char ger ▁is ▁an ▁I HI ▁V F 3 2 . ▁On ▁the ▁exhaust ▁side ▁it ▁uses ▁a ▁ 4 6 . 5 ▁/ ▁ 3 5 . 4   mm ▁ 9 - bla de ▁tur bine ▁wheel , ▁te amed ▁with ▁a ▁ 5 2 . 5 ▁/ ▁ 3 6 . 6   mm ▁ 1 0 - bla de ▁compress or ▁wheel . ▁It ' s ▁r ated ▁at ▁ 1 8 0 , 0 0 0 ▁r pm . ▁Both ▁the ▁primary ▁and ▁secondary ▁tur bo charg ers ▁use ▁a ▁floating ▁metal ▁centre ▁bearing ▁– ▁not ▁ball ▁bear ings . ▁ ▁Inter co ol ing ▁ ▁Like ▁the ▁W R X , ▁the ▁B 4 ▁uses ▁a ▁bon net ▁sc oop ▁to ▁feed ▁a ▁top - mount ▁air - to - air ▁inter co ol er . ▁Man ufact ured ▁by ▁S anden , ▁the ▁inter co ol er ▁has ▁an ▁effective ▁depth ▁of ▁ 7 3   mm , ▁a ▁width