6 - val ve , ▁inter co o led ▁tur bo ▁ 2 - lit re ▁box er ▁four . ▁According ▁to ▁official ▁Sub aru ▁literature , ▁there ▁are ▁several ▁advantages ▁to ▁the ▁box er ▁design . ▁Due ▁to ▁the ▁balance ▁afford ed ▁by ▁hor izont ally ▁opposed ▁cyl ind ers , ▁the ▁c rank sh aft ▁requires ▁less ▁weight ing ▁and ▁there ▁is ▁no ▁need ▁to ▁install ▁balance ▁sh aft s . ▁This ▁results ▁in ▁reduced ▁noise , ▁v ibration ▁and ▁less ▁power ▁loss . ▁Str ength ▁is ▁also ▁an ▁advantage ▁of ▁the ▁box er ▁design ▁– ▁the ▁c rank sh aft ▁is ▁sand wich ed ▁between ▁the ▁left ▁and ▁right ▁hand ▁c rank cases ▁and ▁is ▁supported ▁by ▁ 5 ▁main ▁bear ings . ▁The ▁low ▁and ▁wide ▁engine ▁structure ▁also ▁low ers ▁the ▁vehicle ' s ▁centre ▁of ▁gravity ▁and ▁impro ves ▁mass ▁distribution . ▁ ▁Working ▁from ▁the ▁c rank cases ▁out , ▁the ▁' phase ▁ 2 ' ▁engine ▁sees ▁the ▁c rank ▁thrust ▁bearing ▁re located ▁to ▁the ▁rear ▁of ▁the ▁sh aft ▁– ▁this ▁reduces ▁transfer ▁of ▁natural ▁frequencies ▁to ▁the ▁transmission , ▁resulting ▁in ▁improved ▁N V H . ▁P ist ons ▁are ▁all - new ▁in ▁the ▁B 4 . ▁Despite ▁being ▁made ▁from ▁for ged ▁al umin ium , ▁the ▁p ist ons ▁are ▁heav ier ▁( 1 6 2 ▁up ▁from ▁ 1 5 2   gram s ) ▁and ▁incorpor ate ▁solid ▁sk ir ts , ▁reduced ▁p ist on ▁pin