Thursday, December 19, 2013 – Erich
Just about anyone who has owned a turbo Subaru has at some point wanted more horsepower. One of the easiest ways to increase horsepower output is to replace the undersized factory turbo with a larger aftermarket unit. The downside to increasing turbo size is response otherwise known as turbo lag. Modern turbochargers use lightweight materials and larger port diameters to decrease this lag without hurting top end power. The newest generation of turbochargers use machined from solid “billet” aluminum to bring you the lightest possible compressor wheel and better airflow characteristics than previously possible using cast compressor wheel designs. These aluminum wheels are better balanced and cause less stress on rotational and thrust bearings which prolongs turbo life and allows them to operate more efficiently at higher speeds (turbine rpm) which is just a cool way of saying they make more power with less work. Most vehicles need little to no modification to take advantage of a larger turbocharger unit.
Modern Subaru Turbochargers are available in three styles and a variety of sizes. The styles are Standard Compressor Outlet, Flanged Compressor Outlet (2005+ Legacy GT, 2008+ WRX, etc), and VF54 Style Flanged Outlet (2010+ Legacy, 2014 Forester, etc). These turbochargers are all available in a variety of sizes detailed below. The full line of replacement Subaru turbochargers available from RalliTEK can be found here (http://www.rallitek.com/prodtype.asp?CAT_ID=919)
Turbocharger Sizing Guide
All minimum modifications listed are for 14psi spring pressure. Higher boost may require additional modification.
|2.5L EngineDue to boost creep issues on the 2.5L engines RalliTEK recommends all stock VF series or aftermarket turbochargers have their turbine housings ported to increase wastegate flow. This porting service increases flow to the wastegate flapper door which allows the vehicles boost control system to function properly preventing boost spikes and boost creep. We can provide this service to any turbocharger for $99 plus shipping.TD05-16G