Turbo high flowing!!

[twin eng, twin turbs]

With the desire for a bit more power i decided to upgrade the current turbo on my mk2 gti but with space a very limiting factor and seeing as i had allready made the manifold, down pipe, induction pipe, intercooler pipe work, oil lines etc etc to suit my current turbo i looked into the different options for high flowing the IHI VF22 turbo i had installed.

This model turbo is the biggest subaru used on the wrx sti models, providing great top end with the sacrifice of a little bottom end drivabilty or lag! Not that i experienced any lag with it as my exhaust manifold is short with 4 into 1pipe work merging together at the turbine housing. It was making boost under 2000rpm in all gears. This turbo flows 325hp with peak efficency at 18psi.

A lot of aftermarket companies supply upgrades for the wrx, sti, forestor gt that this turbo can bolt straight onto but at a big price! So i decided to upgrade the internals using the centre core from a garrett GT 25/40 turbo i had saved for the twin eng mk1 and machining it to suit the IHI exhaust and compressor housings. The garrett GT 25/40 is a awesome ball bearing turbo with great drivability flowing 440hp with a 0.64 air ratio exhaust housing and 480hp with the 0.86 air ratio exhaust housing. The vf22 exhaust housing flows almost as well as the garretts 0.86 unmodified but i have ported and polished it to get the most out of it.

Heres a pic of the vf22 after removing it from the engine. I have modified it a lot from standard.