how much roundabout whp is a .42 intake .48 exhaust t3/t4 good for on a 4g63. What would the typical trim size be. And how does it compare to, let's say a big 16g.

 

well first of all we call the intake side as u call it the compressor side and the hot side or side that would bolt to the exhaust manifold, the turbine side. typically a t3- t4 consists mostly of an .60ar intake to .63 and a t-3 section turbine of .48 to .58 or so on, theres a lot of combos out there. yours sounds more like a straght t-3 wich is a pretty good find in a junkyard turbo, its capable of around 300 hp with good tuning and alot of patience. when u make a t-3 t4 u use the compressor of the larger t-4 for its larger air displacement and the smaller t-3 turbine exhaust side for the light weight and smaller a/r for quicker spooling on the typical 4 cylinder engine. the tried and true t-3 t-4 with an a-r of. 60 and exhuast a/r of .58 should put out around 450 hp at 14.5 psi.