Originally Posted by dannanw
why go down in size? we want more cfm not less, sure it would spool faster but worse for flow/hp/egt. If I'm incorrect please enmighten I always love to learn
yes and no. the smaller housing changes the RPMs where the turbo is efficient. in my setup i am running a D66 with a WW2 (a billet wheel) and a smaller 1.0 housing. when i was running the orginial 1.15 housing boost was low, and EGTs high where i did the majority of my driving. the turbo wouldn't light until 21-2200 RPMs which is too high for a daily driver/tow rig. switching to a smaller housing creates more boost lower in the RPM range at 13-1400. and more boost means more air means lower EGTs and more air means less smoke and since i want to build boost and have boost where i normally drive 1200-2500 RPMs it was a wise move to swap. granted at high RPMs the turbo runs out of its efficiency range and falls on it's face around 31-3200. and drive pressures get really out of control, but the engine never sees those speeds.