While on another trip, I pulled out onto the road and the car felt a little sluggish and was making a certain noise it makes when the boost gets higher. I looked down while accelerating, and sure enough, the boost was at 25 lbs, where I usually run 15. The road was fairly flat with a 65 MPH speed limit, so I thought I'd be ok just driving with light acceleration. My turbo is variable vane, GT1749V, and like I assumed, the linkage had unscrewed. An odd thing that I noticed is that even though my EGT's stayed reasonable with the light pedal, my water temp quickly climbed to 230. I pulled over, letting it cool enough to fix, and went on my merry way.
Now, I have a 2.5" exhaust, above mentioned turbo, manifold from a K-14 and an adapter to adapt the turbo to the manifold. What is the likelyhood that my previous to this overheating issues, and maybe those of others, are related to backpressure from either the turbo or the manifold or adapter? I never expected to get hot at partial throttle on a flat road just from backpressure, but obviously it has a bigger effect than I thought. Maybe a 1.6 exhaust manifold just doesn't flow well enough for a 1.9? My other overheating happened at or near full throttle, so there would have been a lot of exhaust gasses.