1. 400hp is right about on the edge of that the turbo is capable of. It's a custom turbo based around a gt2871r compressor. If you look at the compressor map, I made a red line that illustrates basically how I'm running it with this tune. The way I'm pushing it at max boost and max airflow, it's operating on the edge of its efficiency range.
2. Here are the boost numbers:
- BEFORE: 22psi
- AFTER: 22psi to 4500rpm, 26psi from 5500rpm to redline
As far as the temp rise at the end, my guess is that the turbo is running out of breath at the top of the rpm band due to the way I'm pushing it. It's just pumping out a lot of hot air at that point. When I was running a 50/50 mix, I didn't see a temp rise at the end, probably due to the water. However, I also didn't see as large of an overall temperature drop either. Here is a graph of 50/50 vs nothing at all.
The next step will be to continue to tune. I'll probably dial the boost back a bit to keep things safer and more reliable. I've gone about as far as I want in terms of hardware, short of building the motor and replacing the clutch.