Kamps Microturbine Checking rpm vs Pressure vs. Thrust vs. Temperature

My Kamps microturbine is complete and well behaved now, but it lacks thrust.
85000 rpm at 0.52 Bar case pressure with 534 deg C exhaust temperature and 15N thrust running on diesel.
The book with the drawings ("Model Jet Engines by Thomas Kamps") states 85000 rpm at 0.7 Bar case pressure. Thrust nozzle as described in the drawings is mounted.
Rpm's are limited to 85000 because the turbine wheel is made out of 316 stainless steel. I am thinking that the compressor should do more work since the pressure is lower than Kamps describes in his book for this engine.
I see the power graph for a KJ66 using the same compressor 5326-123-2018 will deliver 30N thrust at 80000 rpm.
Why is my engine not producing more thrust?
Is this a diffuser / compressor issue where the compressor is not able to do more work at this rpm? (Starvation / flow restriction / gap loss / air intake too small or wrong shape / sub-optimal geometry)
OR
Is it a thrust nozzle issue since the temperature is relatively low? Would it help to narrow the exhaust opening to create more flow resistance and higher exhaust velocity?
OR
Is this an issue with running diesel fuel?


Update:
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I made a mistake when grinding the turbine wheel. I made the wheel with leading edge to trailing edge 34 degrees - resulting in 20 degrees at the trailing section of the blade. The leading to trailing angle should be 48.5 degrees according to the drawing, leaving the trailing section at 34 degrees.