I’ve recently made a rally car engine (WRC) following the FIA regulations and I found it was an interesting/challenging task.
So the challenge woud be a turbocharged engine with the next restrictions (from FIA and myself):
Maximum displacement: 1600cc / 97.6ci
Max. turbine size: 33mm
Max. turbo pressure: 2.50bar / 36.8PSI
Peak power range: between 5500 - 7200rpm.
Max. RON/AKI: 98/93.1.
Default quality sliders.
The goal would be a peak power around 300hp.
The Polo R WRC specs may give you an idea.
Note: I think the restriction on turbine size should be on the compressor (air restrictor) but in that way I’ve not even been able to get 250hp, so I changed it.
Hope you find the challenge interesting