Theoretical hp limit

120 hp sounds very high, is this reasonable?

no, but it's an approximation, its not taking a lot of things into account so it serves as a rough upper bound. I may have messed up the math, so if you're doubting the numbers, please double check. The major assumption here is steady flow at mach 1 being why the restrictor restricts, which we know isn't true, as engines have pulsed air inflow which drops our hp limit.If you want to, it would really help to list all the other shit that drops the limit and do the math behind it, so this page can be more helpful. There's another limit of enigne speed which is written up on the engine page, which also has a lower limit, which makes the same, faulty assumption.