small, high power hybrid

[DYI]

HGDT assumes standard "air" (roughly 1:4 oxygen/nitrogen) as the oxidizer / buffer. There's not really any way to simulate anything other than air/fuel mixes using the fuels provided without heavily modifying the program. With sufficient knowledge of the physical process and how HGDT approximates it you could possibly, with a great deal of effort, decompile HGDT and make something intelligible out of the resulting code, then modify it to suit you. This would very likely be more time consuming than simply writing a new model.