ΔE 8.4, close: similar, with a visible difference side by side. IJA Chrome Yellow is more saturated than Heartfire.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). IJA Chrome Yellow is more saturated than Heartfire.
The same difference applies the other way round: Heartfire is more muted.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Heartfire on the colour wheel See IJA Chrome Yellow on the colour wheel
All matches: Heartfire equivalents · IJA Chrome Yellow equivalents