b377 -
Ok, this one will bring tears to the vintage flyers amoung you with memories and a soft spot for pistons ...
Tears is right! Only time I get to hear those sounds now is on my Flight Sim.
Of course the Connie had different engines: R-3350 w/o PRTs and R-3350 w/PRTs. Different sounds. But, you mentioned the Supers and they all had the 3350s with PRTs. The "fire" had a lot to do with mixture settings.
All the DC-7s had the 3350s with PRTs. But exhaust stack design has a lot to do with the sound as well. The Convair 340s (R-2800s) with augmenter tubes sounded different from the DC-6s with the same engine.
The R-4360s (corn cobs) were something else!
As to the C-46 vs the DC-3; again two different engines.
Ahh.....the good ol' days.