If you've got a good 'ear' you can tell single row radials from twin rows even WRIGHTS from PRATTS or Russian radials like on the CJ-6 Shenyang/various YAKS, ALLISONS from MERLINS. I really can't discern, nor do I really care to, a CONTINENTAL flat motor from a LYCOMING flat motor.
You can also tell what the engine is on by the exhaust 'report' and 1820's on a HU-16 have a different note from an S2, a 985 on a BEAVER sounds different than one on a Beech 18, or a 985 from a slow turning WRIGHT R-975. There's a local guy with a TRAVELAIR and that old 975 sounds so relaxed and like it's not working hard, and it's different in tone than another local guy with a really nice PT-17 with a Continental radial.
When I lived just off KPAE I got to see and hear what FHC was presenting on a particular 'fly day' as they'd take the subject airplanes out early in the morning of to make sure everything worked as planned, and I loved the sounds coming from the 1820-ski mounted on the Il-6 RATA because it sounds to me like a big hardwood block rolling around in a slowly turning wooden drum, and the DB-601 on the 109 has a bell like background 'ring' to it. ALLISON. basso, MERLIN higher pitched and 'busy'.
THE most distinctive sounds I ever heard were from a B-36 passing overhead when I was a kid in the mid 50's, to this day it's as distinctive as the smell of brake fluid, and why I turn up the surround sound early on in STRATEGIC AIR COMMAND when it's on TCM to make the house just shake for a few seconds.
And if you could figure out a way to bottle the sounds of a DC-6 taxiing with all 4 2800's burbling at idle and sell it to kids with CAMAROS you could make a fortune!!
A 2800 sounds sweet, two 2800's is better, but ain't nothing that sounds bettter than 4 2800's pulling takeoff power!