In article . com,
"Kingfish" wrote:

Bela P. Havasreti wrote:
Go to the Reno Air Races, and at least in the Gold heats, you'll hear
Mustangs/Merlins pulling up to 140+ inches of manifold pressure (more
than double the original war emergency maximum power rating and
approaching triple the maximum manifold pressure allowable with 100LL
fuel).


I'm guessing with that kind of boost, they're running something a
little hotter than avgas : ) Otherwise, the CC would be picking up
pieces of Merlin after each run? I read Rare Bear uses specially mixed
160 octane fuel.

Most likely, as pure naptha has an octane equivalence of about 160.