Re: What does your gas smell like?
One of the guys on the 'Port posted THIS:
I burn Shell V-90 in "da liddle birdie" because it is no-lead and (in Ontario, at least for the moment) un-polluted with corn juice. I can't recall anything smelling unusual, for either the "da liddle birdie" or "da heap" (2000 Neon with approaching 300,000 km on the cheapest gut-rot gas available), but I don't normally go around smelling gas pump nozzles. Sounds kinda weird, doncha know?
The Franklin engine is only 7:1 compression ratio (in 1947, the standard gas was 72 octane, and no lead), so 100LL is merely an expensive and annoyingly effective source of lead-fouled spark plugs. I have noticed that the plugs stay much cleaner since I abandoned avgas (and six cylinders times two plugs each times $60 - $70 a plug (14mm plugs are decidedly non-standard in the aviation world), PLUS shipping/taxes/excise adds up real fast.....).
Is the improved plug performance caused by the absence of tetra-ethyl lead? Or is there something to the nitrogen content claim Shell makes? I'm not a chemist, so I can't say, and I can't/don't want to experiment, because I have precisely zero other no-ethanol choices, but I would note that nitrogen isn't quite as inert as has previously been suggested. Chemical munitions are largely based on nitrogen compounds for a reason.
Oh, one other thing... the "model airplane glue" smell previously mentioned is probably the toluene that is added to avgas, but not mogas. Mogas IS different than avgas because of the differences in additives used for each (octane is octane). Toluene is an excellent solvent for polystyrene; what it does for avgas, I can only guess at. It probably helps keeps the volatility up, correcting for temperature changes (decreases) at altitude.