How nice would high octane gas be?
From what i've found out 10% is fine and don't know anybody who use it that have had problems.
what problems does it cause in carbureted engines?
All OE carbs were calibrated for gasoline, not "Gasohol"(the ugly product of the '70's oil embargo), now it's forced on us due to "air concerns", which means nearly
every engine is running lean on stock jetting. Alcohol(& ethanol is less than methanol) has roughly half the available BTU/lb. of gasoline, enviro-wackos will lie
about this fact using a half-truth, namely if an engine is
DESIGNED & ENGINEERED to run strictly on whatever ethanol blend/E85/pure alky,..they can approach
70-75% taking advantage of the inlet cooling & octane rating alcohol provides........however cold starts are another matter. Any car made to be a "flex fuel" is
going to fail miserably(and has) in the efficiency department. The sad but laughable part is the drop in efficiency means the gasoline burnt was less effectively
utilized, more or less wasted. All of the oxidation, water absorption problems, and corrosive issues are plenty of reason to dislike it alone.