Re: 1937 120 Conv. Sedan - Blanche

Posted by Bob J On 2024/5/15 14:52:09

My 2 cents worth (CDN$ of course!)
Higher octane means harder ignition. It is made for high compression engines that would pre-ignite (ping) otherwise. (The fuel explodes on the compression stroke alone but before the spark plug goes off, also called dieseling. Makes the block 'ring'. Can also be caused by carbon build-up that acts as a glow plug in the combustion chamber, that is why when it was hard to get good gas in the 80's a lot of people with high compression engines had water injection apparatus added.)
These are not high compression so you are actually causing less power due to the make-up of the fuel being wrong for your engine and not fully delivering on the power stroke.
That said, in this part of the world the percentage of ethanol drops the higher the octane rating, but you are already going out and getting ethanol free gas so that is a non-issue.
For what it is worth,
Bob J.