93 octane fuel

[fishfarm]

Hay everyone. I have a question about fuel octane. I have a 1987 mariner 50hp 3 cyl. The motor is all original never been reuilt exept for the carbs a year ago and a new water pump kit. Compression in all 3 clys. are 111,109,114 the motor runs great. I've always ran 87 oct. fuel but want to try 93 oct. will I get any bennefit or harm the engine?

 

[j_martin]

Re: 93 octane fuel

Probably not. Might even get a slight decrease in performance.

Octane is a minimum requirement. The best octane is just above the minimum required. Any further increase in octane in the same setup decreases performance as flame speed decreases.

hope it helps
John

 

[This_lil_fishy]

Re: 93 octane fuel

I'd only move up on octane if you are having that good ol' pre-ignition rattle. Stepping up the octane helps eleviate that...or reducing the spark advance (worked wonders for me!).


Ian