Re: Propane outboard?

[Anonymous]

quote boxcar:

Octane ratings for propane run the gambit from claimed 75 up to 115 octane.
I tend to believe the lower numbers. Call me a pessimist….
……
Rather that you got your Octane information from someone who was trying to sell kits.

I thought higher Octane rated fuel prevented knock (premature detonation) in high compression engines as opposed to containing more energy.

https://en.wikipedia.org/wiki/Octane_rating says:

quote :

Octane ratings are not indicators of the energy content of fuels. (See Effects below and Heat of combustion). They are only a measure of the fuel’s tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where the octane number is raised by blending in ethanol, energy content per volume is reduced.

That page also quotes the 1999 Johnson Operation and Maintenance Manual for Octane for "requirement for a typical two-stroke outboard motor" as US 67 Octane.