Evinrude Etec 90 : Octane level

[Rosco]

The manual states minimum 87 Ron but I've not found any mention of the maximum grade safe for the engine.

Can anyone in the UK help please?
Also has anyone got experience of the impact running premium petrol
on sports boat speed pls?

Cheers

[Last Tango]

I'd guess the same as with a car.....I believe one of the tests found that the very best they could get was a 7% reduction in performance with "premium" petrol.

[Rosco]

It's a bit perverse as why the engine is economical, I'm interested in improved output...fun factor!

[Xk59D]

head on over to the etec owners forum, lots of info there- High Octane vs Regular - Owners Message Board

to save you the hassle if you wish i can sum up- most say makes no difference, some say makes less power and some say makes it smoother.

you would have more joy changing the prop for whatever you deem as fun. i.e hole shot or top end, both require different props.

[Rosco]

Thank you kindly
Yes the prop is next the list once I've launched & tested the boat

[jyasaki]

Octane is a burn retardant; higher octane fuel is needed in engines running higher compression to prevent pinging (premature, pressure-induced ignition.)

If your motor doesn't have problems with pre-ignition, there isn't any reason to go to higher octane rating.

jky

[Last Tango]

Rosco doesn't say where he's based.
Standard unleaded in the UK is RON 95
I believe it varies in different areas of the USA but as Jyasaki says unless you've got a compression problem eg. high altitude, then it's not going to make any perceivable difference.

[Rosco]

Thks LT (uk)