91 Octane or 93 Octane w/ Ethanol?
 

I have a Keith Eickert carbed 540 Blown....800 Horse.

Which gas type do you think is better?

I have always used the 93 with Ethanol but a new gas station opened up by me with straight 91.

What octane rating does your motor need? The biggest difference I hear with ethanol is that the fuel looses its octane rating faster. (Although a recent Boat US article says ethanol makes no difference in how fast the octane rating slips.) So if your motor needs 93 octane, putting anything less in the tank is foolish. If however you have some old 93 octane (with ethanol) fuel laying around, you're probably not much better off.

The other big problem with fuel containing ethanol is phase separation. This too occurs over time and can be quite detrimental to your fuel system. So, if your motor only requires 91 octane and you can find it without ethanol, go for it! I sure wish I could find some of that stuff ...

Thanks....I'm not sure what my engines need....91 or higher I think. I have over 250 hours on them, they run fine, required maintenance always is done. I have never had gas in the boat longer than a couple of weeks old..nor do I intend to.

Saying that is their a benefit or detractor with straight 91 vs the ethanol 93?

Not really - unless your boat is set up to run optimally on 93 octane. If anything, the ethanol takes a bit of power away. Just ask anyone who's run E85.

Personally, I'd love to find high octane fuel without that damn stuff in it because of all of the problems it causes.

91 is fine....

Go to Stabil's web and see what they have to say about Ethanal....Consider Stabil Marine and Quickleen Combo....Recommended by some of the OEM's...Then, don't be surprised with another generation of fuel....Don't know what that is, just that there will probably be one.

Thanks again...I'm going to try the 91 this week and see if I notice a difference in power.