Octain boost.

[uboatcdr]

Does anyone add octain boost to their gas, You can run it in a car just fine. I have a new yamaha f250 f/s is there any reason why you can't run it in an outboard. The owners manual does not address this, only that they recommend 89 octain.

Thanks
Pete

[Perfectcast]

I just run plus in mine and it works good. If i run 87 it hesitates and sputters alot.

[ET]

So is the problem that you can't find 89 or 91 octane to put in it? So do you need to add octane boost to 87 octane fuel already in the tank?

Or do you just mistakenly think adding octane boost to perfectly fine gasoline is a good thing?

If the owners manual recommends 89 octane, give her 89 or 91. No need for octane boost past that! As hard as it is to believe, those engineers probably spent many hours coming up with that recommendation.

Great motor by the way! Congrats to you.

[12pulls]

With the ethenol in the fuel it can cause the motor to run too hot. Ethenol already runs hotter than fuel without. I was warned by the mechanics not even to run premium in my motors with ethenol. Anyway, I suggest that you run what the book suggests.

[Lead Bouncer]

Octane boost is to prevent pre-detination. It doesnt make the gas more powerful.

[veilside180sx]

Octane boost will not help at all, unless you are running more timing. I'm under the assumption you will not be advancing the timing, so there would be no point besides dumping money down the drain.