Which of these two fuels burns hotter and cleaner?

Which burns hotter and cleaner...87 octane w/ 10% Ethanol,...
or 90 octane that is Ethanol Free?
Ussually higher octane burns slower, and not as hot as a lower
octane,...but I see on the internet that in this case, the Ethanol
Free would burn cleaner and somewhat hotter and with better
gas mileage.(my home town has Ethanol Free for $3.40 a gallon
and I want to switch to it in my 2002 MERCURY 40hp. that im
sure wasn't designed for Ethanol back then.

Run it!

You're motor was absolutely designed to run 10% ethanol. Ethanol has been around since the 80s. Find the owners manual and find the octane recommendation and run that.

After contacting MERCURY MARINE, they said that. 2002 MERCURY 40 hp.
Fuel Lines and Carburarted System was never designed to run with any ethanol
blend.( then I forgot to ask about using 90 octane ETHANOL FREE.)

I always run non ethanol 91 octane, why risk water in your fuel with ethanol ? Ethanol only does harm so why risk it !

Perfect! Thank You!

yzf125 said:

I always run non ethanol 91 octane, why risk water in your fuel with ethanol ? Ethanol only does harm so why risk it !

Click to expand...

I strongly agree.
NON ethanol of any octane is better than an ethanol fuel.... the NON ethanol gas has more energy per gallon than the ethanol fuel does, and it will burn a bit hotter because of it, but it is negated by the cleaner more powerful combustion, and so a bit less throttle is needed to get the same results as you would with the diluted fuel..
alcohol burns at a lower temperture than gas does, and it is a lot more hygroscopic than gas, so if there is even a bit of water absorbed into it, it will be slower to ignite and burn much cooler... no matter what they try to tell us about ethanol fuels, ethanol is a very un-necessary filler filler in the gas without any redeeming or positive effects, and it actually does harm in some applications.