So, a gas station down the street from my house recently started carrying ethanol-free gas.

The problem: they only carry it in one grade, mid-grade (89octane). My question is would this be appropriate for the s2k? I understand it should only be fed 91 octane & up (premium), but would the lack of ethanol make up for it?

Btw- the ethanol midi-grade is 4.25 per gallon

 

A stock s2k can and will run fine on as low as 87 octane, but I wouldn't go out of my way to use 89 octane ethanol-free over 91+ octane with some ethanol in it. Just use premium like Honda recommends.

 

Regardless of what contribution etoh is making to the octane, 89 octane is 89 octane (not 91). Of course, this begs the question of how "harmful" it is to run 89 octane in the S.

Frankly, I don't know. Many cars have knock sensors which will automatically retard the timing for less than appropriate octane. I don't know if this is true of the S. But if that is the case, then the only thing you would be giving up is some performance by running sub-optimal conditions.

Personally, I would give priority to the octane rating instead of etoh. Having said that, I use 92 alcohol-free.

 

S2000 has a knock sensor and runs fine on 89 oc. On 87 I noticed it ran rough. I personally would have no problems running 89, but I wouldn't track on it.

You'd buy ethanol free gas to get better mpg, but I'm not sure 89 ethanol free will show you that. Car is going to adjust timing/a/f etc to protect the motor. Producing less power and likely burn more gas.

 

Thanks for the info guys.