You're not going to cause any damage running higher octane, however, you will be very unlikely to see any benefit from it unless you've taken advantage of the additional timing you'd be able to run via ECU tuning. In reality, you want to run the lowest octane you can without knock. Higher octane without advanced timing can actually cost power. Altitude will have an effect on this as well, which is why it's harder to find higher than 91 at higher altitudes (less compressed air = less heat at load).

With that said, I run E85, but not for the octane. I like it because it runs cooler on my track car. I have added a little more timing, but not much.

 

My response was to the post directly above mine...


FWIW, I've seen many cars that have recommended or required premium fuel that actually do not knock running lower octane. Meaning, they don't always "make use of it", especially in an NA application. Results are from logging and tuning cars through the years.

 

It'll be fine. I ran another Honda rate for 91 with 11.1 compression for 60K on the cheapest 87oc gas I could find. Not a single mech/oil problem.

 

Without looking I seem to remember a warning in my 06 OM about using fuel with a very high octane number. Always best to use the recommended octane.
If not available, a slightly lower rather than a slightly higher may actually be preferred. Do not take this as gospel though, I only say this because at strange locations in the USA even the factory recommendation octane may not be available in certain locations in which case, use the highest octane available.

 

There was a guy in the s2000.com forum who was running his S on 89 octane with no problems.

 

Best case scenario by running 87 regular gasoline in an S2000 with a factory tuned F20C/F22C, you will lose a very small amount of power and fuel economy. Worst case, it could lead to expensive engine related repairs after extended use.
Seems like a lose lose to me.

 

Unless it's knocking and pulling timing, you'd likely gain power (small) with the lower octane.

 

Unless it's knocking and pulling timing, you'd likely gain power (small) with the lower octane.
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Interesting thanks for posting this in case I was misleading in any way, I'd like to see dyno results by running 92 in a stock S2000, and then immediately following it up with 87 on the same car after ridding out the gas and hitting the very same dyno with a tank of regular. I imagine it has been done with other cars, but I'd like to see one specifically for a completely unmodified S2000 that has not had anything in the past, but premium gasoline.

Found one comparison with an MKVI GTI, and the GTI had more power with premium gasoline than the regular (albeit slightly).

http://forums.vwvort...-91-octane-dyno
Results as follows: Peak Power (hp) Peak Torque (lb-ft)

91 octane 207 219

87 octane 203 216

Also, a relevant article from road and track.

http://www.roadandtr...um-fuel-futures

Anyway, until I see some definitive evidence, I still maintain that because the S2000 is tuned for premium gasoline, in general it is best to run premium (91-93) gasoline in a stock S2000, and it also makes better use of the power from premium gasoline than regular because it will eventually more than likely end up pinging with the regular 87.

And back to the OP:
I myself fill up with 92 octane as that is what is available here, and that is about 96 RON, so in theory I don't think there should be much of a difference between the gasoline I use and the 95 RON. Though I haven't done enough research to confirm this 100%, so please don't hold me to it

 

Ok thanks all