no because it becomes more voletile. the higher the octane, the less volotile.
i recently put 89in my car and my gas milage has improved drematically.

 

what about those piston motor heads that produce more octane resistance

a lot of times you get more resistance to detonation by increasing swirl or some sort of turbulance

when that happens generally the fuel burns quicker


some fuels if I remember right have a high octane rating
but if you get them to burn.... they burn like the dickens
but that is more or less if I remember right


but the faster you get the fuel to burn many times shoud lead to better detonation resistance

 

and about the orig topic I use 87 and if I can find it 85

use premium fuel twice

both times gas mileage went down to 180miles per tank
and it felt like I was towing something as far as power goes


never use again

 

What do you NA guys with S-AFCs run? Mine little blue box is on the way, and tuning will happen within a week of it being installed, so what do you guys use? So far I've been an 87 believer especially since it's 2.14 a gallon. But I'll run 92 if I can get .3 more hp out of the S-AFC

 

I use 90 octane on my NA, it's only $.02 more/gallon, so I do't mind the small cost difference from that particular station. all other stations though, it's regular 87.

HOwever, on occasion I may by the NOn-oxygenated premium from a station aroudn here.

 

the lower grade the better? I dont think so.

 

I have been in Rx7s for along time buying my first in the fall of 1978. I have tried at different times to play with the octane mix in my cars, and have found that non turbos love the low octane better. It has something to do with the properties of what octane brings to an engine. The lower the octane number the quicker the gas will cause detonation and rotaries love to detonate.

There is a good definition on
http://www.misterfixit.com/deton.htm