High octane thread!
 

Hi there guys, i sneak around this great forum a couple of months now and i though it was time to become a part of it. The rx-8 is a very unique car, and i would like to thank mazda for the respect they show towards new technologies (renesis, suicide doors, etc).

My querry has to do with the gas u guys use with your 8. i have seen some posts that refer to 89 to 93 octane gas. i live in europe, greece, and the gas we use here has at least 96 octanes.
i use the one with 98, and we also got 99 oct gas (a bit expensive). does the octane number of a gas affect the performance of a car in a great way? i know it makes a little difference, but i would appreciate a more experiensed approach.

thanks.

Some engines are more sensitive to higher octane than others. The past non-turbo rotaries have always loved low octane fuel. Many people here claim that because the Renesis has 10:1 compression that it requires higher octane. However the last n/a rotaries were 9.7:1 compression so there isn't so big a margin that low octane should work on one but not the other. Different people here are getting good results with different grades of fuel. Some swear by higher octane and some don't. I personally have always run 87 octane in my rotaries and will continue to do so in the RX-8. Every time I use higher octane gas, the only effect I get is that my wallet gets lighter but that is just me. Others like the higher grade stuff.

Check to see how octane is rated in your country. Here in the US it is measured by R+M/2. Some other countries have higher listed octane numbers but they actually correspond with ours due to the differences in the way each place rates them. See if this applies to you. Higher octane will not hurt the engine so don't be too concerned with it. Any grade of fuel available in the US will work fine and that is probably the case there too.

Welcome to the forum...and from Greece, now I'm jealous.:)

u should be red! ;)
we got summer all year long! great islands, great women ,huge prices for cars! well the last one is on the hefty side, snif:(

Not too sure about the argument vis compression ratios and octane rating. Avgas (aviation gasoline) is usually 100 octane and aircraft engines have more in common with tractor engines than sportscar engines - usually low reving but reasonable torque and pretty understressed for reliability. Anyway - they are generally fairly low compression. Also, I believe the Mid West aero rotary and those based on Mazda designs for aircraft application often use Mogas (normal car fuel) rather than Avgas.

Remember that octane is measured differently in Europe and America.

In Europe, the Research Octane Number (RON) is used.
In America, the R+M/2 Method is used, which results in lower octane ratings (usually around 5 points lower at the same grade, if memory serves). Therefore 99 octane in Europe is probably pretty close to 93 octane here in the US.