So just ran to my local gas station and they have installed a pump the pushes only pure 87 no ethonal added. My buddy that owns it said his sales men told him that pure 87 performs better then 93 with ethonal added. So i put this question to my rotary pros, is this true??

 

I would rather run high octane with ethanol and some StarBrite mixed in, then use the low octane with nothing. But that is just me.

 

I dont think i would try pure 87 with out hard proof and i think pure gas is what was abundant in 03 when the RX8 was first sold so......

 

someone might find this useful

h**p://pure-gas.org/index.jsp

replace ** with tt

 

I'm not going to try it...

 

Well, first you have to start typing "ethanol" correctly.

Then you have to define "performs better". Performs better how? Energy per gallon? Knock resistance? Use as a perfume? Arson?

 

First one comparison:
87 octane of "pure" gasoline vs 87 octane of E10 (90% gasoline, 10% ethanol)
The pure will have better mileage, as it has a higher content of energy per unit of volume.
The pure will be slightly more expensive per unit of volume
The pure will be slightly cheaper per mile driven
Both have the exact same resistance to knock.

Next:
93 octane of "pure" gasoline vs 93 octane of E10
The pure will have better mileage, as it has a higher content of energy per unit of volume.
The pure will be slightly more expensive per unit of volume
The pure will be slightly cheaper per mile driven
Both have the exact same resistance to knock.


With this information, you can add 1 more piece of information:
A good compression Renesis will be damaged by 87 octane, as it is insufficient to prevent knock at high load and high RPM. Only with a nearly dead engine from loss of compression on all 6 faces will 87 be "safe".

With this information, what do you think the value of "pure" 87 has to your RX-8?

 

^
Now thats what I was looking for you rock as always

 

What you want is 93 without ethanol

When you get 87 octane with 10% ethanol, most of the time you will be getting subgrade (84 or 85 octane) clear gas with 10% ethanol bringing the octane up to 87. Depending where you live in the country and what the tank farms have, there is a chance you could get 87 with 10% ethanol, which will get you 89 octane, but you would need to know someone at the plant to know what and how it is being loaded. I used to live in a state where we loaded the exact same thing for Regular and Midgrade, because they didn't have subgrade. It's always ok to give away the octane, just not the other way around.

When you get Premium, they will blend a little bit of either subgrade or 87 (if they have it) to bring the octane down to what Premium is in your area. It has been too long since I have seen the recipe so I can't remember the percent. It's all blended by computer now, we used to have to load each grade separately "splash loading"

Now depending where you live in the country there are three different octanes of premium. There is 91, 92, or 93. I don't know why they have different octanes, but CA is 91 and WA is 92. A few years back I went to WY and SD and Regular was 85 Midgrade was 87 and I can't remember what Premium was.

 

bottom line is if you have a higher compression engine, you need high octane. doesnt matter if its 10% ethanol or pure gasoline. if you run lower octane you gonna have knock which is very bad for the engine.
many people think higher number meaning its purer gasoline which is totally wrong. all grades are the same purity cept higher number meaning its more resistant to knocking.

 

spot on!

i had been running 87 in my blue car, as the front rotor is damaged/weak but i put 91 in it, and mileage went up by 2mpg, which is big.