1Revvin7

I read in a article that on N/A rx7s that the best fuel to use in the lowest octane, at the pump 87. It states that lower octane will provide more power and better gas mileage . Does anyone else know about this issue? Here is the site below, its a FAQ and u need to scroll down to get to this article :sneaky: Felix's own general rotart car faq

JerryLH3

This is true. Normally aspirated rotaries will run best on a low octane fuel. Anything else is just a waste of your money.



With turbocharged cars, there is quite a difference though. To get the best use of the power your engine can make, you need high octane the high octane. The higher octane also serves to help avoid detonation.

1Revvin7

:shocked: I have been ******* wasting my money on 92 octane for the last year. thxs man. You know how companies sell octane boosters. They claim that it raises hp and puts gas mileage up. WTF So is it just n/a rotaries that like low octane or n/a engines period? Either way why do they sell octane boosters for hp if that bullshit?????

JerryLH3

Some cars need high octane to run well and boost power and economy. Not the N/A rotary. In fact, all cars will generally run best on the minimum rating specified by the manufacturer.

1Revvin7

Well why then do race cars run on super high octane like 102? Either way i gotta tell all my friends to stop using premium. But premium seems to make it run smoother and idle better. :sneaky: Oh well its all about speed in the end. so i guess i can do without those luxuries...

JerryLH3

Well, I guess I should be clearer. Cars can make more power and get slightly better economy with a higher octane, but often, the gains are not worth the substantial increase in cost. Yeah, it's only a dime more per gallon, but hey, that adds up!!



Race cars, obviously care nothing about cost. They want maximum power.

1Revvin7

But that statment doens't apply to N/A rotaries right?

NOTA V6

Actually, it is my understanding that octane is simply the resistance of the fuel to pre-detonation (detonation, pinging, knocking or whatever you want to call it). Cars with little risk of pinging simply do not require high octane gas.



I imagine if something is resistant to pre-detonation, it is resistant to combustion somewhat too. This would explain why you would get the most power and mileage from the lowest possible octane gas you can get while still meeting the manufacturers recommended minimum octane level.



<using search engine to back up my babbling>



Upon looking for something to prove or disprove my understanding, I used Alta Vista's search engine and came up with this page, which pretty much agrees with my understanding of how octane works.



Race gas therefore allows resistance to detonation and resulting engine failure (especially in rotaries who's apex seals become small unidentifiable chunks of metal after not much knocking at all) allowing the use of the higher boost or timing levels that would normally cause detonation. Higher octane = ability to push the engine harder without risking the detonation that would occur with a lower octane gas.



So, higher octane only makes sense if you are using forced air induction (i.e. turbo), or some other means to cause more combustion to occur, or if your car has something wrong that causes knocking with regular gasoline.



Rotor on!

1Revvin7

:shocked: very interesting, who knew there was so much too just Rx-7 food. But yes, a lot of people think that higher octane will make your car perform better, i.e. myself, until now. thxs guys.... :wink:

Yokoshima Hikouka

High octane pump gas have less BTU than better low octane gas. High octane gas from pump make more HP only because less knock means more gas may be used in very high compression and forced induction cars. WWII Russian army make more power with many bad soldiers vs. Japanese with fewer better soldiers. If knock not matter, then better to have efficient Japanese soldiers. Russian soldiers only cost more because they desensitized with alcohol. :tounge:



Race gas very different. Anti-knock rating may be similar, but it has many more BTU's because it is not heptane base like pump gas.