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***** WELCOME TO OCTANE RATING 101 *****


OK

i made this thread because ive talked to alot of people that realy don't understand what Octane rating is or what it means to there engine.

lets first start by saying (under normal conditions) a higher octain does "not" burn stronger or explode with more force, it will not make your car faster, and it doesn't burn any cleaner.

the reason for the avalabillity of a higher octane is for engines with a higher combustion ratio because of a high performance engine or forced induction like a turbo or super charger.

Octane rating is a measure of the resistance of gasoline and other fuels to detonation. thats it!
detonation is bad in a gasoline engine!
detonation is when a fuel and air mixture is able to explode without an ignition sorce because of heat and presure.
detonation is also refurred to as knock.
your engine has a knock sensor and when its reading above exceptable numbers the ECU will retard your timing to try and avoid the knock.

now when you are running a forced induction like a turbo or super charger your combustion presure and heat can be high enough to ecceed the 93 Octane rating of avalable "pump gas". this is were race gas like "turbo blue" comes into play with its Octane rating of 110.

OK
with all that being said, the reason some people have obsurved beter MPG on a higher octain is because all engines have very small variables.
one engine might be on the lower or higher end of the factories tolerence for the plane serface of the block or head. another example of this is when the manufacurer rates the HP output of the engine they test 10 engines and then devide by 10 and thats the number that gets published.
so 1 engine might be 108 hp another may be 100 hp, while another may be as high an 120 hp.
the egine producing the 120 hp could have a higher combustion ratio and would run better on a higher octane.

thanks for the lesson

I have not noticed a difference between regular and premium. I had to ride on premium for the last couple tanks due to the gas shortage in the area. The car, from what I felt, ran no different.

that sucks you had to run premium.

im not picking on you, im just using what you said to help make the point
you felt no difference because premium is not any stronger burning then any lower octain.

lets put this way, if you ran 80 octaine you would notice the car being very slugish and un responcive to ecceleration because you would have so much knock the engine would not be running right at all.
the performance is the in the ability of the engine, the octain you run will eather hinder it or alow it operate properly.

you can also look at it this way.
ive got a friend with a 94 Supra with the twin turbo 2JZ set up.
everything is set up and tuned so the engine can run real well and smooth with the turbos pushed to 22 psi.
he must run a 110 octaine gas for every thing to work right.
about a month ago he had it on a dyno for about 4 hours getting every thing tweeked just right.
on 93 octain he was getting so much knock that the car was back firing and just wasnt producing the HP it should have.
the low octaine of his fuel was holding the engine back.
cleaned out his tank and put some 110 octain back in and the car (after a few tweeks again) pushed 433 HP and 450 FTP.
the car was only able to push thease HP nubers because the engine was doing the work and the fuel was alowing it to.

i hope this is making sence to people, and im not just talking you in circles.

i get such a laugh out of reading comments on videos on youtube.

just incase anyone missed it:

HIGHER OCTANE WILL NOT MAKE YOUR CAR FASTER!
there was a time when i myself thaught it did, but i was like 15 years old,
once i started learing about cars i learned the truth.

nice Thanks for the info I am sure some people out there need this.