in the first 600 miles of driving my sti i had alot of detination problems even when using 91 octane..so i invested in a large case of octane boost!!!!..and now just add a bottle to evey fill-up...took care of the problem right away ..
Is someone knows more about this than me, please feel free to correct me, but as I understand it, If your engine isn't pinging, and you're not planning on increasing the boost (or doing something else to make your engine run hotter) or changing your plug firing timings, higher octane shouldn't make any difference.....
if Subaru says the STi will run on 93 Octane it will. i think the owners manual says you can GET BY on 91. basically that means drive to a gas station that sells 93....and in the meantime drive like grandma. i can get 94 Octane right up the road from my house. about $2 a gallon. lucky me, no problems with pinging at all. AKI or "anti-knock index" is what we should all be looking at. a higher octane fuel usually has a better AKI. and higher octane also has a better abilty to resist pre-ignition, better know as detontion. alot of people mistakenly believe that running a higher octane will give more power. run 93 or higher in the STi and be happy. 100 octane might be overkill but it won't hurt anything except your wallet. and...if you can't get 93-94 octane but can get 100 octane and 91 octane, mix them 50/50 and you'll get about 94/95 octane and still have some money left in your pocket.
nothing is ever as simple as yes or no. but i suppose the answer would be "no". running higher ocatne fuel if you're car is'nt designed to run on it won't make any extra power. as a matter of fact it can actually hurt power.
Octane is a rating system to show a fuels resistance to Detonation.In other words, if you have a high compression, or a turbo, or supercharger and you burn low octane gas, your engine might want to act like a Diesel. Compression ignites the mixture prematurly instead of the spark plug causing the knock. I dont notice any difference. I mix 1/2 and 1/2 here in Phx for a octane of 95.5. We only have 91 available here so that is why I mix. I get a real slight ping if I burn just 91.
you guys might find this interesting, SOCAL dealers of cool blue, and a few specs.
I've been running this crap in my sti for a few weeks, it seems to have eliminated the STI stereotypical pinging I was experiencing on 91 octane. I mix in about 2.5 gallons per tank. The pump type places charge about $5/gal and the rest of the places sell it in 5 gal pails anywhere from $35 - $40 per pail. They justify this rip off by saying you pay for the packaging. w/e There's also an add for the performance benefits and one guide to storing this stuff.
If you guys are investing so much money for high octane gas to eliminate detonation, you'd mind as well just upgrade your fuel pump, and/or upgrade your injectors (although i think the stock 550's are more than enough), and get an AFC and tune the car to run richer.
And to the person that said he bought a whole box of octane booster, those things say it adds 3-4 points in the octane. That is very misleading, they make people think it would bring their 91 octane up to 94-95 if they dump a bottle in. But those 3-4 points will actually just make your 91 octane become 91.3-4 octane. Stop wasting your money on silly "octane boosters".
To respond to Bitabur...Engine management nowadays can HANDLE 91 octane, hell, it can handle 89. How does it do this? By retarding ignition. What does this do? "Retarding the spark causes a richer fuel/air mixture, which decreases fuel economy, increases emissions, causes the engine to run hotter, and reduces the longevity of both the engine itself and the catalytic converter. The money you save by pumping low-grade fuel into a car that demands higher octane is lost anyway, in decreased fuel economy and possibly gradual damage."
Quoted from the San Diego Union-Tribune.