if the engine is engineered for 93 of course its gonna run better on 93. without 93 its probably knocking slightly even if its not heard by the ear. but id bet any money that without knowing which gas is in your bikes tank youd never be able to pick out the difference unless you've messed with ignition timing or like i said before extensive modifications. placebo effect lol. all octane is is resistance to knocking. the rest is in your head. here are some references.

http://www.ftc.gov/bcp/edu/pubs/cons...tos/aut12.shtm

http://en.wikipedia.org/wiki/Octane_rating

http://www.wisegeek.com/what-is-high-octane-fuel.htm

 

we need mythbusters to bust this myth once and for all hehe

 

What type of vette do you have btw?


As for this octane issue, check this out:

http://en.wikipedia.org/wiki/Octane_rating

 

"I have seen this claim made before. So...I'll ask for an engineering/technical reference on it. My copy of Taylor's treatise on the thermodynamics of internal combustion engines doesn't suggest this is true.

Higher octane fuels contain essentially the same heat energy as lower octane fuels. The difference is higher octane fuel requires more energy to ignite and burn, thus avoiding detonation. So if it makes chemical and physical sense why this results in less power, I'd like to see the data on it. Always ready to learn something.

But I do agree the F4i runs fine on the 87 octane it's spec'd for. Burning 93 just wastes money. "



I am not arguing a difference in energy burn I am stating there is a difference in the length of burn. Higher octane gas burn slower then lower octance gas. What this does is effectively retard your timing to an extent by delaying the point of peak pressure.

Now I have not done any of the math to see what increase in octane results in what timing retardation nor could I. If anyone wants to take a shot feel free.

What I can tell you from my racing experience is that if you take a car tuned properly for say 89 octane (no knock) and do some runs down the 1/4 mile and then put in 104 octane race fuel and run the car again it will go slower. I have seen this and done this myself over and over.

You need to advance the timing to compensate for the later point of peak pressure of the higher octane fuel to even just get back to the same performance you had at 89 octane.

What the higher octane gas does allow you to do if you have a standalone computer is to advance your timming much more from there and or turn the boost way up or run nitrus without knocking. That's where the gains are made.

But for the street with a stock computer if you aren't knocking at 87 then 93 is either doing nothing or hurting your performance a bit.

 

Alright, here's a question. I've been running 89 octane for a couple months, and the bike runs fine. I'm in my reserve today, and so I stop at BP (adds that invigorate crap, not sure if it makes a difference though), and put in 87, due to all this talk, and so I'm almost home, and my bike seems to be sputtering. It still rides fine, and if I get on it it still moves, but do you guys think it's bad gas? If not what can I do?

 

"I have seen this claim made before. So...I'll ask for an engineering/technical reference on it. My copy of Taylor's treatise on the thermodynamics of internal combustion engines doesn't suggest this is true.

Higher octane fuels contain essentially the same heat energy as lower octane fuels. The difference is higher octane fuel requires more energy to ignite and burn, thus avoiding detonation. So if it makes chemical and physical sense why this results in less power, I'd like to see the data on it. Always ready to learn something.

But I do agree the F4i runs fine on the 87 octane it's spec'd for. Burning 93 just wastes money."

I'm no scientist, but youd think "watering" the fuel down with ethanol or other anti knock chemicals means that less fuel is present in any given amount. Same idea as if you add ice to soda it gets watered down after melting (Less soda more water). In one injector cycle there would be less gasoline, as some of it would be replaced by ethanol. Just a thought.

 

ok guys im going to solve this once and for all......... im personally a 93 octane guy (used to run it in my 300zx and now run it in mustang gt and bike aswell...) i currently have 93 octane gas in my tank atm no problems at all. im on reserve right now and going to get gas in the morning before work. i will put 89 octane in it and run the tank out. then i will stop and get 87 octane and run it out and will keep you guys informed on any changes that i can tell between the octanes... unless its a bad idea to drop octanes like that for some odd reason.

 

You can just go straight to 87. Won't hurt anything at all.
A better test would be to buy 2 identical gas cans. Fill one with 87 and one with 93.
Mix them all around in your garage till you forget which it which. LOL..

Burn one before the other and then tell me if you can tell the difference over the next couple weeks.

 

couple weeks LOL ill burn 2 tanks this week

 

ok guys for all who care to hear the results of the test.... here they are.



first i want all you to know i drove through 2 tanks of gas for the test same route (work) to test the differences. 87 octane ran just as smooth as the 93 octane however towards the end of the tank it seemed a little more noisy than usual... 93 octane did indeed run my engine temp about 4 degrees hotter than the 87. after this test im still going to run my 93 octane in my bike just because it makes me happy. o and i didn't notice any power difference between the 2. (tested at take offs from various speeds at various rpms.)