I am doing a research paper on "octane ratings" On how people do not understand what they really mean. Most people think the higher they are the faster your vehicle will be. Anyways I need some information from a couple people on what they think. Also their opinion on leaded fuel and what they think of race gas. Even if you know nothing just tell me what you think octane ratings mean. I need to give some examples for my paper. So anything you say could be put in my paper... unless you swear... actually go ahead my teacher would probably like that.

 

Octane ratings are octane ratings. Put that in your paper. Teachers love it when people say stuff like that. Anyway all it means is a higher rating needs a higher temperature or pressure for combustion. Since PV= nRT a higher pressure means a higher temperature and vise versa. That is why high compression engines need a higher octane rating. If they ran too low of an octane rating in their fuel, they would have massive preignition of the gas. Also in high elevations where the pressure is lower, the temperature needed for combustion is lower and therefore octane ratings are lower.

 

Not to bad I need some people that don't know crap either. I might have to go to a kawi web site to get that.

 

Well i do have a B.S. in Mechanical Engineering and a B.S. in physics. That was it in some simple terms though.

 

I am working on mine right now. 2 more years. If I can get this stupid 7 page paper done by next week I'll be good for this semester. Total time invested today: 3 hours... 0 of 7 pages complete. bed time [sm=headbang.gif]

 

There's not much left to be said... higher octane is needed in higher compression engine (same as transam stated) All I'm adding is that people are on either end of the spectrum, saying it's all the same or there's a big difference. My example is my car, 04 Pontiac Vibe GT 6sp. When I bought it... the sales guys assured me that the car runs fine on low octane, because they had gas on site and did the free tank of gas for buying it thing. I questioned them and they said not to worry about it... I didn't give it much thought because what could one tank do, right? Wrong. I spent the first month in the shop letting them trouble shoot while I drove the hell out of loaners. They changed all the wires and plugs. A few days later (still on the free tank) I took it back. They changed wires/plugs again... and then the injectors. We're talking some time and money now. But this time... the manager of the garage came out to talk to me. When they tested it, the computer keeps a record of faults and I kept having miss-fires and pre-ignition causing the poor performance and engine light to come on. He starts asking me the standard question... what octane are you using and do I ever leave the engine running while I'm gassing up. NO... I replied. I'm still on the cheap tank of gas your salesmen insisted on giving me. New salesmen, probably got fired, with the high compression engines, they give you a gas voucher to a near-by station for the free fill up. He was a little mad at me for telling them this when I dropped the car off the first time... I stated, I just bought a new car from you! I did my job... you guys have to make good on your end, it's called a warranty. I never thought the gas would cause problems form one tank. The car was in the shop twice with less than 100 miles on it. He gave me a voucher and I gassed up with 93 and haven't had one bit a trouble since.

 

Yea what a pain in the butt. Sales people seem to know nothin about car/bikes or anything. Thanks for the info.

 

the lower the octane rating, the lower the flash point. vise versa for higher octanes. lower octane fuels will ignite before high octane fuel. that is why high compression engines require high octane fuel. the compression causes heat and can ignite the fuel before the piston reaches it's highest point causing major engine problems (read-blowup.)

leaded fuels are now not in use because of pollution concerns. the lead additive helped lubricate engine internals, kind of like premix in a 2-stroke. not all of the lead was burned in the combustion process and exited the tailpipe into the environment.

this is all information passed on the me by my dad(unofficial car nut) back in the day. none of it has been confirmed in facts, but it seems to make sense.

 

Don, theres not much more to say? Then right a dickens novel

Am i right thinking that more octane in fuel also helps `cool` the burn? So if you where runnin boost or high compresion engines you can have more pressurised ignition.

 

I was just saying "not much more to say" after our fuel engineer clemson725 started braking out the math formulas...