Difference b/w Gas Octane

[SenseiAccord]

So what is the difference b/w the regular 87, plus 89 and premium 92/93 octane gases other than octane level and price?

What i think is that premium is a waste of money unless u really need it for high compression or for racing purposes. I say racing b/c during racing the car runs really hot due to high reving and using a higher octane will just let ur car run w/ less chance of knocking. basically what im saying is it will allow u to race safer. I dont think it will give u better gas mileage or even clean ur engine or make it run cleaner. what i think is if u are running less than 10:1 comp then 87 is just fine for you and using anything higher is just wasting ur money. Then again racing gas, 100 octane and up, has lead in it which is good for ur engine but bad for the cat and the environment. i hear even 100 unleaded has some lead in it but not much which in return is still good. ppl claim they get more hp by using high octane but i dont think that is true... 1-2 hp is pretty much impossible to be noticable by human senses and just a psychological thing.

Post ur guys opinions and theories... proof will actually be best here.

[Ricochet]

You pretty much nailed it..

[CivicSpoon]

I personally use the Premium gas whenever I have the $ on me to do it, and I'm just running my stock CX engine. But I definently can tell the difference in when I run a higher grade gas than the 87. My car runs a lot smoother, so much that I stall my car all the time cause I can't feel the engine shake before it stalls like I can with the cheap stuff. Of course I'm not running a high hp setup so I definently don't notice any added hp from it or even better gas mileage. My buddy who's a mechanic tells me that it just burns better than lower grade gas.

[crxlvr]

there is actually an improvement in HP using a higher octane, when the vehicle requires it. Sport Compact Car did a test last year using a modded 350z and then first using 91octane, then switching to race fuel, like 133octane, netted them almost 10-15 more hp. but like you said, it is not needed if the car cant benefit from it.

[YellowITR479]

Yea...ummm.... you did pretty much nail it

[Privatebigandrew]

Higher octane doesn't "give" you HP, it frees up HP. Higher octane is actually bad for your car unless it calls for it like you said. A higher octane fuel burns colder than a lower octane fuel and takes a lot more heat to ignite it. That is why higher compression engines need it, so they don't preignite. Since the higher octane fuel burns colder, putting it in an engine that calls for lower octane (burns hotter) will cause excess carbon deposits. Now, an old engine has carbon deposits on the cylinders and what not, so its gonna have slightly higher compression than when it was brand new, but not enough to put in a higher grade fuel.

[TheAznPersuazun]

higher octane isn't BAD for your car persay...it all depends on the quality of ur plugs, wires, & valves cuz if there's too much octane your the plug will spark b4 they are up all the way so you'll start to hear a "pinging" sound....but don't get higher than 93 octane on a DD. I personally get super all the time just cuz it's cleaner and will help keep your internals running longer. and NO higher octane doesn't add HP

[Privatebigandrew]

don't reply if you don't know what you are talking about. If there where a high amount of octane it would not spark before TDC....the spark is going to occur at the same time regardless of the octane. You are thinking of preignition. It would have a tendency to preignite later not sooner. Higher octane takes more heat before it self ignites, so therfore, the cylinder pressure would have to be greater for more heat. (pressure=heat) cylinder pressure is at its most when the piston is at TDC, unless you have massive overlap. It is not cleaner in the long run. Read my first post. Carbon deposits are not good for your engine my friend.

[Privatebigandrew]

let me clear up the whole idea of high octane gas not being cleaner as i can see it is unclear. Look at it this way. Yes higher octane gas burns cleaner. But, higher octane gas burns colder also. If high octane gas were put in an engine with low compression, there would not be enough heat to burn all of the carbon away, and over time this carbon will build up. In a high compression engine, the cylinders get hot enough to overcome the cooler burning high octane gas. And to think, i paid for this education, and here i am giving it away for free. where's my donations...J/K

[DeleriousZ]

yeah my bud that's got a 98 lude says it's very noticeable when he puts in the 91 octane compared to the 89... then again his car calls for premium anyway, he says he notices highly improved has mileage as well... did something like 350 k on half a tank o gas on the highway..