It was just a question that just popped into my head.

 

whatever can melt your flame suit

 

Your question implies that octane is a measure of the power within the fuel... As in, the higher octane you get the more power or volatility. That is incorrect.

Octane is a measure of the knock resistance of a fuel. Knock is when a fuel pre-detonates or autoignites. For instance, if you compress some fuels they will ignite without a spark. High compression engines (ie like a turbo!) will cause low octane rated fuels to detonate before the spark is lit. This is catastrophic for engines.

The higher the octane the less prone to auto-ignition. People like to use the higher octane fuels because they can turn the boost even higher without damaging the engine. So you see, it's the boost that make the higher power, not the fuel. For most engines, you can put 120 octane in any gas engine and it will run with the same power as normal grade.

 

^ very true. I'd like to add that the speed in which the flame travels across the piston is slower with higher octane, so increased ignition timing can and will be used.

 

so if you run say 120.. it's no different than 93 as far as power made I mean?

 

If your car is tuned for 93 octane you will not make anymore power by running 120 octane. So 100, 105, 110, C16, Q16 would be no different than 93 octane if you're on a 93 octane tune and you dont touch the boost. The only thing running high octane levels (without a tune / turning up the boost) will have an affect on is your pocket book.

The only way to get a gain out of higher octane fuels is to turn up the boost and be tuned for that level of octane. Thats why a lot of people have separate pump and race gas maps.

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

 

do u know what octane levels mean????

a higher octane can hurt the performance if it is not required

 

ok, i'm just trying to understand all of this... I never really read about it.

 

It's my understanding that higher octane fuels actually combust with less energy per unit volume than do your garden variety fuels. Where high octane fuels shine is when you change the parameters (boost, ignition advance) to take advantage of the properties of the fuel.

Use what you're tuned for - going higher gets you nothing except lighter in the wallet.

 

Have you ever took a match to gasoline? What about diesel?

If you have a few drops of each, you could safely take a match to both... The gas will burn very quickly, right? And the diesel will start slower.

But what if you were asked to light a 100 gallon pond of fuel? Which fuel would you prefer? The one that lights very easy? Or the one that take a little more time to get going? Most (sane) people would choose the diesel so they can run away before it really gets going.

When you have high compression, you need lots of fuel. You need a fuel that will burn slightly slower (diesel is an extreme example) than regular 87 octane.

 

if your running high octane gas or race gas make sure not to leave it in your tank at all make sure to burn it up and most high octane fuels and leaded fuels destroy your o2 sensors

 

evo needs minimum 91 octane so anything over 91 octane its all good as long as its not leaded..unless you have no cat

 

Say you have two cars: 1. Evo 8 with boltons on 93 pushing 25 psi ( 350whp)
2. Same Evo 8 with boltons on VP pushing 30 psi(400whp)
The reason why the car made power the second time was because of the increase in psi due to the VP gas. Like said before the higher the octane, the less knock. That is why you can turn up the boost safely on higher octane and therefore gain more horsepower.

This should give you a slight idea. Anyone can chime in if I am wrong.

 

everything being equal - a higher octane will make you run richer, and make _less_ power.



edit: caveat - unless you're knocking and pulling timing

 

^Dude is your sig from that douchebag call youtube vid? Hilarious!