Octane

kinkyllama · Post by **kinkyllama** » Mon Dec 20, 2004 6:46 pm

I understand that higher octane level burns slower. I think someone on here said something about higher octane not really helping or even decrease power on certain applications. Explain what the benifits are of a higher octane fuel? Also for just regular driving can you get better gas milege on higher octane fuel?

KnightWalace · Post by **KnightWalace** » Tue Dec 21, 2004 6:39 am

i believe a lot of it has to do with detonation. The higher the octane the less detonation... to begin with.

woo · Post by **woo** » Tue Dec 21, 2004 7:29 am

i find easier cold weather starts with 98 octane over 91 octane.......

MMamdouh · Post by **MMamdouh** » Wed Dec 22, 2004 10:21 am

generally, fuel has higher tendency to ignite when compressed so the higher the compression ratio in you engine the more octane you should be using... in other words if you used less octane number that the one specified by the manufacturer you will have detonation.

I have practically tested that when I switched from octane 90 to octane 92... I had no extra performance, my fuel economy stayed the same... it is just a waste of money.

MMamdouh

woo · Post by **woo** » Wed Dec 22, 2004 10:54 am

7 octane points higher is noticable for performance, economy and generay well running

kinkyllama · Post by **kinkyllama** » Wed Dec 22, 2004 6:17 pm

I found racing fuel, 100 for $4.99 a gallon Would you even notice a difference in time in the 1/4 with this over the 87 octane on a stock car?

MMamdouh · Post by **MMamdouh** » Wed Dec 22, 2004 7:50 pm

woo wrote:7 octane points higher is noticable for performance, economy and generay well running

i am using now octane 90 and the max. octane in the country (Egypt) is 95 for almost double the price of the 90... so it is too expensive for me to run octane 95 in my woo.

anyway thanks for sharing your experiance bro... enjoy your woo.

MMamdouh

Post by **PrecisionBoost** » Fri Dec 24, 2004 12:21 am

Higher Octane rated fuels will have a better blend of "more expensive" petroleum components.

Generally they will have a higher content of molecule chains with lower carbon numbers and will which will help start the higher carbon number chain components burn.

So higher octane fuels will have a more complete burn where as low octane might not completely burn... which gives you less power and worse fuel economy.

The higher the compression the harder it is to get the "burn" started so higher octane will make the car perform better as well as give it better gas mileage.

I found with my Honda Prelude that it actually cost me less to run 91 octane than it did 87 Octane.... I would get atleast 2 MPG better mileage when using premium fuel.... and the car ran much smoother at high RPM.

The lower the carbon number the higher the octane rating and the more expensive it is to refine because they have to put it through a process to crack the larger chains into smaller chains.... which takes lots of energy.

Diesel fuel has very long carbon chains but it releases lots of power.... if you add propane injection on a Diesel you get major increases in power because the propane helps the Diesel burn better.

You could think of small carbon chain petroleum molecules as catalysts to get things rolling smoother.... and they decrease the chance of a catastrophic "boom" (detonation)