http://theserviceadvisor.com/octane.htm

 

Well I would, but I've done my research, I know how they work. I'm only doing it because I had 30 gallons of free 93 octane through Giant Eagle Fuelperks program... So I guess my theory is correct already! j/k

 

Ive heard 93 octane will make less power if the tune is for 87, dunno how true that is though. But there is no way in hell you will gain the mpg needed to make up the cost of running the higher octane fuel without doing some type of tune. Hell even with a tune you probably wont make up the difference.

EDIT: The only plus side to running the high test fuel other then power obviously, is that a lot of companys will have better fuel system/engine cleaners in their high test fuel.

 

The brand new "5.0" makes more horsepower on higher octane fuel, factory specs, but it is calibrated to recognize the higher octane. Our cars do not have that ability stock, tha's where a tuner comes in and raises the timing advance which requires higher octane to avoid engine damage due to preignition.

I personally blend unleaded 103 octane 50/50 with 91(highest available pump) when I go to the strip to play. It may only make slightly more power, but I sleep better at night beating on it with a little more insurance against motor damage when it is 100 degrees and running 6K RPM.

 

so basically there is no point for me to use 91 octane(there is no 93 in cali)...i thought if you use a higher grade the quality is better and its cleaner??

 

This, http://theserviceadvisor.com/octane.htm presents a rather abbreviated and confused understanding of octane "how and why".

So if you really want to know, here's an unattributed "Octane 101" document I found on the web some time back.

I edited it to correct spelling, grammar and readability however the content needed no editing as it was 110% accurate...

 

that was nice and to the point in detail

 

If anyone is interested I moved the Octane 101 document over to my much neglected blog (I set it up over a year ago and have since ignored it).

It's based on the Thingamablog engine/editor, which is very nice!, and is much more convenient than adding pages to my website.

Because of this I hope to kick myself in the back-end enough to actually use it to provide info for here and other areas of my interest--mostly so I do not have to re-type responses to the common questions...

The blog root URL is: http://www.paladinmicro.com/blog/index.html

 

I run 93 in my car, however it's a higher compression motor so it calls for high octane but I'm in Michigan. I could possibly get away with 87 I know some people do but I'm not willing to try. I don't have an issue paying a little more.

 

1st, what does the owner's manual call for (I'm assuming you are running the stock tune), and 2nd does it ping on that grade. As engines age it is not uncommon for those that have been "babied" (IMHO just about the worst thing one can do to an engine) to pick up a lot of carbon deposits in the head that raise compression a bit and create hot-spots that contribute to pre-ignition.

For maximum cost savings you need to run the lowest octane fuel that does not lead to/cause detonation--for maximum power you need to tune for the highest octane fuel you care to buy...