Octane Boost vs 93 Octane

[97BurbanSLT]

Hey guys new here and new to gas scince the whole ethanol issue, I'm trying to decide if theres anything to counter any negative effects of this as well as octane numbers. My vehicle info is in my signature. Maybe someone with actual facts & knowledge on the subject, or even someone with an opinion supported by facts. I've mainly driven diesels but heres my question:

Which do you prefer or which is better, using an Octane Booster or just forking over the dough at the pump to fill up with 93 octane gasoline? Name your preffered brand if you do prefer an octane boost, and why. If not why do you prefer a higher grade gas?

I'm asking because by the time you buy a pricier Octane boost like 104+ you end up paying the same difference over regular gas if you were to just buy premium grade fuel. I'm assuming theres no substitute for just plain "good" fuel. Or is there a plus to using an octane boost? A side question I noticed on a bottle of 104+ Octane boost it says:
"The only octane boost that doesnt contain the Harmful additive MMT"
Yet all the other Octane Boosts Brag all over the bottle that they have MMT in them????

Lets hear it folks thanks in advance for all the advice.

[1st Synthetics]

I would use premium gas and not the octane boos If it were me, unless I had work done to the motor for performance. Octane bust is mainly for racing and off road use. here is a brief description of AMSOIL's octane boost:

Maximizes power and improves performance in all two-cycle and four-cycle gasoline engines. Increases octane number up to seven points. Reduces engine knock, improves ignition and engine response, helps fuel burn cleaner and inhibits corrosion. Recommended for off-road and racing use.

[97BurbanSLT]

I did some reading and some searching this seems to sum up the theory of selecting the proper level of octane here on this page. Apparently the lowest octane that you can run with out experiencing knock conditions, is going to be the octane level that gives you the best mileage and performance. If anyone has more info please share.
http://volvospeed.com/Reviews/octane_boosters.html

[silveradotrailblazer]

Theres really no benifet of running 93 in a engine that was made for 87 octane. unless you have a very modified engine dont waste your money on higher octane gas or additives. Run a good quality gas not some cheap discount gas.

[KirkW]

Theres really no benifet of running 93 in a engine that was made for 87 octane. unless you have a very modified engine dont waste your money on higher octane gas or additives. Run a good quality gas not some cheap discount gas.

What he said - for the most part, every gallon of gasoline has the same number of BTUs. High or low octane, they both have the same amount of energy.

The ONLY thing an octane-rating measures is how hard it is to get the gasoline to explode by squeezing it.

Squeezing (compressing) a fuel/air mixture makes it burn more efficiently. The more you squeeze it, the better it burns and the more power you are able to extract.

But squeezing the fuel/air mixture causes it to heat up. Squeeze it too much and it explodes. This explosion is called "knocking" or "pinging" or simply "detonation".

"Octane" is simply a measure of how much you can squeeze the fuel/air mix before it goes bang. The higher the number, the more you can squeeze it. And the more you squeeze it, the better it burns.

But the amount an engine squeezes the fuel/air mix is determined solely by how the engine is built. High or low octane, the engine will squeeze both the same amount and extract the same power.

Racing engines squeeze the fuel/air much more (i.e. - higher compression). 87-octane gasoline will explode when squeezed that much, so they run higher octane to keep from damaging things. Because they squeeze the fuel more, they burn it more efficiently. The extra power comes from how the engine is built, not from the extra octane.

The simplest analogy is to think of octane numbers as ladders of different length, and the engine as a wall. A low ladder will let you climb over a low wall. A taller ladder won't climb the wall any easier - the extra length is useless. But, some walls are taller and need a tall ladder - a short ladder won't do it.

Notice that the type of ladder you use doesn't change the wall - a tall ladder doesn't make a short wall any higher. Once you match the ladder to the wall, its job is done. Anything extra is wasted money.

PS - Aviation gasoline is rated at 100 octane. But my airplane has a low-power/low-compression (7.5:1, 100hp). So the 100 octane is wasted money. I'm legally able to burn regular 87-octane automobile gasoline (so long as it doesn't have ethanol). And for many years I did - the engine performed exactly the same, no matter which flavor of gasoline was in the tanks at the time.

PPS - Many cars have 'knock sensors' that can adjust the ignition timing when they sense detonation, reducing combustion pressure and power somewhat. Some engines are designed to be at the edge of detonation at, say, 87-octane. And at some conditions (full throttle, heavily loaded, low RPM, high air density), the combustion pressures may cause some detonation. So in those cases going with a higher-octane fuel (like 91) may restore the performance lost by the knock sensor. It won't make the engine more powerful - it simply keeps the engine from losing power under those conditions. If you hear knocking while towing a trailer up a mountain, for example, then going with 91 or 93 octane may stop the knock and restore the lost power.

[Jimmiee]

Kirk,

Thanks for the great octane explanation with very good analogies! Good point about the knock sensors. One thing I might add is many vehicles with knock sensors will retard the timing and silence the knock before it can be heard with human ears. So if your vehicle requires 87 octane don't buy the cheap 85 that a lot of stations sell for cheap.