Fuel additives Options

[Spectatrix]

Ok, so I'm a little leary about fuel additives. As in, do they do any good or are they just a scam, sucking money from gullible folks wanting to eke another 1 mpg out of their engine?

HEBs around Austin (and elsewhere, I presume) have started tacking on "Additech" machines alongside the pumps, where you can choose to pay some extra moolah and get an additive pumped in along with your gasoline. I do know that their little spiel is bloody obnoxious. What I don't know is if they do any good and whether I should bother trying an additive out one of these days.

[Spectatrix]

The octane level has very little to do with carbon (or other) buildup. Octane is a measure of the fuel's resistance to pre-ignition, which is what we hear as engine knocking. Higher octane fuels can be run at a higher compression ratio, which in turn burns hotter and more completely. So in that respect, yeah, maybe it results in higher buildup. But that has to do with the engine design, not the fuel itself.

And though I'm a girl, I am an ME/physics grad. But fuel additives aren't something you usually discuss in thermodynamics 101.

This post has been edited by Spectatrix: Dec 3 2007, 04:39 PM

[chook]

The octane level has very little to do with carbon (or other) buildup. Octane is a measure of the fuel's resistance to pre-ignition, which is what we hear as engine knocking. Higher octane fuels can be run at a higher compression ratio, which in turn burns hotter and more completely. So in that respect, yeah, maybe it results in higher buildup. But that has to do with the engine design, not the fuel itself.

And though I'm a girl, I am an ME/physics grad. But fuel additives aren't something you usually discuss in thermodynamics 101.

She is right, it is based on the scale of octane. Straight octane is considered 100 and it varies from there. Jet fuel is really low because it is not compressed by a piston and you don't care if it explodes quickly. Prop planes have octane ratings over 100 by using more stable and branched compounds in them. This is something I learned while working for Valero.