Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site fisher.UUCP Path: utzoo!linus!decvax!bellcore!petrus!scherzo!allegra!princeton!astrovax!fisher!djl From: djl@fisher.UUCP (Dan Levin N6BZA ) Newsgroups: net.auto Subject: Of Octane and Mothballs and such... Message-ID: <762@fisher.UUCP> Date: Mon, 23-Sep-85 11:01:25 EDT Article-I.D.: fisher.762 Posted: Mon Sep 23 11:01:25 1985 Date-Received: Wed, 25-Sep-85 12:39:54 EDT Distribution: net Organization: Princeton University.Mathematics Lines: 56 On the topic of octane methods (this gets bounced around now and then, seems like time again..): One methed (the R(esearch) method) is to calculate the theoretical octane rating of a fuel based on its components. The other (the M(something) method) is to take a one cylinder engine, and change the compression until it just barely knocks on your test fuel. Then find the iso-octane and hexane(?) mix that just knocks in the same engine. Since the octane rating is literally the percentage of iso-octane in the equivilent octane/hexane mixture, this rather pragmatic test will reveal the 'true' octane rating. The R+M/2 you see on the pumps in some states means that the octane rating was calculated based on the average of these two methods. About mixing fuels: I am told by people I trust that mixing leaded and unleaded fuels produces a very interesting resulting octane rating. In particular, mixing leaded regular (89 octane) in equal parts with unleaded regular (87 octane) will result in a ~90 octane fuel. Of more interest to older car fans, mixing leaded regular (89) with unleaded super (92) will give you at least 92 octane fuel with enough lead in it for your valves. Your milage may vary based on the amount of alcohol in the unleaded gas. I do not think that mixing leaded fuels of differing octane ratings will do anything unexpected. About mothballs: ( No flames from chemists on minor points please...) Seems that gas is basically just a mixture of carbon chains (in essence at least), the longer the average chain, the higher the effective octane rating. Also seems that some mothballs (there seem to be two kinds, I do no suggest getting the wrong one!) are 100% (in fact lab grade, although not USP) naphthalene(sp?). Seems that naphthalene is a very long carbon chain, and that it dissolves fairly quickly ( ~ten minutes or less) in gas. I have had several chemically oriented Ivy League types consider possible bad side effects, and they all admit that naphthalene should burn completely at combustion chamber temps, and that it is very, very stable stuff, sufficiently so that it will not react and form any nasty compounds in my engine. This all boils down to saying that adding 3 real moth balls per gallon to my tank will make my car run on leaded regular (89), which means that it is bringing the octane up to ~92 or so. So enough on fuels for now. For those of you who are wondering, I drive a '65 Mustang fastback with a 10.5:1 c.r. 289, and it doesn't like 87 octane unleaded fuel too much :-) -- ***dan {allegra,astrovax,princeton,twg}!fisher!djl The misplaced (You call *that* a ski slope??) Californian Brought to you by Super Global Mega Corp .com