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Octane Boosters

I pulled this off the Vette list last year. It's not as complete as I thought, but there's some good info here. First part is Sunoco Fuel info, the second is about various octane boosters and how to mix your own brew.

Mike G.

First, some data about the Sunoco CAM2 fuels from their literature:

SUNCO Fuel Color Research Octane Motor Octane (R+M)/2 Specific Gravity Reid Vapor Pressure Distallation Temp, deg F
Initial 10% 50% Final
Standard Purple 115 107 111 0.725 8# 90 160 220 360
GT Unleaded natural 105 95 100 0.760 8# 90 150 210 230
Supreme Blue 116 109 112 0.715 8# 90 155 215 260
Maximal Red 118 115 117 0.700 6# 100 150 220 240

And from Rich Lassitter's article in the GS Xtra ... how to mix your own brew:

Formula (R+M)/2 Cost Mixtures with 92 Octane Premimum Note
10% 20% 30%
Toulene 114 $2.50/gal 94.2 Octane 96.4 Octane 98.6 Octane (1)
Xylene 117 $2.75/gal 94.5 Octane 97.0 Octane 99.5 Octane (2)
Methyl-tertiary-butyl-ether (MTBE) 118 $3.50/gal 94.6 Octane 97.2 Octane 99.8 Octane (3)
Methanol or Ethanol 101 $0.60 - $1.75/gal 94.3/94.7 Octane Not Recommended Not Recommended (4)
Isopropyl Alcohol and Tertiary Butyl Alcohol 101 $0.60 - $1.50/gal 94.5 Octane Not Recommended Not Recommended (5)

  1. Toulene: Common ingredient in Octane Boosters in a can. 12-16 ounces will only raise octane 2-3 *points*, i.e. from 92 to 92.3. Often costs $3-5 for 12-16 ounces, when it can be purchased for less than $3/gal at chemical supply houses or paint stores.

  2. Xylene: Similar to Toulene. 12-16 ounces will only raise octane 2-3 *points*, i.e. from 92 to 92.3. Usually mixed with Toulene and advertised as *race formula*.

  3. Methyl-tertiary-butyl-ether (MTBE): Oxygenate. Very common in octane booster products. Has lower BTU content than toulene or xylene, but oxygenate effect makes the gasoline burn better and produce more energy.

  4. Methanol or Ethanol: Methanol is wood alcohol. Ethanol is grain alcohol and found in Gasohol in 10% ratios. Both alcohols are mildly corrosive and will eat gas tank linings, rubber and aluminum if used in excessive ratios. Main ingredient in "Gas Dryers", combine with water.

  5. Isopropyl Alcohol and Tertiary Butyl Alcohol: Similar to Methanol/Ethanol. Isopropyl Alcohol is simply rubbing alcohol.

Making your own

How to make your own octane booster (this is the basic formula of one of the popular octane booster products). To make eight 16 ounce bottles (128 oz = 1 gal):

100 oz of toulene for octane boost
25 oz of mineral spirits (cleaning agent)
3 oz of transmission fluid (lubricating agent)

This product is advertised as "octane booster with cleaning agent *and* lubricating agent!". Diesel fuel or kerosene can be substituted for mineral spirits and light turbine oil can be substituted for transmission fluid. Color can be added with petroleum dyes.

-- Ken Mosher
-- Buick Grand National: A *BOOST* of Buick Performance

[Thanks a bazillion for that post. I'll only add one comment regarding using methanol. In a word, don't. It attacks zinc and magnesium very rapidly. Guess what is in carburators and other fuel system parts. I had this graphicly demonstrated to me one time. I was involved in racing chain saws (Oh no, not another one....) In the particular class, my saw ran on 100% methanol. Saws are typically made of a magnesium alloy. I knew I had to clear out the system after each run but one afternoon I forgot. By late evening when I remembered it, the gas tank had already corroded through. I left it to see what would happen and by morning practically the entire saw was a pile of white dust with steel parts interspersed. That included my one-of-a-kind highly ported cylinder I'd spent hours on. *sob*. I saw similar results running methanol in motorcycle engines, though never as bad. JGD]

Posted by: "KEN MOSHER"

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