Mike C :
"XYLENE...3 gals. of 93 unleaded to 1 gallon of Xylene (available at most paint stores, about $5 per gal.) yields 100-101 octane. It is a paint thinner, and also a major component in gasoline already. You should add about 1 ounce of Marvel Mystery oil per gal. of xylene, to replace the lubricants in the fuel. Xylene will help keep your fuel system and combustion chambers clean. It will NOT harm O2 sensors. I use it in my Syclone every time I take it to the track. It WORKS!! HTH
Mike "
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I found this article in the archives now with these figures xylene itself is about 125 octane . Can a car run on straight xylene(and mystery oil) if say you had a turboed c5 with 30 lbs of boost ? It's very interesting .

:reddevil

 

I'm not posting this to start a flame war but rather to spar an intelligent discussion. Has anyone thought about the fact that increasing octane ratings on your fuel really doesn't do much more than make the fuel burn slower due to a smoother propogation of the flame's wave front? It really doesn't change the energy content of the gas and slower burning fuel is not necessarily better. Also, the fact that really high octane fuel can allow you to get greater timing advance is of no benefit by itself either because any fuel that starts burning before TDC is actually *detrimental* to power. Lower octane fuel will burn faster because the wave front propogates faster, but it really shouldn't matter that much because if it burns faster, you don't *need* as much timing advance because all the fuel will be burned off with less advance before the cylinder reaches BDC.

So... lower octane fuel and less timing advance can actually produce better performance than 200 octane fuel and 90 degree timing advance. ;)

So the bottom line question is, if you get detonation running premium 93 octane gas, isn't it just as good (or better) to fix the problem by fixing the timing advance so that you don't get detonation in the first place?

Mike

 

When you run high levels of boost you need the higher octane to prevent detonation because you are increasing the level of oxygen getting to your fuel therefor it burns too fast causing your engine to dangerously lean itself out and for the very reason you just stated (high octane burns slower) this prevents that . Again if someone could commetn on my original question

 

what kind of times is you syclone running...I had a 93 TY for 5 years till I sold it and bought the vette,,,I loved it...

 

The Cyclone mentioned is part of a original quote. Xylene is a common component of over the counter octane boosters. Tolulene is another similar additive. The only reason you would want to use it to increase fuel octane is because you are running high compression (12:1), a supercharger, a turbocharger or over 150hp of nitrous. It would be a good substitute for unleaded race gas in those cases.

Formula 1 cars ran straight Tolulene back during the turbo era.

Cameron


[Modified by Cam Potter, 3:46 PM 9/4/2001]

 

Higher octane is critical for stable combustion in certain setups and if adjustments are made to take advantage of higher octane then the engine will output more. Let's say you have a 10:1 CR motor running 5psi detonation-free with 30 deg. total timing. Let's also say you want to up the boost and the flow capacity of the turbos and fuel system can efficiently and comfortably support upping the boost to 15psi. 15 psi on pump 93 with or without intercooling will result in counterproductive detonation.

Let's say you back off timing so you can use pump 93 for the 15psi setup. In my experience, with the effective compression, it's likely that you may have to back off timing to below 20 degrees overall. Setting timing that late will cause an extremely long burn. In my experience on boosted LT1s, as you approach 15 degrees total timing, the engine begins to miss. And going close to 20 degrees total timing will often result in excessively high EGTs (too little or too much timing is harmful just like too lean or too rich air fuel ratios can be harmful) from late combustion initiation.

So at this point, if one wants to run this boost, then one has to either lower static CR to run pump 93, richen air/fuel ratios (although in this situation, you can richen till the rings wash out and detonation is still not prevented for pump 93), or run higher octane. Personally choose an horsepower range you want to run. Choose the fuel and intended use of the car (e.g. street use and pump 93). Then settle on a compression ratio that will allow you to run no less than 25 degrees total timing for the sake of keeping EGTs in check. Finally iterate between air-fuel ratios and timing for final adjustments. Hopefully if you're okay with the CR for the fuel you will fall around 10.5-11.0:1 air fuel ratios for boosted setups on top-speed extended runs on pump 93. 11.0 to 12.2:1 for general use on pump 93. And hot-tuning on pump 93 would be 12.2 to 13.1:1 air fuel ratios primarily for quick sprints.

Anyways the slower burn of higher octane is critical to maintain stable combustion in certain setups. And actually the energy content on some race fuels is higher than in pump fuels. Finally, the ability to run a higher static compression ratio that higher octane allows and higher energy content of race gases allows serious racers to extract more output for a given size of fuel tank (more power for the given amount of fuel, a term called fuel conversion efficiency that is proportional to static compression among several variables)!!! So that means racers can go further without having to refuel or run smaller lighter fuel tanks or both!!!

~STAGED
ex-owner of '95 T/A 11psi Vortech 381cid. 579.4 rwhp through cat-convertors. (Hot Rod 4/99)
also piloted 100% stock '96 Bonneville to 14.525@94.1mph on full tank fuel and factory Eagle GAs (HPP 10/97)


[Modified by STAGED, 11:07 PM 9/4/2001]

 

From what I've read, octane rating has nothing to do with the propagation speed of the flame front. When detonation occurs there is no flame front, the entire air/fuel charge lights off at the same time.

I have a recipe list around here somewhere for making home-brew high test with a variety of different additives. When I get a chance, I'll scan and post it.

 

Octane Booster formulas
Formula #1 - Toulene
R+M/2.........114
Cost...........$2.50/gal
Mixtures with 92 Octane Premium
10%...........94.2 Octane
20%...........96.4 Octane
30%...........98.6 Octane
Notes: 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.
Formula #2 - Xylene
R+M/2.........117
Cost...........$2.75/gal
Mixtures with 92 Octane Premium
10%...........94.5 Octane
20%...........97.0 Octane
30%...........99.5 Octane
Notes: 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*.
Formula #3 - Methyl-tertiary-butyl-ether (MTBE)
R+M/2.........118
Cost...........$3.50/gal
Mixtures with 92 Octane Premium
10%...........94.6 Octane
20%...........97.2 Octane
30%...........99.8 Octane
Notes: 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.
Formula #4 - Methanol or Ethanol
R+M/2.........101
Cost...........$0.60 - $1.75/gal
Mixtures with 92 Octane Premium
10%...........94.3 Octane (Methanol)
10%...........94.7 Octane (Ethanol)
20%...........Not Recommended
Notes: 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.
Formula #5 - Isopropyl Alcohol and Tertiary Butyl Alcohol
R+M/2.........101
Cost...........$0.60-$1.50/gal
Mixtures with 92 Octane Premium
10%...........94.5 Octane
20%...........Not Recommended
30%...........Not Recommended
Notes: Similar to Methanol/Ethanol. Isopropyl Alcohol is simply rubbing alcohol.
Sample Mixture
To make your own octane booster, it is easiest to make up a large batch, and then bottle it up in "dosage-size" uses.
Below 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.

 

If you want to know the entire history of gasoline and how to make and blend your own go to : http://www.cs.ruu.nl/wais/html/na-di...line-faq/.html or go to google, search for 'gasoline' and click on the first option URL.