Octane ratings... ?Negative affects of PURE XYLENE?

[Teeps]

So I was going to the store the other day for some nice paint stripper. And I saw this big canister of 100% Xylene.
For some reason it reminded me of my Supercharged 4.6 liter V-8 running 500hp on pump gas.
Some times I'll tweak the tune to the ragged edge with the timing and A/f ratio before going to the track. With the hypereutetic pistons, detonation is suicide, but I still want to beat that corvette with my 2 ton sleeper.

For a little insurance, and a little power if it's running lean on a cold day, it's usually a good idea to raise the octane of the fuel with this type of induction combination (hot roots blower).
I have no idea what the difference is between the octane ratings you read at a gas pump, or ratings labeled as "fuel octane", or if you visit this site,

http://www.vpracingfuels.com/vp_01_fuels.html?mgiToken=0C15B7C8BDBE6F21FA#unleaded

They site other terms for octane ratings, "motor octane", "Research Octane", on some of the fuels listed at that link they also site "density", and "specific gravity" at different temperatures for the fuels.

The signifigance, and the differences I have no idea.
I appreciate any insight there, or a good resource if anybody knows of one.

If you look at the ingredients of Octane boosters, the actual fuel is either Tolene (sp?), or Xylene, I think the rest is lubricant, cleaner, filler etc.
Very little actual fuel in these boosters, they advertise 1-3 points boost in octane which means at most you go from 91 octane to 91.3 octane, NOT 94 octane.

I'm a big fan of Mobil as their fuel seems to hold it's octane well over time. As an additive, I plan to add pure Xylene which I believe is about 120 octane. probably 60/40. Putting it around 102 octane or higher. I assume there is a reason for the lubricant in the octane booster?

Would no fuel, and pure xylene damage components in my induction / fuel / exhaust systems?
Injectors? fuel lines? 02 sensors? cats?.... well cats are gone

Well thanks for any tips on deciphering fuel spec's, and your thoughts on xylene.

On a side note:
I also have a naturally aspirated car, that I may raise the compression on and run the tune to the ragget edge to squeeze the potential out of the combo as far as I can, so I'm complating running one of the Vp fuels, supposedly they get get real results from this fuel, however it's leaded, and I'm afraid to run that with 02 sensors. They are kind of vague, I wonder if it has oxygen content, I wonder how the specific gravity plays into fuel performance.
________________________________________________________
"C46
Produces very significant horsepower and torque over all other fuels. Impressive results in normally aspirated compression ratios, from 9:1 to 17:1, drag race or oval track qualifying applications.

• Color: Yellow
• Leaded
• Motor Octane: 98.6
• Specific Gravity: .682 at 60° F "
__________________________________________________________

This is just a hobbie for me, I like to try to take an underdog combination, and realize the maximum possible capability of it, many times you get some impressive and suprising results. Even if I have to cheat with some fuel, heh.

Thanks in advance!

 

[Chumley]

This topic has been discussed many times previously. Instead of going to an advertising/marketing based site, try a link that is more education/information based like this one:

http://blizzard.rwic.und.edu/~nordlie/cars/gasoline.html

or this one:

http://naca.larc.nasa.gov/

or this one:

http://www.atsdr.cdc.gov/toxpro2.html

You'll find most of the blending octanes for various fuel components at the first link and additional extensive, although dated research at the others.

To answer your question, mixed xylene like what you buy at the paint stores is very high in octane and works well to boost the fuel octane under most conditions. It has a high boiling point so its vapor pressure is lower. That could be a problem at high concentrations under colder conditions and at cold start. Xylene is a heavy soot former (which is one of the reasons it's concentration in gasoline is limited) especially when running rich. There are many other options for octane building if you see section 4.13 at the first link. Adding larger volumes of octane builders to fuel reduces the concentration of other beneficial deposit reducing additives so you take your chances.

Chumley

 

[patprimmer]

I'm 100% with Chumley on this one

Regards
pat

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Teeps]

Thanks for the info guys, I should have known better than to post before searching...

Soot is bad, thanks for the fyi.

Off to sift through the archives.

Happy Holidays.

 

[Teeps]

Ok well I've read up quite a bit, I don't think running the xylene for a few quarter mile runs will add too much soot, especially just a 60/40 mix with petrol. Although some acetone wouldn't hurt. The a/f won't be especially rich, the flick of a few buttons, and a tank of gas later it's back to normal pump petrol and tune so I don't think soot will cause a major problem.

Now how to pick up a few ponies on a Naturally aspirated motor, 10 to 1 cr ratio 32v motor spinning to 7000rpm range
I don't know if it will be worth it to blend my own fuel just for a day or two at the track or not. I've used NOS racing blend, didn't seem to hurt performance, used 3 bottles, not cheap. But with knock sensors, the less you are bouncing off them the more power you make.
Just thought there might be a better way to get a little edge on the tune. 13.5 to 1 A/f ratio, and 31 degree's total timing, a little fuel padding won't hurt
I see common practice is nitromethane and ethanol, not looking to use any fuel that will require me to change mixture drastically, or be cost prohibitive. Besides I'm sure I have too much AL, and Rubber in my fuel system/engine that doesn't like caustic substances.
But I know it's possible to squeeze a few ponies out by using the right chemicls. I know a guy that blends his own secret formula, wearing a mask, googles, gloves, and careful amounts of mixing. He's got a Naturally aspirated motor running original oldsmobile block making 887 hp! Fuel injected of course.