Xylene Fuel Additive 1

[Zmann]

I have been reading the threads and I have access to un limited amounts of xylene. What would the ratio be per gallon to mix. It is going in a race engine and it has no pollution controllc on it.
Thanx,
Zmann

 

[ShaunT]

I don't know if it is the same as Toluene. I am told that it has very similar characteristics. In Toluene, a 20% mix to Premium pump gas I.E. 1 gallon to 4/4.5ish, gives approx 100 octane. BTW, what is the setup on the motor?

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

 

[Chumley]

The total aromatic content (xylene is an aromatic
hydrocarbon) is usually limited to about 30% maximum
for current USA street legal gasoline but a mixture of
70% toluene, 30% heptane has been successfully used as F1
racing fuel but not without fuel line heaters. Toluene
and xylene are very siumilar.

Depending on your racing application, you may find that
too much xylene (or total aromatic content) produces
excessive soot especially when running rich and may
create cold start problems in cooler climates.

http://www.atsdr.cdc.gov/toxprofiles/tp71-c3.pdf

http://www.atsdr.cdc.gov/toxprofiles/tp56-c3.pdf

http://www.atsdr.cdc.gov/toxprofiles/tp72-c3.pdf

See the above links for more chemical information on
xylene, toluene, and an obsolete general recipe (1990)
for blending street legal gasoline.

Without knowing the total aromatic content of the gasoline
you use plan on using for blending, and its initial rated
octane, its difficult to guess on an acceptable mix ratio.
Trial and error is the only way. I'd start at about 5%
additional xylene and see what happens with the idea that
adding as little as possible to achieve the desired octane
is the best plan.

Hope this helps,

Chumley

 

[drwebb]

I understood that F1 fuel had to be reasonably close to commercial pump gas under the rules. Does Europe allow higher aromatics? Maybe that's responsible for the higher octane of their fuel.

What are the fuel line heaters for? Toluene should be smack in the middle of most gasoline's distillation curve.

 

[Retracnic]

Under current 2003 FIA Formula 1 technical regulations, fuels can be made up of no more than 35% aromatics (Article 19 section 4.2-4.4.4). Fuels can have a RON (Research Octane Number) no greater than 102. During the days of forced induction use in F1, certain teams were indeed known to run aromatic contents as high as 70%.

During this time of high aromatic content, fuel line heaters were often employed to improve the vapor-air ratio during high RPM operation. Since FIA regulations call for rubber fuel bladders, it was neither safe (nor practical) to heat the fuel in-tank. As far as I know, no team is still making use of heated fuel lines.

Back to the original question…

Ideally you would mix the minimum amount of xylene (or any other octane enhancing agent) required to prevent detonation under operating conditions. There is no performance benefit to be gained from using fuels with excessive octane ratings.

There are no reliable formulae available for predicting the resultant octane rating of mixing xylene with pump gas. You may see websites for do-it-yourself race gas that state “mixing X parts of xylene with Y parts of pump gas will get you Z octane…”. To put it bluntly, these sites are wrong. Gasoline manufacturers each have their own proprietary blends for the various grades of pump gasoline. The pump gas you purchase already contains some quantity of toluene and xylene. Since you have no way of knowing the specific blend in question, you cannot accurately predict the resulting octane rating.

From personal experience, I would advise sticking with commercially available race gas. Regardless of how cheaply you can acquire xylene.

Good Luck,

Bryan Carter

 

[Chumley]

drwebb writes:

"Toluene should be smack in the middle of most gasoline's
distillation curve."

The aromatics are the higher boiling point fractions of
gasoline. See the attached link for some common boiling
points and their RON and MON blending octanes. They are
listed as BP in °C in the chart in section 4.13.

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

As I understood it, the fuel line heaters were to keep
the fuel warm enough to obtain good vaporization
characteristics since the boiling points are so high.
(I'm not an F1 racer!)

Hope this helps,

Chumley

 

[drwebb]

The chart referenced lists boiling ranges from -12 to 170C, (although, to be rigorous one should not say that dicyclopentidiene 'boils' at 170 because it doesn't vaporize but rather decomposes to cyclopentadiene at that temperature through a retro-Diels Alder reaction, and that compound boils at 42 C) with Toluene at 111. "Smack" was a regretably ambiguous word choice, but toluene is still within the thick part of any GC 'hump' of gasoline I've seen, though Chumley is quite correct that it is not in the exact center. Retracnic's explaination that it had to do with the extreme turbo boost- and I would assume the resulting higher induction temperatures- of those race engines seems more precise.

 

[Chumley]

Well, . . . yeah, no big deal. If you read the note in
parenthesis right above the reference to dicyclopentadiene,
it does say that it isn't normally present in significant
amounts in gasoline! Now I don't wonder why. The link I
posted isn't the ultimate source. Like money, those aren't
normally given away for free at an anonymous persons
request with no possible future potential for profit.

Heir Dr.: We're all just learning. No regrets necessary!
Do you have any idea where I can download a program that
will take back all the shit I wish I never said or wrote?
Naahhh! Don't need it. I learn more when I screw up!

Hope this helps!

Chumley