ArcticCzar

Forgive my asking, but where I live the best you can get at the pumps is 91 octane. What exactly are 'xylene' and 'tolulene', and what do you do with them? Any pros and cons? Any help would be greatly appreciated!!

Levish

[quote]Originally posted by ArcticCzar:
<strong>Forgive my asking, but where I live the best you can get at the pumps is 91 octane. What exactly are 'xylene' and 'tolulene', and what do you do with them? Any pros and cons? Any help would be greatly appreciated!!</strong><hr></blockquote>

unlike the 104plus octane boost which claims "up to 7 points" or whatever, what this means is that in your case you go from 91 octane to about 91.7 octane because of the volume of octane boost

and at 4-5$ a pop to get to 93-94 octane would cost a arm and a leg

Toluene and Xylene are avail for about 5$-10$ a gallon and have the same potency so for roughly the same 5$ you would get much more octane (I forget the equation but it's a huge difference)

special tool

The mixing formula is simple: 15parts91 + 1part xylene117 / 16 = 92.65 octane. Those of you nutjobs who will inevitably mix 1 gallon of 91 and 1 gallon of xylene to make 104, you may have difficulty starting your engine without stealing the glowplugs out of your diesel pickup.
Bear in mind that 100% combustion of either of these compounds produces h2o and co2 only.

Levish

I think I have the conversion

so for 10 gallons of 91 adding 1 gallong of toluene would result in 93.1 octane (assuming my math is ok)

and the difference would get even greater with less gas in the tank

for 1 tankful (approx 15-17gallons) generally speaking 2 gallons of Toluene (10$?) should result in approx 94-95 octane

of course for racing a tankfull is overkill and for 4 gallons of 91 octane mixed with 1 gallon of Toluene results in about 96.7 octane which should allow for some really nice ignition timing advance

ArcticCzar

So can you feel a difference in the 2 or 3 octane increase? Or is this done primarily to clean the fuel system?

Russ Murphy

When running my car in stock condition at the track the difference between running 93 octane and 100 octane (probably 98 octane effective mix) for the following session was pretty dramatic.

cheetah chrome

i've read a whole bunch of posts on the tolene and xylene and i havent bought any yet because im still not sure what mixture is best. what is the "just right " mixture?? i usually run 94 (sunoco) or 93 (chevron, when i can find one). does the higher octane noticible increase engine temps? are you guys running aftermarket ignitions? i know theres a bunch of factors but is there anyway we can make an excel spread sheet for this?

Levish

boosting octane has no effect if your car doesn't require it, it is done on tuned cars (a exhaust doesn't count ) that run high boost, advanced timing

the people in CA that can't get to 93-94 Octane might be the only exception since their gas is heavily oxygenated

meaning if your car is running great (no ignition retard or pinging/knocking) you will see no benefit, in fact you make more power on lower octane as long as the engine isn't pulling timing or pining

Probesport

FYI: Some more xylene/toluene experiments over here.

<a href="http://probesport.extremespace.com/cgi-bin/ikonboard/ikonboard.cgi?s=3d860b3e7d45ffff;act=ST;f=6;t=861" target="_blank">http://probesport.extremespace.com/cgi-bin/ikonboard/ikonboard.cgi?s=3d860b3e7d45ffff;act=ST;f=6;t=861</a>

Russ Murphy

Hey Levish,
How do you like your 1.8T? We've got one (an Avant) too.

[quote] boosting octane has no effect if your car doesn't require it <hr></blockquote>

You're absolutely right, but how do you know your car doesn't require it? Unless you've got Knock Link or SDS's new feature how do you know that after running full boost incessantly (like at the track) you're not having some timing pulled back due to detonation.? <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Levish

[quote]Originally posted by Russ Murphy:
Hey Levish,
How do you like your 1.8T? We've got one (an Avant) too. ]<hr></blockquote>

I love it, unfortunately I am moving to Germany in the Spring and I have to sell it. I would bring it with me except I don't know what to expect when I get there.

It's one of the nicest cars for the money you can get IMHO ... very soothing and very solid

I've been lurking around here because I am thinking of getting a 86-87 951 which would become my semi daily driver. I need some more info before I take that plunge though (like insurance rates and the such)


[quote]

You're absolutely right, but how do you know your car doesn't require it? Unless you've got Knock Link or SDS's new feature how do you know that after running full boost incessantly (like at the track) you're not having some timing pulled back due to detonation.? <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" /> [/QB]<hr></blockquote>

pinging can be heard, and sometimes there is a manifestation of boost surge that feels like uneven accel.

of course it takes a good ear to tell and a lot of attention to how the car is running.

the butt dyno is not always the best way to tell but it can hint that somethings may be awry.

For my Audi I have a laptop tool called vag-com
(www.ross-tech.com for more info) which is as good or better than the dealer computer for checking codes and the such and works with the entire ODBI and ODBII lineup of VW/Audi cars.

In this program codes such as cyl misfires are stored as are boost levels (both requested and actual), great program.

Danno

"What exactly are 'xylene' and 'tolulene', and what do you do with them? Any pros and cons?"

Check out the 'Fuel FAQ' section on my <a href="http://members.rennlist.com/951_racerx" target="_blank">951 RacerX website</a> for info on aromatic-hydrocarbon octane boosting. The Gasoline FAQ and F1 Rocket Fuel articles contain the specifics.

As Levish pointed out, it's really bang-for-buck in octane-boosting. Those little bottles of 104+ are simply crap! First they promise a 2-5 'point' increase, which really brings 91-octane up to 91.2-91.5 octane. So you would have to spend 10x more for the equivalent boost as a single gallon of xylene/toluene.

Even worse is that those little bottles use highly carcinogenic organo-metallics to provide the octane boost. That stuff can be absorbed right through your skin if you spill it. They also cause nasty deposits inside your cylinders. That's why they usually mix in solvents like mineral spirits to try and clean off those deposits. And that's also why they include extra lubricants like ATF to try and restore the cylinder oils that's been washed off by the solvents (and to help your rings slide over the deposits).

So, a pure hydrocarbon-based octane booster is the way to go; since toluene is already a moajor component of gasoline. In the U.S. it's about 19% and in Germany about 29%. So adding a gallon or two really just brings our gasoline up to spec. with the stuff Porsche probably designed their cars to use.

"You're absolutely right, but how do you know your car doesn't require it? Unless you've got Knock Link or SDS's new feature how do you know that after running full boost incessantly (like at the track) you're not having some timing pulled back due to detonation.? <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" /> "

I suspect with most 951s under standard conditions, you probably won't notice that much of a difference. But on ones with increased boost, you'll be a little closer to the edge of knock/detonation and the octane boost will help you get as much power out as possible. Otherwise, the knock-sensor will have the computers pull back timing on you.

On our chips, we actually included a separate ignition map with advanced timing for 96-octane gas (2-gallons toluene or 50/50 mix with 100-oct race-gas). You can experiment with this by selecting the Australian MAP#3 region with the coding-plug. I suspect a 2-4% increase in hp/torque and you can definitely feel the difference in instant throttle-response (lag...? what turbo-lag! Vee dun't neeed no steeeekin' turbo-lag!)

toddk911

Is that true that running lower octane actually increases hp?

So is it better to run more ign. retard and lower octane? <img src="confused.gif" border="0">

Levish

lower octane gas has more combustion energy (burns easier)

higher octane gas isn't intended for "higer performance" it is intended for increased saftey margin (knock resistance) with a agressively tuned engine

it also takes more spark engergy to light off a higher octane fuel. As it does with increased boost but that's another story altogether

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Sean Hall

Hey guys,
Realize Toluene is a carcinogen. i.e. produces cancer. Xylene isn't too great either.

There's lots of articles on the net written about both chemicals. To see some of them, do a search on Google for:
"Carcinogen Toluene"
"Carcinogen Xylene"

For those dying for more octane/higher boost, you may want to reconsider race gas or alcohol injection. Both are proven and work well.

-Sean