Xylene or Toluene Octane Boost? 1

[nuker]

I have found multiple "Homebrew Racegas" articles. The majority recommend Toluene as an aromatic. Xylene is also listed and has similar properties. It seems that Toluene has been preferred for cost savings (at the time the arcticle was written). Xylene is now more affordable and would yield the same actane with lower ratios due to higher octane {(R+M)/2}.

Question: Are there any drawbacks to using Xylene over Toluene?

Note: High pressure application (up to 26psi).

 

[evelrod]

The main drawback is that 'homebrew' is unpredictable and mostly illegal in ALL racing orginazitions. Secondary is cost, which is higher than commercially available racing gasoline. I am of an era , the 1950's, when it was acceptable to use toluene to boost our fuel. As the later 50's rolled around you could go down to your corner Chevron station and get 100+ at the 'white' pump for about $.45 a gallon. Homebrew fell out of favor rather quickly after that.
Today I get 114 octane for $3.90+ a gallon at the Sunoco race gas pump(100 and 110 unleaded is available at slightly more $). VP is available as is Trick and Daeco. Of course I live in SoCal and I realize it may be difficult to get in other areas, but so will toluene and xylene most likely.

A great many 'hot rodders' have cheaped out on fuel and regretted it. It may cost a bit more and be a bit more difficult to get but--- you may agonize over the cost but you will never regret using the BEST. (Good advice from my dear old dad)

Rod

 

[joereitman]

This is a review I posted on 11-9-02 on another forum. I have been using Toluene on and off for a while and it works well and has no lead so it does not lead foul the O2 sensor.

"33% Toluene Logged at 20 PSI on Big16G

Tonight I logged 2 runs at 20 psi with 2 gallons of Toluene added to 4 gallons of 93 octane. 4 gallons is based on being just under 1/4 tank, and knowing from draining tank for fuel pump install that means about 4 gallons. I bought a 5 gallon container of Toluene from Porter Paints in Athens, GA in mid June for just under $30 out the door. I think Toluene maintains its octane rating well over time, so I presume it was still 114 octane. By my calculations this means I was running about 100 octane.

I had uncontrollable wheelspin in 1st and 2nd (despite an ultra stiff suspension setup that minimizes weight transfer), so I will focus on the 3rd gear logs. Pull #1 started at 3031 rpm , 22 degrees timing, IAT 71*. O2 started at .88, then .86 most of the run, then .84 at the end as slight knock occurred as I reached 6468 rpm. Knock started at 7 at 4656 rpm and stayed between 3 and 7 until it jumped to 10 at max rpm. Timing stayed between 16 and 20, mostly 20, until dipping to 16 as I hit 10 counts of knock. IPW stayed between 17 and 20.5 ( I have 450's).

The 3rd run was very similar except that I started 3rd at 4625 rpm, and at the very end of the pull above 6200 rpm I saw 12 counts of knock instead of 10, and timing pulled back to 14 at the very end. I also ran to 5125 in 4th with a max of 9 counts of knock and good timing until the 9 counts of knock pulled it to 14*. IAT for the 2nd run was 79* due to increased underhood temps. The car pulled the strongest it has ever run during these 2 pulls. I have never run this much Toluene before. The engine was very smooth, with none of the knock induced roughness I have experienced in the past.

My 2 previous logs from a week or two ago, on 93 octane, were at 17psi creeping to 21 at the end. IAT for those prior runs was 70* for the first run and 66* for the 2nd (later in the evening). The 1st run I hit 20 counts knock sum by 5700 and backed out of it. The 2nd run was to 6281 rpm with 30 counts of knock (ouch!) and perceptible roughness. In one of the runs I had 15 counts knock by 5200 rpm and in the other I had 18 counts by 5400.

The Toluene seems to be a good, convenient alternative to race fuel. Unlike 100 octane low lead aviation fuel, there are no worries about fouling the O2 sensor with lead deposits. 100 octane av is about $2 per gallon around here, so that is a little cheaper than 33% Toluene. I pay about $1.35 per gallon for 93, and $6 per gallon for Toluene, and with a 2 to 1 ratio that is about $8.70 for 3 gallons of the mix, $2.90 per gallon. It is still a lot cheaper than race gas, which is about $5 a gallon around here, and also has lead.

Joe


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[nuker]

Those look like great results for Toluene. Thank you for the accounts. I agree with the safety issue ,both in handling the fuel and with the added safety for the engine. As Toluene is a pure hydrocarbon (C7H8), it will not yield any byproducts other than H2O and CO2 after burning and thus is safe for the entire emissions system (if you have any).

I disagree with the unpredictability of homebrew. Homebrew is precisely as predictable as the octane rating at the pump. That octane rating is the only variable that can not be verified (unless you happen to have a variable compression test engine in your garage). As for price, I'm at $2.10/gal for 100 Octane (non-oxygenated, high aromatic) homebrew. VP's northwest distributer is around a mile from my house and they want $5.00/gal for the same thing (they use Toluene to boost the octane and add the lube, dryers, and solvents).

My question is concerning the use of Xylene. Why do most racers use Toluene? Is it harder to cold start (require more preheat)? Is it not as popular because of availability? Price? safety?

 

[evelrod]

Well, Joe, I only have to take a couple of quotes from your post---
"---that means ABOUT 4 gallons." (emphasis mine)
"I think Toluene maintains it's octane---so I PRESUME it was still 114 octane." (emphasis mine)
"By my CALCULATIONS--- I was running 100 octane."(emphasis mine)
From this beginning you have based all the very meticulous work (down to the EXACT rpm, etc.) Not exactly the approach a qualified scientist or engineer would begin a project of this nature. It puts ?????? to ALL your results!

I am told by my fuel supplier that 100 and 110 unleaded Sonoco and 76 racing fuel is sold where ever they have dealers that handle race gas or by special order. Not the most convenient deal for all but, it IS available.

I am not nit picking in this. I have lost many engines in my youth using the exact methods you are using. If you do not wish to repeat history you need to improve your 'scientific method'. It will pay dividends(and $$$) in the long run by saving you your engine. You may be on the right track , I won't dispute that but, if you wish to 'build a tower, make sure it has a proper foundation'!

nuker---I sure would like to know where you get all your statistics. I live less than 1/2 mile from the west coast district office and distributor of VP and they just laughed when they looked at your post! (I don't use VP because, as you stated, it costs to much)
Oh yes, "most racers use toluene"! No, they don't. Not because it does not work, indeed, it does. They don't use it because the rules won't allow it. Even in SCCA fuel checks are mandatory after each race! Homebrew is for street racers and hot rodders. Works for me, just don't bring the stuff to a sanctioned event if you do not wish to be disqualified.

Rod

 

[nuker]

Well, Rod, pick yourself up a phone and hand it to your VP buddies because this is helarious.

VP Racing Feuls Northwest
151 Dietrich Rd.
Pasco, WA 99301
509-544-0306

$38.50/Pale of Perf unleaded
$276/barrel " " "

$319.48/barrel of C10

I do not dispute the availability of race gas. I also do not dispute the existence of oxygenated or leaded race gas.

"Oh yes, "most racers use toluene"! No, they don't" -Rod

I should have said aromatics instead of Toluene.

I found this arcticle for you to read

http://www.webpak.net/~marriott/gasoline.htm).

Note that Toluene has synonyms -mainly Methacide, Methylbenzene, Methylbenzol, Phenylmethane, and Toluol (that's from the MSDS incase you want to call me on that). If you read carefully, you will notice that aromatic hydrocarbons are used in virtually every fuel. Yes, there are other hydrocarbons, but the most popular is Toluene. The point is that common gas has a significant percentage of aromatics (section 4.13). So, if your running gasoline, your running Toluene or an equivelent. Yes Rod, I know that draggers use Nitro and not Toluene.

Now that we have talked about Toluene, is there anyone who can answer my question and reason for this post?

Post #1-Question: Are there any drawbacks to using Xylene over Toluene?

Reply #2- My question is concerning the use of Xylene. Why do most racers use Toluene? Is it harder to cold start (require more preheat)? Is it not as popular because of availability? Price? safety?

cheers

 

[drwebb]

I don't suppose it is an issue in a low-mileage race engine, but I suspect that such high aromatic content gasoline could lead to greatly increased combustion chamber deposits (CCDs) over the miles, and diluting the detergency of the pump gas likely will promote intake valve deposit formation and possibly even fuel injector fouling.

 

[patprimmer]

Re synonyms for Toluene

I don't doubt the MSDS synonyms, as the MSDS will cover correct and incorrect names, but without getting out my old chemistry books, you have named at least two DIFFERENT chemicals in the list

Tolunene is C7H14, or more precisely, C6H11-CH3. This is also correctly called Methylbenzene, by organic chemical systematic nameing standards

Toluol is C6H11-OH.

As far as I know, toluol is the better octane booster, and was the difference between the old (green)100 octane av gas and the (purple) 115 octane.

All petrol or gasoline (depending on where you come from) contains aromatics, certainly by accident, and probably by design, as aromatics are in petrol feedstock as impurities that cost extra to remove, and some are also useful fuels that help adjust the evaporation rate and octane rateing.

To the best of my knowledge, which may now be out of date, pump gas is a blend produced to a performance specification, not a formula specification. Avgas and raceing fuel are more tightly controlled by formulation specification.


Short chemistry lesson

Aliphatics are hydrocarbons with a linear carbon backbone

Aromatics are hydrocarbons with a cyclic carbon backbone, or ring structure. most essential oils have this ring structure, hence the name.

Benzene is a simple ring with 6 carbons and 2 hydrogens attached to each carbon

Phenyl is 3 benzene rings attached together, a bit like a small block Chevy head stud pattern, but with 6 instead of 5 studs. ie 6 + 4 + 4

Methyl indicates a CH3 group is attached (usually replacing a hydrogen)

Ol indicates a OH or hydroxyl group is attached, usually replaceing a hydrogen


Regards
pat

 

[nuker]

Pat, Thank you for clarifying my synonym statement. I made the poor assumption that the MSDS would only list the correct synonyms.

 

[Chumley]

OK Evelrod, I can't take it anymore, I'll chime in here. To see a chemical picture of Toluene which is C7H8 see this excellent site:

http://zarbi.chem.yale.edu/~matt/MOLECULES/144.html

You'll need to download the plug in so that you can
"tickle" the the molecule in 3D if you wish.

You can look at xylene, it's 2 isomers and all the other common hydrocarbons there too.

You can also look at this excellent site for more non marketing based information on toluene, xylene, benzene, trimethyl benzene, and all the other high octane hotties used in internal combustion fuels.

http://www.atsdr.cdc.gov/toxprofiles/tp56.html

Xylene and toluene are very similar chemically. 2 isomers of xylene have substantially higher octane ratings in both RON and MON than toluene however their boiling points are higher than toluene which means that using too much of it will lower the volatility of your fuel which might make cold starts a little tough especially in cold weather. Both chemicals are common components in regular gasoline. If you look up gasoline at the ATSDR site, it will confirm that. Too much xylene of one isomer may also crystalize out of the mix at lower temperatures with obvious results.

Both toluene and mixed xylene are available at your favorite local industrial chemical supply store should the "need" arise. The CAS numbers are available at the ATSDR site.

There's a great list of the common components in gasoline
and their octane ratings here:

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

See section 4.13

It's very common for gasoline blenders vary the mix of the
various components depending on the grade(octane), ambient
temperature, local laws, and based on what comes off the tanker. Each tanker can vary substantially depending on where the crude oil was sourced.

All the aromatic hydrocarbons which include toluene and xylene are heavy soot formers especially when running
rich and at lower combustion temps so beware. Theres more
that comes out the pipe, loads the engine oil, and, gunks up the combustion chambers than CO2 and H2O when you use too much of it. Gasoline blending isn't that easy.
If it was, we would all be doing it!!!

Happy New Year and happy reading. I hope this is helpful.


Chumley

 

[GregLocock]

Good to see you back.
Cheers

Greg Locock

 

[evelrod]

Yeah, Chumley. Greg and I have wondered how long it would take to get you back. Glad to hear from you. Now you can post a short bio in your profile so we can better know where your "AT".

As to the homebrew deal---I am not a chemist, indeed, in college a BSME only required that I PASS chem. LOL
BUTTTTTTTTTTT---I stick by my previous posts as I AM old enough to have tried all this with the expected variety of results, good and bad. I am just finishing up on $3000 worth of upgrades to the &quot;Money Pit Mini&quot; ($27,000 total so far!) and when it comes to adding the appropriate fuel <I AM GOING TO MIX UP SOME HOMEBREW?> NOT EVEN!!!!!!!

Rod

 

[patprimmer]

I should have dusted of the old chemistry books before shooting off my mouth.
I forgot about the double bonds in the benzene ring Regards
pat

 

[nuker]

Chumley
Thank you for the very helpful and informative post. I plan on starting at 10% added HC with no aim of mixing over 30%.

cheers

 

[jhillyer]

To: patprimmer (Automotive)
D@mned there _are_ sensible people with interest beyond conjecture.

Thank you for the raw facts, especially about the difference between toluene and toluol. I smelled and burned both and seen the distinction since I was a young kid, so I knew they were at least structurally different, but I never researched it until now.

I'm running a blend. I'm at 10.6 compression in a Pasast's Audi ATQ (v6 2.8l), and experimenting. I've noticed amazing difference between a piston car at 8.x compression and 10.6 with fuel, as I also see compared with the rotary -- '87 Turbo II RX-7 (I think it's at 8.6 or so (research it). Also, huge diff with RPM. One blend is smooth over most the RPM, another is incredible at high RPM, another is great at low RPM. At this stroke, I like the longer burns.

I'm wondering if a lithium suspension is bad for my sensors and cat.

Meanwhile, this month in the retail pump Crapifornia 91 octane, in a base of 3 liters ethanol w/ 5% methanol, and a witches brew of MMT*, toluene, acetone, xylene, meth-eth-ketone, 2-butoxy-ethanol (why?), & isopropanol.

*Methylcyclopentadienyl Manganese Tricarbonyl: no, I've not memorized this one yet; the MMT is quite inexpensive, even at retail.

Caution me if I'm risking something. Oh, of course I don't use this on public roads (wink).

 

[patprimmer]

Sorry jhillyer

I am a polymer chemist (re plastics) not a fuel chemist. There are some overlaps re the fact that most plastics are based on oil feedstock, but I do not have detailed knowledge of the finer points of fuel formulation, other than some anecdotal evedience, a lot of years hotrodding, a general knowledge of related chemistry, and what I read here.

The links chumley listed are the best sources of information I have found so far Regards
pat

 

[jhillyer]

joereitman (Automotive), evelrod (Automotive)

Joe, keep it up, buddy. I like your work. You _are_ scientific, learning through experimentation (goons say 'empirical study'), and everyone needs to improve. With you knowing to look for knock, and monitoring it, operate sensibly and do regard other's knowledge. But, go go go. Right-on.

Increase caution when approaching the unknown, I want to read more of your experience.

Nice work.

 

[sciguyjim]

Patprimer,
In refrence to your Jan 16 post, toluol is indeed the same as toluene. It's just an outdated name which most companies don't use anymore. The C6H5-OH you list (corrected for the proper number of hydrogens) is actually phenol. This is an acidic, sharp smelling compound that used to be used as a bactericide long ago, and it will eat away at your skin if concentrated enough. Its smell can't be confused with toluene.

Also, toluene and xylene will definitely not crystalize out of solution no matter how much is used. Their freezing points are too low, and the fact that they are mixed with the thousands of other compounds in gasoline makes the mixture resistant to freezing. Many other compounds in gasoline are solid at room temp, but again, mixing hundreds or thousands of them together makes the mixture a liquid when in fact all the ingredients, by themselves, are solid. This is because each can dissolve to some extent in each of the others. Toluene and xylene are the 2nd and 3rd smallest aromatic molecules in gasoline, so their freezing points will be lower than most other things in the complex gas mixture.

 

[drwebb]

&quot;Many other compounds in gasoline are solid at room temp,&quot;

-er, I think you are confusing gasoline with diesel fuel in this respect.

 

[sciguyjim]

Drwebb,

I'm sure about the solids in gasoline. They remain in liquid form because it is a complex mixture. If purified they would solidify. I spent 8 years in the petroleum industry analyzing gasoline-like petroleum fractions, identifying the possible molecular structures for each compound with a given number of carbons. My lab had dozens of these compounds in pure form which we used to calibrate our instruments. Aromatics with 10, and possibly less, carbons can be solid at room temp, such as naphthalene, which has 10 carbons. There can be compounds with over 40 carbons in gasoline, even though gasoline is a low boiling product. This is also a result of the complex mixture. It has a boiling range rather than a single boiling point like a pure chemical would. The quantity of these high molecular weight compounds is low, <0.01%, but they're there.