Octane made easy: Do-it-yourself race fuel

[Ojref]

Octane rating is an averaging expression of the overall flame-front expansion rate from ignition considering the stoichlometric ratio and the compression ratio, among other things. Suffice it to say that if you are noticing detonation issues or you have built the engine for higher compression, you can benefit from higher octane fuel.

An easy way to obtain a higher octane product fuel if you live in an area that doesn't sell highly rated fuel is to obtain (pure!) Tolulene (paint stores like Sherman Williams sell this in 1, 5, 10 or 55 gal) and mix with a volume of your source fuel using this formula:


((a *b) + (c * 114)) / (b+c)=f

Toluene rated (114)
A= Source fuel octane rating
B=Quantity of source fuel (gallons)
C=Quantity of tolulene (gallons)

F=Product fuel (gallons)

You could put this into a spreadsheet and play with the numbers to see what it would take to produce the amount of octane you desire. For example, If I had a tank of 10 gallons rated 93 octane, to produce 95 octane fuel I would have to mix in 1.1 gallons of Tolulene. Some would comment that Xylene is higher (rated 116) but Xylene is harsh on rubber parts. Please do not do this or you might be out some expensive carburetor parts.

Tolulene is a component of modern fuel, and is much better to use than AV gas, which contains lead and other chemicals to change its vaporization constant at different altitudes / pressures, which can again cause problems for you.

 

[Vic]

Say hello to tolulene and goodbye to throttle response.

There's a lot more to race fuel than just high octane.

 

[bscottr]

Standing by for Dr. Combustion’s response. :)

 

[Faded]

Originally posted by Vic
Say hello to tolulene and goodbye to throttle response.

Yea, found this one out for myself. I experimented with it and when used in large(er) quanties the throttle response really suffers.

 

[factoryRM]

Octain booster always works, its cheaper too.

 

[Rich Rohrich]

Originally posted by factoryRM
Octain booster always works, its cheaper too.

WELL, I guess he told you guys. :confused:
Case closed. :)

 

[Faded]

Originally posted by Rich Rohrich
Case closed. :)

Not yet, now the question is which kind? :think: I can get that STP stuff for like $1.39 for 12oz at Walmart... :confused:

 

[Senior KX Rider]

Originally posted by factoryRM
Octain booster always works, its cheaper too.

HA!!!! you guys have been throwing away a lot of money on race fuel. All this time ya should have been makin yer own :laugh:

 

[Ojref]

So how many of you fine scholars out there work in the petrochemical industry?

 

[Ojref]

Originally posted by Faded


Yea, found this one out for myself. I experimented with it and when used in large(er) quanties the throttle response really suffers.

:rolleyes:

 

[Ojref]

Originally posted by Vic
Say hello to tolulene and goodbye to throttle response.

There's a lot more to race fuel than just high octane.

I've just informed the senior lab chemist of your findings. He will address the executive board tomorrow and suggest we go pure base heptane. We'll pull MTBE as well for grins. Adjust your timing and compression ratios accordingly.

 

[bclapham]

Originally posted by Ojref
So how many of you fine scholars out there work in the petrochemical industry?

i used to, indeed i spent a whole year blending tanks and running countless octane and cetane ratings on fuels, but now, alas, i am merely an Assistant Professor of Organic Chemistry at one of the US's leading biochemical research institutions, so it might not be unconcievable that i know the odd thing or two about chemistry. :thumb:

and by the way, putting toluene in gas only serves to make the bike run like crap, case closed, again! increased amounts only served to make the throttle response yet worse, but i will conceed, it didnt detaonate! :laugh:

go try some MTBE or isoprene and get back to us! :thumb: maybe then we can discuss flame fronts, oxygen content, distillation curves......... :thumb:

 

[bclapham]

Originally posted by Ojref
I've just informed the senior lab chemist of your findings. He will address the executive board tomorrow and suggest we go pure base heptane. We'll pull MTBE as well for grins. Adjust your timing and compression ratios accordingly.

maybe you can ask him to inform you on the theories about the volatlity of a fuel and its relationship to throttle response in high RPM motorcyle engines when you are there!

 

[Rich Rohrich]

This is TOO MUCH fun :)

I get such a thrill out of watching the members of DRN help another member see the light. :laugh:

FYI, Ojref's Profile says he's a Network Admin. So I guess he'll also be able to help us to figure out the minimum octane requirement of an Apache Server. :yeehaw:

 

[426racer]

Toluene? What about pure alky? And what about RVP? I make gasoline for a living. The toluene your talking about isnt't the same at the additive toluene. You can't purchase pure toluene on the open market. So be careful of attempting this.
Just take 4 gallons of 89 oct. add one black bottle of 104 oct, and get 97-99 oct. I know this by running it through a knock engine. Alot more accurate.
Just my two cents worth.

 

[bscottr]

Thought so. :thumb:

:)

 

[Senior KX Rider]

:scream: :scream: :scream: :scream: We need one for these lttle emoticon guys with a head that explodes :)

 

[nephron]

lol, Rich--just unleash and quit holding back.

It's bad for your health, man.

I wouldn't put toluene in my Deere--oh, wait. I do. It's diesel. :silly: Great stuff. ?methylbenzene/phenylmethane?--however you put it, it all drips down to one thing: aromatic hydrocarbon, grease, drool, droolish riding.

Isn't that stuff made not only 'not' from crude, but from tar oil, the 'crude' of 'crude'?

While we're on the topic, Bruce--I was looking at Isoprene in the Merck Index, and was sort of pondering its appearance. It looks like it's produced by either heat lysing rubber or dehydrogenation of similarly structured aliphatic hydrocarbon. This stuff is small, it's hydrocarbon only, and it's got a couple double bonds (excuse my old school b.s. chemistry language :worship: ).

CH2=C(CH3)CH=CH2

What makes this stuff so special? You said NUTEC may use it? Is it some combination of being a relatively 'small' compound, all aliphatic, 50% dehydrogenated (and unstable--extremely capable of oxygenation)?

Where are we here, guys. I'd like to know. I'm certainly not a fuel chemist, but am interested.

 

[Rich Rohrich]

Is it just me or is there a remarkable similarity between ojref's post and this article http://www.elektro.com/~audi/audi/toluene.html .


He might not know much about fuel but it seems clear that he can work a search engine. LOL :)

 

[Faded]

Originally posted by Ojref


:rolleyes:

What's your experience w/toluene? :eek:
:moon:

 

[holeshot]

Originally posted by Ojref
using this formula:


((a *b) + (c * 114)) / (b+c)=f

Toluene rated (114)
A= Source fuel octane rating
B=Quantity of source fuel (gallons)
C=Quantity of tolulene (gallons)

F=Product fuel (gallons)

This formula may be good for an estimate, but it's not easy to predict how chemicals will mix, so mixed fuels and additives will not necessarily produce a linear scale with regards to octane (i.e. - mixing 5 gals of 95 octane fuel with 5 gals of 105 octane fuel will not likely produce exactly 100 octane fuel).

I've worked in the petrochem engineering industry for 25 years, but you could fit all my knowledge of organic chemistry into a thimble. Not all of us are chemists, but sometimes I think guys like like Bclapham are around remind me of my indecisions decades ago (and to torture me) :)

Anyway, everyone knows that the lead chemistry lab guy doesn't hang out with the board of directors (unless they ride together). :silly:

 

[bclapham]

sorry guys, i just read my post, i am beggining to sound like a pompus old fart!

 

[Rich Rohrich]

Originally posted by bclapham
sorry guys, i just read my post, i am beggining to sound like a pompus old fart!

Don't bet on it Bruce. :thumb:

Sometimes a situation arises where someone feels compelled to show their ass in public, and it's nice to have you there with a scientifically valid boot to kick it. :moon:

 

[Mudboy]

I'm certainly no chemist or expert but I've ridden a lot and learned a lot over the years on this site. Correct me if I'm wrong, but for the VAST majority of riders/bikes out there simply getting your jetting right will do more than race gas. We've got one place in town that sells 93 oct. and I could tell no diff. between that and VP Race Gas at the dunes where I ride where you are always wound up and on the pipe. I did spend a lot of time getting my jetting as close to perfect as I can. My point is race gas is overrated if you're not running a heavily modded 4 stroke. Just my 2c....

 

[Faded]

Originally posted by Mudboy
My point is race gas is overrated if you're not running a heavily modded 4 stroke. Just my 2c....

Mudboy, I think this (next few re:'s) is going to hurt...