Rocket fuel FAQ
Copyright ã 1999,2000 by Eliot Lim
This paper may be
freely distributed, provided it is distributed in its
entirety
Last revised: February 8, 2000
Toluene
- R+M/2...114
- Cost...$2.50/gal
Mixtures with 92 Octane Premium
- 10%...94.2 Octane
- 20%...96.4 Octane
- 30%...98.6 Octane
Notes: Common ingredient in Octane Boosters in
a can. 12-16 ounces will only raise octane 2-3 *points*, I.e. from
92 to 92.3. Often costs $3-5 for 12-16 ounces, when it can be
purchased for less than $3/gal at chemical supply houses or paint
stores.
Background
In late 1997 I became the lucky owner of 1 out of 150 1998
Porsche 993 Targas, the very last of the air cooled classics. As I
drove it through the winter of 1997 and into the spring of 1998 I
noticed that the engine lost some of its sweetness. Since this
behavior was strongly related to ambient and engine temperature I
suspected that the engine electronics were retarding its ignition
timing due to insufficient fuel octane.
I started experimenting with octane boosting by first adding
small doses of over the counter octane boosters and noticed
immediate improvement. The engine ran smoother and quieter, was more
willing to rev and had noticeably sharper throttle response. The
octane shortage was confirmed by the sticker on the filler cap that
stated that 93 octane fuel was needed. Since the highest octane
rated fuel that was commonly available in Washington state is 92, I
decided to investigate long term cost effective octane boosting so
that I could fully enjoy the performance that this car offered.
My other car at the time, a 1990 Audi V8 quattro had an even more
dramatic response to octane boosting. I managed to convince a few
good friends to try it and the reaction was overwhelmingly positive.
When I attempted a broader based dissemination of this exciting
find, I was greeted largely by broad unyielding skepticism and
plenty of FUD (fear, uncertainty, doubt) regarding toxicity, safety
and engine damage. There arose a need to more clearly explain the
details of octane boosting, hence giving rise to this article.
Q: Will my car benefit from octane boosting?
A: Consumer organizations have effectively emphasized the larger
markups that oil companies charge for high octane gasoline, implying
that for most vehicles higher octane fuel is a complete waste of
money. It has been quite a long time since the consumer alert was
issued. Since then engine technology has evolved greatly, while
people's perceptions generally have not.
Modern vehicles now use computerized engine management systems
that can react to engine knock and retard ignition timing if low
octane fuel is being used. Consequently cars are now being
manufactured with very high compression ratios that appear to give
good fuel economy and at the same time good performance. This
combination does assume that fuel of adequate octane is being used.
Q: Why bother to boost octane at all since my engine can run just
fine on lower octane fuel?
A: For a high compression engine to run on low octane fuel, the
engine management system will need to retard the ignition timing to
prevent preignition or pinging. Retarding the ignition timing means
that the firing of the spark plug is delayed until a later moment in
the compression stroke. It does not take much to see that a later
onset of combustion means that the combustion is less complete,
which in turn mean less power and poorer fuel economy. It is
possible that the casual driver will still come out ahead in terms
of saving money by using low octane fuel, but the retarded ignition
advance also means a rougher running engine and a much duller
throttle response. Thus octane boosting is not necessarily of
interest to all motorists but rather the enthusiasts.
For turbocharged or supercharged engines, insufficient octane
will also lead the engine management system to curtail the amount of
boost which in turn defeats the purpose of these engines.
Q: How did you discover using toluene?
A: Someone came across a web page that described various DIY home
brew octane booster formulas. One of which used toluene as its main
ingredient. As a Formula 1 racing fan of many years, I recalled that
toluene was used extensively in the turbo era in the 1980s by all
the Formula 1 teams. The 1.5 liter turbocharged engines ran as much
as 5 bars of boost (73 psi) in qualifying and 4 bars (59 psi) in the
actual race. Power output exceeded 1500bhp, which translates into
1000bhp/liter, an astronomical figure.
A motorsports journalist, Ian Bamsey, was able to obtain Honda's
cooperation for his book "McLaren Honda Turbo, a Technical
Appraisal". The book documents the key role that the toluene fuel
played in allowing these tiny engines to run so much turbo boost
without detonation. The term "rocket fuel" originated from the
Formula 1 fraternity as an affectionate nickname to describe its
devastating potency. Thus I concluded that I should focus my
research on using toluene for my octane boosting project.
Individuals with good long term memory will recall that when
unleaded gasoline was first introduced, only low octane grades were
available. While it is not entirely clear that high octane super
unleaded gas came about as a result of the advances in fuel
technology in Formula 1, there is every reason to suspect that this
is indeed the case, since many of the major oil companies were
involved in the escalating race to develop increasingly potent
racing fuel during this era.
Q: Why do you think toluene is better than other types of octane
boosters?
A: Several reasons:
Mindful of the evil reputation of octane boosters in general,
toluene is a very safe choice because it is one of the main octane
boosters used by oil companies in producing ordinary gasoline of all
grades. Thus if toluene is indeed harmful to your engine as feared,
your engine would have disintegrated long, long ago since ordinary
pump gasoline can contain as much as 50% aromatic hydrocarbons.
Toluene is a pure hydrocarbon (C7H8). i.e. it contains only
hydrogen and carbon atoms. It belongs to a particular category of
hydrocarbons called aromatic hydrocarbons. Complete combustion of
toluene yields CO2 and H2O. This fact ensures that the entire
emission control system such as the catalyst and oxygen sensor of
your car is unaffected. There are no metallic compounds (lead,
magnesium etc), no nitro compounds and no oxygen atoms in toluene.
It is made up of exactly the same ingredients as ordinary gasoline.
In fact it is one of the main ingredients of gasoline.
Toluene has a RON octane rating of 121 and a MON rating of 107,
leading to a (R+M)/2 rating of 114. (R+M)/2 is how ordinary fuels
are rated in the US. Note that toluene has a sensitivity rating of
121-107=14. This compares favorably with alcohols which have
sensitivities in the 20-30 range. The more sensitive a fuel is the
more its performance degrades under load. Toluene's low sensitivity
means that it is an excellent fuel for a heavily loaded engine.
Toluene is denser than ordinary gasoline (0.87 g/mL vs.
0.72-0.74) and contains more energy per unit volume. Thus combustion
of toluene leads to more energy being liberated and thus more power
generated. This is in contrast to oxygenated octane boosters like
ethanol or MTBE which contain less energy per unit volume compared
to gasoline. The higher heating value of toluene also means that the
exhaust gases contain more kinetic energy, which in turn means that
there is more energy to drive turbocharger vanes. In practical terms
this is experienced as a faster onset of turbo boost.
Chevron's published composition of 100 octane aviation fuel shows
that toluene comprises up to 14% alone and is the predominant
aromatic hydrocarbon. Unfortunately composition specifications for
automotive gasoline is harder to pin down due to constantly changing
requirements.
Chevron's web site also describes the problems of ethanol being
used in gasoline.
MTBE was heavily touted as a clean additive several years ago,
and became a key ingredient in reformulated gasoline that is sold in
California. But recently new studies arose that showed that MTBE was
far more toxic than previously imagined. Organizations such as
oxybusters have formed around the country to eliminate the use of
MTBE in gasoline and several states, including California have
passed new laws to eventually outlaw MTBE.
Q: How much toluene should I use per tank of gas?
A: Octane ratings can be very easily calculated by simple
averaging. For example, the tank of an Audi A4 1.8TQ is 15.6
gallons. Filling it with 14.6 gallons of 92 octane and 1 gallon of
toluene (114 octane) will yield a fuel mix of:
(14.6 * 92) + (1 * 114) / 15.6 = 93.4
The Audi A4 1.8T is a good example of a car that has very high
octane needs if it has been modified to produce more turbo boost.
The base compression ratio of this car is a very high 9.5:1 and when
an additional 1 bar (14.7 psi) of turbo boost is applied on top of
it, the resulting effective compression ratio is way beyond what 92
or 93 octane fuel can ever hope to cope with. Most modified 1.8Ts
running without octane enhancement are running with severely
retarded ignition timing and boost.
Q: Will toluene damage my engine or other parts of my car?
A: A 5 or 10% increase in the aromatic content of gas will most
likely be well within the refining specifications of gasoline
defined by ASTM D4814, which specify an aromatic content of between
20% and 45%. What this means is that if the 92 octane gas that you
started off with had an aromatic content of say 30% and you
increased it by 10% to 40% you would still be left with a mix that
meets the industry definition of gasoline. So the above question
would amount to: "Will gasoline damage my engine or other parts of
my car?"
Even in the unlikely event that the 92 octane gas has a aromatic
content of 45% the resulting mix would still be within the bounds of
gasoline sold in other countries.
Q: Isn't toluene an extremely toxic substance?
A: The common perception of toluene's toxicity far exceeds
reality. Fortunately there is an ample body of information available
that specifically addresses this question. Toluene is more toxic
than gasoline but it is certainly not agent orange or cyanide.
US Environmental Protection Agency Chemical Summary
US Agency for Toxic Substances and Disease Registry (ATSDR)
National priority list of toxic substances
Note that the ATSDR also rates gasoline as a hazardous substance.
Mobil's spec sheet for toluene even goes as far as saying that
"Based on available toxicological information, it has been
determined that this product poses no significant health risk when
used and handled properly."
Q: Isn't toluene an active ingredient of TNT (trinitrotoluene)
and is thus deadly?
A: In the same way that cotton wool is the base ingredient of
nitrocellulose (guncotton) which in turn is the main ingredient in
modern smokeless gunpowder. Using this reasoning one could conclude
that cotton wool is a deadly substance. This question reflects a
poor understanding of basic chemistry but unfortunately it has been
asked often enough.
Q: How much does toluene cost, and where can I buy some?
A: $10/gallon in a one gallon can at a hardware store, about
$6/gallon in a 5 gallon can from a chemical supply or paint store,
or $3/gallon in a 55 gallon drum from a chemical supply warehouse.
Q: Can I just dump in 100% toluene into the tank like the F1
racers? vroom vroom vroom
A: First of all, the F1 racers did not use 100% toluene, but 84%.
The other 16% in their brew is n-heptane, which has an octane rating
of zero. The reason for this strange combination is because the F1
rocket fuel was limited to the rules to being of 102 RON octane. The
n-heptane is "filler" to make the fuel comply with the rules.
Because toluene is such an effective anti knock fuel it also
means that it is more difficult to ignite at low temperatures. The
Formula 1 cars that ran on 84% toluene needed to have hot radiator
air diverted to heat its fuel tank to 70C to assist its
vaporization. Thus too strong a concentration of toluene will lead
to poor cold start and running characteristics. I recommend that the
concentration of toluene used to not exceed what the engine is
capable of utilizing. i.e. Experiment with small increases in
concentration until you can no longer detect an improvement.
Q: Why not simply use racing gasoline or aviation fuel?
A1: Most types of aviation fuel have very high lead content,
which would rule out cars equipped with catalytic converters. Most
piston engined aircraft burn leaded fuel. Also aviation fuel has a
very different hydrocarbon mix to optimize volatility properties at
high altitude.
A2: Racing gasoline could be a much more convenient way to run
high octane fuel compared to having to constantly mix in toluene
with each fill up. There are, however a few caveats:
You don't know for sure if you are really getting what is being
advertised. You should find out if the fuel inspectors verify the
actual octane of the racing gasoline in addition to ordinary
gasoline. If you paid $3/gallon and only got 94 or 95 octane instead
of 100 octane you may conclude erroneously that your car does not
benefit from octane boosting.
You don't know what octane boosters are used in the racing
gasoline. The worst case scenario is buying leaded racing gasoline
without knowing it. Unleaded racing gasoline may still contain
damaging octane boosters like MMT or methanol. A very high alcohol
content will lead to fuel line erosion, accelerated fuel pump wear,
very poor fuel economy and possibly lower performance, as alcohols
have a less impressive MON rating than aromatics.
It takes smaller quantities of toluene to achieve the same octane
boost compared to 100 octane racing gas. I have not seen unleaded
racing gas for sale that exceeds the octane rating of toluene.
Since toluene is not officially sold as a fuel, gas taxes do not
apply. Also racing gasoline tend to have higher markups being of
interest to the performance minded enthusiast and thus is very
likely to be more expensive to buy and use long term than toluene,
which is typically used in more mundane applications like paint
thinner.
Q: Ok, what is the catch?
A: It should be mentioned that in the US, efforts are underway to
reduce the aromatic content of gasolines in general as a higher
aromatic content leads to higher benzene emissions. Benzene is an
extremely toxic substance. However it should also be noted that the
proportions that is being discussed in this FAQ is relatively small
and in the grand scheme of things is probably insignificant.
Moreover, the industrial standard for defining gasoline composition
allows plenty of leeway in aromatic content and the proportions
present in US gas is already lower than most other countries. I
therefore feel that the information provided here is useful to a
performance minded car enthusiast while not being significantly
detrimental to the environment.
Q: What safety measures can you recommend in handling toluene?
A: The following is a good reference guide:
Q: Do you have testimonies of others who have tried this?
A: Some samples of feedback is reprinted with the names removed
below. You may contact me if you wish to contact the respondents
directly.
Since I didn't have any reference point for how much to use, I
dumped about a half gallon of this mix into a mostly empty tank (the
GT has a 16 gallon tank) and then filled up with Chevron 92 octane.
I didn't get to drive the car until PIR the next morning, (my GF
doesn't like the 200; it's too big) but the report was that there
was no change for a mile or so, and then all of a sudden, the engine
seemed to smooth out and became quite eager to rev and run.
Well, by that calculation, I only managed to bump the octane to
just shy of 93, but it seemed to make a big difference. I ran the
car hard all day, (for reference, it's got an '87 MC turbo motor,
K26, 12psi boost, and currently no intercooler) and even at 12
pounds of boost, I never once felt the ECU backing the timing off.
Granted, the ambient temps never got above 50, and my water and oil
temps were rock solid. (Oil just pushing above 100C)
The only cars that I had to get out of the way for was an Integra
Type R and a couple of race-prepped P-cars. I even managed to lap
the NSX once! It was a really good day!
Okay, kids, gather round. This is important: we spend lots of
money for our car, lot of money modifying and taking care of it,
lots of effort and pride in owning it. So if someone comes along and
proposes to give you something that would increase your enjoyment in
driving by exponential measures and it would only cost you two or
three bucks per tank of gas, would you be suspicious like the 100MPG
carburetors? Would you listen long enough to real-life testimonies
to consider this improvement for yourself?
Well, this is the case for Toluene and what it can do for your
V8Q if you been using anything less than 92+ octane. Get some.Try
it. No harm, no risk. Use about 24-32 ounces per 1/2 to full tank.
You will not look debonair. You will have to suspend your "cool"
look. You may want to try this alone. YOU WILL HAVE THE SHITTEST,
MOST PLASTER, GRIN ON YOUR FACE YOU HAVE EVER HAD! It won't come
off. You'll tell the kids, daddy has his own "transformer". It will
be like a new car...no, better than new!
I took my family out to dinner tonight and could hardly keep from
dropping it into manual and showing off like some teenager (I don't
think my 17 year old daughter was inpressed). I wanna see some posts
here with personal experiences by you guys using this stuff - I
wanna know that my car is normal and hasn't been deprived ever since
I've owned it.
I did the Rocket Fuel thing tonight on my Extremely Modified
5KCSTQ that runs 24 PSI of boost... And I can tell you not only does
my ears and my butt say that the Rocket fuel is doing it's job but
My ECU Data logger that gives me the timing value for all 5 cyls
says it's working too.
Before Rocket Fuel I was running full retard (14 Deg of timing)
on boost and would still on occasion get some knock, now I'm getting
timing numbers around 22 Deg's with ZERO knock ever. I'm running 2
Gallons of Toluene 7oz of ATF and 17.5 gals of 93 oct gas for a net
octane of 95.15. I'm next going to try 3 Gallons of Toluene (96.23
Octane) to see what timing numbers I get.
After being convinced that my car was running below it potential
- Owners manual recommends octane rating between 95 and 99, although
it_will_run on octane as low as 91 - I stopped by Sherwin Williams
and picked up a gallon. It was on sale for $5.85! Anyway, head to
the chevron and pour a half gallon into the tank before pumping in
the premium. The car took 16 gallons so there was still 4 gallons in
the tank. I take off....nothing (obviously burning the fuel still in
the lines). About 10 miles later, HOLY SH*****T!!!!!!!!!! It really
does everything advertised by the list. It is so much more
responsive from a stop and low speed, it really is impressive. I
would agree with the sentiment that it feels like a totally
different car.
For the non believers, you really should try to get some higher
octane fuel in your tank, whether through the use of Toluene or not.
The owners manual recommends 95 to 99 octane** for optimal
performance. With the half gallon of Toluene I added to the 92
octane, I was only running at approximately 92.6 octane and the
difference was simply amazing!
If you haven't tried it, do yourself a favor and give it a whirl
- I swear you'll be impressed.
(**note: this person confused RON octane
mentioned in the owners manual with R+M/2 octane that is sold in the
pump. 95-99 RON is roughly equivalent to 91-94 R+M/2)
After trying rocket fuel for two weeks, I can only say I love it.
The first tank, however, was a disappointment. I think I did not
add enough of rocket fuel for the first tank. So I added a little
more for my second tank, it ran better but not too much improvement.
Then on my 3rd tank, what a difference, the car feels like a
"Rocket" now, even though it is an "Auto". I always feel there is
more power available for me.
I think for my 1st and 2nd tank, I did not have enough rocket
fuel in it, even though I added one gallon per tank. Then, on my 3rd
tank, I had enough because of the left overs from my 1st and 2nd
tank. (I fill up my tank at about the 1/4 mark). Now I only have
about 2 gallons of rocket fuel left, I better get more now!!! :-)
Reference materials:
1. Gasoline FAQ
2. McLaren Honda Turbo - a technical appraisal
Ian Bamsey
ISBN 0-85429-840-1, published 1990
3. Chevron's excellent Motor Gasolines Technical Review
By Part Type
By Part Number
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