Prasith32

Hi,

I was just wondering cuz this situation might happen to me with work. What can I do if my car is tuned for 93 octane and I live in 93 octane areas but will be in california for 3 - 6 months. I can only get 91 octane in California right?

Do I have to buy race gas and mix it in? What is octane booster? Is it safe? Anybody knows or have solutions?

I have heard various solutions involving getting the ecu reflashed for the move but I would not want to do that for such a short time.

Thanks.

Prasith

steve s

u can add octane boosters, they should sell them at any local auto store... there really isn't that much of a problem...u will lose a bit of performance with 91 instead of 93... unless u have specially tuned engine, it should be fine. i don't think mb has certified it's engine to work outside cali and inside cali... unlike some of nissan's engine which do...and produce different power outputs...

xyzpl

Actually, you can buy 100 octane unleaded gas from Unocal 76 in a few selected stations.

If you looking for leaded gas, it goes up to 118!!!

steve s

hmm...only one i saw was a few 76 pumps with varying octane ratings over 93 at sears point...

xyzpl

Here you go Steve, maybe this will help you find them. they are not cheap....

http://www.cosbyoil.com/racegas.htm

E55AMG99

Union 76 still sells 100 octane at selected stations. Go to their website for locations. Also, if you want to use octane boosters, go to the hardware store and buy Tolulene which is 114 octane. Trust me. It is aready a major component in both gasoline and octane boosters and is no more harmful to you or your car than both.

ronnie0738

I believe it's toluene, correct? You can get it real cheap at any chemical warehouse or laboratory...its a common organic solvent. As long as you dont add to much (over 10% of your pump gas volume), you'll be ok.

E55AMG99

Tolulene is a common mispelling for Tuluene :p

F1 race teams back inthe 80's ran as much as 80% Toluene in their tanks! I've gone as high as 25% in my Corvette before I stopped noticing an improvement.

Vadim @ evosport

Toluene is around 97-98 ROM.

So to achieve any kind of meaningful increase in octane number will require several gallons of toluene per gas tank.

It is also a rubber solvent. Very good one, indeed.

None of the O-rings or other rubber parts in MB fuel system are designed to withstand toluene.

Use it at your own risk.

E55AMG99

I don't see how this can be possible. Pump gas can normally contain up to 30% aromatics in California and 40% nationwide. Toluene is 100% aromatic and very high in octane (I remember 114 but have recently read no lower than 104). Most refineries use it to make premium fuels with higher octane. Adding another 10-20% to a tank of gas is not out of the range of what one might find in gas from the pump. 2 gallons in a 20 gallon tank of 91 octane is sufficent quantity to raise octane 1.5-2 points.

I have heard that high octane gasolines made with LITTLE toluene react better to additional Toluene than those with a high content to begin with.

Vadim @ evosport

Toluene is available in different octane ratings. Look at the link below.

Toluene Octane Chart

Do you know which one you will get at local Home Depot? Not likely it will have an octane rating label on the side. If it is cheap stuff rated at 65.1 than you are going in the wrong direction.

This company below makes custom fuels. One of the tests it does is to make sure that the rubber in the fuel system is not adversely affected. How do you know how much toluene, of what grade will still be safe?

Test for rubber compatability

Unocal now sells 104 UL at many stations. You better of using them.

ronnie0738

i believe pump gas has 2 classes of aromatics: benzene and what they call non-benzene "aromatic" compounds or just the aromatics. There are about 33 different aromatics in gasoline. Benzene is around 1%(v/v) & the remaining aromatics are probably around 35%(v/v) according to reports. Here are some:

Benzene & Derivatives

Other aromatics:
Toluene
Xylene
Naphthalene
&Derivatives

Methyl-tert-butyl-ether (MTBE)
Hydrocarbons (Hexane, Heptane, Octane, Isooctane, Decane, Indan, Dodecane)

I dont know the percentage of each aromatic compound added, but there might not be as much toluene in gas as you might think.

E55AMG99

While I agree that the best thing to do is buy 100-104 fuel at the pump, some of your information is not 100% correct. The first link you supplied is for "reference fuels" that are made from Toluene and blended with specific amounts of other products like Heptane. These fuels are NOT available for use in motor vehicles. They use them to calibrate commercial fuels that are for public use, hence the name "reference". Pure Toluene (99+%) is 124 RON to which Heptane (zero octane rating) is added in order to obtain lower octane reference fuels.

The second link only says they tested Toluene for rubber swelling. I don't see the results.

You might not be able to follow this easily but this chart shows the breakdown of gasoline components and their characteristics (RON, MON, Boiling Point, Density, Auto Ignition Temperature)

15% n-paraffins RON MON BP d AIT
n-butane 113 : 114 : -0.5: gas : 370
n-pentane 62 : 66 : 35 : 0.626 : 260
n-hexane 19 : 22 : 69 : 0.659 : 225
n-heptane (0:0 by definition) 0 : 0 : 98 : 0.684 : 225
(you would not want to have the following in gasoline, so you would never blend kerosene with gasoline )
n-octane -18 : -16 : 126 : 0.703 : 220
n-decane -41 : -38 : 174 : 0.730 : 210
n-dodecane -88 : -90 : 216 : 0.750 : 204
n-tetradecane -90 : -99 : 253 : 0.763 : 200

30% iso-paraffins
2-methylpropane 122 : 120 : -12 : gas : 460
2-methylbutane 100 : 104 : 28 : 0.620 : 420
2-methylpentane 82 : 78 : 62 : 0.653 : 306
3-methylpentane 86 : 80 : 64 : 0.664 : -
2-methylhexane 40 : 42 : 90 : 0.679 :
3-methylhexane 56 : 57 : 91 : 0.687 :
2,2-dimethylpentane 89 : 93 : 79 : 0.674 :
2,2,3-trimethylbutane 112 : 112 : 81 : 0.690 : 420
2,2,4-trimethylpentane 100 : 100 : 98 : 0.692 : 415
( 100:100 by definition )

12% cycloparaffins
cyclopentane 141 : 141 : 50 : 0.751 : 380
methylcyclopentane 107 : 99 : 72 : 0.749 :
cyclohexane 110 : 97 : 81 : 0.779 : 245
methylcyclohexane 104 : 84 : 101 : 0.770 : 250

35% aromatics
benzene 98 : 91 : 80 : 0.874 : 560
toluene 124 : 112 : 111 : 0.867 : 480
ethyl benzene 124 : 107 : 136 : 0.867 : 430
meta-xylene 162 : 124 : 138 : 0.868 : 463
para-xylene 155 : 126 : 138 : 0.866 : 530
ortho-xylene 126 : 102 : 144 : 0.870 : 530
3-ethyltoluene 162 : 138 : 158 : 0.865 :
1,3,5-trimethylbenzene 170 : 136 : 163 : 0.864 :
1,2,4-trimethylbenzene 148 : 124 : 168 : 0.889 :

8% olefins
2-pentene 154 : 138 : 37 : 0.649 :
2-methylbutene-2 176 : 140 : 36 : 0.662 :
2-methylpentene-2 159 : 148 : 67 : 0.690 :
cyclopentene 171 : 126 : 44 : 0.774 :
( the following olefins are not present in significant amounts
in gasoline, but have some of the highest blending octanes )
1-methylcyclopentene 184 : 146 : 75 : 0.780 :
1,3 cyclopentadiene 218 : 149 : 42 : 0.805 :
dicyclopentadiene 229 : 167 : 170 : 1.071 :

Oxygenates - Published octane values vary a lot because the rating conditions

methanol 133 : 105 : 65 : 0.796 : 385
ethanol 129 : 102 : 78 : 0.794 : 365
iso propyl alcohol 118 : 98 : 82 : 0.790 : 399
methyl tertiary butyl ether 116 : 103 : 55 : 0.745 :
ethyl tertiary butyl ether 118 : 102 : 72 : 0.745 :
tertiary amyl methyl ether 111 : 98 : 86 : 0.776 :

E55AMG99

Not all of the compounds you listed are aromatics. Of them, only Toluene and Xylene are aromatics. The rest are parafins and oxygenates. Also, Benzene is derived from Toluene by a process known as Dealkylation, not the other way around.

ronnie0738

I am a chemist & I know the others are not, but pump gas Q/C reports group those compounds as "aromatics" on their reports although chemically they are not.

I never said toluene was made from benzene? As I said before & your list, there's a slew of derivatives.

In any case, there are risks dumping toluene into your tank.

Prasith32

what exactly is octane booster made from?

what would it do to an ecu that is tuned for 93 in the case of an ecu upgrade.

Vadim,

with the powerchips upgrade do you have to reflash to go from 93 to 91?

E55AMG99

Sorry, I mistook the use of the word derivative to mean derived from. Very true about the misuse of the term aromatics. Many don't understand how their usage has been effected over the years and misusing the term makes it worse.

The risks of using Toluene are immeasurably small if treated properly. It can already be present in gasoline blends in concentrations as high as 40%. In Cailifornia, the legal limit is 30%.

E55AMG99

TOLUENE! (mostly and among others)

carl

if your ecu tuned to 93 and using 91, your engine ideling would be not as stable. that's what Car and Driver claims to our C32. My ecu is stock (91), and i'm using 91 fuel, i don't see any unstableness at all... just same as any V8 benz. so i guess the c32 tested in 2001 is a europe spec c32 with high RON setting.

by the way, where did you tune your fuel setting? at dealer?

Prasith32

Hi,

Yes I tuned the fuel setting at my dealer. They showed it to me on the star diagnostic computer and it is a changeable setting.

However my question is not in the interest of just that setting. I was talking about third party tuned ecu's powerchip, h&s etc. I know there are different power outputs for different octanes. This means that there must be some differences that they are taking into account with the timing etc. It is with this that is my problem because I hope to get the pulley and ecu sometime in spring.

Is race fuel the only option in that case? is there a marked difference in 91 fuel with octane booster vs. 94 (what i fill up now)

Prasith

Vadim @ evosport

Prasith32: Both of our Power Stages are tuned for CA91. This where we are and what we use when tuning cars.

If your car is set for 93, our programming overrides 93 ignition tables set by the dealer.

Prasith32

Vadim,

So for your non california customers you do not tune for 93 octane? I saw on the powerchips site that there is a difference in the performance between 91 and 93 octane is that not the case with you as well since you use the powerchips program? I am sure the majority of the c32's sold are outside of CA where 93 octane is freely available. Why does cali have to be so weird??

Thanks,
Prasith

E55AMG99

To find the answer. ask the BHL/CTH contingent. They feel it's necessary to make everyone's lives as miserable as their own.

CRB

I just love organic chemistry.

Prasith32

Vadim,

Can you clarify on if you have different tuning for 91 vs. 93 octane? I saw on the powerchips site that they have two different ones each making different power.

Thanks.