Start:8:27 am

When fuel is burning properly in your,engine those thousland of small fires provide the energy to power your car. If something goes wrong in the combustion process, though the cumulative effect of those fires can be ugly. We're talking catastrophic damage, from burned pistons to bend rods and salvaged heads.

To keep that from happening you have to choose the right fuel. It's even more of an issue if you've modified your car's engine, as performance mods demand more from gasoline than a stock engine. Got boost or high comression heads? Then its time to step up, fuel-wise.

The numbers you see at the pump-87 for regular 89 for mid grade or silver, and 91-94 are a measure of the fuel's octane. Now, octane does not refer to the fuel's energy content, flame speed, or some other power related characterstic. Octane is purely a measure of a gasoline's resistance to detonation.

Under normal circumstances, air and fuel in the combustion chamber burn from the spark plug- the point of ignition-outward. Detonation occurs when some condition with in the chamber, such as increased cylinder pressure or an overly lean air/fuel misture causes a portion of the charge to ignite before the normal flame reaches it. When the two flame front collide you get a telltale knock or ping. which signifies temperature and pressure surges that can damage the engine . Pre-ignition is similar, only worse it occurs when pressure in the combustion chamber gets so high that the air/fuel mix explodes all at once prior to ignition. when that happens "You can burn a hole in your pistons in 40 seconds" said shell racing fuels' mark Ferner. Octane, a hydrocarbon with a specially formulated string of carbon atoms, resists this tendence to explode or ignite prior to the spark plug fireing.

Why do modified engines require more octane? Tim Wusz, and engineer wiwth Rockett Brand Racing Fuel, explained "More power meens more cylinder pressure, which meens a greater need for higher octane gasoline,". Do all mods require an octane increase? No, says Bruce Hendel, global sales manager for VP Racing Fuels. "If its something as simple as a new exhaust you wouldnt need to change fuels. If it's more ex: agressive chip, additional boost, nitrous and so on you will have to run something better than pump gas."

Turs out the engine's state of tune is just one of the variables involved in determining the proper octane rating. Ambient conditions come into play too. "As engine inlet air temperature increases the octane requirement increases," explained tim. "for every 25 degrees F in the air inlet temperature the engine octaine requirement goes up one octane number. This meens that if your engine ingests 100 degree air from a fresh air source rather than 200 degree underhood air your engine octane requiremnt will be reduced by 4 octane numbers.

Tim,bruce, and mark all recomended a frank discussion with your engine builder or afermarket parts manufacture to determine the proper octane level for optimized engine operation. "The supercharger, turbocharger, or chip manufacturer should be able to give you some indication of what octane has been used in the past to give you the performance that you have been looking for.

If that information isnt available to you, you can run tests on your engine, starting with a octane number high that you expect to need. Then bring the number down until you detect detonation. I dont recomend putting in the fuel you think will work and then immediately runing a WOT (wide open throttle) test. Work your way up to it. Dont go out to the track the first time your using a new octane level. Drive it difference places and listen for detonation.

Yet you may never know that your engine, modified or not is in neeed for more octane, thanks to its knock sensor. it can be difficult to identify detonation because of the knock sensor will identify very low levels of detonation and retard the timeing before the driver ever hears the knock. This saves the engine but reduces the performance because the optimum spark timing is compromised.

Their are a couple of ways to determine if your engines knock sensor is pulling back timing before you hear the tell tale knock or ping."On a street car you'll notice it when your gas mileage goes down" said Dr. Tom wicks, manager of product development for gold eagle (makers of 104+ octane booster). Tim recomends back to back performance tests. Make an acceleration run in any ger between two predetermined engine speeds or vehicle speeds and measure the time with a stopwatch. repeat the test with a gasoline that is at least 3 or 4 octane numbers higher than the first test. If the acceleration time is quicker with the higher octane gasoline, then the knock sensor retared the spark timing when using the lower octane gasoline.

What do you do if your already using premium pump fuel and your engine is crying for more octane? you have two options: octane boosters and racing fuel? Octane boosters are the least expensive option selling anywhere from $2-$15 for a 12 or 16 oz bottle as opposed to race gas, which runs an active ingredient that like octane reduces the fuel's tendency to ignite prior to normal ignition. those ingredients fall into several general types, includeing solvents, alcohols, and manganese (aka MMT which stands for methyl cyclopentadienyl manganese tricarbonyl for you detail freaks).

Alcohol additives do boost octane- theres a reason indy cars run on methanol but chemically alcohol tends to bond with any water than may be in your fuel tank and will seperate from the gasoline creating a alcohol/water based cocktail at the bottom of the tank. solvent based additives such as Touene or xylene provide minimal octane boost according to tom "put 16-20 oz of it in your tank and maybe your see a tenth of a octane number. Thats not a full octane number you will never be able to feel that.

MMT probaly offers the most significant potential boost. Claims of 3 to 5 octane numbers are typical. we have seen advertisements go as high as 8. But MMT has its drawbacks its more toxic than other ingredients and it also has been shown to foul spark plugs, oxygen sensors and other emission equipment. Thats why its not the real blend pool for canadian or us fuels. Refiners dont like it. Plus according to tom the manganese deposits that MMT leaves in the combustion chamber will eventually increase your engines appetite for octane by creating hot spots that cause detonation, requiring even more octane to overcome. Thats why MMT is a good choice for any racers they will fix any deposit problem when the engine is torn down and there is no emissions equipment on a race car to clog.

Tom believes the iron based catalyst used in Gold eagle's 104+ booster is a better choice for a street car. "its not toxic, it wont poison the emission system and we put fuel ingector clear into the product to clean out any deposits including those left behind by MMT". Tom said that "104+ will boost a fuels octane level by a solid 3 numbers what ever fuel grade you start with.

The actual octane number that results from adding a booster isnt critical for the street car driver. Some people like to add this product thinking it will help performance. adding more octane than your engine demands wont improve performance. but if you use it to reduce pinging you will feel the difference. and thats what its all about you will feel the difference and use it again.

Ahhh sweet, race gas. Pump it straight into your tank and you have 100 octane or better fuel flowing to your engine. Or if your octane needs arent as great (and your wallet isnt as fat) you can bled race and pump gas to augment the pump gas's octane most race gas supplies offer blending charts that exact octane ratings giver to the gallon to gallon ratio of race gas to pump gas.

Race gas has other advantages too the most obvious differences between street gas and racing fuel are octance and performance. Racing fuel is erived from purer base stocks high energy components and high octane components.
Then formulated to develop the most poewr for a particular application and or fuel rule.

most manufactures offer street legal, unleaded racing fuel typically with octane rating that range from 100-103 higher octane level such at 118-120 are also available, but those are typically reacher by adding tetra-ethyl lead to the fuel. leaded based additives were long ago banned from street use for emissions reases, and leaded fuel will wereak havoc with a catalytic converter. so leaded racing fuels are strictly for on track competition only. When recommending a racing fuel, the manufacturers use compression ratio and boost levels as octane rules of thumb. Tim said rockett brand 100 octane would be appopriate up to compression ratios as high as 14:1. i recomend 100 octane up to 10:1 and 105 octane for 12:1 engine. bruce said his companys 103 octane street blaze (part of a new fuel line designed specifically for sport compact owners) can accommodate boost pressure up to 25 psi.

Is there such thing as too much octane you ask? Some theories have been floated that excess octane can slow a fuels burn rate. but tim said this isnt the case unless someone has done a very poor job of blending such a fuel. all of our experts agreeed that the biggest price you pay for to much octane is from your wallet " your paying too much for a fuel you dont really need." said bruce. "More octane isnt giong to make you go any faster" More octane allows you to run more timing, compression, boost and so on, which help make more power. But octane alone does not meen more power !

finish 9:00 am


more to come soon

You many need more octane if....

* compression ration: higher ration requires more octane
* cylinder bore size: bigger requires more octane
* iron cylinder heads: need more octane than aluminum
* lean fuel mixtures: require more octane
* coolant temp: higher needs more octane
* spark advance: more adance requires more octane
* Humidity: dry air (low humidity) requires more octane
* intake air temp: higher air temp requires more octane
* barometric prssure: higher need more octane
* Alitude: more octane is needed at lower elevations

but all you supras running 91-93 are fine so ignore this

sources:

Gold eagle: (104+ octane boost)
Phone number:800-621-1251
www.goldeagle.com

Rockett Brand racing fuel
phone number: 800-345-0076

Shell oil
phone number: 800-GO-SHELL
email: Shellracing@shell.com

VP Racing fuels
210-635-7744
www.vpracingfuels.com

Good information Boostin. I'm going to add one more link to this. I have first hand experiance in the fuels from Torco. This is the only octane booster that I found to work well in the Supra.

Torco fuel link

good write up! though i do think some of that info is biased.

heres a link with some more useful info about homemade octane booster (toulene).

heres a chart for easy referance:
Formula #1 - Toulene
R+M/2.........114
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.


Formula #2 - Xylene
R+M/2.........117
Mixtures with 92 Octane Premium
10%...........94.5 Octane
20%...........97.0 Octane
30%...........99.5 Octane
Notes: Similar to Toulene. 12-16 ounces will only raise octane 2-3
*points*, i.e. from 92 to 92.3. Usually mixed with Toulene and
advertised as *race formula*.


Formula #3 - Methyl-tertiary-butyl-ether (MTBE)
R+M/2.........118
Mixtures with 92 Octane Premium
10%...........94.6 Octane
20%...........97.2 Octane
30%...........99.8 Octane
Notes: Oxygenate. Very common in octane booster products. Has lower BTU
content than toulene or xylene, but oxygenate effect makes the gasoline
burn better and produce more energy.


Formula #4 - Methanol or Ethanol
R+M/2.........101
Mixtures with 92 Octane Premium
10%...........94.3 Octane (Methanol)
10%...........94.7 Octane (Ethanol)
20%...........Not Recommended
Notes: Methanol is wood alcohol. Ethanol is grain alcohol and found in
Gasohol in 10% ratios. Both alcohols are mildly corrosive and will eat
gas tank linings, rubber and aluminum if used in excessive ratios. Main
ingredient in "Gas Dryers", combine with water.


Formula #5 -
Isopropyl Alcohol and Tertiary Butyl Alcohol
R+M/2.........101
Mixtures with 92 Octane Premium
10%...........94.5 Octane
20%...........Not Recommended
30%...........Not Recommended
Notes: Similar to Methanol/Ethanol. Isopropyl Alcohol is simply rubbing
alcohol. Sample Mixture To make your own octane booster, it is easiest
to make up a large batch, and then bottle it up in "dosage-size" uses.


Below is the basic formula of one of the popular octane booster products.
To make eight 16 ounce bottles (128 oz = 1 gal):
100 oz of toulene for octane boost
25 oz of mineral spirits (cleaning agent)
3 oz of transmission fluid (lubricating agent)
This product is advertised as "octane booster with cleaning agent *and*
lubricating agent!". Diesel fuel or kerosene can be substituted for
mineral spirits and light turbine oil can be substituted for
transmission fluid. Color can be added with petroleum dyes.

thanks let me know if anyone else wants me to do a indepth write up about this because if you guys want me to i will just give me time to research it and do it

quote:

Originally posted by supras_own_u:
good write up! though i do think some of that info is biased.

heres a link with some more useful info about homemade octane booster (toulene).

heres a chart for easy referance:
Formula #1 - Toulene
R+M/2.........114
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.


Formula #2 - Xylene
R+M/2.........117
Mixtures with 92 Octane Premium
10%...........94.5 Octane
20%...........97.0 Octane
30%...........99.5 Octane
Notes: Similar to Toulene. 12-16 ounces will only raise octane 2-3
*points*, i.e. from 92 to 92.3. Usually mixed with Toulene and
advertised as *race formula*.


Formula #3 - Methyl-tertiary-butyl-ether (MTBE)
R+M/2.........118
Mixtures with 92 Octane Premium
10%...........94.6 Octane
20%...........97.2 Octane
30%...........99.8 Octane
Notes: Oxygenate. Very common in octane booster products. Has lower BTU
content than toulene or xylene, but oxygenate effect makes the gasoline
burn better and produce more energy.


Formula #4 - Methanol or Ethanol
R+M/2.........101
Mixtures with 92 Octane Premium
10%...........94.3 Octane (Methanol)
10%...........94.7 Octane (Ethanol)
20%...........Not Recommended
Notes: Methanol is wood alcohol. Ethanol is grain alcohol and found in
Gasohol in 10% ratios. Both alcohols are mildly corrosive and will eat
gas tank linings, rubber and aluminum if used in excessive ratios. Main
ingredient in "Gas Dryers", combine with water.


Formula #5 -
Isopropyl Alcohol and Tertiary Butyl Alcohol
R+M/2.........101
Mixtures with 92 Octane Premium
10%...........94.5 Octane
20%...........Not Recommended
30%...........Not Recommended
Notes: Similar to Methanol/Ethanol. Isopropyl Alcohol is simply rubbing
alcohol. Sample Mixture To make your own octane booster, it is easiest
to make up a large batch, and then bottle it up in "dosage-size" uses.


Below is the basic formula of one of the popular octane booster products.
To make eight 16 ounce bottles (128 oz = 1 gal):
100 oz of toulene for octane boost
25 oz of mineral spirits (cleaning agent)
3 oz of transmission fluid (lubricating agent)
This product is advertised as "octane booster with cleaning agent *and*
lubricating agent!". Diesel fuel or kerosene can be substituted for
mineral spirits and light turbine oil can be substituted for
transmission fluid. Color can be added with petroleum dyes.

This article is very interesting. I have a '97 Supra NA with a single turbo conversion. I currently run the highest octane fuel available at the gas station's which is 93 Octane. I was wondering if I would gain much from using Toulene in my NA motor or if it would do more damage than good. I did the calculation that was posted in the article and here is what I came up with.

(16.5*93)+(2*114)/18.5 = 95.27

Would this mixture work well for my setup. Mods are in my signature. Thanks for the help.

They sell 100 and 110 at some gas stations sometimes if your lucky

yes, toluene will make a differences, it always makes a difference compared to pump gas.

I'll give it a try and post the results.