I am going to try running it next time i go to the track....And im gonna be spraying it as well

 

Whatever you do, skip the avgas. 100/130 octane Low-lead avgas has a tremendous amount of lead in it. I run it in my airplane and in 30 hours of operation, my oil will have 3000ppm of lead in it.

100 *unleaded* pump gas or racing fuel won't hurt anything. It makes a nice rich smell from the exhaust.

You can mix 3-3.5 gallons of it with your premium 91 octane to top off. That will give you about around 94 octane, which is more than the engine requires. That's plenty to ensure no spark retard.

If you can find fuel without ethanol in it, that will give you slightly more power and economy. Ethanol blended gasoline has less heating value than straight gasoline.

 

I agree, if there is ZERO KR, higher octane will do nothing. On the other hand, if under hard driving conditions you get some KR which will cause the computer to pull some timing, then higher octane fuel will help you to maintain the same HP, by keeping all the timing.

I've been mixing one quart can of Torco with every ten gallons of gas for over 5 years now! it brings me up to 96.5 octane, and is cheaper and way more convenient then mixing in 100.

I get the most out of the mixture, since I've retuned for the higher octane that I run in every tank.

I happen to have Torco on sale right now for $160 a 5 gallon jug delivered!!!

PM me for details...

JB

 

It all depends are your setup. A little explanation maybe in order. Higher octane fuel burns SLOWER....why is this better? Because it allows you to advance the timing and increase the pressure in the cylinder by burning more octane molecules = more power. Detonation happends when the burn is expanding as the piston is still coming up....slower burning fuel (higher octane) keeps this from happening (there is more to it, but this is the elevator speech)

So if your car has any kind of timing retarded...as ALL blower cars do running on ANY pump gas....higher octane fuel will allow the timing to be advanced and you can make SIGNIFICANTLY more power. The same is true for high compression setups 12to1 etc.

However if you vette is basically stock and your timing is not retarded based on either the tune or your Knock Sensors working (just so you know knock sensors RETARD timing to eliminate detonation) your potential is more of an insurance policy. It will cause minor stress, very minor stress as the CAT will burn the excess octane unused by the engine (that is why a CAT is HOT)...Your O2 sensors will try to keep everything in balance by adjusting the timing.....

Final word of advice....run the higher octane fuel on your trip to the track....this will allow your O2 sensors to adjust your timing to use as much fuel as they can based on the tune (they have a range to work with that can be adjusted by a good tuner)

 

Higher octane fuels DO NOT burn slower ....

See :

http://www.rockettbrand.com/technica...olineMyths.pdf

Rockett Brand is the division of Union 76 that was spun off after being bought out by Conoco/Phillips ... these guys have experience providing fuel for NASCAR, NHRA, and many other racing organizations.

Check it out .....

 

Knock, also known as detonation, occurs when part of the fuel-air mixture in one or more of your car's cylinders ignites spontaneously due to compression, independent of the combustion initiated by the spark plug. (The ideal gas law tells us that a gas heats up when compressed.) Instead of a controlled burn, you get what amounts to an explosion--not a good thing for your engine. To avoid this, high-octane gas is formulated to burn slower than regular, making it less likely to ignite without benefit of spark.

Bill

 

Bill,

I'll choose to believe the guys who MAKE racing fuels when they say it doesn't burn slower. (Hence my link to the Rockett Fuel site).

Octane is effectively a measure of the temperature/pressure required to ignite the fuel. Higher octane fuels require a higher temperature to ignite them, but once burning, they burn at the same speed as a lower octane gasoline.

Diesel fuel is a classic example of this, it takes a much higher temperature/pressure to ignite, but once lit, it BURNS fast !!

HTH

Steve

 

You are missing the point.........it has more octane molecules to burn so it takes longer for the charge to burn..it may burn just as fast but has more to burn so it takes lONGER..FACT

 

WRONG and WRONG.


Gasoline is composed of many different kinds of carbon chained hydrocarbons, from 2 and 3 carbon chains to six carbons (hexane), 7 carbons (heptane), and 8 carbons (octane). There are also a few longer chains but these are generally refined out. The most common molecule in gasoline is heptane, the 7 chain hydrocarbon. Attached to these carbon chains are atoms of oxygen and hydrogen, along with smaller quantities of sulfur, nitrogen, and other impurities.

When gasoline burns it is actually a multi-step process. The long chain molecules must first be broken down by heat into short (2 or 3 atom chains) before oxidation can take place. Then, the short chain molecules break down and actually burn... the carbon, hydrogen, and other atoms get oxygen attached to them to form carbon monoxide, carbon dioxide, water vapor, and pollutants like oxides of sufur and nitrogen.

As it turns out, the 5, 6, and 7 chain hydrocarbons break down at a rather low temperature. But, one isomer of the 8 chain molecules (octane) is much more resistant to breaking down until higher tempertures have been reached. This is why gasoline's anti-knock properties are measured in terms of an octane rating, and the reason that high octane gas resists pre detonation is that it takes a higher temperature to break down the molecules so that they will burn.

Simply refining gasoline with more octane in it is the simple way of getting high octane gas, but the process is very expensive. It was discovered that various additives could also enhance the perceived octane rating of a gasoline. For years gasoline came with tetra ethyl lead in it. 100 octane gas had between 2 and 3 grams of lead in it. Since tetra ethyl lead is very bad for us and has been banned, the alternative additive that has been used almost all over the country in unleaded fuel is MTBE... yes, exactly the same stuff as in oxygenated fuels, but only about 1 cup per gallon for premium gasoline, versus 2 or 3 cups for oxygenated fuels.

The additives work much like adding salt to ice works... it changes the temperature at which the long chain molecules begin to break down. Thus, heptane which normally breaks down at a lower temperature begins to act like octane and breaks down at a higher temperature. So, premium gasoline does not burn "slower" than regular gas, because in fact, it is exactly the same gasoline, with an additive in it. It is all about the temperature at which burn begins, not the speed of the burn.

 

I get this odd feeling someone has sat through some of the same Chemistry classes that I have and probablly a couple more for now.

 

I also suspect that Blue02ws6 got a WAY better grade in Chemistry than I did !!!!

 

Now that's an explanation!!!

I've gone to a lab and had them do an octane rating on a mix of 10 gallons of 91 octane mixed with one quart of Torco race fuel concetrate. The M+R/2 was 96.5 octane. So Torco helps to raise the temp of the molicules before they burn, hence raising the octane???

Thanks professor!

JB

 

Wish I could say that was all first hand knowledge but I just like to be well informed and read way too much online. Just passing on some info.

 

I'll chime in .....

I think what you're saying is correct ("So Torco helps to raise the temp of the molicules before they burn, hence raising the octane") but another way to put it is....

Torco helps to raise the temperature AT WHICH the fuel would self ignite.

Here's the issue ....

First, a little chemistry ... when you compress a gas you raise its temperature (PV=NRT). For example, if you've ever touched a SCUBA cylinder after it has just been filled it will be warm/hot to the touch.

When the piston rises on the compression stroke in a gasoline engine, it raises the temperature of the fuel/air mix. If the fuel is too low an octane, it can start burning before the spark plug fires to ignite it. It burns because it has reached a temperature hot enough to ignite the fuel (Which is how a diesel engine runs - the heat of compression ignites the fuel ... a diesel doesn't have spark plugs).

By raising the octane, you raise the temperature required to ignite the fuel. With a high enough octane, the fuel won't burn until it is lit off by the spark plug (a Spark being VERY hot).

When the fuel ignites early (pre-ignition) we hear that as a "knock". On cars with "Knock Retard", which the Corvette C5's have, the PCM can sense knock via the knock sensors, and retards the timing until knock is eliminated. Retarding the timing means the spark is fired off EARLIER than it would "normally" be. The spark is fired early to start the fuel burn BEFORE the fuel has pre-ignited. This means that you're engine is producing less power as the burn is started earlier in the compression stroke.

Octane is a measure of the temperature required to self ignite the fuel. The higher the octane of the fuel, the higher temperature (compression) the fuel can pushed to. This is why high compression engines need high octane fuel while low compression (9 to 1 or so) engines can run on low octane fuel.

HTH

 

You are absolutely correct. AV gas 100LL has LOTS of lead in it, and you'll toast your cats. Pump premium is all I run..I don't race, but still, I can't see benifits of 100 for the cost, even if you can get it.

 

I would say octane is a measurement of resistance to compression detonation or self igniting.
And you forgot that once spark ignites the fuel a wave (flame propagation) is produced, this wave can compress and ignite the end gas (the fuel that has not yet ignited) and cause pinging.

 

Semantics my friend.... it takes longer for the charge to burn because it doesn't start burning until it is hotter...... same impact bottom line, Higher octane fuel will help you add timing.. PERIOD

 

You are thinking wrong. By it not burning until it gets hotter, you don't have to worry about Pre-ignition of fuel. It allows us to decide when the fuel ignites with the actual use of the ignition system. The flame propagation rates are the same for the same fuel type whether it's 89 or 93.

Now if you change the chemistry of the fuel to, let's say, a special race gas that has other differing characteristics to it besides the elvated octane. Then the fuel burn rate may be altered.

Hammer

 

Keep telling yourself that. Higher octane does help in preventing detonation. It does NOT mean you can just add timing. What a simplistic and wrong way to summarize octane ratings, you should really pick up a book or do some research before ou try and offer advice in a tech section again.

 

Maybe YOU should read what your OWN state has to say about Octane and burning.... See Link Below D.S.

http://dnr.louisiana.gov/sec/execdiv.../trans/b/b.htm

I will quote it for you...."Posted octane numbers on gasoline pumps are a result of testing fuel performance under laboratory and actual operating conditions. The higher the octane rating on fuel the less volatile (evaporative qualities) and the slower the fuel burns


Of Course this IS an simplification......I will Explain Why it is Still TRUE!

Octane is a measurement of a fuel's resistance to ignition. Ideally, the air/fuel mixture will ignite at the proper time and burn smoothly through the power stroke. The idea is that one powerful combustion of the air/fuel mixture is better than several randomly-ignited small flame fronts. When you can precisely control the point at which the fuel will ignite, maximum performance of the engine can be achieved, and power-robbing knock and ping will be eliminated. Knock and ping are a result of abnormal ignition, or multiple flame fronts colliding within the combustion chamber during the compression stroke.

All reputable fuel manufacturers determine the octane rating of their gasoline in the research lab using a special, dedicated single cylinder engine. Comparing the gasoline to a series of standard reference fuels in the test engine results in either a research octane number (RON) or a motor octane number (MON) depending on a set of operating conditions. The RON is determined with the test engine operating at 600 rpm, at standard barometric pressure, and the intake air temperature set at 125 degrees Fahrenheit. RON is primarily used to address part-throttle knock and ping problems. The MON addresses wide open throttle operation and is determined with the test engine spinning at 900 rpm, also at standard barometric pressure, and the intake air temperature pumped up to 300 degrees.

The best predictor of a fuel's performance in a street/strip machine is the Anti-Knock index (AKI). This is simply the average of the RON and MON numbers, or (RON + MON) / 2. Most all octane ratings posted at the pumps are determined by this AKI formula, and are the minimum values you could expect to see. The minimum octane requirement
of your engine is determined by several variables besides the compression ratio. The engine and cylinder head configuration, air/fuel mixture, timing, coolant temperature, atmospheric pressure, relative humidity, and ambient air temperature will also affect the octane required to make your mill produce maximum power.

The burn rate of a fuel is a measurement of the time required for complete combustion of the air/fuel mixture. The notion that octane ratings affect the burn rate of fuel is about 180-degrees from reality; burn rate is a function of several variables, and the two are completely independent, although there is generally a correlation between octane ratings and burn rates.