Warp Factor

OK, since you're getting occassional ping already with 93 (assuming what you're hearing is detonation), continue to run the 93, or 94 if you have it available.
The premium grades also typically have better detergent packages.

Another possible option would be to de-carb the engine.

Evil-Twin

What do you mean IF????? An LS1/6 has the highest compression of any motor produced in the United States( 10.1:1 / 10.5:1 ) up until the introduction of the C6.There are no production 11:1 compression motors built today. With every gas station selling High Octane gas, what do you think they make that for...In 1972 when a base corvette had 200 hp and 8.5:1 compression you could run regular gas. If I was still working at GM I could have shown you hundreds of pictures of our test results running 89 octane for long periods of time.. WE test to failure, with catastrophic results... somewhere between 100,000 and 150, K.. but long before that your engine is slowly dying. An LS1/6 can easily see 200K + with regular maintenance using the correct fuel.

So many of these Cheap people out there trying to convince people to do the wrong thing...as if to make them feel good in their decision to do the wrong thing.

I hate to see these Know it alls in this forum trying to ram this BS down other peoples throats...
89 Octane will destroy your motor. This guy is just a couple of start ups away from bearing or Piston failure.,it usually takes out the whole motor, because the whole motor is under severe stress. It's a 10,000 dollar mistake to run 89 octane in your car. Some people struggle with 91 octane, especially after the motor is carboned up...

Octane allows your car to produce it's potential energy. It will not produce any HP on its own..

Jstyle

This is so sad every arguement over octante ends with oh look at me mine's 8 inches... Well mines 9... Damn come on guys stop taking yourself so seriously this is the f'in internet. Not once have I read a thread where I just thought wow that guy is the smartest man alive, so stop thinking of yourself as that.

Jstyle

to answer your question plain and simple 93 is better it cost more but it is better...

DRR

NB's question is now answered. He is hearing detonation. Octane increase is needed if you are getting any detionation. If he already is using 93 and still gets occasional detonation he could add octane with an octane boost as needed. (IE - in hot weather) As the article stated you can hear detonation (an explosion instead of a steady even burn, caused by high heat or high pressure or both), but you cannot hear preignition (firing before the spark plug sparks by caused by something getting red hot - which always causes catastrophic failure because it happens on the compression stroke and forces the piston down as it is moving up).

So the knock sensor senses detonation and pulls timing, causing a loss of power. I get that. Can anyone explain how more octane causes a loss of power? louzon tried in the post quoted below, but does -less likely to detonate equal not burn as well?
(I want to know, I'm not trying to get in a urination competition or flame someone.)

Quote from louzon - More "octane" means it's harder to light off.
Harder to light off means it is less likely to light off on it own under high compression.
So the higher octane will not burn as well so you lose HP if you don't have an engine with a high enough compression ratio.
Corvettes call out for 91 min.

Again, thanks for the info and the respectful discussion.

TYSON1997

Higher octane fuel contains less energy per same unit of volume. So if you ran 89 and switch to 110 you will have to feed it more gas to achieve the same amount of energy. Since horsepower is essentially a measurement of energy it will make less horesepower if same amout of fuel is used. It is less efficient.

http://en.wikipedia.org/wiki/Octane_rating

DRR

Thanks for the link. Quote from it follows;

Many high-performance engines are designed to operate with a high maximum compression and thus need a high quality (high energy) fuel usually associated with high octane numbers and thus demand high-octane premium gasoline.

The power output of an engine depends on the energy content of its fuel, and this bears no simple relationship to the octane rating. A common myth amongst petrol consumers is that adding a higher octane fuel to a vehicle's engine will increase its performance and/or lessen its fuel consumption; this is mostly false—engines perform best when using fuel with the octane rating they were designed for and any increase in performance by using a fuel with a different octane rating is minimal.

If a fuel with below recommended octane is used, then the engine will knock. Modern engines have anti-knock provisions built into the control systems and this is usually achieved by dynamically de-tuning the engine while under load by increasing the fuel-air mixture and retarding the spark. Here is a white paper that gives an example: In this example the engine maximum power is reduced by about 4% with a fuel switch from 93 to 91 octane (11 hp, from 291 to 280 hp).

Higher octane ratings correlate to higher activation energies. Activation energy is the amount of energy necessary to start a chemical reaction. Since higher octane fuels have higher activation energies, it is less likely that a given compression will cause knocking. (Note that it is the absolute pressure (compression) in the combustion chamber which is important - not the compression ratio. The compression ratio only governs the maximum compression that can be achieved).

It might seem odd that fuels with higher octane ratings burn less easily, yet are popularly thought of as more powerful. The misunderstanding is caused by confusing the ability of the fuel to resist compression detonation (pre-ignition = engine knock) as opposed to the ability of the fuel to burn (combustion). However, premium grades of petrol often contain more energy per litre due to the composition of the fuel as well as increased octane.


Fuel Net energy Units
Gasoline 2.92 MJ/kg
Ethanol 3.00 MJ/kg
Methanol 3.08 MJ/kg

Quote from T97 - Higher octane fuel contains less energy per same unit of volume.

Seems like the info given may contradict this. I read the wiki page and you know sometimes I don't know any more after thinking than before I'd begun...

TYSON1997

Hmm.. your right i must have misread this.

Zuti

I hope that you did better in Physics than English and Grammar. Just a little ribbing.... Zuti

DRR

T97, Its all good. I still wonder if the notion put forward above about too much octane equals less power is correct? I am sure someone will come up with info to clear this up. And good luck with the shift linkage, I hope that fixes the problem.

Ol'55

I related (easier for me to understand) octane rating = the percentage of antiknock compounds. The earlier antiknock compound used was "lead." Lead doesn't BURN and does nothing to offer in either horse power or improvements in mileage. The newer antiknock compounds found in "unleaded" gas don't either. So I believe we probably get "a bigger BANG for the buck" (more HP and better mileage) if we run the lowest amount of antiknock compound that our compression ratio specific engine will comfortably run on without experiancing DETONATION. It wouldn't surprise me to find out (depending on the way a person drives their car and maybe their geographical location) that we in deed don't all need to use over 90 octane gas. I'm not making this statement from fact, more as a possibility. Your thoughts?

EStreeter

I gotta here this one too

DRR

Old55, My thoughts come from the wiki article linked by T97 above, I just read. Your thoughts about lead may by close, but not about the chemicals used now to boost octane. They are oxidizers, they help the fuel burn, but, also prevent detionation. Below is a list of chemicals and their octane numbers, from the wiki link.

2-methylheptane 23
n-hexane 25
2-methylhexane 44
1-heptene 60
n-pentane 62
1-pentene 84
n-butane 91
cyclohexane 97
benzene 101
toluene 112

Ol'55

That makes sense to me. I'd have to agree.

mqqn

Hi Neil -

Well - I am no physicist or nuclear scientist but......

I would run the highest octane fuel I could generally find, and I usually run 92 octane unleaded premium that I buy from a Phillips 66 station locally.

Some of the local stations have 93 octane, but I don't go out of my way to find it.

I think the manual calls for at least 91, so I think you can safely assume that 91 or higher (in general - not to extreme race fuel or av gas) would all work equally well. As Evil Twin pointed out (good to see you back here ET) your car calls for premium fuel - at least follow GM's fuel specification.

Simple answer to your question - run the 93.

best regards -

mqqn

toxdoc

DRR

Just when you thought this topic died on the vine...I found this in
Motor Trend. Reads kind of like an infomercial for the product though.

Here is the link if you want to go there-Or read below for hilights.
http://www.motortrend.com/features/p...h_octane_fuel/

Enjoy...

Motor Trend: If higher octane fuel is used, will an engine make more power?
Rockett Brand: The answer is maybe. If your car pings/detonates, you will benefit from a higher octane. In some cases, even when detonation is not present, higher octane fuel can improve power because of its special fuel chemistry that promotes improved combustion efficiency. Improved combustion efficiency means that more of the gasoline is being burned in the combustion chamber thus making more horsepower; less is being burned/expelled in the exhaust.

Motor Trend: There are various octane race fuels available. Why not just choose the highest octane and be done with it?
Rockett Brand: In short, higher octane usually costs more. Besides the increased octane, higher end fuels offer a performance improvement over the lower octane fuel due to better burning characteristics. Rockett Brand makes lower octane racing fuel to satisfy a wide range of engine parameters, and some racers do not have the desire to buy the higher priced gasoline. The fact is you may need a higher octane fuel than you think, because your engine may be detonating despite you not being able to hear the knock. You have to look for signs of detonation by carefully inspecting the spark plugs. If you think you might have detonation, try the next higher octane with out making any other changes. You can not "over octane" an engine regardless of what others might say.

Motor Trend: 100 octane aviation "AV" gas is usually cheaper that 100 octane race gas. What is the difference between race gas and AV gas?
Rockett Brand: Aviation gasoline with an octane quality of 100 is often cheaper than 100 unleaded, thus it may look attractive to performance enthusiasts. First and foremost, 100 octane Aviation fuel contains tetraethyl lead (TEL); since 1996 it has been illegal to use leaded gasoline in a licensed street vehicle and you can be fined us to $25,000 for using it. Plus, leaded gasoline will damage the oxygen sensor(s) and catalytic converter(s) found in modern vehicles.

Aviation fuel is designed for low speed aircraft engines that run at 2700 to 2800 RPM at 10,000 feet altitude. Aviation fuel often contains hydrocarbons that are detrimental to the performance of a high-horsepower street car.

There are two grades of 100 octane aviation gasoline. One is identified as 100LL and is blue in color. The other is 100/130 and is green in color. The second number (130) shown for the green fuel is a measurement using a supercharged octane test engine. Although this 130 octane number is higher, it is achieved from an entirely different test and rating system than octane numbers determined with normally aspirated engines. For comparison, Rockett Brand 111 octane tests out at over 160 octane using the supercharged aviation method that indicates Rockett Brand 111 has a significant advantage in anti-knock ability over 100/130 aviation gasoline.

Motor Trend: If traditional pump-available 92/93 octane premium unleaded fuel isn't high enough octane, can I blend race gas with it? How do I know how much to blend?
Rockett Brand: First, remember that you should not blend leaded racing gasoline with normal pump gasoline for street use. You can blend unleaded gasoline with a high octane race unleaded fuel such as Rockett Brand 100. RocketBrand has blending charts that allow you to accurately blend to your desired octane number. You cannot accurately blend with traditional octane boosters. If your only goal is increased octane, blending pump gas with Rockett Brand 100 is an OK way to go. If you are trying to get the most performance out of your engine, use100 octane without mixing it with street gasoline. Our 100 octane burns more completely than street gasoline, thereby offering more power and less unburned hydrocarbons in the exhaust--in other words less tailpipe emissions.

Motor Trend: Octane boosters claim to significantly raise fuel octane. Why not just run octane booster to save money?
Rockett Brand: A typical 92 or 93 octane pump gas contains hydrocarbons that evaporate in a range from about 80 degrees F to over 400 degrees F. Rockett Brand 100 Octane unleaded contains hydrocarbons that evaporate from about 100 degrees F to 270 degrees F. The higher evaporation temperature means that it takes longer for vaporization to take place as well needing a higher temperature to do so. At wide open throttle, and as RPM increases, there is increasingly little time for evaporation to take place. The 100 octane gasoline will vaporize more readily, and convert more chemical energy to mechanical energy than the 92/93 octane fuel, and therefore the 100 octane will make more power and improve vehicle performance when compared to the 92/93 octane gasoline (with or without octane improvers). Putting an octane improver into 92/93 octane gasoline does not change that high temperature for evaporation. Plus, there is no guarantee as to what octane you will end up with even if you follow the manufacturer's suggested dose. Unfortunately, the octane improver industry is not regulated like the retail gasoline business, and they can make bold claims without having to back them up. Octane boosters are addressed in a tech bulletin on Rockett Brand's website.

Motor Trend: Is octane number the best way to rate a gasoline?
Rockett Brand: Octane is a good place to start when trying to pick the correct gasoline for your vehicle, but there is more to consider. Another thing to find out is if the gasoline contains an oxygenate like ethanol or MTBE. Both are used extensively in gasoline to help reduce exhaust emissions.

In the case of racing gasoline, it depends again on what your engine needs. Rockett Brand 100 octane unleaded contains an oxygenate while Rockett Brand 111 does not. If an engine only needs 100 octane to run with without detonation, the engine will make more horsepower on the 100 than on the 111 octane. The reason is that the 100 contains an oxygenate which is like adding more barometric pressure (more oxygen means more potential power). If your engine detonates on 100 octane, then 111 is certainly a better choice. Motor Trend: I understand that the new E-85 fuel is over 100 octane. Is it similar to race gas and can I use it?
Rockett Brand: E-85 "Flex Fuel" (containing 85-percent ethanol and 15-percent gasoline) is rated over 100 octane. However, if E-85 is put in an engine that is calibrated only for gasoline, you will be unhappy because the engine will be extremely lean (thus causing extensive detonation) and may not even run. E-85 is only for hybrid engines that are calibrated to use it. Each manufacturer has a different name for this type of vehicle, but basically they can run on any fuel ranging from straight gasoline to E-85 flex fuel. An optic sensor in the fuel line tells the computer what air/fuel mixture calibration to use. Also, remember that the E85 may not have the other components necessary to make a high performance fuel.

Motor Trend: Are the published octane ratings in the various race fuel brands literature legitimate?
Rockett Brand: The numbers published in the Rockett Brand Racing Fuels literature are legitimate. Every batch of fuel goes through a battery of tests to meet specifications for that particular product before it is released for sale. We cannot speak for the quality control of other manufacturers but we do know that at least one of our competitors blends to a recipe and does not verify results, which is a risky way to do business.

Motor Trend: Why is race gas so expensive?
Rockett Brand: The components used in Rockett Brand Racing Fuel are far more refined and pure than those used in ordinary street gasoline, hence the increased cost. Racing gasoline is not made at just any refinery or blending facility, so added transportation costs are involved in getting components to the blending location as well as the transportation required to get it to the end user.

Think of it this way. Although racing fuel may be more expensive, if it saves a $20,000-75,000 engine from destroying itself from detonation, the added cost of the race fuel looks downright inexpensive.

Motor Trend: Do most race fuel manufacturers make their product the same way, but just make it different colors?
Rockett Brand: Each racing gasoline manufacturer makes their fuels from select components that they feel are the best combination. In some cases fuels are similar. Fuel color only serves as a means of identification; it aids the manufacturer as well as the racing sanctioning bodies.

Motor Trend: What is the normal shelf life of racing fuel?
Rockett Brand: Rockett Brand fuels can be stored for two years or more when proper storage procedures are followed using sealed metal containers. Long-term storage in plastic jugs is not recommended. For more information, see the Tech Bulletin identified as "Gasoline Storage" at www.Rockett Brand.com.

Motor Trend: Rockett Brand is a new name that's only been out for a few years. Where did Rockett Brand come from? What qualifies you to comment on gasoline?
Rockett Brand: Rockett Brand was started at the beginning of 2004 and is staffed by former engineers and employees of Union 76. ConocoPhillips became the owner of the 76 brand in 2002 and elected not to renew the NASCAR contract, and it also decided to get out of all racing fuel and motorsports activities at the end of 2003. Thus, although the Rockett Brand name may be a new, its employees have provided direct engineering and technical support on fuels and lubricants to NASCAR for many years.

Motor Trend: How can I get technical support regarding Rockett Brand race fuel?
Rockett Brand: Tech support varies from the vendors, but all of those that distribute Rockett Brand have our information brochures. If you have more technically oriented questions, call 800-345-0076 to get specific recommendations for your application, or to get information on what the differences are from one product to another with respect to tuning. Our main tech engineer has over 40 years experience with gasoline quality control and R&D. He developed the line of racing gasoline used by Union 76/Unocal while working for that company for 39 years and has been exposed to a significant amount of high level gasoline technology.

Motor Trend: Where can I purchase Rockett Brand?
Rockett Brand: There is a network of Rockett Brand distributors throughout the United States. Our fuel is available directly at the pump at many traditional gas stations as well as is available at many local speed shops. Check the website (www.Rockett Brand.com) for locations in your area.

louzon

I stated Corvettes call out for 91 min. (can't read?)
I used the word IF in general, maybe his other car is a Yugo?
"Cheap people" I'm sorry but where did I say he should be running 89?
I only stated what I was doing. There are many variables that may allow me to run 89, like manufacturing tolerances, driving style, etc...

I watch engines run on the dyno every day here at Ford and let me tell you we put those engines thru a lot more than anyone in their right mind would do to their own car and they still run for hundreds of hours!

Not working at GM anymore? I bet you got a package didn't you.

.

Robert T.

DRR

E-T, I thank you.
And I am sure many more like me also thank you. You are a well of LS1 info.

Of all the things I read related to octane none mentioned too much octane caused a loss of power.

Proof?