Horse, you are right. I called and talked to him. He said it does not physically burn hotter. Just said he wasn't crazy about some of the additives they put in the higher octane. Basically said that it runs best on midgrade and I should continue to run it. He laughed at me and said it is way too anal about that stuff! Lol

That's great.....if I ever need a mechanic in your area, I may ask you for his name/number.

I own Fast Lane Nitrous Systems and have traveled all over the world tuning professional drag racer's cars. If your engine is not experiencing detonation/pinging then running a higher octane will not increase power. You guys need to listen to "slodsm". What he is telling you guys is fact.


Some of my work:

Sounds like my OP raised one heck of a discussion lol. Anyway, I wanted to add some info to my post. The truck that got the performance increase from the 91 octane fuel is an old/high mileage 2000 Isuzu Rodeo. The truck could barely pull my 19 foot Bass Tracker without hesitation and after my girlfriend added the higher grade fuel it felt like I was towing with a super charged Hemi or something lol.

It sounds like ya'll have your opinions and many seem valid, but there is no doubt in my mind that the truck performs a HECK of a lot better with 91 vs. 89. Now, maybe that doesn't translate to all vehicles or boats but in my particular case it worked wonders.

I now fill up with super before a long tow. I know some may think I'm throwing away money, but I definitely notice a MAJOR difference in her truck at least.

A Superflo 901 Engine Dyno can test an engine under many different conditions. A Engine Dyno puts more of a load on a engine since it is 1 to 1 ratio from the begining of testing range. The load is equivalent of taking off from a redlight in high gear. If it doesn't detonate on the dyno, it will not in the real world.

Dadicka,

A senior Houston peto engineer confirms that the major refinery he supports (Shell Oil, but sold to many brands) start out their Premium grade refining with a better grade of raw gas (less potash for example) with the poorer quality Raw gas being made into Regular grades.

For the fuel trucks supplying Shell branded stations, they add a much better additive mix including detergents that can help dissolve and clean older engines with accumulated deposits. Discounted stations usually add only the minimum additives as required by federal law.

Try going back now to Regular once you use up the Premium grade tank...you may find that you will still may have your improved performance even on the lower octane Regular.

thanks for the intel Lou.

Did you used to have a part in TnT perhaps? I used a LOT of TnT products out on the east coast when I was doing this, I know they were originally from Tyler and I know Jamie Duresky pretty well. I know he had a partner/financier but never met him.

And outboards/inboards/car/bike/RC/2 stroke and 4 stroke all function off the same principle, an air pump. Timing and dynamic compression as well as sharp objects (super sharp dome pistons can benefit from polishing and re-balancing for example) in the combustion chamber play a big role in required octane. I once ran 15000 miles on the street and god knows how many passes on a motor I built for my street car that had a static compression ratio of 13.3:1 on 93 octane. Granted I had a LOT of duration, a late intake closing point, and only 18 degrees of total timing but the fact remains, it was 13:1 street motor and I was running pump gas raping people's "race cars".

A dyno is a controlled environment to a point but I also stated "thousands of track passes". A Dyno doesn't do everything for you, from a peak number on a printout to a best ET at the track is two very different things. Once you start reading plugs, the data logger, and 60-330 times you make changes that actually may make LESS power on the dyno but put up better numbers where it counts. It's a culmination of testing that nets results.

As I stated before, I'm not knocking anyone, myself and several others here are just trying to help other people understand because that's what we're here for right? If it offends you, then chalk it up to the inability to express emotion properly through the written word or think about getting thicker skin because nothing I've said has been rude to anyone, I'm just stating the facts so everyone can know a bit more about this.

I could see how this may be true since it would be alot like performing a carbon clean to an engine with a miss or stumble.

Your Isuzu engine was experiencing some detonation. Pulling a heavy load will make it worse. When an engine detonates it loses power. Using the 91-octane fuel stopped some or all of the detonation and thus prevented your engine from losing additional power. On 4 cycle engines when oil gets in the combustion chamber it can also cause detonation. When engine get older/high mileage they have more wear on the cylinder walls and rings. This additional clearance will allow oil to get into the combustion chamber. An engine that has too high a water temperature will also have detonation. Engine timing being too advanced will cause detonation and likewise the timing being too far retarded will also cause detonation. When an engine is running too lean a.k.a too high of an air/fuel ratio), it will also detonate. There are many things that can cause an engine to have detonation, higher-octane fuel will help it, but it is a band-aid fix for a more serious issue. Anytime higher-octane fuel helps an engine that was designed to run best on a lower octane fuel then you have a detonation problem.

As far as putting it in your Outboard. If the outboard engine isn’t experiencing detonation with the current fuel, then putting in higher octane fuel will not make it run any faster or make any additional horsepower.

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.

No TNT was one of my competitors.

Seems like you won

You DO all know that all the gas companies fill their tanker trucks from the same refineries, and that the only difference between one brand and another is the additive package... Right? Ok. With that out of the way...Chevron's "Techron" additive and Texaco's "System 3" additive are basically the same thing: They're detergent packages that help to keep deposits from forming on the backs of your intake valves and in your fuel-injectors, etc. However... There's not enough detergent in EITHER brand (or any of the others) to keep your valves PERFECTLY clean, so if you care about that sort of thing, you should periodically run a bottle of valve/injector cleaner through your fuel system. Any Chevron station will sell you a bottle of Techron; it's pretty cheap and is recommended (by name) by Porsche, BMW, and a couple other manufacturers. Personally, I prefer Redline SI-1 or SI-2 (same stuff, different bottle sizes). It costs about the same, but may be harder to find. The recommended dosage for prophylactic purposes is one bottle every few thousand miles. For curative purposes -- like if your car's running poorly and you suspect clogged injectors -- the dosage is two bottles in a tankful of gas followed by one bottle in each of the next two tankfuls. Be aware, if you've never poured a bottle of Techron or SI-1 into your tank before, that it may loosen deposits that have formed in the fuel system ahead of the fuel filter. Those deposits will break free and be captured by the filter, potentially clogging it and necessitating its replacement.

LOL...

Yes, that's consistent with what was contained in earlier post. What I can add is that the refineries raw untreated Premium grade fuel (without additives and octane boosting) is from a better quality refined raw gas than found in Regular grade. Pot Ash contamination is one significant difference, being allowed to be 'much higher in Regular grade than in Premium grade.

I also understand from the chem engineer that the additive packages added in fuels sold in major branded stations are generally much better than those added in so called discounted gas stations.

People tend to say all brands are the same or that the only differences between a gas company's fuel grades is the octane levels and that is just not the case according to my refinery engineer source.

People above this post are explaining the posters improvements in engine performance as being due/not due to octane levels. But there are other consideratons explaining his improvment besides octane level.

Diesel makes my motor run hotter.

Credentials:
Ph.D. Organic chemist, 21 years as a practising chemist, 28 US patents (many on gasoline additves), work for a major oil company that is a leading (by volume) retailer of gasoline in the world. I've had engine tests (meaning an engine on a fixed engine stand run by a computer) and road tests (meaning cars driven by humans -- some on a course, some not) run on gasoline additives I've invented (while employed at the oil company). These additives have been tested in the US, England, and France under a variety of conditions. Many of my additives have also been tested in the BMW test (10,000 miles). I'm still employed by said oil company.

Disclaimers:
The views expressed here are my own and not the company I work for (which is why I don't mention the company, although I realize any enterprising person could easily find out).

Copyright:
This entire note is copyrighted by the author. Participants in this mail group may store and make one copy for their own use. Participants may refer to, copy, send, and re-send to particpants of this mail group and post or re-post sections of this note as long as this copyright notice is attached. Except for these specific exceptions, this note may not be copied, quoted, or transmitted in any form for profit or non-profit, or used for any type of publication without written permission from the author.

Corvette:
Mine is a 1979 that is on its second trip through the odometer (and its second engine, and third interior). I've owned it approximately 12 years, love it, and may never get rid of it.

Octane:
I've seen many consummer magazines tell their readers that they are wasting money to buy a higher octane gasoline if their car doesn't knock. If octane were not related to any other feature of the gasoline, I would agree. However, how companies get higher octane gasoline does make it different than regular and mid-grade gasoline. So the question to me then is, do these differences make a difference? The short answer is what do I use, and I use regular in all my cars and my truck. I use premium in my Corvette. Why? Because as any Corvette enthusiast (to separate us from people who merely own one -- no flames, please) knows, a Corvette is not a car, it's an experience. If you want to know the long answer keep reading.

Base gasoline:
Crude oil differs depending on where it's from, and consequently, what comes out of it when it's refined also differs. There are books on the subject and I can't possibly do the subject justice here. As the oil differs, what is available for blending and cutting is different. In the end, however, the refiner has to make economic choices, based on what's available to him from the oil he is refining, on how to get the required octane to sell (as well as meet MANY other criteria that make gasoline, gasoline -- again I can't do justice to it here). What I generally (but not exclusively) see is that BASE (no additve added to it -- you can't buy this, it isn't offered for sale) premium gasoline leaves less deposits behind than other grades. There are certain types of molecules in regular and mid-grade BASE gasolines that simply do not exist in premium gasoline that cause much of this. Additives (see definition below) are added to the gasoline to help get rid of these deposits, and modern additives do a marvelous job of this. What you buy is additized gasoline.

Blending components vs additives:
MTBE (methyl tertiary butyl ether -- this is ether) and ethanol are blending components, not additives. However, you'll see them called additives in many places by many people. Blending components are part of base gasoline. The simplest differentiation between an additve and a blending component is that the former are added in ppm (parts-per-million) levels; whereas, the latter are added in percentage quantities.

Brand of gasoline:
Some of you probably know this, others may be shocked by it. Oil companies swap base gasoline all the time. Let's say I have a refinery in Houston and you have one in Dallas. It makes little sense for me to truck my Houston gasoline to Dallas and for you to truck your gasoline from Dallas to Houston when gasoline is a commodity product. So, I let you draw 100,000 gallons of base gasoline from my storage tank in Houston for your Houston gas stations, and you let me draw 100,000 gallons of base gasoline from your Dallas holding tanks for my Dallas gas stations. That way, we both save on shipping. Yup, Texaco gasoline may have come from a Shell refinery and vice-versa. At a gasoline terminal you may see trucks from up to six different companies all loading at the SAME terminal (that for example may be supplied exclusively by Shell). What comes next, however, is what makes Texaco Texaco and Shell Shell. Additive. Each company has its own additive and adds it to the base gasoline. So while the base gasoline may be the same, the additive is different, and hence the brand of gasoline you use is different because of the additive, not the base gasoline.

Which additive is better?:
Given the above discourse, it's obvious that we all want the gasoline with the best additive. Unfortunately, it's not that simple. Additves respond differently in different base gasolines (even of the same grade). Also, some additves work better with gasolines used in a carbureted car vs one that uses fuel injection. On a practical level, additives are going to be developed today for today's cars -- meaning fuel injected cars. For Corvette owners who have carbureted Vettes (like me), this is unfortunate. Carbureted engines leave a LOT more deposits behind than fuel injected cars. From a regulatory stand point, California was the first to call for all gasolines to pass the BMW test (port-fuel-injected engine) in all grades of gasoline. Like all regulations, this one had various massages put to it, but the net effect was that all oil companies went to work developing additives that are a LOT better today than 10 years ago AND they are used in all grades (not just premium -- hence the argument to use premium to get a better additive went out the window).

Insider's trick on gasoline additives:
No matter what you do or what you drive, this trick will help you keep down deposits inside your engine. You see, additives themselves will make deposits and/or create a deposit that is different from the one made by base gasoline alone. If you think about this for a moment, you'll come to realize that your engine will build some kind of deposit based upon what additive you are using. Yes, it will build at a slower rate, but it will build deposits. At some level this will taper off (but this is maximum deposits and what Corvette owner wants that!). So what do you do? Simple, switch to a different brand of gasoline (this will almost assure you of getting a different additive but not always. Some companies buy additives from other companies, so it could be the same. More on this later). What this will do, is the new additve will look at the deposit formed from the old additive as foreign and begin removing it. Now after 5000 miles, you'll be rid of this deposit but you'll have a new one from your most recent additive, so switch back and start the process all over again. As an analogy, this is like building an immune response to an anti-biotic, so your doctor gives you a new one. I know of absolutely no additive that will work as well as switching back and forth between additives. On a molecular level this makes perfect sense.

So what's a Vette owner to do?:
(1) Whether you buy regular, mid-grade, or premium, use one brand for about 5000 miles, then switch to another brand for 5000 miles. I use Shell, then Chevron, then Exxon, then back to Shell, etc. (this is not an endorsement). These companies have historically had there own additive research groups/companies, so they'll likely use their own additive and not something they bought from each other. It is completely posible, however, to use a sequence like Amoco, Shell, Texaco and still come out fine. (Again these are not endorsements). I use three companies and 5000 miles based on what I've observed working in the research area. 7,000 miles and two different brands will still do wonders. As an aside, it takes most vehicles 7-13,000 miles to build their maximum deposit levels.

(2) If your Vette is carbureted or TBI, buy premium. These fuel-delivery systems build deposits rapidly and to much much higher levels than PFI (port fuel injection) systems You need every edge you can get (if you're an enthusiast). If I had a PFI Vette I'd still buy premium, but must tell you the effect will not be like in the carbureted version.



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Smoke, I thought you were pre-med