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Octane Boosters

2294 Views 22 Replies 10 Participants Last post by  Pinecone
Anyone tried these? I tried them on motorcycles in another life...not sure if I want to experiment with my passenger vehicles :confused: Anyway, after reading Hacks thread on his 100 octane fuel, just curious if anyones had any experiences with Octane boosters.
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1) Boeing aircraft and F-16 burn Jet Fuel, which is basically diesel fuel. NOT good for your engine. Octane rating about 40.

2) Avgas is 100 octane, not 110 octane. And the ratings are different due to different operating conditions. Actually you can buy two grades of avgas in the US today. 80/87 octane and 100 LL (Low Lead). In the old days there was 91/96 and 100/130 both replaced by 100LL and the 115/145. Aviation gasoline has two octane numbers kind of like RON and MON for car gas.

3) All currently available avgas is LEADED. Use this and plan on replacing the O2 sensors and the cats. NOT cheap. OH, and you will have to drain and flush the entire fuel system to keep from destroying another set of sensors and cats. Unleaded avgas is coming.

Higher octane fuel does not clog injectors, not even avgas. If it did, there would be a lot of planes falling out of the sky, many aircraft are fuel injected.

Higher octane fuel is not harder to ignite, does not burn cooler, does not burn slower. It resists detonation. That's it. In another post I go into more detail about how it does this from a chemical point of view.

Running higher octane fuel allows your engine to produce the full rated HP at a much greater range of conditions. It doesn't mean you will get more HP, but you certainly won't get less. And int he right conditions you will get more than running lower octane fuel.

Now, as to octane boosters. They sort of work. But how well they work depends on the particular one and the particular gas you add it to. And the same brand and grade of gas is different in different parts of the country and different times of the year, even trying to test all the combos is almost impossible.

The concern with some octane boosters is not the injectors, but the O2 sensors. Some of the octane boosters over the years have used methanol as the primary ingredient. Methanol KILLS O2 sensors. And when your O2 sensor fails, the ECU goes to full rich running. This leads to excessive fuel consumption, excessive emissions, and poor performance.
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Ripsnort said:
Good informational Post pinecone, you work in that business sector?
Thanks. No, but have done some research as a total gear head for many years. :)

I have found some good references and have a friend in the business.
Oh, and a lot of the info about avgas is from being a pilot and having flown many different aircraft from Piper Cubs to supersonic jets.
Patrick 320d said:

I may be totally wrong about this, but I was under the impression that higher octane fuel makes combustion engines run cooler.

I also thought the reason for cars "these days" having lower compression ratios was due to the lower octane fuel, i.e., cut down on the compression to deal with the lower rated fuels so avoid over-heating.

Am I horribly mistaken?

I had a very radical 2110cc engine in one of my Beetles and I had the heads cut for a 11:1 CR. I found out quickly that unless I could find at least 99 octane gasoline, I would need to rebuild that engine about every 10,000km. Of course, heat is a killer in an engine that is cooled by air and oil.

You are mistaken, but not horribly. :)

Higher octane JUST relates to the fuel's ability to resist detonation, nothing else. It does not burn cooler, slower, faster, or anything else. At least not by virtue of higher octane.

The way a fuel is rated for octane may explain more to you. To determine the octane of a fuel they run it ina special single cylinder engine that has variable compression. ALL varibles are strictly controlled. Oil temp, RPM, cylinder head temp, intake air temp, etc. A side note, the different between RON (Research Octane Number) and MON (Motor Octane Number) is the difference in the parameters during testing. MON has higher intake air temp for one.

The engine is run on the fuel and the compression is raised until the engine reaches a certain level of "knock" measured by a Knock Meter (yes there is such a thing). Then the engine is run on various calibration fuels. Once they find the fule that knocks just a little more and the one that knocks just a little less, they know the rating of the fuel they are testing.

The calibration or reference fules are mixtures of n-hexane and iso-octane. These two were chosen for various reason. The % of iso-octane is the "octane rating" of the fuel. So 90 octane gas has the same knock reducing capabiltity as a mixture of 90% iso-octane and 10% n-hexane.

The reason compression ratios went down was due to the removal of lead, and the inability at the time to produce higher octane fuels with using lead.
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chukiechz said:
I tried the NOS octane booster in my car, and it really made no difference. Performance was the same. I was using it to prevent detonation (my car was running lean at the time). Best to save your money for a hamburger and some fries
If it prevented detonation then it worked to increase octane.

Increased octane fuel in modern cars MAY produce better performance, but it is a day to day, hour to hour thing. Changes in air temperature and air pressure can prevent the ECU for allowing max performance settings. In that case, higher octane will allow more performance. If the settings are already maxed out, more octane does not help, but it also doesn't hurt, except your wallet.

If the car does not have electronically controlled engine management with a knock sensor, higher octane than needed to prevent knock will do NOTHING for performance.
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