Do octane boosters work?

[Edbear]

Had to chuckle today. I was watching 5th Gear and they had a test of most of the fuel additives available like Wynns, Nulon etc. They used a dyno to establish the benchmark for the test engine and tested each additive. There were about five additives, all popular and all sold in automotive stores here as well.

Result? Each additive, reduced the available horsepower by the same 2%! With one specifically marketed to boost peak power, actually reducing it by 6%!

So before you go and buy a fuel additive and tell everyone how good it is...

[SMOKEU]

I sometimes put some homebrew spirit in the fuel tank of my car and bike. It's a good enough octane booster!

[JATZ]

AvGas FTW

[DEATH_INC.]

AvGas FTW

It's been said time and time again, you make most power with the LOWEST octane your engine will run properly on.

[JATZ]

It's been said time and time again, you make most power with the LOWEST octane your engine will run properly on.

Yebut.... AvGas has a kown octane rating and burns cleaner, engine runs cooler too which is a bonus for an aircooled single

[Slyer]

When looking at a long line of identical looking bottles that each claim to solve different common auto problems, comparisons are easily drawn between them and homeopathic "remedies"...

[Slyer]

Yebut.... AvGas has a kown octane rating and burns cleaner, engine runs cooler too which is a bonus for an aircooled single

Are you saying it burns cleaner because it's high octane?

[JATZ]

Are you saying it burns cleaner because it's high octane?

Nope.... It's a cleaner fuel, not full of the aditives that gets put into the tanks at your local servo...ergo, it burns a bit cleaner.It must be top quality to go into planes, surely. So i'm told. However, if you have other info, I would be more than happy to hear it,I have an open mind

[Flip]

Avgas goes back to the second world war when a bunch of nutters were putting 2000 hp 16 liter turbocharged V12 engines in planes with 8 machine guns and went looking for a fight, and they needed very high quality, leaded, high octane fuel to run on. The specification and regulations on piston engine air craft fuel goes back to WW2.

It amazes me how many people think octane and calorific value is the same thing. Octane is the fuels ability not to ignite under compression, however as the octane goes up the flame front speed of the fuel drops. Taken to the extreme if you run race gas in a low compression vintage motor the fuel burns too slow and is still burning as it leaves the cylinder and heats up the exhaust because of the radiant energy from the still burning fuel.

Avgas is a narrow cut fuel. It has bugger all small volatile molecules, remember it burns slowly. These small molecules in pump fuel are ignited by the spark first and greatly increase ability of the fuel to be ignited cleanly and burnt by a spark. Most motors with a average ignition system just won't run well on Avgas, they spit, backfire and just run badly.

To all those folk who say their std motors run better on avgas or with some expensive dope, well sorry but "bollox". If I am wrong about this well so is Mr Honda, Mr Suzuki and Mr Yamaha who only spends about the GDP of a small country making sure their motors run as well as they possibly can on pump gas. I guess you know more than they do.

There may be some advante in adding a little tetraethyllead to pump gas because the lead might promote a little better (more complete) combustion, but only in a very few motors.

[Motu]

Did they expect a power increase? You won't get a power increase going from 91 to 95 or 98,what makes them think they will get more power with an octane booster? I think 5th Gear wear as sucked in as the consumer.

However,if you have a high compression ratio that knocks on available fuel,an octane booster can help.When lead was dropped from our fuel I used to use an octane booster in my old 250 Falcon engine to stop the rattle.When 98 came out it ran sweet on that.But no power increase on any fuels.

[Slyer]

Avgas goes back to the second world war when a bunch of nutters....

Good writeup. Confirms what I thought.
In summary, you only need high octane if you are running a high compression engine and it may actually be worse for engines that don't need it.
The disadvantages of high octane pale in comparison to pre-ignition...

[Woodman]

Correct there Flip.

I was running my klr on 95 until I read somewhere that 91 was the correct fuel, so I tried it and the performance was so much better .

[JATZ]

Interesting stuff typed by flip.......

Thanks for that Flip, I guess you do learn some interesting stuff on the www. BUT.... why is it the local bike shop sells it to joe average who's fanging around the forest on the weekend, and to mxers racing at events 'round the district ?

[SMOKEU]

Did they expect a power increase? You won't get a power increase going from 91 to 95 or 98,what makes them think they will get more power with an octane booster? I think 5th Gear wear as sucked in as the consumer.

.

In relatively modern, high performance engines the knock sensors may reduce engine power output if the engine is starting to detonate when a fuel of too low an octane is being used.

[Flip]

Thanks for that Flip, I guess you do learn some interesting stuff on the www. BUT.... why is it the local bike shop sells it to joe average who's fanging around the forest on the weekend, and to mxers racing at events 'round the district ?

The local bike shop sell it because there is a buck in it for them.

It's snake oil.