91, 95 or 98 - How potent is your go-go juice?

[Ants]

A Bang for you Buck question - literally.

Car or Bike, I always skip the 91 as I figure it's a false economy - more wear on the engine from crappier quality, and less mpg anyway as you'll have your foot harder on the gas (metaphorically speaking) to make up for less power.

So what's everyone else's thought? Would be good to hear opinions from any mechanics out there too ...

[slofox]

I use that stuff out of the old black drum behind the shed...I fink me Grampa used to distill it or sumpfink...

[Flip]

The calorific value of all the petrols is the same, ie they all contain the same ammount of energy. The lower the octane number the faster the fuel burns because it has more small volatile molecules which is also called flame front speed and the higher the octane number the more a motor can compress the fuel before the temperature created by compressing the mixture causes the fuel to ignite, because high octane fuels contain more larger stable molecules.

Octane is a way to put a number to a fuels ability not to ignite under compression.

High preformance motors are high compression motors. The more you can compress the mixture before you ignite it the more cylinder pressure the motor can generate and the harder the pistons can be pushed down, this is called volumetric efficiency. There are real limits to this because the higher the compression the higher the chance the mixture will pre ignite and any motor will melt it pistons if they try to compress a burning charge.

91 is fine for a motor in a standard state of tune. 95-98 if fine for a fast road motor. Avgas is a bugger of a fuel for a road motor because it needs a better spark to ignite than many std motors have.

[Fast Eddie]

this has been discussed in another thread already..

[steve_t]

I use that stuff out of the old black drum behind the shed...I fink me Grampa used to distill it or sumpfink...

You run your gixxer on Moonshine?

Flip is right about octane. Not sure about the calorific value of different RON fuels.

And Fast Eddie is right about the other threads so Ants, the search function is your friend

[SMOKEU]

I use whichever fuel my neighbour uses. He's always complaining how his 1.3L Corolla drinks like a V8.

[slofox]

I use whichever fuel my neighbour uses. He's always complaining how his 1.3L Corolla drinks like a V8.

Has to be post of the week.

[caspernz]

I use whichever fuel my neighbour uses. He's always complaining how his 1.3L Corolla drinks like a V8.

There's a crackup!

I wonder if the fella complaining of a thirsty GN250 has a neighbour like you?

[BigAl]

My R1 runs like shit on 95 and shittier on 91 so it's 98 or synery 8000 for me unless really really desperate.

Try them all and see.

[Ants]

The calorific value of all the petrols is the same, ie they all contain the same ammount of energy. The lower the octane number the faster the fuel burns because it has more small volatile molecules which is also called flame front speed and the higher the octane number the more a motor can compress the fuel before the temperature created by compressing the mixture causes the fuel to ignite, because high octane fuels contain more larger stable molecules.

Octane is a way to put a number to a fuels ability not to ignite under compression.

High preformance motors are high compression motors. The more you can compress the mixture before you ignite it the more cylinder pressure the motor can generate and the harder the pistons can be pushed down, this is called volumetric efficiency. There are real limits to this because the higher the compression the higher the chance the mixture will pre ignite and any motor will melt it pistons if they try to compress a burning charge.

91 is fine for a motor in a standard state of tune. 95-98 if fine for a fast road motor. Avgas is a bugger of a fuel for a road motor because it needs a better spark to ignite than many std motors have.

W.O.W.

this has been discussed in another thread already..

Yeah, my bad. Found and read 2 other threads. Not sure I'm any the wiser now though

[KiWiP]

I use whichever fuel my neighbour uses. He's always complaining how his 1.3L Corolla drinks like a V8.

Tell him to get a motorbike much better fuel economy. Yours does 450k/litre doesn't it

[ducatilover]

The calorific value of all the petrols is the same, ie they all contain the same ammount of energy. The lower the octane number the faster the fuel burns because it has more small volatile molecules which is also called flame front speed and the higher the octane number the more a motor can compress the fuel before the temperature created by compressing the mixture causes the fuel to ignite, because high octane fuels contain more larger stable molecules.

Octane is a way to put a number to a fuels ability not to ignite under compression.

High preformance motors are high compression motors. The more you can compress the mixture before you ignite it the more cylinder pressure the motor can generate and the harder the pistons can be pushed down, this is called volumetric efficiency. There are real limits to this because the higher the compression the higher the chance the mixture will pre ignite and any motor will melt it pistons if they try to compress a burning charge.

91 is fine for a motor in a standard state of tune. 95-98 if fine for a fast road motor. Avgas is a bugger of a fuel for a road motor because it needs a better spark to ignite than many std motors have.

Well written.
Higher octane = less detonation and the possibility of running more advanced timing.

I use whichever fuel my neighbour uses. He's always complaining how his 1.3L Corolla drinks like a V8.

Champ! Rep!