Gas

[Clickjack]

well crap!    If it wasn't for all the good information I would say I was sorry I asked.  Religion, politics, sex and what octane to run in a monster.


Any one have any clue why some people report better mpg with 87?

[krolik]

Any one have any clue why some people report better mpg with 87?

Because they are liars. 












Just kidding!





I use 87.

[ducpainter]

<snip>


Any one have any clue why some people report better mpg with 87?

It has something to do with quantum physics...

or fluid dynamics...

or petro-chemical engineering.

I think....

[Spidey]

You get more bang with 87.  Lower octane means more boom.  Higher octane is less combustible (which is why it is good for high compression motors.  It prevents pre-detonation), but has less "oomph". 

It's just like 87 proof v. 91 proof booze.   'cept that it's exactly opposite.  So it's not like that at all.     Feck. 

[Clickjack]

I use to do yard work for people.  I had a dieing Lawn mower and couldn't afford a new one.  Somebody told me to run premium in it.... damn thing came back to life and was still running when I sold my contracts and move on to the next job.

Everything seems to run better on higher octane.  Everything except my buddies 80-some odd 550 Secca.  It runs like crap on anything but 87.

[redxblack]

I was getting some occasional intermittent sputters in my bike running 87. I ran a tank of 93 through it before tearing everything apart to troubleshoot the issue and the issue "magically" went away. I'm running 89 now and so far, so good.

[Popeye the Sailor]

<engineer hat on>

The *only* difference between octanes are their resisitance to pre-ignition (pinging). They do not burn cleaner, longer, or have more power. NO difference whatsoever.


If you have a high compression motor, you most likely need a higher octane.


I do not know if it's true for the more modern bikes, however if you run a lower octane in a modern car that was set up for a *higher* octane, the little car computer will retard the timing of the motor. This will prevent pre-ignition. It also means you are not running are an optimal engine state, and are probably getting worse mileage.


Dependent on how refined our ducs are, this may also be the case. So as an FYI, a lack of ping does not necessarily mean you are running the proper octane.


A difference in mileage is most likely attributable to any number of other factors, however, the octane, should not be one of them (save for the timing retardation if it takes place).

</engineer hat off>

[Triple J]

<engineer hat on>

I do not know if it's true for the more modern bikes, however if you run a lower octane in a modern car that was set up for a *higher* octane, the little car computer will retard the timing of the motor. This will prevent pre-ignition. It also means you are not running are an optimal

</engineer hat off>

Ducati can't even make their bikes run right with an O2 sensor, or make a fuel gauge that works. What makes you think they could get the computer to prevent pinging? 

[ryandalling]

the  computer will retard the timing of the motor.

Crikeys.... I don't want my motor to retard... better use 11ty billion octance.

[gage]

(my RS is happy on premium)

As discussed at DIMBY, I and my burning eyes, still think you are a bit rich 

The reason octane matters is this:

In a high compression motor >12:1
too low of an octane will predetonate as mentioned which means that the explosion taking place inside the engine will occur before the piston is at TDC which means that the piston is actually being slowed as it travels up to TDC and then down through the stroke.

In a normal engine <12:1 (just about all engines which have not had internal work done.)
Too high an octane will cause the explosion to take place after the piston has reached TDC and is on it it's way down. Think of it as the explosion is taking place in a larger space and therefore more energy is transferred to the cylinder walls and less is transferred to the piston itself and down to the crankshaft.

gage

[silentbob]

<engineer hat on>

The *only* difference between octanes are their resisitance to pre-ignition (pinging). They do not burn cleaner, longer, or have more power. NO difference whatsoever.

</engineer hat off>

It is true that the measure of octane does not have a direct correlation to energy density and other factors but depending on the formulation used to achieve a certain octane there may be a difference between different grades of gasoline.

[Statler]

As discussed at DIMBY, I and my burning eyes, still think you are a bit rich 

what's a little unburnt gas out the back amongst freinds?
(as long as I'm not sweeper)

[ducpainter]

what's a little unburnt gas out the back amongst freinds?
(as long as I'm not sweeper)

weren't you the one that broke down and we had to wait for?     

[gage]

weren't you the one that broke down and we had to wait for?     

I do believe you are right, I didn't realize he had broke down though 

[Statler]

loose rearset bolt nothing to do with octane, you threadjackers.