Gasoline octane

[fordboy628]

Yes, there is NO relationship, direct, indirect, inverse or other, between octane rating and burn rate.

As hotrod stated, burn rate is a function of the components of the fuel blend, and the proportion of each component in the mixture.

This also is: "Complicated".

Choosing the correct fuel for your engine depends on MANY factors, and there are probably several choices that will work well enough, unless you are in Nascar or F/1 . . . .
 
Fordboy

[Milwaukee Midget]

So it's probably fortunate that we're limited in our choices at Bonneville. 

Seeking out and tuning to the "magic pale" could get complicated and expensive.

[fordboy628]

Seeking out and tuning to the "magic pale" could get complicated and expensive.
 

I only, and selfishly, want to "tune" myself to the "magic pale" . . . . . .

And I don't care about the "expense", although something darker, aged in wood, with a higher ABV is always a personal favorite . . . . .

 
Fordboy

[wobblywalrus]

In response to Reply #4, switching to fuels with different specific gravity affects the mixture ratio on a carbed motor.  It is best to use a fuel with the same specific gravity as the gas that was used to set the mixture and timing on the dyno.   

[Dynoroom]

I would like to throw something out for fodder.

If you consider the modest compression ratio of ~ 13.5:1 both of the A19-A & 110K are able to do the job and then some. The A19-A being able to handle compression ratios more than two points higher AND also deal with engine speeds over 10,000 rpm (burn time).
What many of us fail to look at is the MULA-B 101 unleaded. Unleaded racing fuels tend to have more oxygen molecules. If testing you my find those oxygen molecules will help with the engines power output, especially at the altitude of Bonneville........ 

Now would be a good time for Harold to stop by.

Carry on.

[fordboy628]

I would like to throw something out for fodder.

If you consider the modest compression ratio of ~ 13.5:1 both of the A19-A & 110K are able to do the job and then some. The A19-A being able to handle compression ratios more than two points higher AND also deal with engine speeds over 10,000 rpm (burn time).
What many of us fail to look at is the MULA-B 101 unleaded. Unleaded racing fuels tend to have more oxygen molecules. If testing you my find those oxygen molecules will help with the engines power output, especially at the altitude of Bonneville........ 

Now would be a good time for Harold to stop by.

Carry on.

In the world I live in, oxygen already in the fuel is always a good thing . . . . . . .
 
Fordboy

[Seldom Seen Slim]

As an example -- we run the MUL-B (or whatever the latest concoction is) in the '09 Kawasaki ZX14.  Rick Gold suggested that we stick with it when we first asked (and were already using it).  Enough octane to keep things under control in the 10,000++ stroker motor, a couple of percent oxygenated, and -- well, it sure seemed to work for us.

[Harold Bettes]

Saw the thread title "octane" and rose to the item like an old trout goes for a bug appearing fly......

Octane is a term that is almost as misunderstood and abused as horsepower and invokes more emotion than logic, methinks. Let us reason together.

What a racer wants to select is the fuel that A) is legal and B) offers the minimum octane to decrease detonation (knock) while not tearing up one's fuel budget. The burn speed is an important issue (relative to bore size and compression ratio) and that kind of info should be available from the fuel mfg. Some fuels such as those like triptane bearing fuels are nice in that they are not prone to detonate even with high CR.....However, they become very expensive and thus hard to come by.

Oh a guy could rant on and on about fuel but simply put is that A) Bonneville is at a fairly high elevation (thus poor density) and is as a result fairly forgiving of higher CR and B) IF the rules permit doing so, choose a fuel that has oxygen within.

Talk to a fuel guy that is not into hype but into chemistry because that is what the engine works on in the combustion chamber. Once the intake valve closes, all the excitement begins and the hype will not illuminate the darkness nearly as well as a happy fuel burn will.

Regards to all that like this kind of stuff,
HB2

[Dynoroom]

Said it much better than I.......

Good to hear from you Harold!