Pure Premium Petrol

[MGPilot]

Over the course of a year, I track 10-15% better mpg on non-alcohol fuel.

I don't detect that my engines run any better. Seems like octane is octane....a simple quality that lets you expose a fuel to higher compression without it combusting spontaneously (i.e., pinging & engine damage). Engine should only run better if you were using an inadequate level of octane in a previous fuel. Higher octane than needed for an engine can simply waste money and can even reduce mpg.

On the other hand, alcohol tends to be tough on fuel line components & doesn't seem to store as well. So, I just use it for all my cars, motorcycles -- and especially in cans with Stabil for the generator (one of those pleasant PNW accessories).

[TBShorty]

We have a favorite station here in Salt Lake City that sells ethanol free premium.  I use it in all the motorcycles and mower/trimmers.  I have to remember to top off the V7 and fill my gas cans on a week day.  On nice days the line at the pumps can be 1/2 block long with motorcycles.

[Rough Edge racing]

Yeah , and now some company is marketing oil made from natural gas , you guys sink your teeth into that 

 Oh , gasoline can be made to burn at different rates , and high performance engines require fast burn . High octane only makes gasoline harder to ignite , not burn at a slower rate . Where is Chuckie ?

 Dusty

 Close, high octane gas has additives to prevent spontaneous combustion of the end gases...Detonation and pre ignition are quite complex and there's a lot to it...
 

[Cross-tie Walker]

I run "Premium" (albeit E10 mostly) 95% of the time in my Calvin.

Once or twice a summer I'll find myself in a very small town or rural area without any choice other than "regular" I don't know if its all in my mind or perhaps some weird chemical mixture of the two, but it "seems" to run better after one of these "regular" fill -ups.

Thanks for the pure gas app info...looks like it could be useful

[sib]

I run "Premium" (albeit E10 mostly) 95% of the time in my Calvin.

Once or twice a summer I'll find myself in a very small town or rural area without any choice other than "regular" I don't know if its all in my mind or perhaps some weird chemical mixture of the two, but it "seems" to run better after one of these "regular" fill -ups.

Thanks for the pure gas app info...looks like it could be useful

Yep, they always run better after you wash them, too.

[atavar]

I will throw a little fuel on the fire here speaking allegorically..  in the cold winter months ethanol can have some benefits as the ethanol will assist to some degree in handling moisture and condensation. 

[Two Checks]

If the fuel burns too fast it causes detonation. The higher octane resists the tendancy to explode, therefore reducing the burn rate.
To extract more power you increase compression. If you use 87 octane with high compression the fuel explodes. That's when you hear the pinging (pinking).
If you use high octane with low compression you get no added power.

In my buddy's race cars we use either P116 octane gas or ethanol. The ethanol burns slower and has higher octane. But, to use it we have to rejet almost three times as rich and advance timing a few degrees.

[oldbike54]

If the fuel burns too fast it causes detonation. The higher octane resists the tendancy to explode, therefore reducing the burn rate.
To extract more power you increase compression. If you use 87 octane with high compression the fuel explodes. That's when you hear the pinging (pinking).
If you use high octane with low compression you get no added power.

In my buddy's race cars we use either P116 octane gas or ethanol. The ethanol burns slower and has higher octane. But, to use it we have to rejet almost three times as rich and advance timing a few degrees.

 No , if the fuel ignites to "early" it causes detonation . A rapid flame front  is a good thing in high compression engines .The reason why 87 causes early ignition is that it ignites too easily . Even spark ignitions are capable of enough heat and pressure before the spark to effectively diesel .

 Dusty

[beetle]

Not another petrol thread.
Nooooo.....

[PJPR01]

Not another petrol thread.
Nooooo.....

  We could revive the VW Diesel debacle instead!   

[Rough Edge racing]

No , if the fuel ignites to "early" it causes detonation . A rapid flame front  is a good thing in high compression engines .The reason why 87 causes early ignition is that it ignites too easily . Even spark ignitions are capable of enough heat and pressure before the spark to effectively diesel .

 Dusty

 Dusty is correct.....This excellent article explains detonation and preignition . Read it, there will be a test   

    http://www.contactmagazine.com/Issue54

/EngineBasics.html

 And this is by Kevin Cameron.

      http://www.factorypipe.com/t_deto.php

[oldbike54]

Dusty is correct.....This excellent article explains detonation and preignition . Read it, there will be a test   

    http://www.contactmagazine.com/Issue54/EngineBasics.html

 Thanks Rough , although now reading what I wrote , there needs to be a correction . Detonation occurs in the unburned mixture after ignition , pre-ignition is what most people refer to as pinging, and happens before ignition . Pre-ignition is the more harmful of the two .

 Dusty

[Rough Edge racing]

 Hole in the piston is classic preignition.... Oh, sorry to confuse you with the departed L man in another post 

[atavar]

Hole in the piston is classic preignition.... Oh, sorry to confuse you with the departed L man in another post 

I have had that happen to me.  makes a mess. 

[Two Checks]

That's right. 87 octane ignites too easily-it explodes quickly in high compression engines. PING! So we increase octane to slow the rate of burn or the volitility so it doesn't explode. And it burns more completely allowing the engine to extract more power available.

Gasoline has the same amount of energy no matter the octane. Higer compression alows more power while controlling the rate of combustion without damaging the engine.

[oldbike54]

That's right. 87 octane ignites too easily-it explodes quickly in high compression engines. PING! So we increase octane to slow the rate of burn or the volitility so it doesn't explode. And it burns more completely allowing the engine to extract more power available.

Gasoline has the same amount of energy no matter the octane. Higer compression alows more power while controlling the rate of combustion without damaging the engine.

 OK , don't believe me , how about these two guys ?

 

Dusty is correct.....This excellent article explains detonation and preignition . Read it, there will be a test   

    http://www.contactmagazine.com/Issue54

/EngineBasics.html

 And this is by Kevin Cameron.

      http://www.factorypipe.com/t_deto.php

 You aren't slowing the rate of flame propagation , only starting the process later . If you slow down the rate of propagation you will run into detonation issues and complete combustion will not occur until after the moment of location of peak pressure , 14 degrees after TDC . This causes more heat and also decreased power .

 Dusty

[Rough Edge racing]

That's right. 87 octane ignites too easily-it explodes quickly in high compression engines. PING! So we increase octane to slow the rate of burn or the volitility so it doesn't explode. And it burns more completely allowing the engine to extract more power available.

Gasoline has the same amount of energy no matter the octane. Higer compression alows more power while controlling the rate of combustion without damaging the engine.

  Read this paragraph by Kevin Cameron , faster combustion lessens detonation!

         

Anything that contributes to lowering the temperature that the endgas reaches will make detonation less likely. Anything that slows the process of conversion from normal gasoline into a sensitive explosive, will make detonation less likely. Anything that speeds up combustion, so that is it completed before the conditions needed for detonation can develop fully, will make deto less likely.

[cj750]

While not motorcycle specific, here's an informative article where a wide range of fuels are tested in the same vehicle under controlled conditions: https://grassrootsmotorsports.com/articles/fuel-truth/
Bottom line, the power output from various pump fuels varies surprisingly little, IF the engine is tuned for that fuel. (We're talking naturally aspirated, moderate compression engines here, like most Guzzis. The results would likely vary much more if forced induction or ultra-high compression were a factor.)
Many modern cars have the ability to sense what is in the tank, and adjust the ignition timing curve and fuel injector pulses to suit. No Guzzis have such capabilities, to the best of my knowledge, so if you find a fuel that works well with your bike's particular tuning, its probably wise to stick with it. Unless the weather turns significantly hotter or colder. Or you're riding at a different altitude....

[oldbike54]

 More facts cluttering up the place  I am curious about the "relatively" low compression of the Miata .

 Dusty

[atavar]

when I had a a little red Miata it ran like a scalded ape on 87 Octane, it loved the stuff.  Compression ratio was under 10 if I remember correctly.  The only problem with the car was my 6 foot 300 pound size.  I didn't get in to that car, I put it on.

[wymple]

I run an 84 Cal II, and an 81 GS850 Suzuki. I can run anything in either one and see no noticeable difference in power or mileage. Sometimes I can't help but wonder what kind of junk the refineries push on you guys outside the Midwest. My old GS1100 Suzuki would ping on regular, but not on ethanol, in hot weather. The fuel mileage computers on our cars show little discernible difference between ethanol and regular fuels, maybe 1/10th of a mile per gallon. I think that may be because the cars now have computer controlled timing, and the timing is automatically retarded some when preignition is detected. Ethanol pings less, so the timing runs more advanced.