Race fuel

[slipperymongoose]

Now that's just silly. We all know its paint thinner

[twocool]

http://www.rc51.org/fuel.htm

[twinrat]

the 87 octane fuel in the manual is the minium octane that should be used in your engine .The lower the octane means more oil in it after all most of it is refined from oil. I run on the highest octane at the pump and use 14 .5 litres to every 350 km Dry exhaust and sparkplugs burn cleaner.

[piresito]

...once i get going i can literally hear the difference, my engine sounds to be running smoother, my acceleration feels increased and i'm cruising at a hgher speed with much lower RPM's

Higher speed at lower rpms...did he changed your gearing?!! 

[burning1]

the 87 octane fuel in the manual is the minium octane that should be used in your engine .The lower the octane means more oil in it after all most of it is refined from oil. I run on the highest octane at the pump and use 14 .5 litres to every 350 km Dry exhaust and sparkplugs burn cleaner.

Read up on octane ratings and the placebo effect.

Short version: Octane rating has nothing to do with the quality of refinement. The words 'regular' and 'premium' are marketing drivel. Octane rating is a measure of how resistant the fuel is to detonation using an average of the Research Octane number and the Motor Octane Number as compared to pure chemical octane.

Generally, premium fuels contain more additives and slightly less actual fuel. Most engines will make slightly more power on the lowest octane rating that they can run without suffering from pre-ignition (which can result in timing retard or reduced boost on modern engines.)

I ran 87 in my race bike with no issues.

[twocool]

Placebo effect!!!!

Finally somebody understands the difference between actual performance and "the feeling of performance"......


Cookie

the 87 octane fuel in the manual is the minium octane that should be used in your engine .The lower the octane means more oil in it after all most of it is refined from oil. I run on the highest octane at the pump and use 14 .5 litres to every 350 km Dry exhaust and sparkplugs burn cleaner.

Read up on octane ratings and the placebo effect.

Short version: Octane rating has nothing to do with the quality of refinement. The words 'regular' and 'premium' are marketing drivel. Octane rating is a measure of how resistant the fuel is to detonation using an average of the Research Octane number and the Motor Octane Number as compared to pure chemical octane.

Generally, premium fuels contain more additives and slightly less actual fuel. Most engines will make slightly more power on the lowest octane rating that they can run without suffering from pre-ignition (which can result in timing retard or reduced boost on modern engines.)

I ran 87 in my race bike with no issues.

[mass-hole]

There was probably no ethanol in it which is a +

[RossLH]

There was probably no ethanol in it which is a +

This train of thought makes no sense. Adding ethanol effectively raises the octane of gasoline. The only way ethanol free fuels are a good thing is if your seals and fuel lines aren't ethanol rated and/or the fuel system cant add enough fuel to make up for the lean condition caused by the lower stoichiometric air/fuel ratio of ethanol.

That said, someone mentioned engines make more power running the lowest octane possible....this is not true at all, unless you're trying to run leaded race fuel in an economy car designed to run on unleaded 87 octane. Higher octane means higher resistance to knock, higher resistance to knock means more ignition advance, more ignition advance means more power. If you can somehow find the minimum octane in which an engine has absolutely zero knock, then raise the octane number by a couple, you will make the exact same power numbers. And it never hurts to be safe.

[burning1]

This train of thought makes no sense. Adding ethanol effectively raises the octane of gasoline. The only way ethanol free fuels are a good thing is if your seals and fuel lines aren't ethanol rated and/or the fuel system cant add enough fuel to make up for the lean condition caused by the lower stoichiometric air/fuel ratio of ethanol.

Aside from acting as an octane additive, ethanol has a significantly lower energy density than gasoline and a very different stoichiometric air-fuel ratio. This is more or less fine if you've properly tuned the engine for the gasoline ethanol mixture you're running, but, the exact mixture of ethanol to petrol is inconsistent from pump to pump, and most engines * aren't* tuned to run ethanol.

Another issue is that ethanol blends don't tend to store nearly as well as pure gasoline blends. Water will tend to settle at the bottom a tank of gas, where it will easily mix with ethanol, producing a sludge that doesn't burn so well in the engine (and further throws off your air-fuel ratios. This isn't just an issue for the fuel in your tank; the process starts while the ethanol mixture is transported, and stored at the pumping station.

The issues with rubber hoeses, carb components, etc you mention are also a factor.

You can read more about the difficulties of handling ethanol as a fuel: http://www.usafuelservice.com/ethanol.html

That said, someone mentioned engines make more power running the lowest octane possible....this is not true at all, unless you're trying to run leaded race fuel in an economy car designed to run on unleaded 87 octane. Higher octane means higher resistance to knock, higher resistance to knock means more ignition advance, more ignition advance means more power. If you can somehow find the minimum octane in which an engine has absolutely zero knock, then raise the octane number by a couple, you will make the exact same power numbers. And it never hurts to be safe.

I said that, and in practice, this is completely true, especially for motorcycles such as our GS500. Our engines are tuned to run 87 octane fuel. If you run 91 octane fuel in our engines, you reduce the energy density of the fuel and gain nothing*.

Running 91 in a vehicle tuned for 87 may or may not cost you some power, depending on how the 91 octane rating is achieved. The 91 octane fuel is going to be slightly harder to ignite. However, the big question is "What was added to obtain that higher octane rating?" If more ethanol is added, mileage and power will suffer on 91 unless you tune for whatever mixture you're actually burning. Water will also increase the AKI of your fuel. There are lots of ways to increase octane rating that will actually reduce the power of the fuel.

In order to enjoy the benefits of higher octane fuel, you have to tune the engine to run the fuel. Tuning the engine can mean increasing the compression ratio of the engines (new pistons/block/cylinder modifications,) ignition advance, VI improvements (intake runner length, ram-air, etc) turbocharging, etc. etc. etc. However, pretty much all of these changes will increase the minimum octane requirement of the engine, leaving you in the same situation... If you tune your GS500 to run 91 octane fuel, you still won't benefit from a 100 octane fill.

Your argument has some validity on modern engines. My BMW has a knock sensor, as do most cars. Those engines can be built for higher octane ratings, and simply de-tune themselves for 87 octane fuel. BMW says 89 is what's required for my bike, but that 87 is fine if I'm willing to tolerate a hit in power and mileage. Some engines will see more power on premium, even if they recommend 87. Others won't. With most of these engines, there is a limit on how much the ECU will permit the ignition and fuel maps to be adjusted. Few cars will benefit from 100+ octane fuel without heavy mods.

Again, there are real benefits to high octane race fuel, that are unrelated to the octane rating. You might see a benefit even in an engine designed for 87. However, those cases won't have much to do with the rating it's self.

Andother consideration, is that there's only so much you can do to take advantage of high test fuel. For example, the GS500 has a hemispherical piston. You can only raise the compression ratio so much before the extreme shape of the combustion chamber costs you more power than the additional compression gains. Ignition can only be advanced so far.

Turbocharged engines with adjustable boost controllers do tend to benefit from running the highest test fuel available. Knock can be a major limiting factor on boost. High test fuel, along with massive engine mods have been known to get huge amounts of power from small engines. There are some hayabusa engines pushing 800HP.

[burning1]

I can't believe I wasted so much time writing that.

The tl;dr version of that: Fuel is much more complex subject than you think.

I'm by no means an expert on the subject.

[RossLH]

I can't believe I wasted so much time writing that.

The tl;dr version of that: Fuel is much more complex subject than you think.

I'm by no means an expert on the subject.

That was quite the dictionary you wrote. For the record, I studied mechanical engineering with a specialty in automotive powertrain. This stuff is not new to me, I just tend to simplify things when I post in order to avoid writing out posts such as yours.

[slipperymongoose]

This is why I cringe when I see fuel and oil threads pop up

[BassWoW]

All I can say is when I use a higher grade octane- I end up getting better mileage

[twocool]

All I can say is when I use a higher grade octane- I end up getting better mileage

Over how many miles, how many tank fulls, how many varied conditions, ..?  How much better MPG?

As I say again and again....factors other than gas can influence mileage up to 20% or so.....

Go to the Fuelly website and look up the bunch of GS 500 listed there....just look at the variations of each bike... each fill up.... and each rider.........


Cookie

[burning1]

I find that I get better gas mileage when I switch to decaf.

[twocool]

I find that I get better gas mileage when I switch to decaf.

Actually some science behind that statement!  Driving smoother, calmer, less jumpy...will certainly net quite a bit better mileage than "being hopped up on caffeine".  (assuming the decaf for the rider, not in the tank)

There is no science whatsoever to show any possibility of higher octane giving better mileage in a GS 500.

But seriously, I did notice a slight jump in mileage after I installed Suburban Machinery handlebars....I would think that the lowered body position...less frontal area...less drag would do that........but then again, might be wishful thinking.......

Seriously,  if you ride smooth, with few stops, constant speed, 55 mph, no jack rabbit starts, shift at 5000...you will get low to mid 60's MPG.

If you are more raspanorious....high revs, speed up in the 70MPH or 80 MPH, you will get mid to upper 50's mpg.....

WOT all the time and you will get in the 40's or less..........

Gas, plugs, jets, exhaust, oil, or whatever cannot do anything significant to change that!



Cookie

[Funderb]

YOU TELL 'EM BURNING1! yeah!    hahahahaha

hahaha, I love your own call out for TL;DR, considering its one of my most favoritest illustrations in internet nomenclature of how today's youth are totally f%&ked.

Can we link this bad boy to the other discussion we had on octane level? i'll look for it.


Found it: http://gstwins.com/gsboard/index.php?topic=59347.0

read and enjoy

[BockinBboy]

You wanna talk about fuel and race? Here is a shocking stat:  African Americans who don't drive get an average of nearly 20 mpgs MORE than Caucasians who drive!

 

- Bboy

[burning1]

For what it's worth, my GS500 got about 13MPG, regular or premium. Your right wrist has a significantly greater impact on your fuel economy than pretty much anything else you can do to your bike.