Cooloer on 91 Octane?

dgfella · Aug 2, 2007

I just read something in this months Rider magazine pertaining to the FZ1. A reader commented that his FZ1 runs coller when he fuels with 91 octane rather than the recommended 87 octane. This does not really make sense to me, can anyone explain?

I normally run 87, but would consider running 91 in the summer if it makes my bike cooler. Today it was 93 degrees, and I chose not to ride. I hate when that happens!

FYI, I did a search and nothing jumped out at me pertaining to this issue.

GunMD · Aug 2, 2007

Ignacio · Aug 2, 2007

Oy vay! You didn't try a search on octane? It's one of our most recurring and rarely agreed upon subjects.

Try searching on octane with the member Jestal as author and I think you'll find the most definitive and reliable information.....like here.

Octane is one of the most misunderstood properties of fuel.

dgfella · Aug 2, 2007

Ig, thanks for pointing me to Jestal's comments. I did search for octane, and saw that most of the threads/responses pertained to detonation, then moved on. After re-reading everything Jestal mentioned, I see he points to "87 Octane on Death Valley..." I'm going to fuel up with premium for the rest of the summer and see if there is an improvement.

One universal constant, you guys are smater than me

Thanks for the help, and minimal flaming...

dcarver · Aug 2, 2007

So.. I've noticed a 4 - 6 mpg improvement using supreme... serious..

dgfella · Aug 3, 2007

Since I'm a nut about tracking mileage, I'll make the switch and see what happens. If it's 4-6 mpg, + what Jestal says, it's worth the extra money.

radman · Aug 3, 2007

dgfella said:
Thanks for the help, and minimal flaming...

I'm on the wagon, and you guyz ain't makin it any easier, I tellz ya.....

MikeYork5 · Aug 3, 2007

radman said:
dgfella said:

Thanks for the help, and minimal flaming...

Click to expand...

I'm on the wagon, and you guyz ain't makin it any easier, I tellz ya.....

Yeah, well......I quit drinking! (more than I usually do that is)

conwest · Aug 3, 2007

dgfella said:
I just read something in this months Rider magazine pertaining to the FZ1. A reader commented that his FZ1 runs coller when he fuels with 91 octane rather than the recommended 87 octane. This does not really make sense to me, can anyone explain?
I normally run 87, but would consider running 91 in the summer if it makes my bike cooler. Today it was 93 degrees, and I chose not to ride. I hate when that happens!

FYI, I did a search and nothing jumped out at me pertaining to this issue.

...well dgfella, it indeed does not make sense. Your wasting your time, money and reputation on 91 octane if yer engine is set up normally. And by the way, yer bike is hot and it`s gonna stay that way.

h34r:

FJR1300Mark · Aug 3, 2007

There is no reason to use a higher octane than the engine is designed to use.

Or

I had an RX7 (rotary engine) and I kept very accurate records for the first 100K miles. It ran no better as far as I could tell from the driver's seat, but it did get better gas milage by 1 to 2 mpg about 5 to 10% better.

I never did feel any difference in the acceleration or in any way the engine responded to the throttle. This was in Va in 93 to 95. Gas may have changed since then too.

I was going to try aviation 100LL avgas as a test also. However doing the research I found out 100LL has considerably more lead than auto low lead and one tank would destroy the catalytic converter. That test never happened.

In aviation piston engines you can lower the cylinder head temperature by increasing the fuel air ratio. As you add more fuel, the temperature of the combustion will decrease. The peak temperature will occur when you have the optimal fuel air mixture. INcreasing or decreasing the fuel air ration from the optimum will lower the combustion temp. and hense the amount of heat the engine/radiator/or cooling fines have to disipate.

Also lowering the fuel air mixture lean of peak is only recommended when the engine is in a steady state (constant rpm) and running at less than 60%.

With a PCiii you could add more fuel and lower the temp of the cylinders, and it is worth a try using higher octane to see if it works for you. Just thinking it is cooler may help.

do I use more than 87 in my 07? very rarely. almost never. once when i headed to the mountains. And I might try anything to get cooler in Death Valley.

v65 · Aug 3, 2007

FJR1300Mark said:
There is no reason to use a higher octane than the engine is designed to use.

You might want to read some of those octane threads. I made some of the same arguments, and got my *** handed to me. :blink:

Rickster · Aug 3, 2007

If you get 5% to 10% better gas mileage....

and Premium costs 78% more (that is using 2.819 reg, 2.949 plus, 3.039 premium)...

EDIT: 7.8% (typo)

Then does it really matter?

mike25 · Aug 3, 2007

Math is hard!!!!!!!!!!

2WheelTiger · Aug 3, 2007

Rickster said:
If you get 5% to 10% better gas mileage....
and Premium costs 78% more (that is using 2.819 reg, 2.949 plus, 3.039 premium)...

Then does it really matter?

Uhhh.... 2.819 to 3.039 is 78%???? Odd math to me. How about 7.8 %.

If you get a 10% improvement in mileage, then a 7.8% cost increase is still a bargain. Question is, how do you test the mileage? Really. I mean accurately enough to see if you're really getting a 10% improvement.

airboss · Aug 3, 2007

I run a tank of premium after every oil change(to get the additive pkg ie: clean out the fuel system) I haven't noticed any performace or milage gains. Really can't tell the differance beween 87 octane and 93 octane.

jojofjr1300 · Aug 5, 2007

airboss said:
I run a tank of premium after every oil change(to get the additive pkg ie: clean out the fuel system) I haven't noticed any performace or milage gains. Really can't tell the differance beween 87 octane and 93 octane.

What happened to proper spelling?

markjenn · Aug 5, 2007

dcarver said:
So.. I've noticed a 4 - 6 mpg improvement using supreme... serious..

This sorts of reports make you realize how important it is to rely on valid engineering theory and scientifically valid experiments when drawing conclusions, not anecdotal experiences which are all over the map. Since the energy content of higher-octane gas is actually slightly less, it makes no sense that it can raise mileage and there's never been a good scientifically-valid experiment that shows that octane, in and off itself, can raise mileage. There might be some engines in poor state of tune or with special software that might run differently on higher-octane gas, but the FJR engine is in a fixed state of tune.

Higher octane make a bike run cooler? I don't know, but I do feel pretty confident that the effect, if any, is likely to be insignificant and cerrtainly not worth the expense. It would be like placing an ice cube in your living room and wondering if your thermostatically-controlled house was going to suddenly feel cooler. When these subjects come up, I sometimes wonder if owners really understand that the temperature of the FJR engine is regulated by a thermostat and that even if you did change the engine's heat load, it would just cause the thermostat to change position and hold essentially the same temperature.

- Mark

Wingman · Aug 6, 2007

markjenn said:
When these subjects come up, I sometimes wonder if owners really understand that the temperature of the FJR engine is regulated by a thermostat and that even if you did change the engine's heat load, it would just cause the thermostat to change position and hold essentially the same temperature.
- Mark

Even though the thermostat holds the minimum engine temp more or less constant, the excess heat has to go somewhere. In this case the excess heat is sent to the radiator, passed to the air flowing over the radiator, then blasted onto the rider. :angry2:

I have no idea if combustion temp would decrease significantly by using higher octane ratings. However, adding (or reducing) fuel does indeed decrease combustion temps. If you decrease the amount of heat produced, you will also decrease the amount of heat that the radiator must pass to the air.

To get this reduction in temp by adding fuel, you sacrifice some power (and generally a drop in mpg) in the process. I'm sure it is not nearly as noticable as some other things that could be done to reduce heat (removing the cats or improving cooling airflow for instance), but every little bit counts when it's your chesnuts roasting by the proverbial fire.

David

burnergold2B · Aug 6, 2007

You will see a more significant difference in fuels that have %10 Ethanol v. straight fuel, than an octane differentiation of 4 points. Mobil stations here in Wisconsin still have what I call good gas that has ZERO ethanol in it. Rumor has it that on Jan. 1 '08, ethanol mixed in will be state law mandatory.

For a hands on moto tuner op/ed piece in octanes go to motorcycleperf.com and look for the High octane level article of warning. Bill W., the owner of said shop, has been tuning race bikes, drag cars, etc., for a LONG time. (He dyno tunes my race bikes.) I believe Bill's articles of warning on octane are clear and concise. He knows it's a waste of money.

Running cooler on 91 v. 87? Probably not. If you want to run cooler change to a cooler set of plugs, drop a # in the heat range, ie go to a 7 from an 8.

Cooloer on 91 Octane?

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