[RE-Memphis]

Oil, tires, and octane ratings. 3 topic to start an opinion stampede?

The bike had 700miles on it "new". I've added about 500 to that number. (not bad for 4 weeks - sez I)

I've been using 89 Octane the whole time. Options in my area are 87, 89, or 93. 

Thoughts?

[GSS]

I have tried all 3 and they all work about the same. Most helpful thing has been to add Seafoam on a regular basis and use NGK plugs......makes for a nice smooth engine and no fouled plugs.

GSS

[RE-Memphis]

Replacing the spark was one of my very first moves. I haven't gotten around to the plug wire yet...

Seafoam, check.

Last week I watched my neighbor pour year old mow gas into his Suzuki. He seemed pleased at this gas saving venture. I spotted him later by the side of the road and pulled over to help arrange a pick up. 

I can't imagine what went wrong. 

[mattsz]

I've been told 87 without any additives is fine, and so far, it is.  One of the reasons I bought it...

[Desi Bike]

Pennies on the dollar..  I get 94 octane Sunoco here in southern Ontario. Main reason for me is that the owner of the station is from India an goes ape-feces over the bike when I arrive. The bikes run fine on REAL gasoline at 87 octane. I pay the extra 40 cents a tank for the conversation.

[gremlin]

..............to start an opinion stampede?.........
........
.............I've been using 89 Octane the whole time. Options in my area are 87, 89, or 93......... 

HA HA HA ..... oh .... you are serious ?

the lower the better.  Higher octane fuels have a higher flashpoint, but, they also have fewer BTUs per unit.

fewer BTUs = less heat

less heat = less power.

'nuff said ?

[RE-Memphis]

'nuff said ?

Doubt it!  Why was I always of the thought higher = hotter?

(And truly - I know little about gasoline other then lessons learned from a loss of an eyebrow or two in Scouts.)

[Arizoni]

Lots of people think higher octane = more power.
After all, all of those high performance high horsepower cars have to use it.

What most people don't know is that high octane is needed to keep the air/fuel mixture from igniting from the high compression or detonating because of the shape of the combustion chamber.

Some people say the major fuel companies put more or better additives into their high octane fuel but I don't know that this is true.  I suspect it is not.

[benknrobbers]

Lots of people think higher octane = more power.
After all, all of those high performance high horsepower cars have to use it.

What most people don't know is that high octane is needed to keep the air/fuel mixture from igniting from the high compression or detonating because of the shape of the combustion chamber.

Some people say the major fuel companies put more or better additives into their high octane fuel but I don't know that this is true.  I suspect it is not.

The higher the octane the higher the compression ratio without premature detonation. The only basic way to increase compression ratio is through physical modification of the combustion chamber. You can add a turbo charger or supercharger, but it's not quite the same.  I've tested the better gas mileage/better performance theory about higher octane gas in a few different vehicles, and the only times I've seen an increase it's not been enough MPG to pay for the difference in price.  If a vehicle requires 89 or 91 octane gas to operate at peak efficiency it will say so in the manual.

 On a side note, has anyone supercharged a RE? I know it would be like giving ben stein speed before a performance but there's always someone.

[bob bezin]

around here, lower octane =alcohol 

[gremlin]

................ giving ben stein speed ..................

 

[gremlin]

around here, lower octane =alcohol

In Minnesota all gas has alcohol, irregardless of RON.

[High On Octane]

Yeah, there's a huge misconception on what different octanes actually mean.  As Arizoni stated, higher octane fuel is only required for higher compression motors.  As the octane rating increases in the fuel so does the stability of the fuel itself.  Meaning that it takes a higher amount of compression for the fuel to ignite.  The reason high octane fuel is required for high compression motors is this: If you ran say 87 octane in a 11.5-1 compression ratio motor, the fuel in the cylinder would ignite before the piston reached the top of it's stroke, forcing the piston back down before it completes it rotation.  This is commonly known as "ping".

So to answer your question, being that our motors aren't more than 8.5-1 compression, 87 octane is more than sufficient for our engines to operate efficiently.  Though, I will add, that using additives such as Seafoam and Lucas Fuel Additive DO increase the QUALITY of the fuel and eliminate most fuel problems like rough idle and poor performance at WOT.  So it a good idea, especially if you have trouble finding a good quality gasoline, to add a few ounces of one of a fore mentioned fuel additives on a regular basis.
Scottie

[Ducati Scotty]

What kinda opinion thread is this anyway?  A few answers in and people are presenting actual facts and science!  BORING!  Isn't this supposed to be a heated debate without the slightest lick of proof or evidence? 

Sheesh, what's the internet coming to these days?

Scott

[RE-Memphis]

What kinda opinion thread is this anyway?  A few answers in and people are presenting actual facts and science!  BORING!  Isn't this supposed to be a heated debate without the slightest lick of proof or evidence? 

Sheesh, what's the internet coming to these days?

Scott

I seem to have attracted the wrong crowd. 

So 87 with a bit o' seafoam it is.

[barenekd]

Real simple, if it ain't pingin', don't bother raising the octane. It's money down the drain.
Bare

[ace.cafe]

Real simple, if it ain't pingin', don't bother raising the octane. It's money down the drain.
Bare

^^^^^^^^^^^
This.

[Gypsyjon]

What kinda opinion thread is this anyway?  A few answers in and people are presenting actual facts and science!  BORING!  Isn't this supposed to be a heated debate without the slightest lick of proof or evidence? 

Sheesh, what's the internet coming to these days?

Scott

I run Chevron 93 octane exclusively. Have run it in all my  bikes for well over a hundred years. So there!!

[Arizoni]

Nothing beats that 93 octane fuel for sheer power unless your lucky enough to have a small airport handy so you can buy that 103 octane ave-gas.

Not only do these high test fuels provide all the power your engine can make but you get to contribute more money to the big oil companies profits.

There!  Something we can argue about.

[barenekd]

I used run 100 octane avgas in the old Matchlesses. They didn't run any better, but the price was right. We had to drain the sumps on the gas trucks every morning. Some that stuff always found its way into my tank.
Bare

[benknrobbers]

I used run 100 octane avgas in the old Matchlesses. They didn't run any better, but the price was right. We had to drain the sumps on the gas trucks every morning. Some that stuff always found its way into my tank.
Bare

I think we have a winner in the 'when to use higher octane category'

[RE-Memphis]

I think we have a winner in the 'when to use higher octane category'

Second that!

[dandy]

Turns out I know way too much about octane and knock for my own good (phd in combustion). Knock happens when the unburned mixture autoignites away from the flame.  Usually this is when the endgas gets compression heated by the propagating flame and spontaneously explodes before the flame gets there.  Higher octane fuels are more resistant to autoignition.  Higher compression ratio engines will produce higher endgas temperature and be more prone to knock.  Higher speed engines are less prone to knock because there is less time for reactions to occur.  Lower turbulence engines can be more knock-prone because slow flame propagation leads to more time for the endgas to react.  Running rich reduces knock propensity because excess fuel keeps the temperatures lower.

The UCE has a modest compression ratio of 8.5 with a RPM range typical of a standard 4-cylinder automotive engine (2000-5000). I have a hard time imagining it would have any issues with knock using 87 octane gasoline. Anyway, that's what I use in my G5.

A couple of notes on other comments:
1) Flash point doesn't have anything to do with autoignition, it has to do with vaporization to a combustible mixture.  Gasoline has a low flashpoint and high autoignition temperature relative to Diesel which has a high flash point and low autoignition temperature.

2) Ethanol is usually a gasoline octane enhancer.  Here in California I believe the amount of ethanol is one of the knobs they can tune in the blending process to provide the different grades of gasoline (as in higher octane gasoline has more ethanol).  Ethanol has lower energy content than most other components, so higher octane can mean lower energy (though this is a very small effect, like 2%).

[RE-Memphis]

^^^ I feel schooled! My next tank will be 87. That's in what..2 or 3 hundred miles 

[gremlin]

Turns out I know way too much about octane and knock for my own good (phd in combustion)........

Cool, thanks for the schooling.

Question about an urban legend .....  I once heard about an alcohol fueled piston engine that runs so cold it actually pulls heat from its environment  ( tales of frost forming on the head & block ).

Is that even possible ?  Or, was it the April issue of CarCraft ?

[dandy]

Question about an urban legend .....  I once heard about an alcohol fueled piston engine that runs so cold it actually pulls heat from its environment  ( tales of frost forming on the head & block ).

Is that even possible ?  Or, was it the April issue of CarCraft ?

Methanol and ethanol have large "latent heats of vaporization," so port injection can cool the intake air to well below the freezing point of water as the fuel vaporizes.  I can imagine that metal could be locally cold enough during cold start to freeze condensation on the outside.  But I think this will be a short lived effect once the engine warms up.

[kammersangerin]

OK, I will ask a foolish question. I bought Seafoam in a can with a small feeder tube. This looks more like carb cleaner such as when i want to track down a vacuum leak. Is this what I am supposed to add to the gas in the tank? And how much?

Gas. I am assuming, but did not find in the manual - the engine compression. I can't imagine that it is that high being as its from India and the quality of fuel isn't great in lots of places there. The vspa is a different matter and runs on mid grade.

[Arizoni]

I can't help much with the Seafoam because I've never used it.
I do know that most of the available products on the market are made for automobiles and they usually have 10-15 gallon fuel tanks so if I'm adding something like a fuel injection cleaner and the container says to dump it into my fuel tank I figure that with my RE's 3 gallon tank it needs about 1/4 of the stuff in the container.

The compression of the RE allows using 87 octane fuel without a problem.
There's several posts about this on the forum but they all pretty much agree that buying fuels higher than 87 is a waste of money.