High octane gas for 110F+ blistering summers?

[jedd_imp]

It's gotten so hot in the late afternoons, my thighs get baked to death as I get stuck in gridlock that stretches for miles and miles when I'm coming home from a full day's ride. I'm not going to lie....I worry alot when I find myself stuck in traffic and the ambient temps are in the triple digits. It used to not be this way, gridlock that is, but this city of mine's one of the top 10 mega-growth cities in all of the country. They're trying to expand hwys and streets everywhere, and that itself causes most of the gridlock.

On air cooled motors, I've heard that it's more beneficial to run 93 oct (vs. 87), which aids in reducing preignition when sitting in bumper to bumper traffic and thus reducing engine temps.

True, or myth?

[the Ferret]

not sure, but I think if Honda was worried about it, they might have mentioned that in the manual?

"Contrary to popular belief, high-octane fuel will not make your car more powerful, improve your gas mileage or make your engine run cooler or hotter", said Doug Wilmot, an engine performance development engineer at Chrysler Corp.

[4 Paws_imp]

I run ethanol free 93 octane in one of my older technology bikes and it makes a noticeable difference in quite a few ways including what passes for traffic in my area but in the CB I haven't felt or heard any change so I just run regular grade gas in it now. Never been in serious traffic on the CB but did sit through 10-15 minutes of mostly stop and little go traffic recently on a hot (93 degree) and humid afternoon and didn't experience any unusual problems.

[Roper_imp]

Hey Jedd, I'm up the road in Fort Worth. And yes, when you're stopped in 100+ heat, it gets hot really fast.

I don't know about higher octane fuel. There are some who state that the motor runs a little lean (and therefore hotter) with the factory ECU map, and that a Power Commander V or sending the ECU to Guhl for a reflash will make it run richer and therefore slightly cooler.

For comfort, maybe a good set of chaps will help insulate from the heat.

Another thought: I've started riding with a cell phone mount (Quad Lock) so I can program the GPS to avoid construction and traffic. It gets me where I need to go by a circuitous route which takes longer, but I get to keep moving and ride through a lot of new places.

[immgunn_imp]

Yes, higher octane fuel equates to a cooler combustion chamber. Reciprocating internal combustion engines (RICE) have 2 high pressure events. High pressure equals high heat. Don't believe me - then touch the cylinder head of an electric air compressor after it's been running a few minutes. The 1st high pressure event is maximum pressure due to compression. This occurs a couple of degrees past top dead center (TDC) compression. The 2nd high pressure event happens about 17 to 21 degrees past TDC (spark ignited engines (gasoline)). The higher the octane, the slower the burn. The slower the burn, the farther away the 2nd high pressure event is from the 1st. The farther the 2 high pressure events are from each other, the lower the overall combustion chamber pressure, therefore temperature. This is an undisputed fact you learn from testing emissions from cars. Measure NOx (burnt air) from the same engine under the same conditions except octane. NOx is a by-product of heat. The higher the octane fuel, the lower the NOx.

Having said this, I agree with The Ferret. If high octane fuel was necessary, Honda would say so (but I still run the highest octane just for safe measure. Sacramento, CA if freaking hot in the summer + it doesn't hurt).

Bottom line - its all good. Whatever floats your boat. Good times.

[flynrider]

I go from regular 87 octane to mid grade 89 octane in the summer on both of my CBs (and my little Nissan pickup). At temperatures above 110 (in the shade), intake temperatures above heat soaked asphalt can reach 130+ degrees. This tends to cause slight pinging or knocking (detonation, which is different from preignition) under hard acceleration in all three of my vehicles when using regular gas. Using mid grade gas for a few months out of the year solves that problem.

That being said, if you're not experiencing heat related knocking or pinging, using a higher octane won't buy you anything. If you have to sit still in traffic for a prolonged period in high temps, I'd recommend shutting off the engine. I've only had two overheating events in my 35+ years riding air cooled bikes in the desert and both involved sitting still with the engine idling for more than 20 min. in temps above 100 degrees.

[Ulvetanna_imp]

I have been using 93 almost from the beginning, in all my bikes. I noticed the CB1100 pinging on several occasions under hard throttle. I do it simply because even if the bike is designed to run under normal conditions just fine on 87, when one rides hard or under more extreme conditions of heat, it's a bit of insurance. It's often hot where I live and I like to ride hard. Also I always use 10W40 oil, 15W50 in the F800GS.

[jedd_imp]

Thanks for everyone's input.

Since this bike of mine's only 5 months new to me,
AND AIR COOLED,
I think I'm going give it 93 octane to give me a little peace of mind.
I'm not looking for increased power or more mpg,
just want to make sure it doesn't get too hot and ping,
since our bikes don't have a knock sensor.

coming back home from a full day's spirited ride,
We hit 97 deg F yesterday ( 1st day of summer). It can only get hotter from here on out.
Premium 93 octane is currently @ $2.30/gal. in my neck of the woods. What a deal.

[the Ferret]

That is a deal. 93 here is about $3 gal. 87 is $ 2.50

[redbirds_imp]

One exception where high octane gas will deliver more power is in an engine with a knock sensor. When knock is detected ignition advance is dialed back until knock is eliminated. I think some BMW's have this feature so to allow them to run on low octane fuel. Of course BMW's are designed to use high octane gas and this does not apply to most engines designed to run on regular gas like our CB's.