Could Excess Heat Be Related to Octane Levels?

[rojodawg]

Ran across an article on octane levels as follows:

"Using low octane fuel in a high octane engine will result in severely reduced performance because the engine will attempt to adjust to the lower octane gasoline. In extreme cases, or with prolonged use of low octane gasoline in these engines, pinging or pre-detonation can occur and can eventually destroy your engine. Pre-detonation causes very hot conditions in your engine and can melt spark plugs and pistons."

I always run 91 to 93 octane gas in my 2013 ST and have never experienced heat problems. For those 2013's with excess heat, what octane gas are you running? Could running lower octane gas at least be one of the contributors to excess heat?

[cuznjohn]

i use 93 octane and i still have heat

[Bob Denman]

I don't think that it's directly related to octane levels...
The computers might play with ignition timing to try and preven pre-detonation, but it would take some pretty wild circumstances to cause the temperatures to rise a significant amount...
It has been said that the 2013s were set up to run a bit leaner; in theory to gain some better fuel economy...
Running lean can raise combustion chamber temperatures ...
If the computers start sensing high temps; I wonder if they would richen the mixture in an attempt to cool off the combution chamber?
And THAT; would LOWER fuel mileage!

Oops ... I got off topic!
Sorry!

[shelbydave]

I don't think that it's directly related to octane levels...
The computers might play with ignition timing to try and preven pre-detonation, but it would take some pretty wild circumstances to cause the temperatures to rise a significant amount...
It has been said that the 2013s were set up to run a bit leaner; in theory to gain some better fuel economy...
Running lean can raise combustion chamber temperatures ...
If the computers start sensing high temps; I wonder if they would richen the mixture in an attempt to cool off the combution chamber?
And THAT; would LOWER fuel mileage!

Oops ... I got off topic!
Sorry!

I don't think that is really too off topic...

I don't know if there would be a noticeable difference - externally, unless there was a lot of hard riding / acceleration.

Lower octane fuel will contribute to detonation in higher compression, or performance engines. This will REALLY be noticed in the combustion chamber, where the heat is produced, however it will also reflect in higher exhaust gas temps, which would therefore raise the temps of the exhaust pipes.
If the '13s were leaned out, then this would most likely be seen in some higher temps under the tupperware, and lower octane gas could contribute, but I don't really know if you could directly put a figure on it.

The only comparison I can do is with my car... At idle, regardless of the octane gas, EGT is around 800-1000*. Now the difference comes in under acceleration / boost - 87 Octane will get me to 1500*+ EGT at about 10-13 lbs boost, where 93 I can run above 17 lbs. 17 is the max I've run, and EGT is 1400-1500*

So, I can imagine that on these, if they are supposed to run premium, and we run regular, we could indeed see increased heat build up, but again, not sure how much.

[rojodawg]

I don't think that it's directly related to octane levels...
The computers might play with ignition timing to try and preven pre-detonation, but it would take some pretty wild circumstances to cause the temperatures to rise a significant amount...
It has been said that the 2013s were set up to run a bit leaner; in theory to gain some better fuel economy...
Running lean can raise combustion chamber temperatures ...
If the computers start sensing high temps; I wonder if they would richen the mixture in an attempt to cool off the combution chamber?
And THAT; would LOWER fuel mileage!

Oops ... I got off topic!
Sorry!

Bob, I can't find any definitive studies that quantify the increased heat from early detonation, but to cause engine damage, it has to be very significant. When riders are using their "skin" to ascertain whether they feel excess heat on thighs, feet, etc., couldn't even a small increase in heat from using lower octane fuel be a contributing factor? Wouldn't even a few degrees potentially make a difference? Why do you say it would take "pretty wild circumstances" to raise temperatures significantly? Some folks are taking dramatic measures in an effort to get their spyders to cool enough simply to ryde, so every little bit of heat reduction helps, and upping the octane is a simple measure IF it helps....that's the unknown....how much does it help?

[Bob Denman]

I think that we're both kind of comparing bowling balls to cardboard...
There's no doubt at all that riders are taking extreme measures to find ways to combat the perceived heat that is causing discomfort...
That cannot be quantified; it is simply too subjective...
We all know what "hot" is when we feel it...
But it would vary due to person and cirucmstances widely.
Now... combustion chamber heat, and what it does to the rings, pistons, cylinders and valves; THAT can b measured, and there are known values beyond which you and your bike are in trouble...
The two issues are tangentially related; but are not QUITE the same...
But we'd need Scotty to make some sense out of the mess that I just threw in here...

[OldCowboy]

Ran across an article on octane levels as follows:

"Using low octane fuel in a high octane engine will result in severely reduced performance because the engine will attempt to adjust to the lower octane gasoline. In extreme cases, or with prolonged use of low octane gasoline in these engines, pinging or pre-detonation can occur and can eventually destroy your engine. Pre-detonation causes very hot conditions in your engine and can melt spark plugs and pistons."

The Rotax engine in our have knock sensors. When the engine starts to knock (ping) the computer retards the spark until the knock goes away. Based on BRP's recommendation of at least 87 octane fuel, it appears that the computer has enough range to account for the increased pinging potential of 87 octane fuel.

[JkRbbt]

I sure hope lower octane doesn't cause a lot of damage. I use 91 when I have access to it, but a lot of small towns out here in the Dakotas, Iowa, WY, etc, only have 87 and 89. With a range of 130-150 miles, a lot of times your choice is gas or no gas.

[happyspyder2039]

Ran across an article on octane levels as follows:

"Using low octane fuel in a high octane engine will result in severely reduced performance because the engine will attempt to adjust to the lower octane gasoline. In extreme cases, or with prolonged use of low octane gasoline in these engines, pinging or pre-detonation can occur and can eventually destroy your engine. Pre-detonation causes very hot conditions in your engine and can melt spark plugs and pistons."

I always run 91 to 93 octane gas in my 2013 ST and have never experienced heat problems. For those 2013's with excess heat, what octane gas are you running? Could running lower octane gas at least be one of the contributors to excess heat?

Interesting! I have a 2012 RT-S and run 91 in it. NO heat issues

[flamingobabe]

I have run all 3 grades for a whole day of riding...400-650 miles using same grade.....and the results are no different.....of course...all I know is what I feel....I think I have tried everything to cool this bike down

[Bob Ledford]

The basic problem has to be the lack of cool air flow across the engine assembly itself. Being a water cooled engine assembly pretty well trashes the octane contreversational idea.

Being a 2011 RTL SE-5 owner/operator I can tell that with my unit if I change octane rating at a fill up point on a long ride I can tell almost immediately that I have gone from higher to lower as the engine does not operate as smoothly and the I get the same opposite effect when going from lower to higher. In the meantime the heat gage just sits there at its normal operating position. Some of the engines idiosyncrasies are a sharp sound of fuel detention at cold start, rough idle and a distinct lack of enthusiasm when called upon to GO!!!!

[Gunny]

I have used both in my 2013 and I do not notice a difference in the heat factor, it is still hot regardless, but i do notice a difference in performance. I have also found certain gas stations to stay away from becuse even the high octain fuel causes the spyder to have the sniffles. The spyder really likes QT and Shell gas so just like the long haired Col, the spyder gets what it wants.

[jerpinoy]

luck of air circulation and space. imagine how close the exhaust pipe to the fuel tank. plastic part are melting due to convection heat. The heat accumulate on top areas enclose by tupperware and not enough escape route (vent) provision. Most riders tolerate this heat and others don't. The BRP heat recall will apply heat shield to protect the plastic part from melting due to the direct convection heat. The heat will still there until slowly cools off.

[billybovine]

I have used regular gas and found a big drop in gas mileage, performance. Have not seen any signs of more heat.

[billrob71]

I try to stick with Shell but never lower the 89 octain try to switch back and forth between 89 and 93

[billybovine]

I've always used 87 with no ill effect except that I still have gas. Must be all that BBQ.

Of course yours runs well on 87 octane. That is the recommended fuel. Different engine than the 2013's.

[Bob Denman]

...I still have gas. Must be all that BBQ.

You need a leaner cut of meat maybe?