Spark Plugs

[Butta]

what you really need to ask yourself is, why are you running 91 octane? the sled only requires 87, anything above that (especially at higher elevation) is wasting money and performance.

you want to run the lowest octane you can run without causing detonation in the motor. this motor was designed for low octane regular fuel. you do not increase performance at all by taking a stock motor and running premium fuel. and in some cases you are hurting the performance by using too much octane. also higher octane gets purchased alot less than lower grade fuels, sometimes you might be getting ALOT older fuel than what you think you are getting.

the cr10eks show power gains at the dyno but not anything you will feel in the seat of your pants. it is like 1-2 hp (maybe) with the right conditions. i run them in mine and cannot tell a definate difference from the stockers.

for the guys that can, my hats off to you, cause i cant. ski

^x2! Nice post, ski! Octane ratings and fuel quality are commonly misconceived as being the same thing. NOT true. Octane rating, is, more or less, a fuel's ability to resist spontaneous ignition (i.e. detonate prior to the introduction of a spark). The higher the number, the more resistance. Higher octane is used for higher compression or altered timed motors so that detonation is eliminated, but yet once spark occurs the fuel is burned quickly and completely, thus getting as much power from that fuel as possible. Use too low of octane rated fuel and it will detonate causing engine damage....use too high of octane rated fuel and you will have a less than optimum fuel burn in the cylinder, actually dropping performance.

I've been told you can sit at the distribution center for gasoline and watch the trucks from different companies pull up to the same pump and get the same fuel, no matter what grade of fuel it will be marked at the pump as...this is because the base of all the grades of fuels is the same, it's the additives the individual companies put in their fuels that changes the grade (detergents, octane boosters, ethanol, etc etc). The "premium" fuel has more additives in it, but does that make it better??? I would argue no.....

Use what the engine is designed to burn, and you'll get the most out of your engine. Where I ride, at 10,000', I burn 85 all day long. The higher the elevation the lower the absolute cylinder pressure, thus the lower required octane rated fuel.

 

[MAMILLA]

[quote="So i ride between 8000-10000 feet you think i should un just the 87 octane or regular unleaded whatever the octane is?

 

[skidooboy]

yep,

ski

 

[Muleskinner]

See below, It explains the octane issue. Short summary - run what the engine is designed for and understand what you are buying. The tunnel is marked 91 RON octane rating. This is the standard for most of the rest of the world and as usual North America decides to make the system different and more complicated. This is equivalent to 86 PON octane as used in North America.


Octane rating of a spark ignition engine fuel is the detonation resistance (anti-knock rating) compared to a mixture of iso-octane (2,2,4-trimethylpentane, an isomer of octane) and n-heptane. By definition, iso-octane is assigned an octane rating of 100 and heptane is assigned an octane rating of zero. An 87-octane gasoline, for example, possesses the same anti-knock rating of a mixture of 87% (by volume) iso-octane and 13% (by volume) n-heptane. This does not mean, however, that the gasoline actually contains these hydrocarbons in these proportions. It simply means that it has the same detonation resistance as the described mixture.

Octane rating does not relate to the energy content of the fuel (see heating value). It is only a measure of the fuel's tendency to burn rather than explode.

In most countries the "headline" octane rating, shown on the pump, is the RON, but in the United States, Canada and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 8 to 10 point difference noted above, the octane rating shown in the United States is 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in the US and Canada, is 91–92 in Europe. However most European pumps deliver 95 (RON) as "unleaded", equivalent to 90–91 US (R+M)/2, and some even deliver 98 (RON), 100 (RON), or 102 (RON).[2]