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-   -   "Octane for dummies" (https://www.raptorforum.com/forums/63-general-660-discussion/9257-octane-dummies.html)

rt 04-24-2007 10:44 PM

"Octane for dummies"
 
http://en.wikipedia.org/wiki/Octane_rating


It also has links of the topic that relate to the octane. I know we've had many discussions in the past with octane, but this article and all of its links pretty much sums it all up.

Mad Dog 04-24-2007 10:54 PM

Re: "Octane for dummies"
 
Wikis can sometimes have some questionable or controversial information but the last time I checked their octane page it was in good shape. Looks similar if not the same now.


Good thinking RT, I think this deserves a sticky.


IF YOUR RAPTOR IS INTERNALLY STOCK AND YOU'RE NOT USING FORCED INDUCTION OR NITROUS THEN YOU SHOULD NOT BE RUNNING RACE GAS.

rt 04-25-2007 06:23 PM

Re: "Octane for dummies"
 
Your welcome :thumbsup:

DECEPTiON21 04-27-2007 12:41 AM

Re: "Octane for dummies"
 
Just reading and thinking (never at the same time, that's dangerous).

"Octane number is the number which gives the percentage, by volume, of iso-octane in a mixture of iso-octane and normal heptane, that would have the same anti-knocking capacity as the fuel which is under consideration. For example, gasoline with the same knocking characteristics as a mixture of 90% iso-octane and 10% heptane would have an octane rating of 90. [1]"

What about avgas that is over 100, like 110LL?

Mad Dog 04-27-2007 12:55 AM

Re: "Octane for dummies"
 
Just need to keep reading a little:

It is possible for a fuel to have a RON greater than 100, because isooctane is not the most knock-resistant substance available. Racing fuels, straight ethanol, Avgas and liquified petroleum gas (LPG) typically have octane ratings of 110 or significantly higher - ethanol's RON is 129 (MON 102, AKI 116).


:thumbsup:

onehotbird2002 04-27-2007 10:55 AM

Re: "Octane for dummies"
 
Ok call me stupid but some of that is a little confusing. Let's break it down and just let me ask everyone what they run in their Raptor's (no major engine work). I typically run 90+ in mine, but am I wasting my money?

Mad Dog 04-27-2007 11:24 AM

Re: "Octane for dummies"
 
For internally stock Raptor 660 atvs;

As a general guideline the vast majority bikes with proper jetting and limited extreme situations can run 85-87 octane which is typically considered "regular" pump gas.

Some people can experience pinging/pre-detonation/pre-ignition or whatever you want to call it with that octane but most of the instances I've come accrossed were a result of running too hot or other problems.

Low elevations combined with high temperatures contribute to the likelihood of pinging but very rarely are the sole cause, returning back to a possible problem with the bike itself.

Again this is all my opinion drawn from my experiences, but I don't see a reason why you'd need to run anything more than typical regular fuel in an internally stock machine.

DECEPTiON21 04-27-2007 08:27 PM

Re: "Octane for dummies"
 
Should have read past my nose. :lol:

I run 91 octane in my internally stock rappy. I ride in Glamis, Phoenix and Tucson without problems. For an extra buck per 5 gallons, i like being sure i have enough octane.


pewterpecker 04-27-2007 08:30 PM

Re: "Octane for dummies"
 
Anyone here tried running e85 in their rappy? It's cheaper than race gas and has plenty of knock-resistance to boot. All you would need to do is increase the fuel flow a bit to make up for the lower BTU's.

Mad Dog 04-27-2007 08:57 PM

Re: "Octane for dummies"
 
Quote:

Originally Posted by pewterpecker
Anyone here tried running e85 in their rappy? It's cheaper than race gas and has plenty of knock-resistance to boot. All you would need to do is increase the fuel flow a bit to make up for the lower BTU's.

Ethanol is 116 octane, E85 is much lower.

E85 would require more than just bigger jets, but also a water separator (or very careful storage) and the fuel system would need to be protected from the corrosive properties of the alcohol. Basically you'd need a similar procedure to run E85 as you would for running alcohol.

E85 has a signficantly lower specific energy than regular grade pump gasoline, it's only about 70% as potent. In other words I wouldn't recommend it.


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