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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.
 

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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?
 

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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:
 

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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?
 

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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.
 

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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.
 

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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.
 

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pewterpecker said:
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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This came out of the article, u say 9.2:1 stock will run on 87octane and u tell me that my 11:1 doesnt need hight octane, well it says 104, i know temp elevation will effect it but, what were u guys trying to tell me, i just need it explained



Compression Octane Number Brake Thermal Efficiency
Ratio Requirement ( Full Throttle )
5:1 72 -
6:1 81 25 %
7:1 87 28 %
8:1 92 30 %
9:1 96 32 %
10:1 100 33 %
11:1 104 34 %
12:1 108 35 %
 

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Discussion Starter #13
those are static numbers, in reality when your motor is running a 11:1 with a cam its actually pushing out around 8:1 to 9:1 at the most. so for your 11:1 static it should run (8:1 dynamic) or so. which means you should only need 92-93 or so octane..find 94 and 11.5:1 is likely, run a very aggressive cam with high flow porting and its possible to run a 12:1 on 94 octane (which is still pump in most states, sunoco). Every motor is different, therefore requires a different dynamic compression. although static compression remains the same regardless.
dynamic comp. for a 9.2:1 is around 7:1
 

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Discussion Starter #16
put 87 octane in your $6k 14:1 compression motor and see how long it last.- Evidently you don't have one with that much money into it. :slap:
 

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kal1fornia said:
will running a higher octane rating in your atv help the engine last longer and perform better?
Your atv will be most reliable and perform best when it gets just enough octane to keep it from pre-detonating/pinging, no more and no less. If your bike runs right on 89 you're not going to gain any benefit by using a similar fuel with higher octane.
 

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DECEPTiON21 said:
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.
 
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