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  1. #1
    Will work on YOUR ski for FREE! GeoRXT's Avatar
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    Gas octane rating question....

    I've read at the RIVA site and some other places that our pwc should always run 93+ ocatane to get the best performance. While I know this is definately true for cars, I can't say the same thing about my RXT.

    I always used the 93 octane gas as I do in my turbo car. One day gas got so expensive I decided to try the regular 89 octane gas. When I did this the ski got to 71mph (non-gps) and 8050 rpm with me (175lbs), half tank of gas, and with my 190lbs friend! The riding conditions were the same as always! Same water temp, same exterior temp, same lake, pretty much identical riding conditions. It had never done this having 93 octane in the tank!

    Can anyone explain this? I have since stopped buying 93 octane gas for the ski.


  2. #2

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    Did the same with an xpl it ran good and fast the first 4 miles I think for performance you can get too much octane and slow the burn too much.

  3. #3
    It says on the sticker 89 minimum. When you modify your RXT you will need 91 or 92 minimum. If you put in 89 you need to keep the speed down.

  4. #4
    Will work on YOUR ski for FREE! GeoRXT's Avatar
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    Quote Originally Posted by Kinchyle
    It says on the sticker 89 minimum. When you modify your RXT you will need 91 or 92 minimum. If you put in 89 you need to keep the speed down.
    Any special reason why?

    Using 89 octane I've gone faster than what I've gone with 93 though.

  5. #5

    Great article on Octane and gas engines

    Attached is a great article that was previously posted either here or at the Riva site on the role that octane pays on engines. One of the best I've ever read.........maybe this will help.

    http://www.prime-mover.org/Engines/G...es/octane.html

  6. #6
    EZ Dock of Long Island Shibby1485's Avatar
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    here on long island... we have 87, 89, or 93..... most of the time i used 93... sometimes my cheap side came out, or i wanted extra money for lunch and i went with 89...

    i never noticed a different whatsoever.... but i never went so far as using regular 87.. lookin at what? 1.50 price difference on a full tank? ... not worth it...

    octane, boost, timing, blah blah.... all beyond my intelligence for now, but i'm trying to learn about it all

  7. #7
    captain obvious Lurker's Avatar
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    In a nutshell the higher the octane rating the harder it is for the fuel to ignite. You want the lowest octane possible without causing pre-detonation, or "knocking"

    http://dnr.louisiana.gov/sec/execdi...p/trans/b/b.htm
    http://toyotaperformance.com/fuel_octane.htm
    http://www.answers.com/topic/petrol
    http://auto.howstuffworks.com/question90.htm

  8. #8
    Will work on YOUR ski for FREE! GeoRXT's Avatar
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    Here we have 89, 91, 93 I've been using the 89!

    I put 93 on my car because the ECU chip program is supposed to run on 93 and I am hurting a bit! I have an Explorer which gulps gas and the 1.8T Jetta which uses the 93 and at $2.58 it's no bargain.

  9. #9
    My particular model requires 91 or better. GTX SC.

    simply put: the higher octane numbers act as a cushion against detonation, lower compression auto`s with PCM controlled timing as in todays cars , overall run best with the reg fuel, 87 octane, using premium in this senario will yeild nothing, but using lesser octane in the ski`s that require 91 or better will have knock and detonation up on top and the ecu will retard timing to the point that it will lack in performance. There are many different situations because of the dif temps we all live in, the hotter the climates the more prone to pinging will be...

    That`s why you riders in hotter climates would greatly benefit in the RR thermostat for several reasons, cooler engine temps + less heat fade...
    I`m in the NE, and really don`t have a need for it, besides I don`t have my machine pegged all the time...PR...

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