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    Formula SAE Transmissions
    #1
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    Hey all this is a little different than the usual off road stuff we're used to, but I was just having a discussion with other members of my college's FSAE team about switching engine/transmission combos. We currently run a turbocharged 500cc 2 cylinder Phazer engine (the circa 2009 four stroke 5 valve engine, not the older 2 stroke one most are familiar with) with the stock CVT. We have had this motor and trans setup for a number of years, but last year is our first with forced induction. The problem comes from no one on the team has taken the time to learn how to tune our clutches, so we aren't happy with how we put our power down (small CCs plus bad CVT tuning equals lots of turbo lag).

    One solution offered was to switch to a street bike engine (R6) so we would eliminate the CVT. Other teams with these engines are making about the same power as we are with our boosted engine (both engines have to suck through a restrictor per the rules), but the R6 weighs more than our engine and CVT setup, plus it is a larger motor (although taking the clutches into account it may be a slightly smaller setup overall).

    A second solution proposed was finding a way to adapt a manual transmission onto the Phazer engine to eliminate the issue of tuning the clutches. I'm not sure if that would mean finding an external transmission, or grafting a motorcycle transmission to the bottom with custom cases.

    I was wondering if anyone in this wealth of knowledge had any opinions to share on the matter, I'd love to hear what others think
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    Re: Formula SAE Transmissions
    #2
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    Honestly switching to a common street bike engine, or even dirt bike engine may be the way to go. One team I am quite familiar with runs a cycle cylinder 450 Yamaha with forced induction. But as an alternative you can just take the internals of a dirt bike gear case and make your own case to adapt to your engine, but at that point you might as well just use the dirt bike engine.
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    Re: Formula SAE Transmissions
    #3
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    One of the main reasons some people are opposed to completely switching engines is that would mean we would be at square one as far as any engine tuning/calibration goes, and we would likely burn up a few of the new motors before we got it dialed in, which would take a good bit of time. We also have a number of the Phazer engines on hand for spares already.
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    Re: Formula SAE Transmissions
    #4
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    Those are all valid reasons to stick with the CVT Phazer, but sticking with the CVT Phazers means you're going to struggle getting the power down properly. Everything has a cost...that's your cost. Your best bet to get the most out of your engine would probably to be to contact someone like Schmidt Bros, explain your setup and goals, and let them build you something.
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    Re: Formula SAE Transmissions
    #5
    Intense Moderator Rat4020's Avatar
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    Clutching from na to forced induction isnt that much of a deal. With mine all i did was increase the base weight of the primary weights 10g and leaving the low mid and high weights as they where and a heavier spring in the driven clutch. Now with the Phazer being a twin and the Apex as mine 4 banger i would say 5 grams added would be a starting point. I should ask if your using adjustable weights such as Thunder Products heavy hitters adjustable weights ?
    The question is not if its gona roll. Its when ..

    That be some kind of church cruzzer or commuter bike thingy ?
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    Re: Formula SAE Transmissions
    #6
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    The thing is I don't believe our clutching was tuned very well even before we added the turbo, but that was before I joined the team so I can't say for certain. As far as weights go, I believe we are just using the stock Yamaha clutches, I am not aware of any aftermarket parts in them anyway.
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    Re: Formula SAE Transmissions
    #7
    Keeper of the Asylum K-fab's Avatar
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    Stick with the CVT! The system is in, works, etc.. Don’t rebuild/redesign it, it’s not needed.

    Get your hands on the Aaen snowmobile clutch tuning manual http://www.aaenperformance.com/Handbooks.asp and learn how you get your clutches dialed in. A set of clutch arms is going to be a lot less expensive than a motor swap.

    I guarantee there are clutch tuning kits for the Yamaha primary available - let me know what you find, gonna need one for the Mini-Raptor.
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    Re: Formula SAE Transmissions
    #8
    The Bob Ross of MBN Bullnerd's Avatar
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    Watch some of the drag snowmobile vids if you don't think CVT's and transfer power! lol!
    "Speed is time-time is speed"-Dennis Hopper

    Quote Originally Posted by TALON View Post
    did you use a special bigfoot camera or something ,you know all blurry could be a tree stump kinda thing .
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    Re: Formula SAE Transmissions
    #9
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    I've done some general research on the basics of CVT tuning in my free time just because I was curious, and I understand the concept. I think no one has taken the time on the team to test and tune it is the issue, as our testing time is limited up here in the great white north due to the weather (300+ inches of snow on average every year) but also due to the fact that when we get time to test the car once it's built and the snow is gone, we're using the time to validate the other parts of the car instead.
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