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Forced Induction: How and Why

    As stated in in earlier sections, forced induction increases horsepower by increasing the torque that an engine puts out.  It does this by shoving more and and fuel into the cylinders by way of some sort of blower. If you are going to use forced induction, first you have to figure out what type you will use: supercharging or turbocharging.
    Supercharging has been around almost as long as the auto. Back in the early days of Grand Prix, racers discovered they could yield tremendous horsepower gains by increasing the inlet manifold pressure of their cars using a mechnical blower driven off the engine. Unfortunately, engine technology and metallurgy were not up to the task, and the reliabilty of these 'blower' engines was certainly suspect. (ie like blower bentleys). Also, some of the engines increased output was absorbed by the supercharger. Fast foward to today. Now we have much better engines to supercharge, and two basic types of superchargers to do it: positive pressure (roots, lysholm, whipple) and centrifugal (paxton, vortech, etc). Positive pressure blowers provide very even boost, even at low rpm, whereas the pressure increase on a cent. blower increases with the square of the speed. Thus, they only provide boost at higher engine speeds. Because of this, they are usually installed on larger engines (v8s) that have a decent amount of torque without the boost from the supercharger. Positive pressure blowers can be found on almost every type of engine, from Pontiac GTP's to top fuel dragsters, because of their linear boost output.  Superchargers do have a couple of disadvantages: 1. You have to find someplace to drive them from. 2. They mooch some of the horsepower gained to drive themselves.

    Detonation etc.

My Sleds:

    1972 Élan 250:

    1972 Élan 250 with a 71' TNT 335 engine, drivetrain, and suspension:

    1973 T'nT Silver Bullet 294:

    1980 Blizzard 5500:


    Bob's Snowmobile Page
        :Big site full of info on T'nT and Blizzard SkiDoo's

    Antique Ski-Doo & Vintage Ski-Doo Restoration Resources

    Tech Report on Power Valve Maintenance
        :Keep those R.A.V.E. valves clean

    Ram Air Article
        :An interesting article on the fable of "ram air"

    Rear Cylinder Siezures
        :A tech article about rear cylinder siezures in PWC twins due to crankshaft torsion (very interesting)

    Polaris Triple FAQ
        :A page that has the skinny on Polaris triples (ie which ones to avoid)

    New Hampshire Snowmobile Association

     Don's Vintage Arctic Cat Site

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