From my website: movingsnow.com. Five years ago the power output of every snowblower sold here in the United States was measured in hp or horsepower. It was a nice simple measurement that everyone was used to. Three years ago they changed the rules and started selling snowthrowers with the power measured in gross torque. Of course no one understood what this meant and even though companies like Briggs & Stratton tried to explain it, it still didn't make much sense. Well they changed the rules on us again. So we just start to get used to measuring an engine's output in torque and now for the 2009/2010 season a lot of the snow blower manufacturers are dropping the torque measurement and only giving us engine size in cc's. I spent a great deal of time researching this and I'm not going to spend time trying to explain why the engine manufactures have changed their terminology. Instead I'm just going to show you a formula you can use to figure it out yourself. Here's the formula I used from the Briggs & Stratton website (rpm x torque / 5,252) The engine manufacturer's used 3600 rpm most of the time to rate the engine's horsepower so I will use that number in the formula. I also used the torque ratings from the Briggs & Stratton website for their motors to keep this chart simple. Other manufactures (like Powermore) may have different torque ratings for their motors. If you are trying to get exact hp measurements you should research the torque ratings for the specific brand. For 2009/2010 MTD has dropped all torque ratings on snow throwers. The engines are only labeled in cc's. Here is a simple chart of approximate cc to torque to horsepower conversions. It's not exact, but it will give you a better idea of how big the new engines are. I used 3600 rpm in the formula for this comparison. Assume that your new snowblower motoe runs at less rpm. 123 cc = 4 hp 179 cc = 5 hp 208 cc = 8 to 9 Gross Torque = 5.5 to 6 hp 277 cc = 11 to 11.5 Gross Torque = 7 to 8 hp 305 cc = 13.5 to 14.5 Gross Torque = 9 to 10 hp 342 cc = 15.5 to 16.5 Gross Torque = 11 to 12 hp 357 cc = 12-14? 420 cc = 14-15? To me cc's is not a good comparison from one motor to another. It is also not a good comparison from one manufacture to another. For example, a 190cc Briggs & Stratton side valve motor will not have the same power as a Honda 190cc overhead valve motor. cc'c doesn't give you a good measurement of what the engine is capable of. True, an overhead valve motor from a specific manufacture should have more power with more cc's but there are a lot of other factors that go into determining how much power is available for you to use. The true power of a motor is determined by engine type, (overhead valve/side valve) carburetor (naturally aspirated/fuel injected/turbo) rpm you use it at (2750/3100/3650) and many other factors. I hope this helps.
Not unlike agriculture tractors in the 1920/30s, the HP ratings were being used (abused) in a specmanship war by the manufactures and then the lawyers got involved, so HP and torque ratings have all but disappeared.
Most small engines are now OHV so for a ball park HP figure simply divide cubic centimeters by 30 and don't get hung up by a couple of horsepower difference so long as the engine type is the same, e.g. OHV/carburetor and the application is the same, e.g. push mower, ZTR mower, pressure washer, or generator... just take it in faith that a 357cc engine delivers the same power regardless of manufacturer.
Php = PkW / 0.746 (2)
or
Php = (?m U I / 1000) / 0.746
= ?m U I / 746 (2b)
where
Php = horsepower (hp)
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