is there a rule of thumb or rough way to convert cubic centemeters to horsepower? An example 205cc=?, 208cc=?etc,etc,I'll risk a guess that this is an effort to compare snowthrowing capability, now that we have older units rated in hp and newer ones rated by torque and/or cc.
Engine design is a major factor in comparing an older used unit to a new one. For instance a 195 cc L-head (or side valve) Tecumseh is rated at 5 hp (2003 model HSSK50), but most newer 5 hp engines are only 179 cc because they use overhead valves which process the combustion mixture more efficiently.
Impeller design is the second important consideration in throwing distance. My neighbor's older MTD has 312 cc, but uses the traditional small, high bypass impeller with a large 14 mm gap from blade tip to housing. This gap provides stone damage protection but bypasses snow inside the impeller housing with each revolution instead of throwing it. The impeller housing and chute clogs and the traditional answer has been to apply more power. (Stuff a big enough Pratt & Whitney into an F4 Phantom and it will eventually fly.)
Some manufactureres have now finally modernized impeller design. Toro's Power Max system has a very tight 3 mm impeller housing gap for efficient throwing and a large channel on the downstroke side that recirculates excess snow back to the auger. Feeding it back to the auger keeps the impeller from jamming up, thus maintaining throwing power.
The net result is my modern 250 cc Toro throws fresh powder and EOD farther than my neighbor's 312 cc traditional design.
For the average winter of 8" snowfalls a 205 cc with advanced impeller should do. With the 20" blasts the northeast has gotten this year 250 cc would be better.
This message was modified Mar 1, 2010 by samdog
