Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

Does anyone know what Tecumseh changes to yield 11HP from the same block as the 9HP Snow King?  I would guess it's either the carb., induction system, valves or maybe all of the above?

Sometimes to change the torque of a motor they change the flywheel (from aluminum to cast steel ),   this form what I understand absorbs the amount of available horspower at the ptu shaft but increases torque..

I remimber right..

Friiy

friiy wrote:
I agree that a heavier flywheel will maintain a more linear  torque supply.  Particularly under load.  The heavier flywheel's momentum will not be as sensitive to load variations as a lighter flywheel.  I cannot see how this could possibly reduce horse power though.   Once the engines are spinning at equal rpms, power output should be the same.   If the heavier flywheel restricted the ability to achieve equivalent rpms, I'd agree with you.  Otherwise, I'm having trouble understanding how it would inhibit power output.   I know with drag racing engines, savvy racers will put in a lighter flywheel to aid in acceleration by having the engine spin up fractionally quicker.  Overall, engine power output was virtually no different between the two flywheels once the engine was at full rpms.   

  about the only things that will effect hp or torque are,   parasitc loads   example once you start putting  blade adapters, pulleys, belts  etc  all these items will rob the unit of actual hp.  this is how briggs and stratton got into trouble.   the advertised a specific unit was 6 hp.......... now what the didn't exactly disclose was this was "raw"   meaning now parasitc load on it.  well someone   dyno'ed an engine and it was only 5 hp......  anyway  later

A flywheel is the mechanical equivalent of a capacitor, it stores power for a little while. A heavy flywheel will cause an engine to take longer to come up to speed but does not change the overall power output. Once the engine is up to speed the flywheel will smooth out the power output and cause the engine to take longer to slow down once it is turned off.

Flywheels are particularly important in low cyclinder count engines ( singles for instance) since there are fewer power storkes per RPM. It stores some of the energy created in the power stroke and uses it to keep the engine turning over until the next power stroke occurs.

There is also a gyroscopic effect which can be kind of weird if you ever pick up a generator and try to turn it.

Several years ago I started a thread(http://www.abbysguide.com/ope/discussions/7869-A-1.html)that grew to over 154 posts regarding this very subject. While it was with regard to a Briggs engine Tecumseh does(did) the same thing. It appears that the change to torque ratings rather than horsepower which is now being used is an attempt to further obfiscate the truth and reveals the shady way in which engine manufacturers rate their products.Try and make it through the entire thread-It makes for interesting reading!!

Marc