Many times I've run mine at lower than full blast. Most people on realize that the fan cools the motor, but many neglect to realize that the crank generates airflow inside the motor to also help keep it cool.
Hold on - 1st are we talking about a 21" HP or a Z or a WB. Todays engine are designed & built to run their best at full RPM. On a Z running one for long periods of time on less than full rpm will not only cause engine problems but also pump & wheel motors. On a HP slowing down the rpm slows down blade speed. On a WB blade speed suffers & if it is a hydro the pump & wheel motors suffer. Slowing one down for a short time (to help keep stuff out of beds) shouldn't have an effect on the engine. But it is not a good idea to run them at less than full RPMOriginally posted by geogunn
IMHO I believe mower rpm for the sake of the motor is a non issue.
the motors are designed to run at any speed up to the max rating.
but for the sake of discussion...as the rpm's are lowered so is the cooling effect of the crank fan, however...so is the heat generating combustion of the engine.
it always operates within its tolerances.
GEO
sir--can you back your statment up with proof of what you are saying?Originally posted by redbull
Hold on - 1st are we talking about a 21" HP or a Z or a WB. Todays engine are designed & built to run their best at full RPM. On a Z running one for long periods of time on less than full rpm will not only cause engine problems but also pump & wheel motors. On a HP slowing down the rpm slows down blade speed. On a WB blade speed suffers & if it is a hydro the pump & wheel motors suffer. Slowing one down for a short time (to help keep stuff out of beds) shouldn't have an effect on the engine. But it is not a good idea to run them at less than full RPM
redbull--as for effieiency of rpms, blade speed and cutting, there is no disagreement.Originally posted by redbull
I feel I can back up this statement by reading the engine/owners manuals (specific the engine manuals) that come with the verious units out there. Most manufactures use the same engines. Or you can contact the manufacture direct. All I said was the engine were designed to run their best (most efficient) at full rpm.
perhaps you didn't really mean it when you said " less than full rpm will not only cause engine problems but also pump & wheel motors" but you did say it and that is why I questioned your statment.Originally posted by redbull
On a Z running one for long periods of time on less than full rpm will not only cause engine problems but also pump & wheel motors. On a HP slowing down the rpm slows down blade speed. On a WB blade speed suffers & if it is a hydro the pump & wheel motors suffer. Slowing one down for a short time (to help keep stuff out of beds) shouldn't have an effect on the engine. But it is not a good idea to run them at less than full RPM
Have you ever put a tach on a new machine? I always do. Most come at 3600 or just a little under. Then once you engage the blades the rpm's drop some. You may only be getting 3400 rpm's. If running at 3600 was a must don't you think the mfg's would up the rpm's to allow for working conditions. Or maybe the mower mfg's would be concerned over this.Originally posted by redbull
I feel I can back up this statement by reading the engine/owners manuals (specific the engine manuals) that come with the verious units out there. Most manufactures use the same engines. Or you can contact the manufacture direct. All I said was the engine were designed to run their best (most efficient) at full rpm.