SkunkWerX
Platinum Member
To continue adding information on this topic.......
I agree that 5 HP per width of cut is a general rule of thumb, but there are a LOT of variables to take into account, as many have mentioned.
Hills, dry/wet conditions, type of vegetation, height of cut, etc.
Back in the 80s my tractor was a Ford 1210 4x4 gear drive machine. It was a great little tractor for our 2.5 acres. It was 16hp with 13.5hp out the PTO.
I wasn't sure if it would run any kind of bush hog at all. Back then they didn't have as many smaller options, like the ones for Sub Compacts, so 4 foot was about as small as you could find. I bit the bullet and tried it, luckily it worked!
I learned quickly to take it easy, watch the ground speed, take Half-Swipes in thicker stuff and make sure my height was set properly. So that was 3.4HP per foot, violating the 5HP rule of thumb by a fair amount. The BX was 23.5HP with about 19HP out the back, and it felt no more powerful with the same old 4 foot cutter. It was a hydro machine but I think I figured out why the higher HP didn't feel any more powerful, which I will discuss further down.*
Hills: When I have cut on slopes with a decent incline, and found uphill to be a problem, I just mow thick stuff on the downhill, and return uphill in an already cut swath, or maybe do a Half-Overlap on the way back uphill.
Wet: Speaks for itself, whether it's bush hogging 2' tall weeds, or finish mowing the lawn, wet conditions rob HP and dull blades at a faster rate.
About the only positive thing i can say about wet conditions is that it keeps the dust down, which is nice during allergy season, but not efficient for the machinery.
Height of Cut: This one I learned with the Ford 1210.... if I set up the bush hog for a taller cut, it could go through rough stuff without bogging. If clearing for good, like to expand the yard/lawn area, then go back over it set lower, to get down to a low height of vegetation. Otherwise, if you're mowing down 2' or 3' stuff and bogging a lot, bring the deck up 3" or so, and there is a difference.
*Ok, here is what I think I have learned after several tractors and many pieces of PTO equipment: Centrifugal Force and Mass is important. Size does matter.
Back in the old days, Pre-WWII, engines didn't generate as much HP as today. They made up for it by running large flywheels. Once the large mass was spinning, it could power through bigger jobs. If it bogged, you had to wait for it to get back up to speed, but farmers were able to get work done with smaller HP machines.
I think that was the difference between the 1210 and the BX tractor. The 1210 was lower HP, but likely had a larger flywheel and more metal mass spinning around going out the back end. The BX, I can tell you, makes it's HP at high revs, but didn't seem like it was as torquey as it could have been.
So, besides PTO HP, overall size plays a part.
Bottomline is: There are more factors to weigh than simple PTO HP. Once someone has looked at it all, then, there is the operator and experience.
The reason I stumbled on this post is that the current tractor is a Kioti 24.5HP, hydro, with about 20HP out the back. Not much different than the BX rating, right?
Wrong. It feels so much more powerful. It is also a bit wider than the 48" rotary cutter, so I am probably going up to a 5 foot cutter.
BX subcompact vs. Kioti compact
The toughest attachment in my stable, to get up to speed, is the wood chipper. ~110 lb. flywheel, triple belts, pulleys, etc.
It was a bit large for the BX anyway, weight-wise, like tail wagging the dog. But, also, it would tax the BX on start-up to get up to speed. And, depending on limb size, it could bog it down the same way and I had to wait a few seconds for it to regain it's RPM. The Kioti is only 1+ more HP, but it's like having 50% more HP. It spins up the chipper immediately, and doesn't slow down on branches that would nearly choke the BX.
HP matters, but (humble opinion) so does overall size and spinning mass. The operator and technique also play a large roll once the tractor is moving and the blades are spinning.
I agree that 5 HP per width of cut is a general rule of thumb, but there are a LOT of variables to take into account, as many have mentioned.
Hills, dry/wet conditions, type of vegetation, height of cut, etc.
Back in the 80s my tractor was a Ford 1210 4x4 gear drive machine. It was a great little tractor for our 2.5 acres. It was 16hp with 13.5hp out the PTO.
I wasn't sure if it would run any kind of bush hog at all. Back then they didn't have as many smaller options, like the ones for Sub Compacts, so 4 foot was about as small as you could find. I bit the bullet and tried it, luckily it worked!
I learned quickly to take it easy, watch the ground speed, take Half-Swipes in thicker stuff and make sure my height was set properly. So that was 3.4HP per foot, violating the 5HP rule of thumb by a fair amount. The BX was 23.5HP with about 19HP out the back, and it felt no more powerful with the same old 4 foot cutter. It was a hydro machine but I think I figured out why the higher HP didn't feel any more powerful, which I will discuss further down.*
Hills: When I have cut on slopes with a decent incline, and found uphill to be a problem, I just mow thick stuff on the downhill, and return uphill in an already cut swath, or maybe do a Half-Overlap on the way back uphill.
Wet: Speaks for itself, whether it's bush hogging 2' tall weeds, or finish mowing the lawn, wet conditions rob HP and dull blades at a faster rate.
About the only positive thing i can say about wet conditions is that it keeps the dust down, which is nice during allergy season, but not efficient for the machinery.
Height of Cut: This one I learned with the Ford 1210.... if I set up the bush hog for a taller cut, it could go through rough stuff without bogging. If clearing for good, like to expand the yard/lawn area, then go back over it set lower, to get down to a low height of vegetation. Otherwise, if you're mowing down 2' or 3' stuff and bogging a lot, bring the deck up 3" or so, and there is a difference.
*Ok, here is what I think I have learned after several tractors and many pieces of PTO equipment: Centrifugal Force and Mass is important. Size does matter.
Back in the old days, Pre-WWII, engines didn't generate as much HP as today. They made up for it by running large flywheels. Once the large mass was spinning, it could power through bigger jobs. If it bogged, you had to wait for it to get back up to speed, but farmers were able to get work done with smaller HP machines.
I think that was the difference between the 1210 and the BX tractor. The 1210 was lower HP, but likely had a larger flywheel and more metal mass spinning around going out the back end. The BX, I can tell you, makes it's HP at high revs, but didn't seem like it was as torquey as it could have been.
So, besides PTO HP, overall size plays a part.
Bottomline is: There are more factors to weigh than simple PTO HP. Once someone has looked at it all, then, there is the operator and experience.
The reason I stumbled on this post is that the current tractor is a Kioti 24.5HP, hydro, with about 20HP out the back. Not much different than the BX rating, right?
Wrong. It feels so much more powerful. It is also a bit wider than the 48" rotary cutter, so I am probably going up to a 5 foot cutter.
BX subcompact vs. Kioti compact
The toughest attachment in my stable, to get up to speed, is the wood chipper. ~110 lb. flywheel, triple belts, pulleys, etc.
It was a bit large for the BX anyway, weight-wise, like tail wagging the dog. But, also, it would tax the BX on start-up to get up to speed. And, depending on limb size, it could bog it down the same way and I had to wait a few seconds for it to regain it's RPM. The Kioti is only 1+ more HP, but it's like having 50% more HP. It spins up the chipper immediately, and doesn't slow down on branches that would nearly choke the BX.
HP matters, but (humble opinion) so does overall size and spinning mass. The operator and technique also play a large roll once the tractor is moving and the blades are spinning.
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