What Does Horsepower Get You?

[71_Bronco 1,072]

Just curious on this topic. I have a Commando 8 that mows very nicely and pushes snow without issue. The 8HP seems to be plenty strong for what I need.

 

What would more HP get?

 

I've heard some people say that the 8HP isn't enough for a deck larger than 36". Is it because it needs the higher torque / HP to spin the larger blades?

 

I would assume something like a ground tiller will need more power due to the task it's attempting.

 

Obviously pulling power would be something to consider, but due to the size / weight of these little machines, I would think traction would be more important on that front.

 

Discuss

 

EDIT: I've also usually only heard HP numbers getting thrown out. I don't think I've ever heard someone refer to torque figures.

 

Is there a reason Torque is not discussed as much?

Edited October 14, 2020 by 71_Bronco

[ebinmaine 63,097]

Well now this right here is a great thread idea!

 

Could be a million different answers and most of them are going to be correct.

 

Horsepower is a great number for us to look at and that's what the manufacturers have taught us to read over the years but in reality it's TORQUE that actually does all the work.

 

And of course like you mentioned you got to have enough physical weight and combine that with traction to get whatever amount of horsepower you have stuck to the ground and keep it that way.

 

As most of you know Trina and I don't have any implements that are driven or ground engaging.

The only type of real world experience I can offer you is that when I had Patriot as a plow horse which is an 8 horse engine I noticed an immediate upgrade in the ability to go faster while pushing slightly more snow with the 16 horse engine that is on Cinnamon. Weight of the tractors was very close to equal.

 

There are those that say a 16 single is sort of the holy grail of these rides while other folk will tell you it's the 20 horse twin Onan.

 

In our herd at my acreage Trina and I have several 8 horse engines, my 16, and I'm building a 23. Why? Do I need it? Absolutely not. I just kind of like the idea....

I'll be looking forward to the other responses.

[Achto 26,548]

In my opinion it is hard to get more that 12hp to the ground with most garden tractors. You will loose traction way be for you lose HP. More HP can be needed to run implements though. Hook a 10hp engine to a 60" deck & you will see that 10hp fall on it's face in heavy cutting conditions. Same goes for a large 2 stage snow blower.

 

Torque is what gets your engine up to speed or helps it recover. If you look at most dyno read outs, peak torque will start to fall off before peak HP is reached. More torque will allow an engine to have more HP at a lower speed.

 

Here is a graph of the Mopar Hellcat engine. You will see a similar pattern on most dyno read outs.

 

Edited October 14, 2020 by Achto

[1995 520H+96+97 935]

More HP, less seat time doing the job.

[71_Bronco 1,072]

1 hour ago, ebinmaine said:

There are those that say a 16 single is sort of the holy grail of these rides while other folk will tell you it's the 20 horse twin Onan.

 

There's a whole new can of worms, Single Cylinder vs a Twin...

[ebinmaine 63,097]

3 minutes ago, 71_Bronco said:

 

There's a whole new can of worms, Single Cylinder vs a Twin...

Yes sir. Quite true.

I don't have enough experience with the whole realm of garden tractor engines to know what ones I would prefer by performance but they sure do have a different sound.

 

 

[71_Bronco 1,072]

3 minutes ago, ebinmaine said:

Yes sir. Quite true.

I don't have enough experience with the whole realm of garden tractor engines to know what ones I would prefer by performance but they sure do have a different sound.

 

One of the reasons I posted this thread, is that I am trying to negotiate a deal on a Wisconsin in-line twin, putting out approximately 18hp at 3,600 RPM.

 

Will it be overkill for a little Wheel Horse? Yeah, probably. Would it be a cool little beast? Heck yeah!

[Pullstart 59,686]

I don’t think many people will believe that my 8 hp Kohler will run a tiller, but it can, in good conditions.  Typically I struggle with the belt slipping long before I lose power.

 

Now, the question is bigger better?  Absolutely!  I set this up back when all I had was Putt Putt running the mower, tiller, disc, plow, etc.

 

 

[lynnmor 6,773]

Horsepower is the measure of work that an engine can do, you adjust the gearing to get the torque required to make things move, but of course as you gear down less work can be done.  I wish the automotive would never have started this torque nonsense, now that is the new bragging rights number.  An engine with twice the torque but the same horsepower as another will be turning at half the speed, with twice the cylinder pressure and twice the load on everything, but people somehow think the low RPM is good for engine life.

[Achto 26,548]

1 hour ago, lynnmor said:

but people somehow think the low RPM is good for engine life.

 

If you take a look at most newer push mowers with a Briggs engine, you will notice that there is no throttle control on them. The reason behind this is that Briggs grew tired of warrantying engines because people would run them at low RPMs and wreck them. Now you pull the rope & then engine goes directly to 3600RPMs when it starts, which is where their engine and most small engines are designed to run. 

 

RPM & engine life go hand and hand by engine design. A 4cyl 2.5L VW Jetta engine has a cruising RPM of around 3000. My Dodge truck with a 4.7L V8 has a cruising RPM of about 1800. A Lamborghini 6.2L V12 has a cruising RPM of about 2250. All the above cruising speeds are at 65 to 70mph. Most car engines are designed to run at their best efficiency & longevity at cruising speeds. ( Well, may be not the Lambo. )  

Edited October 14, 2020 by Achto

[Pullstart 59,686]

Horsepower is how fast you can hit the wall.  Torque is how far you can push it.

[ebinmaine 63,097]

1 hour ago, pullstart said:

Horsepower is how fast you can hit the wall.  Torque is how far you can push it.

Horsepower is BBT. Torque is the Large Bear.

[oliver2-44 8,852]

Most will agree that a Kohler K series 8hp Will run a 36/38” deck all day long. So why do Manufacturers of new riding mowers need a 16/18 hp engine To run a 38” deck  Why do the new small the engines have less torque per HP?

I realize the new small engines have less rotating mass I.e. plastic flywheels, short stroke, etc .  More Rotating mass equals more torque 

 

[Guest 88vic]

2 hours ago, pullstart said:

Horsepower is how fast you can hit the wall.  Torque is how far you can push it.

 I've always loved this saying. 

[Achto 26,548]

1 hour ago, oliver2-44 said:

Why do the new small the engines have less torque per HP?

 

I can answer this real simply - STROKE

 

Kohler 8HP K181 - 2.938" bore by 2.75" stroke

Kohler Command Pro 9HP - 3.1" bore by 2.3" stroke.

 

A longer stroke puts the crank pin further away from the center of the crank. This allows for more torque to turn the crank around when the cylinder fires. Same theory as grabbing a longer wrench so that you can get a rusty bolt loose.

 

[pfrederi 17,146]

4 hours ago, Achto said:

 

If you take a look at most newer push mowers with a Briggs engine, you will notice that there is no throttle control on them. The reason behind this is that Briggs grew tired of warrantying engines because people would run them at low RPMs and wreck them. Now you pull the rope & then engine goes directly to 3600RPMs when it starts, which is where their engine and most small engines are designed to run. 

 

RPM

  Or they figured it was cheaper to build carbs with out an idle circuit....

[953 nut 51,650]

What Does Horsepower Get You?

When I was a kid it got me lots of speeding tickets.                                                       

[SylvanLakeWH 24,126]

2 minutes ago, 953 nut said:

What Does Horsepower Get You?

When I was a kid it got me lots of speeding tickets.                                                       

...and a much lighter wallet...

[tom2p 2,393]

7 hours ago, 1995 520H+96+97 said:

More HP, less seat time doing the job.

^^^^
this 

 

with more horsepower you can cut more grass faster

 

if you cut a lot of grass - more horsepower can make big difference 

I cut around 3 acres ; cut it with three tractors :

   704

   312-8

   416-H

 

Cut it one time with the 704 - and purchased the 312-8.  Cut the time significantly - still long but doable.  Then got the 416-H - cut the time again.

 

[WheelhorseBob 1,548]

In new tractors HP sells. It’s that simple. In my way of thinking one horse power will run ground engaging equipment.....

[lynnmor 6,773]

1 minute ago, WheelhorseBob said:

In new tractors HP sells. It’s that simple. In my way of thinking one horse power will run ground engaging equipment.....

 

Plus the exhaust adds fertilizer.

[Stepney 2,314]

A healthy 12hp will swing a 48" WH deck and manual tractor very well, 10hp is pushing it.. Manual 8 speeds i can run a 42", forget it with an 8hp Hydro..

All the same.. every 10hp Hydro even with a 36" deck Ive owned seriously struggle on hills.

Heck my 14hp GT1848 running a 42" struggles on grades..

 

All the same.. my whopping 9hp 1951 Farmall Cub will swing a 60" mower moving at a good clip all day with its little 60ci 4 banger.

All the while turning 1800rpm..

 

And my 2hp 1928 Fairbanks Morse engine pulls a buzz saw better than a 16hp Kohler K series does..

Torque is everything. 

[SylvanLakeWH 24,126]

My 10 hp C 105 cut through this just fine... slow yes... but just fine...  

 

Gearing made it happen...

 

[tom2p 2,393]

1 hour ago, tom2p said:

^^^^
this 

 

with more horsepower you can cut more grass faster

 

if you cut a lot of grass - more horsepower can make big difference 

I cut around 3 acres ; cut it with three tractors :

   704

   312-8

   416-H

 

Cut it one time with the 704 - and purchased the 312-8.  Cut the time significantly - still long but doable.  Then got the 416-H - cut the time again.

 

the 312-8 is a great runner - had it since late mid/late 90's 

 

got 416-H few years later 

 

416 is on a different level - feels like it has twice the power 

 

exaggeration obviously - but the difference is so significant that when the 416 reached around 1000 hours - I got another 416 

can only imagine what the 520 is like 

 

[JAinVA 4,619]

Everything posted by these folks is valid in my opinion.The tractor itself takes very little power to move it around and say pull a cart.It is the attachments that take the power.A 10 or 12 horse can handle a tiller,or a 42" deck no problem.Using a 48" deck in tall grass may take a little more.The 2 stage blower or 60" mower are better matched to a 20 horse.Since the engines mounted to the WHs are rated at 3600 rpm the higher the HP then the higher the torque or twisting force at the crankshaft.

Edited October 15, 2020 by JAinVA