How does CCs affect blade power and torque?

[GearHead36]

Does HP do anything? StarTech said it was torque. Is HP a better way to measure power output than torque?

For OPE, it really doesn't matter. Both are measures of the ability to cut grass. More HP = better ability to cut. More torque = better ability to cut. The problem comes when you try to compare engines rated in HP vs those rated in torque. Torque is probably a better measure, as it's easier to fudge HP numbers. If you increase RPMs by, say, 1000, the HP will increase, but that does nothing for cutting grass, which is done at a set RPM. Torque curves are flatter than HP curves, so increasing RPMs by 1000 won't result in the same torque increase as you'd get with HP. And, I think, engines are now rated in torque at a specific RPM, so comparing engines is easier.

But really, if cutting super-tall wet grass is what you want to do, a 21" Craftsman with a bigger engine is not the answer. You need something commercial.

 

[Little Fish]

For OPE, it really doesn't matter. Both are measures of the ability to cut grass. More HP = better ability to cut. More torque = better ability to cut. The problem comes when you try to compare engines rated in HP vs those rated in torque. Torque is probably a better measure, as it's easier to fudge HP numbers. If you increase RPMs by, say, 1000, the HP will increase, but that does nothing for cutting grass, which is done at a set RPM. Torque curves are flatter than HP curves, so increasing RPMs by 1000 won't result in the same torque increase as you'd get with HP. And, I think, engines are now rated in torque at a specific RPM, so comparing engines is easier.

But really, if cutting super-tall wet grass is what you want to do, a 21" Craftsman with a bigger engine is not the answer. You need something commercial.

Yeah, that makes sense (and I know HP is fudged all the time based on my shop vac purchases LOL).

Any recommendations on a relatively cheap commercial walk behind? I know cheap doesn't exist, but the Toro time master isn't even worth $500 imo, since it just clogs immediately by all accounts

 

[StarTech]

The Toro Recycler needs to be upgraded a little to a Super Recycler by adding the accelerator blade as to increase the air flow for wet grass. But I have gotten a chance to the clearance for the added blade. Darn customer brought a $450 Recycler and just plain gave it away less than a week later. Boy it take some time to get in parts just to try a mod a times.

The problem is the blade used just don't have enough air lift to bag properly.

 

[ILENGINE]

That's what I am planning to do. I'm letting the grass lift up a bit because it was pretty wet the other day when I mowed (no choice on that).

Does HP do anything? StarTech said it was torque. Is HP a better way to measure power output than torque?

Without torque, HP means nothing. And you are getting hung up over numbers for the most part don't vary enough to be able to make a difference. And a third factor that can eat up any additional torque, or HP produced by the engine. And that is air flow dynamics of the deck, blade interaction.

 

[Little Fish]

Without torque, HP means nothing. And you are getting hung up over numbers for the most part don't vary enough to be able to make a difference. And a third factor that can eat up any additional torque, or HP produced by the engine. And that is air flow dynamics of the deck, blade interaction.

Yeah, I could see that with this mower. The engine has "enough" power, but only if the cut grass is evacuated fast. Like out the bag chute. But the only way to not have it clog the blade and stall is if the bagger chute is completely open ans spraying me with grass.

The key takeaway for me is torque. I know I'll sound like Tim from Home Improvement when I say it, but it needs MORE POWER! (Ugh ugh snort)

If I put a 15HP 10 or 12ft-lb engine on there, it won't care if the deck or Gras is clogged and I can put a better blade on it (like the Oregon g5 mulching blade). It would cut better, and could handle taller grass. The issue is finding a vertical shaft engine that has enough torque to do that.

 

[Chuckers]

I want to get a mower engine and swap onto my little 21" 140cc Craftsman. I let my yard get way too high and went to mow it, but it was barely able to handle it, and I had to push it 2ft, backtrack 3, then go forward slowly.

Anyway, I was looking at a new mower, but they're all 150 or 170 or 163 cc (for the well rated ones. There's several 200ish cc ones for outrageous money, or with like 2 stars.

So, I'm curious. How much does engine CC actually do? Will I notice a difference between my 140cc and a 150? What about 163 or 170? Where would I need to go to buy a bigger engine that I could just swap onto the mower?

I think you need to step back and think a little more clearly.

1. Your current push mower worked fine for your purposes (presumably),
2. until you let your lawn get overgrown, then it gave you problems,
3. leading you to believe that the mower engine is anemic,
4. now you want to replace the engine to get more power.

The fact is, push/walk-behind mowers are not made for overgrown mowing. You can upgrade to a 170cc engine with more torque but you'll still have the same issues in the same situation as any extra "power" will still be anemic for overgrown mowing with a push mower. You are basically overreacting based on one incident, which may not happen again. But even if it does happen again, there is a solution that actually works if using a push mower for overgrown lawns....

Step 1. Raise your cutting height
Step 2. Bag the clippings as you mow
Step 3. Lower the height and mow again, preferably bagging again.

You took the hard way out by using the back-and-forth method. While bagging and mowing twice sounds like the hard way out, mowing 2ft, then backing-up 3ft, then moving forward slowly is the actual hard way out. In fact, you likely spent the same amount of time (if not more) and exerted more effort than using my solution above.

In the future, if you are going to (or have to) continue using a push mower (no shame, I mow about 15 lots with a push mower), the solution going forward is not to change the engine, rather...

1. Don't let your lawn overgrow past the point of a push mower's usability
or
2. If you do let it overgrow (for whatever reason, not judging you), use the solution above.

 

[ILENGINE]

Yeah, I could see that with this mower. The engine has "enough" power, but only if the cut grass is evacuated fast. Like out the bag chute. But the only way to not have it clog the blade and stall is if the bagger chute is completely open ans spraying me with grass.

The key takeaway for me is torque. I know I'll sound like Tim from Home Improvement when I say it, but it needs MORE POWER! (Ugh ugh snort)

If I put a 15HP 10 or 12ft-lb engine on there, it won't care if the deck or Gras is clogged and I can put a better blade on it (like the Oregon g5 mulching blade). It would cut better, and could handle taller grass. The issue is finding a vertical shaft engine that has enough torque to do that.

More HP or Torque and a better blade may not cut any better than your have now. I have a 72" mower connected to a 45 HP 4 cylinder diesel. And if the grass is more than 6 inches high I have to slow to about 2 mph or mow it twice with it.

 

[GearHead36]

So you want to be able to mow super-tall wet grass, and bag it? With a Craftsman 21" push mower? Now I'm thinking this is a troll. This job is in the territory of $10000 stand-on mowers. How long would it take to fill a bag while mowing super-tall wet grass? I'm thinking about a minute. So you'd be spending more time emptying the bag than you would be mowing.

If this is not a troll, then you seem intent on spending a lot of energy just to avoid mowing at regular intervals. Energy that could better invested in, say, mowing at regular intervals.

Still, in the Tim Taylor vein... overpowering a small push mower could be a fun project. Just don't be surprised when this thing won't do the job you're hoping it will do. As much as we like to rag on mfrs and design engineers here, they DO kinda know what they're doing. They don't put 5HP engines on 60" ZTRs, and they don't put 20HP engines on 21" push mowers. Bigger, tougher jobs that require more power also require more in other areas, like deck size and design, blades, drive systems, etc. The deck on your 21" Craftsman isn't designed to flow the amount of grass you're wanting it to. And nothing, short of commercial, is going to do well with tall wet grass. I have an entry level commercial ZTR with a 27HP engine, and I won't mow if the grass is tall and wet.

Does your mower have side discharge? If it does, I suggest discharging away from the uncut grass, and mowing 6" strips at a time. Your deck might be able to handle that amount of grass.

 

[Little Fish]

So you want to be able to mow super-tall wet grass, and bag it? With a Craftsman 21" push mower? Now I'm thinking this is a troll. This job is in the territory of $10000 stand-on mowers. How long would it take to fill a bag while mowing super-tall wet grass? I'm thinking about a minute. So you'd be spending more time emptying the bag than you would be mowing.

If this is not a troll, then you seem intent on spending a lot of energy just to avoid mowing at regular intervals. Energy that could better invested in, say, mowing at regular intervals.

Still, in the Tim Taylor vein... overpowering a small push mower could be a fun project. Just don't be surprised when this thing won't do the job you're hoping it will do. As much as we like to rag on mfrs and design engineers here, they DO kinda know what they're doing. They don't put 5HP engines on 60" ZTRs, and they don't put 20HP engines on 21" push mowers. Bigger, tougher jobs that require more power also require more in other areas, like deck size and design, blades, drive systems, etc. The deck on your 21" Craftsman isn't designed to flow the amount of grass you're wanting it to. And nothing, short of commercial, is going to do well with tall wet grass. I have an entry level commercial ZTR with a 27HP engine, and I won't mow if the grass is tall and wet.

Does your mower have side discharge? If it does, I suggest discharging away from the uncut grass, and mowing 6" strips at a time. Your deck might be able to handle that amount of grass.

I don't want to bag. I never said anything about a bag, other than the bag chute had to be open. (I don't own a bag, so grass was just flying). No, it's not safe. No, I didn't like that solution. I did that because I had to.

I came here to ask what engine size I would need to do the job. I got the answer (a commercial mower). I don't plan on leaving the grass that long again, but my area has been getting rain once a week anyway, and my lawn is ALWAYS wet (I'm talking almost clumping to shoes wet) and I don't water it. It just gets rain, and apparently there's an underground spring under my back yard.

What brands should I be looking at for a prosumer mower? Would a lawn tractor be able to do anything? (And if I got a cheapo one, would any random horizontal shaft engine work? Or would I need to match hole patterns ans things? (I'm handy, but have no welding equipment)

 

[Chuckers]

How big of a lawn are we talking here? I have 3 neighbors that have lawns about 50'x75' and they use riding mowers. It takes them longer to mow than it would on foot lol. But I guess it makes them feel like "a man"? That's the only reason I can figure.