How does CCs affect blade power and torque?

Little Fish

Member
Joined
May 5, 2024
Threads
1
Messages
18
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?
 

StarTech

Lawn Royalty
Top Poster Of Month
Joined
Feb 19, 2020
Threads
82
Messages
10,391
Well it sorta comparing apples to oranges. It all depend ft/lbs torque the engine are rated for. Manufactures can limit ft/lbs torque on larger engines and a smaller engine might have the same power so you must know the current engine's specs and compare to the possible replacement specs.

https://www.smallenginesurplus.com/

Also a dull blade will cause cutting problems.
 

7394

Lawn Addict
Joined
Sep 5, 2014
Threads
84
Messages
4,786
Start in on it with yer string trimmer.. Then clean up with the push mow.
 

Little Fish

Member
Joined
May 5, 2024
Threads
1
Messages
18
Well it sorta comparing apples to oranges. It all depend ft/lbs torque the engine are rated for. Manufactures can limit ft/lbs torque on larger engines and a smaller engine might have the same power so you must know the current engine's specs and compare to the possible replacement specs.

https://www.smallenginesurplus.com/

Also a dull blade will cause cutting problems.
Thanks! The 140cc one is 5.5ft-lbs. Apparently the Honda ($550 model) is 8.2.

Does 8ft lbs sound like enough for tall grass?

Start in on it with yer string trimmer.. Then clean up with the push mow.
Nope. That made it worse. Then I tried mowing it, and it was worse, if anything. Definitely not better.
 

GearHead36

Well-Known Member
Joined
Apr 26, 2023
Threads
9
Messages
130
Simple. Don't let your grass get that tall. Mow often with a properly working mower. The rule-of-thumb is to cut no more than 1/3 the length of the grass. So if you want your grass at 2", mow when it gets to 3". In the growing season, that's usually around once a week. Make sure the deck is not clogged with grass. Once a year, clean out the deck of dried, caked-on grass. Twice a year, sharpen the blade, and check the air filter. Blow out the air filter with compressed air if it's not wet with gas or oil. Replace if it is. Use side discharge. Mulching only works well on well maintained (short) grass.

A properly working mower has no problem cutting through properly maintained grass. This is a better, easier, and cheaper option than an engine swap. Your grass will look much better too, and your yard won't become a habitat for snakes and other unwanted critters.

For mowing through super tall grass, I would set your mower to its max height, and mow. Tomorrow or the next day, lower your mower a couple of notches, and mow again. Repeat this until you get the grass at the height you need it. Then keep it mowed.
 
Last edited:

Little Fish

Member
Joined
May 5, 2024
Threads
1
Messages
18
Simple. Don't let your grass get that tall. Mow often with a properly working mower. The rule-of-thumb is to cut no more than 1/3 the length of the grass. So if you want your grass at 2", mow when it gets to 3". In the growing season, that's usually around once a week. Make sure the deck is not clogged with grass. Once a year, clean out the deck of dried, caked-on grass. Twice a year, sharpen the blade, and check the air filter. Blow out the air filter with compressed air if it's not wet with gas or oil. Replace if it is. Use side discharge. Mulching only works well on well maintained (short) grass.

A properly working mower has no problem cutting through properly maintained grass. This is a better, easier, and cheaper option than an engine swap. Your grass will look much better too, and your yard won't become a habitat for snakes and other unwanted critters.

For mowing through super tall grass, I would set your mower to its max height, and mow. Tomorrow or the next day, lower your mower a couple of notches, and mow again. Repeat this until you get the grass at the height you need it. Then keep it mowed.
Obviously, if I mowed it before this, it would be as much of an issue. I was asking about how engine size affects power.

I agree that cutting it regularly is better. The problem is that I wasn't able to mow it earlier because of other circumstances.

As for it getting moved, its done now. I mowed professionally for years, but I just had a honda, which isn't really an option now. Someone gave me a craftsman, but it's underpowered for this, and clogs all the time (side chute, mulch, even opening the rear chute only worked if it was fully open.) I was trying to get information on what mowers would be worth buying based on actual power, and not just a random number, or as much as that's possible.
 

Little Fish

Member
Joined
May 5, 2024
Threads
1
Messages
18
Pay someone to mow it this time with equipment rated for that type of mowing . Now you know this isn't a enjinerreng site and the answer you be looking for may not be available .
Did you read the first reply to this thread? It answered my question. Only issue after that was what would be enough power to get through the grass. Which I would still ask a pro, since they have more experience than I do (I was actually a pro, but I only ran a Honda and did small jobs, so I never experienced other movers and how they work).

And where else would I ask about this? Car guys won't know, and engineers are too busy making money and working to death to reply to some random guy on a forum LOL
 

Tiger Small Engine

Well-Known Member
Joined
Dec 7, 2022
Threads
1
Messages
745
Did you read the first reply to this thread? It answered my question. Only issue after that was what would be enough power to get through the grass. Which I would still ask a pro, since they have more experience than I do (I was actually a pro, but I only ran a Honda and did small jobs, so I never experienced other movers and how they work).

And where else would I ask about this? Car guys won't know, and engineers are too busy making money and working to death to reply to some random guy on a forum LOL
You are talking about the difference of about 1 horsepower either way. So no big difference.

Raise cutting height to maximum and double cut it at opposite patterns.
 

Little Fish

Member
Joined
May 5, 2024
Threads
1
Messages
18
You are talking about the difference of about 1 horsepower either way. So no big difference.

Raise cutting height to maximum and double cut it at opposite patterns.
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?
 
Top