Can a 173cc engine be more powerful than a 196cc?

[Gibaldi]

I'm in the process of buying a new push rotary to scalp thick lawn down to dirt in the shortest possible time and with as little effort. So I'm after a big powerful engine that can cut really low.

I have narrowed it down to a mower that has a AL-KO 196cc engine and cuts to 6mm, I have very little knowledge when it comes to engines so in saying that I was thinking that the more CCs the more powerful it will be until I rang up a shop asking if they sold that particular mower.

When I spoke to them they were saying that the mower they sell has a Kohler 173cc engine on it and is more powerful and durable than the 196cc AL-KO since it has a cast iron sleeve, the AL-KO also has one too.

I asked so the power doesn't relate to the CCs? They said it doesn't, so now I'm confused and don't know what to do.

Guess I should listen to the expert in the shop but thought I'd check to see if there's some people on here that are really clued up on engine sizes and power and can explain to me how to choose the most powerful engine.

I was also going by the torque and the Kohler has 10.5Nm and AL-KO has 12Nm

 

[bertsmobile1]

Hp and engine size are not directly proportional
I have a 1924 250cc motorcycle that is rated at 2 Hp
I have a 1936 250cc motorcycle that is rated at 5 Hp
! have a 1954 250cc motorcycle that is rated at 10 hp
I have a 1972 250cc motorcycle that is rated at 15 Hp
All with the same bore & stroke, all cast iron barrels

Now for a lawn mower the Hp is insignificant because it is the torque that does all the work
Torque x rpm = Hp

 

[ILENGINE]

Normally people will say that there is no replacement for displacement, and in most cases they are correct. It is very possible to have two different size engines and making different torque or horse power ratings. It is very common through timing and fuel jet changes to have different horse power ratings for the same engine block.

The big thing that I think about is were is the torque made. Is the larger 196 engine getting their torque rating at 3200 rpm but the engine on a push mower application only turns 2800. or is the torque rated at the operating rpm for that application. So in other words if both engines are running at 2800 and the Kohler is rated at 3000 rpm and the al-ko is rated at 3600 rpm it is possible that the Kohler could have more torque at the rated operating speed than the al-ko.

 

[Gibaldi]

I'm in the process of buying a new push rotary to scalp thick lawn down to dirt in the shortest possible time and with as little effort. So I'm after a big powerful engine that can cut really low.

I have narrowed it down to a mower that has a AL-KO 196cc engine and cuts to 6mm, I have very little knowledge when it comes to engines so in saying that I was thinking that the more CCs the more powerful it will be until I rang up a shop asking if they sold that particular mower.

When I spoke to them they were saying that the mower they sell has a Kohler 173cc engine on it and is more powerful and durable than the 196cc AL-KO since it has a cast iron sleeve, the AL-KO also has one too.

I asked so the power doesn't relate to the CCs? They said it doesn't, so now I'm confused and don't know what to do.

Guess I should listen to the expert in the shop but thought I'd check to see if there's some people on here that are really clued up on engine sizes and power and can explain to me how to choose the most powerful engine.

I was also going by the torque and the Kohler has 10.5Nm and AL-KO has 12Nm

I see, so forget power, I'm after what has most torque so it doesn't bog down when mowing through thick grass

 

[Gibaldi]

Normally people will say that there is no replacement for displacement, and in most cases they are correct. It is very possible to have two different size engines and making different torque or horse power ratings. It is very common through timing and fuel jet changes to have different horse power ratings for the same engine block.

The big thing that I think about is were is the torque made. Is the larger 196 engine getting their torque rating at 3200 rpm but the engine on a push mower application only turns 2800. or is the torque rated at the operating rpm for that application. So in other words if both engines are running at 2800 and the Kohler is rated at 3000 rpm and the al-ko is rated at 3600 rpm it is possible that the Kohler could have more torque at the rated operating speed than the al-ko.

That makes sense, just had a look at the specs and the al-ko 196 is rated 12Nm at 2500.

700 ST S19 2'n1 | Masport Australia

Cut, catch or mulch with the added capability to mow the lawn edge to edge thanks to Masport's Dual Mowzone® feature. This robust 19" steel mower is power

masport.com.au

The 173 Kohler engine doesn't list the rpm

 

[Gibaldi]

That makes sense, just had a look at the specs and the al-ko 196 is rated 12Nm at 2500.

700 ST S19 2'n1 | Masport Australia

Cut, catch or mulch with the added capability to mow the lawn edge to edge thanks to Masport's Dual Mowzone® feature. This robust 19" steel mower is power

masport.com.au

The 173 Kohler engine doesn't list the rpm

Just found the specs for the 173c Kohler engine.

It has two torque ratings, masport website that lists the mower has used the higher torque rating under the specs.

J1940 Torque lbs. ft (Nm) 17.75 (10.5)

J1995 Torque lbs ft (Nm) 37.46 (10.11)

J1995 Rated Speed (RPM) 2800

So looks like the 196cc Al-co has an extra 1.89Nm of torque at 2500rpm compared to the 173cc Kohler. Not sure what the guy the the shop is on about, what makes him think the 173 is better in that regards.

Thanks Ilengine for explaining that, it helped a lot

 

[sgkent]

HP can increase as the engine RPM goes up. For example, I was built a 1438cc SCCA GP race car that could go faster than its twin, a SCCA FP 1608cc because the shorter stroke 1438cc reved higher - hence more HP overall. But off the hard corners the 1608cc would pull away at first. The 1438cc was also lighter due to regs so it could brake later and go deeper into the corners. But, the larger cc engine will almost always have more torque than the smaller displacement unless the marketing folks fibbed more. Since we are dealing with a set RPM that these small engines run the best and longest at, personally I would go with the larger displacement for your use. The blade tip speed of the mower is what will determine the fastest that the engine should go. The speed of the tip is what the mower manufacturer sets the engine RPM to. Personally I would set the mower to a low height setting and almost scalp the area, then use a couple passes from a dethatcher to knock the rest loose. Hit the area with roundup. Let it die for a week, mow close and dethatch. You'll have mostly dirt left - although right now is late in the season to be doing this. If you can water it for 15 to 20 days and roundup again you'l get rid of many of the weeds but not those that need heat to germinate. Then plant your seed or put down your sod, if that is what you are doing.

 

[Gibaldi]

HP can increase as the engine RPM goes up. For example, I was built a 1438cc SCCA GP race car that could go faster than its twin, a SCCA FP 1608cc because the shorter stroke 1438cc reved higher - hence more HP overall. But off the hard corners the 1608cc would pull away at first. The 1438cc was also lighter due to regs so it could brake later and go deeper into the corners. But, the larger cc engine will almost always have more torque than the smaller displacement unless the marketing folks fibbed more. Since we are dealing with a set RPM that these small engines run the best and longest at, personally I would go with the larger displacement for your use. The blade tip speed of the mower is what will determine the fastest that the engine should go. The speed of the tip is what the mower manufacturer sets the engine RPM to. Personally I would set the mower to a low height setting and almost scalp the area, then use a couple passes from a dethatcher to knock the rest loose. Hit the area with roundup. Let it die for a week, mow close and dethatch. You'll have mostly dirt left - although right now is late in the season to be doing this. If you can water it for 15 to 20 days and roundup again you'l get rid of many of the weeds but not those that need heat to germinate. Then plant your seed or put down your sod, if that is what you are doing.

Aweosme response, thank you.

So what I was originally thinking was right but then spoke to the shop and had me doubting myself as I don't really know that much when it comes to this.

Oh I forgot to say that I'm from Australia so it's just the start of our season. I have Kikuyu, so will be scarifying it and then scalping and top dress as it's become really thick since last season.

Think I'll go for my original decision and buy the mower with the 196cc alko

 

[sgkent]

some places say to dethatch kikuyu, others say to scalp it. Some say both. I don't know what is best for it. I got some here that a bird or something brought in, and it took three tries to kill it all off. I will tell you that you should get basic soil tests from a local soil lab for minerals etc., before doing anything. The right soil chemistry will make all the difference in the world when it comes back. You can be too high in one thing and accidentally add more, or you can have just a couple minerals that are low and a regular fertilizer won't even it out.

 

[Gibaldi]

some places say to dethatch kikuyu, others say to scalp it. Some say both. I don't know what is best for it. I got some here that a bird or something brought in, and it took three tries to kill it all off. I will tell you that you should get basic soil tests from a local soil lab for minerals etc., before doing anything. The right soil chemistry will make all the difference in the world when it comes back. You can be too high in one thing and accidentally add more, or you can have just a couple minerals that are low and a regular fertilizer won't even it out.

That would have been frustrating trying to kill off the kik, surprised you did, it seems like it never dies off completely and always comes back.

I actually did have a soil test done a few months ago and had a custom 12 month program done, so really looking forward to see the results over the next 12 months