3 cylinder vs 4 cylinder debate

[Industrial Toys]

Interesting. I never knew that. Why is that? It's actually worse than that. They run at 3600 to make 60 hz.

 

[RickB]

Interesting. I never knew that. Why is that? It's actually worse than that. They run at 3600 to make 60 hz.

He said industrial gensets.

 

[Egon]

I think that this is a trick question. The number of cylinders doesn't have nearly as much to do with efficiency and smoothness of operation as do numerous other design factors. A certain three cylinder can be better that a certain 4 cylinder in these regards, while a different 4 cylinder can be better than that three cylinder. I agree all the answers you get her will be highly opinionated and non-factual.

There are some cylinder configurations that are naturally balanced. The others need some extra gear to run smoothly.

 

[Industrial Toys]

Curious wht INDUSTIAL gensets run at 3000rpm and how the poles are arranged?

 

[mo1]

You are going to see more difference between a 3 and 4 cylinder engine due to other design features than you are the number of cylinders. 3 and 4 cylinder engines aren't perfectly balanced and are all even-fire engines so they behave and sound fairly similar.

- An engine with a larger number of smaller cylinders will seem smoother than an engine with fewer larger cylinders and have a higher RPM where it achieves peak torque and power.
- Inline six cylinder engines are perfectly balanced and will seem much smoother than engines with fewer cylinders. Their cylinders can also be made enormous without the engine vibrating excessively, unlike engines with fewer cylinders.
- Crossplane V8s are nearly perfectly balanced and will be smooth as well, but have a very distinctive sound that immediately distinguishes them from essentially all other diesel engines out there, which are even-firing.

There is a reason the industrial gen sets run at 1800 RPM.

Yeah, they are coupled to a four-pole generator head and you want 60 Hz AC. A two-pole head requires 3600 RPM which is too fast for most diesel engines. A six-pole head requires 1200 RPM which is below the typical ideal operating range of most transportable diesel engines. You would rather not have to deal with speed-changing gears if you can help it, so 1800 RPM it is.

 

[Mat4644]

The inline six is naturally balanced!

How about a boxer 4? Subaru 4!

 

[VIEWQUEST]

3 cylinder designs cancel out there own vibration without the need for balancing shafts. Plus they have alot less moving parts.

 

[Mat4644]

3 cylinder designs cancel out there own vibration without the need for balancing shafts. Plus they have alot less moving parts.

?

Maybe for small engines but once into larger horsepowers three big cylinders banging gets harder to deal with vibration.

 

[BrokeFarmerJohn]

Our generators at work are v16 engines, we don’t have RPM gauges but I would assume they are cranking around 2000-2500RPM. Our are Caterpillar but a Detroit sounds like it’s going twice as fast as what it is so idk, it’s not the easiest to guess RPM lol.

 

[Industrial Toys]

At idle, the 3 cyl Kubota D722, in my little Steiner, seems to want to jump right off it's rubber mounts! Too bad this litle engine is so rough. And a hard starter in the cold.

 

[RickB]

Curious wht INDUSTIAL gensets run at 3000rpm and how the poles are arranged?

Get busy and check out some specs if you’re curious.

 

[Katahdin]

I don't think the number of cylinders has anything to do with PTO RPM speeds.

The Mahindra 5555 pistons have to travel further per stroke than the LS, that it's why it's RPM is lower:

Mahindra 5555
96mm Bore x 122 mm Stroke

LS 6168
88mm Bore x 103 mm Stroke

 

[Egon]

For those interested some information on engine balance. Lots of variables.

[video]https://en.wikipedia.org/wiki/Engine_balance[/video]

 

[Smokeydog]

Hard comparison to make. My observations over 40 years bush hogging the same fields/pastures with a 6’ cutter.

MF-135, 3cyl, 45HP, 20 hours, 15 gal fuel.

Kubota M5030, 6cyl, 56HP, 12 hours, 12 gallons fuel.

Kubota M59, 4cyl turbo, 59HP, 12 hours, 15-16 gallons of fuel.

Kubotas 4x4 engaged.

 

[RickB]

Hard comparison to make. My observations over 40 years bush hogging the same fields/pastures with a 6’ cutter.

MF-135, 3cyl, 45HP, 20 hours, 15 gal fuel.

Kubota M5030, 6cyl, 56HP, 12 hours, 12 gallons fuel.

Kubota M59, 4cyl turbo, 59HP, 12 hours, 15-16 gallons of fuel.

Kubotas 4x4 engaged.

The Kubota numbers speak more to the efficiency of a gear transmission vs Hydrostatic than anything else.
The apples and oranges are not all in front of the flywheel.

 

[Industrial Toys]

What's hydro?

Trying to make sense of the numbers, I only noticed later that the 135 took 20 hours. Before that, I thought the Kubota fuel numbers were impressive by comparison.

Now if you somehow figure in, the cost of the equipment to get that same job done. The Massey cost around three grand in early 70s dollars. AND that tractor is probably still working today.

 

[RickB]

What's hydro?

The M59, which I suspect also has a significant weight disadvantage to the M5030.
The Massey is a different class of machine.

 

[Smokeydog]

Agree there are significant differences other than number of cylinders. Big differences comfort and convenience. Stay cleaner mowing 6’ weeds with the bigger tractors.

M59 hydrostatic plus (two speeds in each range) transmission.

M5030 early 80s, full size ag cab tractor, taller, wider, heavier than the M59.

 

[RickB]

M5030 early 80s, full size ag cab tractor, heavier than the M59.

I suspect not. Would depend on whether it has a loader and other factors.

 

[Industrial Toys]

Seems a terrible waste(in time if nothing else) running nice big tractors with a 6 foot mower. When there was no market for our fields, I pulled a 14 or 16' ALAMO Flex Wing Finishing mower with our JD 6200. Quite a blast seeing a swath like that cut in one pass.