3 cylinder vs 4 cylinder

[4tillingdirt]

I know most if not all of the 30 - 40 HP compacts either have a 3 or 4 cylinder. Wouldn't the 4 cylinder be a smoother engine by default? If you had a choice between a 3 or 4 cylinder, which would you choose?

 

[Agvg]

This is more of a question on how well the engine is designed, not the number of cylinders. 3 cyl is very common on all kinds of tractors well past 100hp so it has advantages over a 4 cyl.

 

[jeff9366]

I owned one Kubota B3300 SU with a four cylinder, 91.4 cubic inch displacement engine.

I now own a Kubota L3560 with a three cylinder, 111.4 cubic inch displacement engine.

The three cylinder L3560 is smoother and considerably quieter than the four cylinder B3300 SU.
The L3560 is a Kubota deluxe model. The B3300 SU was a Kubota economy model. Both were purchased new.


A three cylinder engine has fewer parts to go wrong.

 

[rScotty]

I know most if not all of the 30 - 40 HP compacts either have a 3 or 4 cylinder. Wouldn't the 4 cylinder be a smoother engine by default? If you had a choice between a 3 or 4 cylinder, which would you choose?

It's easier to design dynamic balance into a 3 cylinder. In general the 3 cylinder config is noticibly smoother.
rScotty

 

[Monster5601]

The difference is a 3-cylinder has a power stroke every 120 degrees versus a 4 cylinder's 90 degrees. I've got both and I like the sound of the 4-cylinder much better than the 3-cylinder at idle. At working RPM they both sound good and they get the work they were designed to do, done.

Now I'm wondering what criteria manufacture like Kubota uses to make the choice of either a 3 or 4 cylinder engine in smaller tractors and mowers. I'm sure size has something to do with it as well as engine costs. My B3030 has a 4-cylinder while my ZD has a 3-cylinder and only a couple of horsepower difference. More room in the B3030 for an engine than the ZD.

 

[ericm979]

Both 3 and 4 cylinder in line engines can have perfect primary balance. But they both suffer from secondary imbalances. Both need balancer shafts to counteract those imbalances. Many engines don't have the balancer shafts and their applications deal with the vibration in some other way, such as floppy motor mounts in cars. CUTS all seem to have solid mounted motors so that's not an option.

Bottom line is you need to test drive the particular models you are interested in and see what they're like. My Branson 3725 has a counter balanced four that's smooth and quiet. The 3520's triple sounds more tractor like and more powerful. Neither one is a wrong choice.

 

[ruffdog]

I would not "choose" a tractor just because it had a 3 or 4. I would choose a tractor after I drove several of them.

 

[Fragger]

My 3 cyclinder mf 2300 has a shake rattle and roll when it starts , after a few years the muffler and bracket have been an issue , they have broken from all the vibration , :shocked:

I know most if not all of the 30 - 40 HP compacts either have a 3 or 4 cylinder. Wouldn't the 4 cylinder be a smoother engine by default? If you had a choice between a 3 or 4 cylinder, which would you choose?

 

[kenmac]

Have a 3 cyl and a 4 cyl. The 4 cyl is much smoother engine than the 3

 

[HarryVanderpool]

The difference is a 3-cylinder has a power stroke every 120 degrees versus a 4 cylinder's 90 degrees.

Well, Not EVERY 120 degrees.
That would hold true if the engine was a two stroke.