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.

 

[chriswheeler]

In my relatively short time owning and using tractors, I've owned 3 all in the 30 hp. range. a Yanmar 3000, a Deere 950, and the Deere 970. The first 2 were 3 cyl. and the one I current is a 4 cyl. All other things aside, starting on a cold morning goes to the 4 cyl starting in less than 1/2 revolution. The other 2 engines with 3 cyl. needed block heaters or pre-heaters under the same conditions. Running and operating goes to the 4 cyl. engine as well, smoother running as well. Nothing technical here, just real life. Every engine was a Yanmar and in comparable condition. I have less than 3000 hours total of seat time total with all 3. The 4 cyl happened as a consequence of trading up. Now,, if trading up, I would be looking for a 4 cyl. Some of the other members here have years of tractor operation here, not me. I'm still in the new operator class.
Chris

 

[zzvyb6]

I built a metal bracket from a cup holder to shake and stir the paint in new and used rattle cans. At low idle, my F935 3 cylinder does a great job of resurrecting paint that's been setting in my paint cabinet for a long time. When not shaking, I set the throttle up to the smoove setting.

 

[ruffdog]

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

True. The pistons come to TDC every 120 degrees but the power strokes are at every 240 degrees because they are 4 strokes. Three cyl engines have an issue with vibes because no 2 cyls are hitting TDC at the same time. You will have a engine that wants to rock end to end. Same with a parallel twin with a 180 degree crank. A twin with a 360 degree crank up and down but will not have the rocking motion. A 4 cyl is basically two twins with 180 degree cranks that balance each other out. A 3 cyl can be made to be somewhat smooth with the added cost of balance shafts and well designed motor mounts. My TC33D had a 3 cyl in it and I never thought it vibrated bad and it did not have a balance shaft. Was it smoother because the flywheel was heavier and it had large/heavy counterweights on the crank?

Here's The Problem With Three-Cylinder Engines

 

[RickB]

Few 3 cylinder Diesels have dynamic balancers. All but a few 4 cylinder Diesels do.

 

[BobG_in_VA]

We all remember the old adage, that "there's no replacement for cubic inches"....well, that's where the turbo charger (TB) comes in...a 3 cyl with TB may put out as much HP as a non TB 4 cly, and I'm pretty sure that 3 cly engines are "cheaper" for the manf. to build....I'd rather have a non TB 4 cyl putting out 60hp than a 3 cly putting out the same hp. For one thing, the 4 cly, with normal maintenance will most likely outlast the TB 3cly...also no cool down on the 4 cly. engine....just my 2 cents... BobG in VA

 

[Agvg]

We all remember the old adage, that "there's no replacement for cubic inches"....well, that's where the turbo charger (TB) comes in...a 3 cyl with TB may put out as much HP as a non TB 4 cly, and I'm pretty sure that 3 cly engines are "cheaper" for the manf. to build....I'd rather have a non TB 4 cyl putting out 60hp than a 3 cly putting out the same hp. For one thing, the 4 cly, with normal maintenance will most likely outlast the TB 3cly...also no cool down on the 4 cly. engine....just my 2 cents... BobG in VA

Diesel without turbo is a bad design, or any engine without turbo is a bad design if we are talking above lawnmowers

 

[Roadworthy]

I prefer my engines without turbos. I'd rather have more cubic inches to derive the power I want. I like simplicity and believe the turbo stresses the engine. I prefer the sound of a four cylinder engine but when push comes to shove for me three cylinders does the job just as well if the horsepower is there. I've always thought three cylinder engines were an oddity but they seem to be the norm in the small tractor world. I notice nobody brought up two cylinder engines though they have been used in tractors as well.

 

[RickB]

I've always thought three cylinder engines were an oddity

3 cylinder engines have dominated the utility tractor class since the mid 1960s.

 

[murphy1244]

And on the 7th day God introduces Perkins Diesels.

 

[Industrial Toys]

And on the eighth day he rested, for the Perkins gave him a splitting headache. They do me anyway.

I have a bunch of little Diesels that I am glad don't have a turbo. Just like I would never chip a p/u truck. Stock, slow and modest is right for me.

As far as 3 or 4 cylinders. I have a bunch of both, and can't really narrow down a characteristic that would apply to one or the other accross various brands. I know, part of me finds any odd number kind of weird. 3, 5, how about a 7? Never heard of that.