I guess there will always be some debate on what number of cylinders is ideal for a particular application, but what I really was wondering is why Kubota went with a four in their latest compact tractor (B3030), when three cylinders made up the majority of their stock? Many times, when a manufacturer does this, it has more to do with what will fit in a particular engine compartment. Maybe the slope-nosed B3030 needed a lower profile engine? Perhaps the 3-cyl was too tall? Who knows...
is there any advantage to four cylinders?
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ronjhall
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Barnboy
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B2400
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Looking thru the Kubota engine specs it would appear that they use a number of the same parts for different engine configurations.I recall that the 2410 and the 2910 use the same bore and stroke, but the 2910 has more displacement via the extra cylinder and thus more horsepower. This would allow Kubota to use a part for more than one engine series and thus cut down on overhead for parts manufacturing.
Sorry, I know I didn't help explain a thing reguarding our topic but it might be a reason the BIG K uses 3 and 4 cyl engines across it's product line.
Sorry, I know I didn't help explain a thing reguarding our topic but it might be a reason the BIG K uses 3 and 4 cyl engines across it's product line.
_RaT_
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lawn_king
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Having owned both 3 & 4 cylinder kubotas, i perfer the 4, its quieter.
fishpick
Platinum Member
Not that this is gospel - but after doing some digging my $0.02 throws in this:
* Anything that's an in-line wears longer/better (my understanding of this has something to do with the real up/down, as opposed to something on an angle always wearing on a side)
* Multiples of 3 make easier in-line engines (why, cause that's what a guy told me)
* Horse for horse, the more chambers involved in combustion - the quieter the sound output (meaning 2 engines producing 50hp - all other things consider equal, the 3 cylinder fellow will be louder than the 4, because a bigger pop happens each combustion cycle)
* Anything that's an in-line wears longer/better (my understanding of this has something to do with the real up/down, as opposed to something on an angle always wearing on a side)
* Multiples of 3 make easier in-line engines (why, cause that's what a guy told me)
* Horse for horse, the more chambers involved in combustion - the quieter the sound output (meaning 2 engines producing 50hp - all other things consider equal, the 3 cylinder fellow will be louder than the 4, because a bigger pop happens each combustion cycle)
rbargeron
Elite Member
The number of cylinders in a tractor engine is mostly a manufacturing decision. (Unlike in cars where it is influenced by marketing too) To have a good picture of this subject it is probably important to consider the whole range of engines being produced by a manufacturer. The production tooling to make engines can be set up for a different number of cylinders, provided the bore center distance is the same. One example of this is GM's 4.3L V6 which is 3/4 of a 5.7L V8 which has the same cylinder dimensions. They share a lot of tooling and other parts. Once a basic in-line tractor engine design is set, making 3, 4 or 5-cylinder variants can be more efficient than developing 3 completely different engines.
I'm no expert, but I do know that to run smoothly a 4 cylinder inline engine needs to have two counter-rotating balancer shafts. Otherwise they really tend to shake, especially at idle. Honda uses counter balance shafts in all their inline 4s, and years ago I had a Misubishi Turbo Diesel pickup with an inline 4 and counter balancers. It was a very smooth running engine because of it.
Also, back in the 80s Audi designed and used an inline 5 cylinder engine because it inherently is much smoother then a 4 cylinder, w/o the need for counter balancers. My Kubota L4150 uses a very smooth 5 cylinder direct injection design, and it never ceases to amaze me at how well it starts even in below freezing weather w/o using glow plugs, and how smoothly it idles and runs, with tons of power. I don't know why Kubota used a 5 cylinder design on some engines like this tractor, but since then has gone to 3 or 4 cylinders on most things. I suspect it is because more cylinders costs quite a bit more, and keeping costs down is a paramont issue in the competitive mfg environment.
Also, back in the 80s Audi designed and used an inline 5 cylinder engine because it inherently is much smoother then a 4 cylinder, w/o the need for counter balancers. My Kubota L4150 uses a very smooth 5 cylinder direct injection design, and it never ceases to amaze me at how well it starts even in below freezing weather w/o using glow plugs, and how smoothly it idles and runs, with tons of power. I don't know why Kubota used a 5 cylinder design on some engines like this tractor, but since then has gone to 3 or 4 cylinders on most things. I suspect it is because more cylinders costs quite a bit more, and keeping costs down is a paramont issue in the competitive mfg environment.