3 cyl vs. 2 cyl?

[Ginormous]

Hi guys,

Any fresh opinions on 3 cyl vs. 2 cyl? I understand the 3 cyl engines run more smoothly. What other differences? Noise? Fuel economy? etc?

 

[whistlepig]

On a two cylinder there is a longer time between the firing of the pistons. Although I dearly love the old John Deere two cylinders they don't make them anymore.

 

[kenmac]

My 3 cyl is very good on fuel.

 

[284 International]

My experience is that the 2 cylinders are louder but more user friendly, since the power band is flatter. They will pull their load at lower RPM than the 3 cylinder engines. I think they are all too loud, and always wear hearing protection. The 2 cylinders make a lot of noise from the engine. A better muffler wouldn't really help. The 3 cylinders are smoother, and the sound is attenuated better. Additional muffling might dampen the sound even more.


Fuel economy is excellent for either type, with an insignificant edge to the twin cylinder. There really isn't much to choose as fuel consumption goes. All of them impress me, especially every time I run my 17 hp gas engine riding mower.

For reference, I have 14 and 15 PTO horsepower rated versions of the 3T72 in my 1401D and 186D respectively, and the twins are all some 2TR20 variant. My 186D is fortunate to have Powershift. It is very heavily ballasted, and really benefits from the ability to start off in first gear and shift up up and down to keep the RPM in the working range. My YM240 with a loader weighs the same or more, but will start in any gear from idle, and clank away happily. The 186D has no hope of doing that, and needs to be above about 2000 RPM to do much good, but the transmission lets it stay there. My 1401D has a loader but is quite light, compared to the 186D, and the power is much more tractable. I always run out of traction before power with that machine.

I don't advocate lugging the engines, and the 186D shows excellent fuel economy, so isn't suffering from being revved up, but the big two cylinders are very affable and friendly to deal with.

Others may have different thoughts or experiences.

 

[kenmac]

Fuel economy is excellent for either type, with an insignificant edge to the twin cylinder. There really isn't much to choose as fuel consumption goes. All of them impress me, especially every time I run my 17 hp gas engine riding mower.

.

I know what you mean. I have a 22 HP on my zero turn. I have to re fill the tank with gasoline so, I can finish mowing.. I can fill my yanmar & run all day:thumbsup:

 

[Pete Judd]

I have had or delivered boats with, 1/2/3/4 ect. cly. Yanmar engines. The more the better as they get quieter mostly because of the smaller injectors,

Wistleplig, I to miss the old 2 cyl JD's had one on the family farm for mowing and raking the hay.

 

[nazbom2]

The Only experience I have personally is with a 2 Cyl on the YM 2000. It has the yammer hammer but as discussed elsewhere and before my fuel efficiency is incredible. I can have a 1/4 tank and have learned I can decide to bush hog my pasture and not use it all and when the tank is full it seems to last forever. Anectodal for sure but outlast my friends 3 cyl Kubota by leaps and bounds. Power has always been there for anyting I have asked it to do.

 

[Egon]

A lot of variables come to mind for the two cylinder. Inline, Opposed, V configuration?

Then on to comparing them; bore and stroke, valve train, RPM, balancing, etc etc.

Chances are well designed two or three cylinder engines will be quite comparable in operation.

Just think about the 60 degree V twin as compared to a nice opposed twin??:thumbsup:

 

[Smoody]

I have had both and like the 2 cyl better. 3 cyl was smoother with less vibration but it was just as loud, ear protection is a must with any yanmar I have used.

 

[Freakingstang]

I have a 2 cyl mitsu in my Satoh beaver 4wd. (15hp)

I have a 3 cyl kubota in my garden tractor. (19hp)

The 2 cylinder seems to have tons more torque and gets better GPG (grass per gallon)than the kubota. The kubota has to be screaming, and I think the hst robs a little power too. the Satoh beaver only has a 2 1/2 gallon tank (maybe 2 3/4 gallon) and will run all day long draging dirt, a finish mower etc and still have plenty of fuel left in it. I'm honestly amazed at how effiecient the little mini tractor is and how capable it is.

 

[nazbom2]

Speaking of # of Cyl's what about 1 cyl vs 2 cyl i.e. Single vs. V Twin? I go back to the anecdotal argument that 1 cyl produces more torque but less HP due to larger mass of 1 piston displacing same/similar amount. Would this be tru for 2 vs 3 cyl?

 

[California]

I think that question gets off into the realm of theory rather than anything the operator can experience. For smoothness, the more cylinders the better. For absolute economy, the fewer the better due to heat radiation loss. (Wasn't the Geo Metro a three cylinder engine?).

Aside from the racket, Yanmar's twins are never going to feel smooth because of the firing order. One piston rises while the other descends. This keeps the crankcase volume approximately the same throughout the 4 cycles (unlike the old British motorcycle twins with both pistons rising side by side simultaneously) but it means the cylinders fire 180 degrees apart then nothing happens for another 540 degrees of crankshaft rotation. Galump .... galump ... galump .... . Forget smoothness.

 

[Dadof3]

Ain't nothin like the sound of triple at 1900 rpm!

 

[nazbom2]

Right I agree on the course correction and apologize! Anyway I love my two cylinder and I guess ignorance is bliss haveing never owned a 3 cyl so am happy with my "smooth" running 2 cyl Yanmar!!

 

[Egon]

Engine balance - Wikipedia, the free encyclopedia

A little information on engine balance.

 

[Car Doc]

Fuel economy is excellent for either type, with an insignificant edge to the twin cylinder. There really isn't much to choose as fuel consumption goes. All of them impress me, especially every time I run my 17 hp gas engine riding mower.

Yeah isn't that the truth I only can speak on 3 cyl though and it is real smooth and quiet especially when its warmed up good. My wife has a 23hp v-twin 50" garden mower it uses 1/2-3/4 tank or about 3 g to do the 2 acres here at the shop.

My 3810 on the other hand is about 90 ci and 38 pto hp supposedly and will do it on less than a gallon its not even real easy to measure with my stick only running it that long and takes me 45 minutes-1hr. fwtw

I would have to run in high gear to catch her but besides that I can do it quite a bit cheaper albeit a little slower.

 

[deepNdirt]

Speaking of # of Cyl's what about 1 cyl vs 2 cyl i.e. Single vs. V Twin? I go back to the anecdotal argument that 1 cyl produces more torque but less HP due to larger mass of 1 piston displacing same/similar amount. Would this be tru for 2 vs 3 cyl?

I've had experience in owning/operating a 1 cyl. diesel compact tractor, and I can assure you the power/torque is somewhat different than that of a multiple cyl engine, a single cyl engine has low end torque from lower range RPM's, as where a multiple cylinder engines will require revving up into higher range of rpm's to achieve equal torque, when I sold my 1 cyl kubota and got the 2 cyl yanmar I had to learn over again where to set the throttle,and what gear to run in, in comparing the 1 cylinder Kubota I could run it in low gear 3rd. at around 1400 rpms to pull the harrows, The ym-1700 needs to run in 2nd. gear high range at 1800 to pull at the same rate, if I were to use the 3rd gear low of the yanmar I'd have to rev it into the 2000+ range to pull at the same rate ultimately working the engine much harder,
I really have'nt found much use for the lower range gears ofthe ym-1700 , the tractor is much too slow in the low gears, But on the other hand so was the 1 cyl kubota. I could set the kubota in 1st low and actually walk faster then it would move, in fact you have to watch it closly to tell it was moving at all,

 

[winston1]

Somebody once said the only thing you would use the creeper gear for on these Yanmars is so you could watch the seasons change while putting it in the barn.

 

[pesaventoc]

Somebody once said the only thing you would use the creeper gear for on these Yanmars is so you could watch the seasons change while putting it in the barn.

I asked my 86 year old mother in law if she would like to run my yanmar. To my surprise she said yes. Talk about good use for the creeper gear!!!

 

[Egon]

I've had experience in owning/operating a 1 cyl. diesel compact tractor, and I can assure you the power/torque is somewhat different than that of a multiple cyl engine, a single cyl engine has low end torque from lower range RPM's, as where a multiple cylinder engines will require revving up into higher range of rpm's to achieve equal torque,QUOTE]


Wouldn't the engine design be the big factor? Note all the small single cylinder engines running at 3600 RPM.

Then consider an older Lister Twin maxing out at 600 RPM.