3 cyl. vs 4 cyl.

[whitetiger]

Anybody here knowledgeable in Rotational Dynamics ??

If you rotate your self in quick tight circles you will get dizzy and fall down, go boom...How's that?

 

[Egon]

Really, is that talking from personal experience?

 

[_RaT_]

Anybody here knowledgeable in Rotational Dynamics ??

Egon let me put this in layman terms. Basically you have your CW and then you have your CCW. This of course in no why way takes into consideration the earths rotation AKA spin nor its rotation around the sun which rotates yet further around even bigger stuff. The whole process turns into one gigantic rotational circle of confusion because its difficult to measure the many rotational paths and forces that a planet such as earth is subjected to without observing from a neutral non rotational reference. This of course leads one to question whether a neutral roation actually exists as how would you know? Its all theory of course but experts say we are all spinning out of control but don't know it. My best guess estimate is that the crankshaft on your 3 or 4 cylinder diesel engine is rotating in many thousands of directions. To the naked eye, it would appear that there is only one, that being a CW or CCW depending on which end of the 3 or 4 cylinder you are referencing. So see, its really that simple. Let me know if you have any questions... RaT...

 

[Egon]

Now the bulb is slowly starting to brighten; but only slowly!

Its just a low wattage type anyway so the luminem measurement is insignificant.

 

[whitetiger]

Really, is that talking from personal experience?

Ummmmmmmmmm ,yep.....

 

[Gizmo36]

I have farm all my life and I like the 2 banger .That is the best ever made I think. But there is a lot it won't do . And then you have to get out the 3 cylinder .And there is a lot it won't do so you get out the 4 and the 6 .Now the 6 is a power house, Now I don't know witch one is the best .What I do know is if the work is bigger then there has to be more cylinder. And I do know the 2 banger will run all day on 5 gal . The big 6 cylinder with a big load it takes about 5 gal ever two hour.That is $$$$$ . It don't take me long to see witch one I like the best.

 

[montanaman]

WOW! I read most of this thread and I think I came to a conclusion that everyone will agree on 100% and that is that we will NEVER get an answer to this that we all agree on!!

The smaller tractors that I sell have 3 cylinders and the larger ones have 4cyl normally asperated engines. I believe that a larger engine that can make good power without the use of a turbo, provided the altitude isn't too high, should last longer. Some may agree, some may argue and that's fine.

I also agree that there is a cost difference to produce 3 vs 4 cylinder engines.

All but my smallest tractors are 4cyl Mitsubishi powered and I can tell you that my customers really like these engines. I also know that customers really like the 3cyl tractors so this could all just be a wash out.

Most of the things that I have bought were NOT based on the number of cylinders but based on the number of pages this thing has gone, it really is an interesting topic!

SO, this is what I own and why. I have a Duramax that I bought because I really like the Allison tranny and a lot of other things about the GM truck. That decision was not based on number of cylinders at all and MANY will argue that the 6cyl Cummins is a FAR better engine than the Isuzu. They may be absolutely right but I know that I bought a complete vehicle, not just an engine and not to bring up another debate, I just don't care for Dodge trucks. I feel that in my mind, I have the best total package and I think the Duramax, even though others will argue isn't the best engine, will serve my needs fine and has all the HP and torque for my towing needs. It has a turbo that I absolutely love so what does that say about my thoughts on the non-turbo vs turbo??

My wife drives a Subaru with a flat 4 and it is snowing today and she will get home from work just fine. Again, didn't base that buy on the engine at all but I do like it.

My daily beater is a 4cyl clapped out oil burning Saturn. It's good on fuel and a full tank of it would exceed the cars current value. Don't care how many cylinders, just that it starts and runs a while longer.

All this being said, I do have a place in me heart for three cylinder engines. I used to be a GM tech in the 80s when the little Chevy Sprints were out and that was a long running powerful little 3cyl in those cars.

I also own a Triumph motorcycle with a 955cc injected three cylinder and you could not give me a 4cyl motorcycle now that I have owner that one.

Both of these examples are much higer RPM gas engines but they do have a completely different sound and feel to them that a 4cyl of the same size and on the motorcycle where the engine is bolted right to the frame, it is MUCH smoother running than a four cylinder and seems to me to have more torque at a lower RPM. Keep in mind that the torque curve starts at about 500-1000RPM under the max RPM of a 3cyl diesel so this is apples to bananas here!

I really enjoyed reading all of the posts in this thread but I think for most tractor needs, a 3 or 4 is going to do about the same job.

I also have to agree with some that the cost savings of the 3cyl is more of a factor that some realise.

Ken

 

[napabavarian]

Not so.....you have answered your own question. Cummins engine is a known trade name for quality, power, and Durability. So they charge more for the product. Just as a Perkins is known for the same and charge more. Money truly is the real difference in 3 vs 4 engines. Who can produce what the cheapest. Thats why they are almost all foriegn engines....cheaper to produce.

Have you ever seen a lineup of connecting rods? When I saw this the GM rods were the smallest, ford rods significantly larger, and even figuring that the Cummins rods should be 33% larger they were huge, Cummins is an engine built to last, a medium duty engine in a light duty truck quite literally, so you pay more for a stronger engine.

As far as displacement and cylinders, a lot of small cylenders are better for a high RPM engine and a few large cylinders are better for low end torque on a slow rotating engine, think of Fords 5.0L V8 vs their 5.0L I6, same size, but the V8 is a dog with a loaded truck and the I6, while not fast, is almost unstopable.

Edit...something about ballance, Inline 6, Flat 6, Flat 12, and either a 60 degree or 90 degree V12 (cant remember what one) are all perfectly ballanced engines, no primary or secondary vibrations, you can ballance any engine with weights, but then you are using some of the fuel and power to move the weights, simply having more cylinders won't always improve ballance, but I do prefer the V8 rumble in many instances, the I6 sound good too

This being said I have heard that the inline 3 engines have similar ballancing to the inline 6, but with half the cylinders, perhaps we need to do some testing and teardowns

 

[Egon]

AutoZine Technical School - Engine

This sight may give a little insight to the rotational dynamics of piston engines.

 

[_RaT_]

AutoZine Technical School - Engine

This sight may give a little insight to the rotational dynamics of piston engines.

Thanks Egon, I think I'll stick with the link you showed for my conclusion on this matter. Very interesting.