Oil & Fuel 4 cylinder vs. 3 cylinder diesel

[Poncho]

Interesting thread....... but I agree with the observation and preference for more cubes/cylinders. I'm old school hotrod and believe there's no substitution for cubic inches /forums/images/graemlins/cool.gif I've been shopping around now for a couple of months and have moved to looking at cylinders, compression ratio, hp (gross and pto) and cubic inches. I have an old MF135 with Perkins diesel.... and it runs like a tractor. I've test driven just about everything around (MF/NH/Bota/Hindra) and to me the Kubota was the smoothest there was followed by the NH. JD & Challenger was'nt real good in there customer service area so I've shied away from them. I do like what I see in the JD 5205 and will be checking out a dealer about 45 miles away one weekend. What I test drove was the Mahindra 4500 & 5500, Massey 451, New Holland TN 55 & 65 and Kubota M5900 and MX5000.

 

[TNCHRIS]

i still have my 135, it's in the yard for sale. i went to buy a JD 5103 and found it just to big. however for it's size and options it's the best value on the market. the L3830Hst is the same size as the 135, check the specs(wheel base and weight)with more ground clearance.i thought i was going smaller but this thing will outwork the massey in everything i've done.could have probally got by with a 3130 or 3430 but like the extra power.

 

[Soundguy]

</font><font color="blue" class="small">( I also don't expect any difference in longevity based on number of cylinders. If anything I would expect the 3 cylinder TN to last longer based on much lower operating rpm's.
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That's not an apples to apples comparison... The comparison I made between my 1920 and a tc33 is apples to apples... based on the same exact engine and pto dealer rated hp.. yet they are using a much smaller cid power plant to produce it. ( 91 ci compaired to 122 ci.. a very substantial amount..25% increase in size on that engine.. ) .. and I wouldn't expect it to have the same longevity as my 1920. For one.. on this unit.. the tc33 is having to run at a higher rpm to get that rated hp.... I deffinately would expect it to wear out faster under its stress.

Less machine to do more work is great.. if there is substantial difference in materials and workmanship and technology. For instance.. I expect any big 3 brand compact tractor in the 25 hp rang to out work my 26.5 for N-series tractor that is 60 years old... however.. Given that technology, materials and workmanship is virtually identical... on the tc-33 and my 1920... I expect the overworked model to expire faster... not to mention that all the fiberglass and rubber and plastic they are sticking onthem these days doesn't seem to hold up as good as the metal they used to use...

Soundguy

 

[jmc]

One technical tidbit: a 3 cylinder will have more low end torque than a four cylinder, all other things being equal. The rationale for this is the ratio of displacement to piston perimeter. Piston ring blowby is more pronounced at low speed and since a 4 cylinder has more piston perimeter than an equal displacement 3 cylinder, it loses more, especially at the low end.

Improvements in piston sealing technology in the 30 or 40 years since I read this in some car magazine probably minimizes this though.

 

[TNCHRIS]

the big engines at lower rpms may well be producing more engine wear than a smaller one at higher rpm. the long stoke of the big cid, old machines, has a higher piston speed in inches per minute than a lost of the newer ones.if a piston is moving fewer inches in the sametime then theres less wear on piston rings, usually the first thing to wear out.

Stroke X 2 X rpm = inches per minute of piston speed.

piston speed is a major factor of redline.

 

[eieio]

You have hit the nail on the head when you compare the low end torque of a 3 vs a 4 cyl. with the same displacement. the other benifit of the 3 cyl of the same displacement will be that the piston rods and the crank will be heavier. and will most likley give a longer life. Look a5t the comparisson of the In line 6 cyl. cummins vs/ chevy and ford v-8 offerings. you may have whatever opinon you have but fact is the big 6 is a medium duty motor compared to the light duty rating in the v-8's the cummins mtr is a 500,000 mile mtr and has proven to make the most torque and horsepower. anyway this is not a truck thread but the same principals apply. I would like to see the stats on the both these motors to really see how they stack up. remember that bore and stroke make torque and if you are comparing tractors forget the H.P and look at the torque. H.P. = torque X R.P.M. \ 5225 so if I can make my torque @ a lower R.P.M. then my horsepower is made with less burden on the mechanical components. That should equal longevity if all else is equal. One interesting issue that may be wort looking at is how the new desiel standards will effect these tractor mtrs. the lower sulfer contents may leave us with some lubricity issues. I wonder if the offr road Mix is going to have the same regulations?

 

[yellowsocks93]

I agree with Soundguy on this one. From owing the 3 cylinder 4300 JD to the new 4 cylinder JD 990 the 990 has loads more torque at a lower RPM, idles smoother, and I just plain like it more. Fuel economy is not as good but one is an eco friendly motor the 990's is old school from '89. Soundguy is also right about the metal!

 

[_RaT_]

That can simply be a design of the 2 Yanmar diesels in those 2 tractors, not an inherent advantage of 4 over 3 cylinders. My 3 cylinder IH eats considerably more fuel then my 4 cylinder L48 did, but then, it also had tons more torque, neither was smoother then the other at any RPM. The L48 was 148 cu in while the IH is 179 cu in which helps explain the torque difference. The L48 had more HP. I'd say both were very well designed diesels. Perhaps the one found in the 4300 you had was not.

 

[yellowsocks93]

I don't really have a preference when it comes to motors and I would rather compare motors on the terms of PTO HP and who makes it. Yanmar and Kubota are 2 of the best. The motor in the 4300 was a great motor but the older 990 motor just is stronger. Look now once I sell the old one the 990 is in for a new rear engine seal.

 

[rockyridgefarm]

Much of the cummins inherent advantages come from being an inline design vs. the 'v' configuration on Ford and Chevy. On tractors we are comparing inline designs accross the board. But it is definately long lived. 500K engines are the norm at our shop, 1000K isn'r at all unheard of...

Yellowsocks found that the 4TNE84 is more powerful than a 3TNE84. WOW! add one cylinder ant you do get more. Amazing. Now what if we compared equal displacement 3 and 4s...