3 cylinder engine vs 4 cylinder engine

[arto98607]

The two stroke two cylinder 2-53 Detroit Diesel in my 1959 JD bulldozer runs incredibly smooth!

No kidding, really nice for an old heavy duty engine but I wish it had the low rpm torque 4 stroke Diesels have...

 

[BravoXray]

Not sure thats true. A power stroke every 90* in a four is smoother, inherently, than one every 120* in a three.

A four cylinder engine delivers a power stroke every 180°.
A three cylinder engine delivers a power stroke every 240°.

Each cylinder in a four stroke engine delivers a power stroke every 720° of crank rotation.
Divide 720 by the number of cylinders to get the power stroke interval.

 

[neilkingent]

A four cylinder engine delivers a power stroke every 180°.
A three cylinder engine delivers a power stroke every 240°.

Each cylinder in a four stroke engine delivers a power stroke every 720° of crank rotation.
Divide 720 by the number of cylinders to get the power stroke interval.

not necessarily true, especially on even number cylinder engines. Firing degrees are a function of crank and cam shaft timing. Firing sequence is not always equally spaced and sometimes more than one cylinder is on a compression stroke at the same time.

 

[Hermio]

Number of cylinders does not determine power or torque. Total displacement is closer to determining it, but a low displacement engine can put out more power by running at higher rpm. Look at race car engines! Naval ships often have few cylinders but huge displacement at low rpm. I was on a retired battleship now acting as a floating museum that got 7500 hp from 3 cylinder Diesel engines. They were direct drive to the props at a few hundred rpm. Each cylinder was over 4 feet diameter. The crankshaft bolts were about 8" head diameter; I would guess the bolts were about 3-4".

 

[ruffdog]

Walmart agrees to test 3 cylinder engines in their semis.

A New 10.6L Two-Stroke Diesel Engine Has 3 Cylinders And 6 Pistons

 

[CADplans]

I have a 2 cylinder, a 3 cylinder, and a 4 cylinder diesel,,
In my case of tractors,, the more cylinders, the smoother running the engine,,
BUT, with each tractor, as the # of cylinders increases,, the tractor weight at least doubles,,
so, it is hard to tell if the smooth running is from # of cylinders, or tractor weight,,

One thing is for sure, if my JD 650 ever dies, and can not be fixed,,
I will find a replacement for it,,

Riding that tractor around at just above an idle,, (1,200 to 1,500 RPMs)
the tractor sounds JUST like a mini of the 1958 JD 820 that I spent hundreds of hours plowing fields with.

The JD 820 was the first real field tractor that I drove,, that tractor had a >300 pound flywheel that was trying to smooth out the thump of that engine,,

Interesting enough,, you can look at and compare horsepower-hours per gallon of fuel in the Nebraska tractor tests,,
It is almost impossible to find a more fuel efficient engine than the JD 820 that only has 2 cylinders,,,

Turbos, modern computers, new style injection systems,, that 1958 tractor was SUPER fuel efficient,, without any of those "modern" features,,,
Go figure!!~??

 

[Bentrim]

Just for a thought. Engines of similar displacement a three cylinder will have a bigger bore and or longer stroke. A four cylinder will have a smaller bore and or shorter stroke. Most 3 cylinders use no balance shaft but four cylinders do. Interesting to note MF used Perkins diesels. the three cylinders (3.152)use weights bolted to the crank on each end. The also built a gas engine using as many diesel components as possible. A smooth operating engine. For the next size engine (4.203) the same bore and stroke as the 3 cylinder, when used in the 165 was OK when they used it in a new model the 255 it would vibrate badly. Probably upped the RPM slightly. Customer complained about hand and feet going to sleep and there were always a line vibrating and breaking on the tractor. This engine did not use a balancer. To satisfy customers MF made kits to include rubber line and mount the foot board on rubber mounts. The also derated the next larger engine to put in the tractor. The 4.236 did use a balancer. The 4.236 had the same bore and stroke as the six cylinder 6.354. But to note MF also used a four cylinder 4.318 which used 4 inch bore and had head gasket issues with that one. Note also, these engine all had five inch strokes. A lot of operators were surprised at how little fuel the three cylinder diesel used. I was always told that three cylinders were inherently balance like a six cylinder, and four cylinders always had more vibration due to the difference in piston speed in the top half and bottom half of the stroke being different, that is why they use balance shafts in 4 cylinders. Personally I would prefer a 3 cylinder for the bigger bore/ longer stroke.

 

[Hay Dude]

All this information about 3cyl v. 4cyl is fine, but the best news is you‘ll be getting a KUBOTA diesel no matter which one you select.
I just picked up an F3680 with a 36HP 4-cyl. V-1505 and it does feel a little more buzzy on the steering wheel in my "XL hands" than my ZD331 with a 31HP 3-cyl D-1305.
Could be the configuration of the chassis or any other number of factors, but its not a big deal to me.
Sometimes I wish equipment came with a NVH value.

 

[mo1]

I just noticed a bobcat ct 4045 only has a 3 cylinder engine. Looking at Kubota's similar weight/hp class with L4701 is a 4 cylinder engine. How much power difference is this between the two?

I have had three cylinder diesel engines in tractors and four cylinder diesel engines in tractors. In the simplest terms I prefer three cylinder, naturally aspirated engines simply because there are fewer parts to go wrong.

Note that Kubota uses just one four cylinder engine in the L4701 (naturally aspirated), MX series (turbocharged) and all the Kubota Grand L tractors (some naturally aspirated, some turbocharged), less the three cylinder L3560.
As one who used to study the efficiency of winery bottling lines I can tell you long production runs lower unit volume costs by significant $$. Same for tractor engines production runs.

You can easily determine the factory stated horsepower but it is difficult to determine if spec is for gross or net horsepower. All engine horsepower has to pass through the tractor transmission before it can accomplish work, which varies from 8% to 20% power loss. Therefore PTO horsepower will give go the most useful information for comparing tractor functional power output ~~~ but few consumers researching compact tractors are interested in this spec.

Deere 5075E has the most powerful three cylinder diesel engine I know of. Approximately 20% power loss from engine to PTO.

John Deere 5075E Engine​

2008 - 2022 Model year 2008-20122013-20142015-2022 5E Series Utility tractor

Series:

5065E ←

5075E

→ 5083E

Engine Detail
John Deere PowerTech 3029H
turbocharged diesel
3-cylinder
liquid-cooled
Displacement:	179 ci 2.9 L
Bore/Stroke:	4.19x4.33 inches 106 x 110 mm
Rated Power (EC 97/98):	75 hp 55.9 kW
PTO Power (Claimed)	61 hp

Also I've noticed bobcat has bigger hydraulic flow which means a loader and backhoe should move faster?

I've also read where the Bobcats lift capcity on the specs is off as it doesn't include the loader weight. The lift is actually minus the loader weight. Are all tractor specs like this?

All 'regulars' contributing to T-B-N grope for accurate information.

No governement agency directly polices published tractor specs. Nor are there agreed industry standards. "Trade puffery" is legal. Fraud is not.

The comprehensive Nebraska state tractor tests show Nebraska measured results but almost all tractors tested are Big Ag tractors. Few compact category or utility category tractors are tested.


Take some time to research the service reputations for your local tractor dealers. Also research the service reputations of local welding shops.


A quality dealer, reasonably close, available for coaching, is important for tractor neophytes. Most new tractors are delivered with a glitch or two requiring correction. My kubota dealer is six miles away. I feel my local dealer continues to add value to my equipment after eight years. Dealer proximity is less important for those experienced with tractors and qualified to perform their own maintenance.

1. The most powerful 3 cylinder diesel engine used in a currently produced tractor is AGCO's 3.3 L unit used in the Massey Ferguson 4700 series. The most powerful iteration of that engine is 100 HP in the Massey Ferguson 4710. Deere offers the turbocharged 3029 up to 86 HP in marine applications but it never had a version rated at more than 74 HP in a tractor. The 3029 has been made by Deere since the 1970s and is the only surviving member of what was the fairly large Sarna engine family that spanned several 3, 4, and 6 cylinder engines of varying displacements but all of the other members were replaced by the mid-1990s with other engines, mainly the 4045 which also was made off and on since the 1970s as well.

2. Most compact tractors aren't tested at Nebraska as the state doesn't require testing on tractors under 100 PTO HP in order for them to be sold in the state. Any testing on smaller tractors is voluntary and abbreviated compared to testing on 100 PTO HP and over units. The only testing currently done on <100 PTO HP tractors appears to be Deere and CNH utility tractors, and most of those models had been tested as Deere had anything from the 5055E on up tested and CNH tested their 55+ HP utility tractors as well.

3. Nebraska does police published specifications on 100+ PTO HP tractors, they look at PTO horsepower, 3 point lift capacity, hydraulic pressure and flow, noise, and fuel consumption. They do not look at anything related to loaders. They will also look at this on >100 PTO HP tractors if a manufacturer elects to submit a unit for testing.

4. Typical engine to PTO power loss is 8-12% according to testing results. Some manufacturers have been known to significantly under-rate PTO horsepower. For example, the current version of the 5075E you listed above is rated at 60.3 PTO HP in an open station and 73.7 flywheel engine HP. I expect the 73.7 flywheel HP to be pretty much spot-on as the engine must be below 75 HP to not violate EPA regulations as it doesn't have the SCR setup required on 75+ HP engines. However, Nebraska tested the tractor at 64.2 PTO HP at rated PTO speed, and 65.1 PTO HP maximum. 65.1 PTO HP at the speed where the engine is making its 73.7 peak HP gives a 12% driveline loss, not the 20% that Deere suggested. The newest compact tractor with a hydrostatic transmission tested by Nebraska was the 58 engine HP John Deere 4720 which made 51.8 PTO HP, for an 11% driveline loss assuming the engine HP was rated properly, so I would suspect it's fairly safe to guess the actual PTO HP of a compact is roughly 10% less than engine HP as well.

 

[Tx Jim]

I'm confused due to the JD 3179 engine is shown in JD5115M built for European sales parts catalog.