horsepower vs. durability

[vtsnowedin]

While I'm waiting for my 5045E to get here on a slow boat from India I've had time to read through all of the brochure and spec sheets on the 5 series tractors. One question comes to mind. Does increasing the horsepower of a given block by changing the turbo and injector settings reduce the expected lifespan of the engine and if it does by how much.
Consider the Power Tech 3029. It is 179 cu. in. block that you can get in four different horse power configurations 45, 55, 65, and 75 all at the same rated engine RPM of 2400. To my basic six grade math mind that means that every power-stroke of the 75 exerts 145% of the force that a 45 does on the same sized crank shaft and main bearings. As the engine parts must be sized to take the stresses of 75 HP operation using them at a reduced 45HP settings should reduce wear and fatigue stresses and hence the engine of a 45 should last quite a bit longer. Also strain and impact loads transmitted to the transmission and the other drive line parts would also vary with the horsepower being applied to the system.
The question really is how much does this amount to in real in the field applications. Also I realise that a foolish throttle jockey could hammer a 45 into submission trying to make it do the work of a 75 and an experienced operator of a 75 would work it for thousands of hours without ever over stressing anything knowing that if the job is too big the cheapest thing is to get a bigger tractor.
Anybody have any experience or facts and figures on the durability to horsepower ratio?

 

[jonyyuma]

Do you know that the bearings and all other components are the same for the lower powered blocks? A good turbo-powered engine will have define up grades to it internally.. For instance, oil jets fitted to spray the pistons and bore with oil instead of bleed-off or slinging??The pistons will be re-inforced and have passges for the sprayed oil and cooling and will the head gasket, be the same on all engines..How about he waterpump??Just askin..??

 

[Verticaltrx]

Do you know that the bearings and all other components are the same for the lower powered blocks? A good turbo-powered engine will have define up grades to it internally.. For instance, oil jets fitted to spray the pistons and bore with oil instead of bleed-off or slinging??The pistons will be re-inforced and have passges for the sprayed oil and cooling and will the head gasket, be the same on all engines..How about he waterpump??Just askin..??

I would be really surprised if there is anything internal different about the engines. A quick check of the parts book could confirm this, but I haven't time to look now.

With that said, my guess is the engines are designed for the 75hp level and detuned for the lower power outputs. There might be an increase in longevity in the lower power models (there will be in the clutch and powertrain), but my guess is it will be slight. Also, I doubt you'd see any differences until you get towards the 10,000hr mark.

Something I will be interested to see is the difference in longevity now that all the models in that series are turbocharged, whereas the smaller ones used to be naturally aspirated.

 

[vtsnowedin]

Do you know that the bearings and all other components are the same for the lower powered blocks? A good turbo-powered engine will have define up grades to it internally.. For instance, oil jets fitted to spray the pistons and bore with oil instead of bleed-off or slinging??The pistons will be re-inforced and have passges for the sprayed oil and cooling and will the head gasket, be the same on all engines..How about he waterpump??Just askin..??

No I don't know that for sure but I expect that Verticaltrx has the right answer on that. I'm not sure why he thinks the wear out time difference is small. Perhaps that although the bearings are wearing more slowly things like gaskets and hoses are still getting the same amount of sun and rain and the first thing that fails is what makes it fail. The 75's die one way the 45's another.

 

[tcartwri]

RPM is way more significant than the ultimate power output in the durability of an engine.

 

[vtsnowedin]

RPM is way more significant than the ultimate power output in the durability of an engine.

Well yes putting an engine up near it's red line wears it out but all of these options are rated at the same 2400RPM and it is the difference in force applied on each power stroke from the piston top face through the connecting rod to the crank bearings that creates the wear. The engine does not increase RPMs to put out more HP just applies more fuel air mixture to each power stroke to maintain 2400 under increased load. The 45 will run out of ability sooner and begin to lug down and force the operator to select a lower gear. The 75 will pound the bejesus out of the rod bearings and the mains while it maintains 2400RPM under the 45% higher load it is rated for before it begins to lug down.
I suppose it would take multiple engine tear-downs at 5000 hours to measure the difference in wear between the various options. If JD or anyone else has done that I expect they hold the data quite close to the chest and use it for future designs while not scaring the owners of product already in the field.

 

[tcartwri]

Well yes putting an engine up near it's red line wears it out but all of these options are rated at the same 2400RPM and it is the difference in force applied on each power stroke from the piston top face through the connecting rod to the crank bearings that creates the wear.

Those loads are insignificant in comparison to rotational forces. Usually you find the limit in a diesel when the head gasket can't hold the cylinder pressure from the boost of the turbo(s)

 

[RollingsFarms]

that 2.9 3cyl has been around since Jesus was a kid. It was in tractors BEFORE the 5000 series was introduced in the mid 90's (I just can't recall the model numbers right off hand). Durability of that specific engine wouldn't even be a question for me, it's tried and true and then some. They haven't recently turbo'ed those engines either, if I recall correctly the engine was turbo'ed in various models (5400, 5320, 5310, the late 500'3 series and now the 5D/E series). As for the 9/3 suny shuttle, that transmission is in applications all the way up to 90hp so no worries about putting too much strain on it either. This engine and tranny combo has been around for years, and years, and years. I had a JD engineer that worked on the early design team of the 5003 series tell me that basically all they did was put a 5000/5010/5020 drivetrain into the tractors which made the price "cheaper" since it was not the newest and latest design by Deere. The rear end of your tractor is the same rear end that was in the early 5000 series tractors too. So basically you have a drivetrain that was used in the mid 90's and is still being used today. Deere just switched to a 4cyl and 5 cyl engines in the upscale utility tractors when they brought out the 5420/5520/5025 series and 5m series. I think the 5500 and 5510 were 4 cyl too.

The engine, tranny, and rear end was one of the things that drove me to purchase this tractor because I knew the history of it and how long it had been around and was proven.

 

[AKfish]

In many cases, Deere engineers (and other manufacturer's as well) test and trial the basic engine in numerous horsepower configurations. That provides a baseline understanding of power output versus longevity or Mean Time Before Failure - MTBF.

I recently bought a 5075M with a 5030T powerplant. The engine is a 5 cylinder variant of the 4000 series engine - 4024T - which is a 4 cylinder model. Identical bore x stroke for both engines.

Nonetheless, I was interested in longevity and what other horsepower configurations as well as what other uses that Deere has used the 5030T powerplant.

Come to find out; the engine has been put into service @ 99 horsepower and used in standby power generators, skid steers, and I believe some of the older excavators.

I was greatly reassured that working my tractor at 75hp would not likely jepordize the life of the engine.

That said; I'd be very surprised that your 179 cu. in. engine is only ever been operational at 45hp, 55hp, 65hp and 75hp. I'd bet that the "white coat" back room boys have fired up that engine in more horsepower flavors than that!! :thumbsup:

And they know from experience; even @ 75hp the engine is gonna outlast the clutch, the hydraulic pump, the water pump; probably the front and rear differentials and the transmission!! All of those components with likely have to be repaired or replaced long before the engine signs off...

AKfish

 

[vtsnowedin]

Those loads are insignificant in comparison to rotational forces. Usually you find the limit in a diesel when the head gasket can't hold the cylinder pressure from the boost of the turbo(s)

I hadn't thought of it that way. The head gasket either holds the pressure or it doesn't. The pressure on the head and it's gasket would be equal and opposite to the pressure sent down the connecting rod. But the rod bearing is a much smaller area to absorb that force.??? Then you have that the rod bearings are bathed in relatively cool lubricating oil while the face of the head and the gasket work at temps just under red hot. They need to have the radiator sized right for 75 HP loads on a Texas summer day.
Interesting.