tractor diesels vs. pickup diesels

[hydrovane218]

I am guessing the answer to this question is yes, but is there one or two main reasons for the large power difference between tractor and truck engines? If so, feel free to ramble.
My 3203 for example is 32hp and 52? ft/lbs and I believe 1.9L displacement. I had a 1.9L TDI jetta(turbo....yes I know vs no turbo in said Yanmar tractor engine) rated at I believe 90hp and 149ft/lbs.
I believe most pickups now run around 6 - 7L engines, all turbo and direct injection also, and put out around 350hp and 500 - 600 ft/lbs.
Is the difference solely due to the turbo and maybe jamming more fuel in it?
It appears as though tractor diesels put out only 1/3 to 1/4 the hp and torque numbers as on road vehicle diesels... is this right and if so, why?

 

[Builder]

I am guessing the answer to this question is yes, but is there one or two main reasons for the large power difference between tractor and truck engines? If so, feel free to ramble.
My 3203 for example is 32hp and 52? ft/lbs and I believe 1.9L displacement. I had a 1.9L TDI jetta(turbo....yes I know vs no turbo in said Yanmar tractor engine) rated at I believe 90hp and 149ft/lbs.
I believe most pickups now run around 6 - 7L engines, all turbo and direct injection also, and put out around 350hp and 500 - 600 ft/lbs.
Is the difference solely due to the turbo and maybe jamming more fuel in it?
It appears as though tractor diesels put out only 1/3 to 1/4 the hp and torque numbers as on road vehicle diesels... is this right and if so, why?

Couple reasons. A tractor travels at slower speeds and has much greater gear reduction so it doesn't require as much power. A tractor is required to run at a much higher output level and more often than a diesel pickup in most cases. A day long of pulling a bottom plow or cutting heavy brush will require a much higher demand on the tractor diesel compared to an ocassional tow up a hill with a load from a diesel pickup. Therefore the tractor diesel is "turned down" more than the diesel pickup so it will last a long life.

You see this in medium duty v. light duty truck applications, too. A 5.9L Cummins diesel may crank out 325Hp stock from the factory in a Dodge pickup, but in a medium duty F-650 dumptruck, it will be down rated to 210-260HP because it will be required to run at a much higher percentage of its' available power for longer periods of time. Medium duty trucks place more demand on the same model diesel than a light duty pickup. Therefore, it is turned down to lower HP levels.

For the owner of a medium duty diesel truck or tractor to expect a long service life, the max power level is typically turned down so the diesel will last longer due to much greater demand on the engine for a greater percentage of its' life.

 

[Z-Michigan]

Exactly what builder said. Big difference between making max hp for a few minutes vs. making it for hours on end, day after day, week after week like a big tillage tractor. For another fun comparison, look at those pickup truck diesels vs. large over the road semi diesels. Some of the big OTR engines are in the 12-15L range and yet make "only" 400-550hp. Of course maybe 1200-1800 ft-lbs of torque! Those big engines can make max hp for long stretches without overheating or wearing out. The pickup engines likely can't.

 

[daTeacha]

Yep, engines are like people. The more highly stressed they are the quicker they die.

 

[Egon]

Sounds like the Cumin's in my old truck should last forever. It's only got 185 HP!

 

[john_bud]

As the other fellows said, the tractor is producing HP that can be used continuously at that level until the fuel tank runs dry. It can do it at -20F and it can do it at 120F. It's the difference between instantaneous and continuous output.


If you rig up a big parachute on the back of a 350 HP 3/4 ton diesel pickup truck and I mean a really big one. One that only allows the truck to go 18-20 mph in 1st gear with the peddle mashed to the floorboard and the floorboard dented down. How long do you think it would be until that truck has a catastrophic engine failure? 10 miles? 20?, 40? It would be sooner than we would like to think, probably in 10 miles or even less. Now, if you de-tune that truck until it can do the same pull for 10 hours without stoping, it would probably be real close (proportionally) to what the tractor has for hp taking into account the turbo makes the truck engine effectively 2-3x the physical displacement.

jb

 

[tomd999]

Hiya,

There isn't a lot of difference between my W250 Dodge Cummins and say a Deere 3720. The Deere makes 29.3HP/Liter (44hp/1.5L), my '92 Dodge Cummins makes 27.96HP/L (165/5.9L). My Dodge is already 16 years old and running just like new with over 250K on the clock. I held it to the wood over the Alleghenies on the old road towing a steel trailer with a Grand National to Hershey one year and back again with a 340 Duster in second gear for the each assent, didn't seem to phase it at all.

Since it's less stressed than a 3720, it should outlast my tractor.

Tom

 

[Wayne County Hose]

A tractor engine is designed purely for high torque at a given rpm. Over the road vehicles see a much broader range of rpm's due to acceleration needed. If you need high torque without a broad rpm range, you build a long stroke, low rpm engine. Even though both your engines are 1.9 liter, your tractor has a smaller bore and a longer stroke, giving more torque. In a long stroke engine, the piston travels further on the power stroke, giving it more torque. The cam profiles are also way different as are the intake and exhaust ports. You also don't want to look at the horsepower ratings, look at the torque ratings and at what rpm they occur. Like the racers in the sixties said, horsepower sells cars, torque wins races.

 

[machmeter62]

A tractor engine is designed purely for high torque at a given rpm. Over the road vehicles see a much broader range of rpm's due to acceleration needed. If you need high torque without a broad rpm range, you build a long stroke, low rpm engine. Even though both your engines are 1.9 liter, your tractor has a smaller bore and a longer stroke, giving more torque. In a long stroke engine, the piston travels further on the power stroke, giving it more torque. The cam profiles are also way different as are the intake and exhaust ports. You also don't want to look at the horsepower ratings, look at the torque ratings and at what rpm they occur. Like the racers in the sixties said, horsepower sells cars, torque wins races.

Diesel fuel burns/expanding at a slower rate than gasoline requiring a longer stroke too!

 

[Egon]

torque wins races.

Wasn't that "426`s win races!