Why are tractors so under-powered?

[IH782]

Modern diesel engines have come a long way in a short time. The Big 3 have diesels engines that are starting to push triple digits in torque straight from the factory. But meanwhile we are left with engines that are VERY, VERY low on the HP and Torque range for their size. Take for instance the engine in the Mahindra 2555, it is a 2.6L, Common Rail, High Pressure, Direct Injection, Turbo Charged, Intercooled diesel with its own dedicated OBDII ECU just like the diesel engines the big 3 use. The 2.6L, as with its automotive cousins, can vary injection timing, pulse width and number of injections per stroke. If the 2.6L in the Mahindra 2555 were in an automotive application, based on the averages from the Big 3, it would produce 153 HP and 315 ft/lbs of torque. With nothing more than a software flash you could triple you HP and Tq numbers. So why are manufacturers not using the technology, they are incorporating, in their engines to its fullest extent?

Here is a very rough chart I put together to compare the Big 3 with a Kubota 2650 and the Mahindra 2555.

Engine Size HP Tq HP per L Tq per L
_____________________________
Cummins 6.7L 350 800 52 119
Duramax 6.6L 397 765 60 116
Powerstroke 6.7L 440 860 65 128
Mahindra 2555 2.6L 55 113* 21 43*
Kubota 2650 1.3L 26 53* 20 41*

*Calculated


Torque as a % of horsepower: 105%
Average horsepower per Liter: 59
Average ft/lbs of torque per Liter: 121

 

[WilliamBos]

You cannot compare the two. Tractors are geared much lower, so you can get more done more efficiently with lower hp & torque.

The duramax now puts out 440hp/910 foot pounds.

 

[IH782]

You cannot compare the two. Tractors are geared much lower, so you can get more done more efficiently with lower hp & torque.

The duramax now puts out 440hp/910 foot pounds.

Thanks for the update.

 

[CalG]

What difference does it make?

You may purchase a tractor from any range of power you may require. And then add weight to meet your traction demands.

There is NO REASON to extract more raw horsepower from any power plant. The purpose of the tractor is to get the job done. The present arrangements seem to fill the requirement only too well. i.e. there are an over abundance of choices at reasonable cost.

ETA The 1952 modle year Fordson E27n is rated at 25 horsepower.
I want to tell you that my 300 HP four wheel drive sedan (Audi A8) will not out work or out pull those few "old timey" ponys. But I also don't ask the Fordson to send me down the highway at 70mph in comfort.

So ...different horses for different courses.

 

[IH782]

What difference does it make?

You may purchase a tractor from any range of power you may require. And then add weight to meet your traction demands.

There is NO REASON to extract more raw horsepower from any power plant. The purpose of the tractor is to get the job done. The present arrangements seem to fill the requirement only too well. i.e. there are an over abundance of choices at reasonable cost.

Their are many reasons to "extract" more power. From being able to do tasks at a lower RPM to being able to maintain speed on a grade to running implements more efficiently.

 

[CalG]

You are equating the wrong things.

Pick a tractor based on rated HORSEPOWER,

No one buys a tractor based on engine displacement.

WTF are you going to do with a tractor that outputs 300 HP and weighs 2000#?
Spin the wheels?

 

[IH782]

You are equating the wrong things.

Pick a tractor based on rated HORSEPOWER,

No one buys a tractor based on engine displacement.

WTF are you going to do with a tractor that outputs 300 HP and weighs 2000#?
Spin the wheels?

Never said people buy based on displacement, I am simply trying to show that with the technology available more HP and Tq are easily achievable.

Yes, if I had a 2000 lb, 300hp tractor I'd do burnouts any and everywhere I could.

 

[CalG]

You know that the majority of traction engine users favor efficiency above all.

If I can work a field all day on a tank of fuel at a rated 60hp, that means much more to me than working the same field using two tanks of fuel while boasting of 100HP.

But, I agree, burnouts are fun when money is not the issue.
Play on....

 

[MinnesotaEric]

Why are tractors lower power for their engine displacement?

I imagine because they are low revving engines that sip fuel.

And because the rest of the drivetrain would need to become significantly tougher to handle the additional power.

 

[pmsmechanic]

Big three rate their trucks at maximum horse power while tractor manufacturers rate their tractors at continuous horsepower. There is a big difference. None of the big three motors would last a day at maximum hp while your tractor will run all day at continuous hp, then... get up the next morning and do it again.

A top fuel dragster can put out 6-7000 hp for 3-4 seconds. It needs to be rebuilt after a few runs.

A 391 Ford hopped up puts out 5-600 hp. Factory stock would have been about 200. Continuous duty on a pumping unit for irrigation they were rated at 80 hp.

A 5.9 Cummins in a truck sled puller is putting out about 5000 hp. In a truck they hit about 250 -300. I don't remember exactly. In a Versatile tractor they were rated at 150 hp.