Same Engine, Different Horsepower

[J W Bishop]

I致e been looking at some compact tractors and I知 confused about something. Spec sheets show 3 different HP ratings (40, 45, 50) but all 3 tractors have same engine, same frame, and same weight. What makes the difference in HP?

 

[nards444]

I致e been looking at some compact tractors and I知 confused about something. Spec sheets show 3 different HP ratings (40, 45, 50) but all 3 tractors have same engine, same frame, and same weight. What makes the difference in HP?

same size doesnt always mean same engine. To answer your question, programming, fuel delivery, gearing, many things

 

[ptsg]

I'll give you the case for the 15 Series on a Branson.

There is the 3015 (with the Kukje/Cummins A1700 derated at 30HP, then there is the 3515 with the same A1700 engine with 35 HP and last there is the 4015 with the yet again A1700 engine but with turbo. All mechanical engines, not computer used.

Different fuel setup and adding a turbo will cause those changes on the same engine.

 

[shooterdon]

The LS 4100 series engines are identical...or so I am told be the dealer. Different HP is due to computer program. He can make my 40 hp into a 50 hp but LS monitors his computer and they will freak if he does that. I would not do it unless I find I need more HP but so far so good. I would wait until the warranty is over as well.

 

[nards444]

The LS 4100 series engines are identical...or so I am told be the dealer. Different HP is due to computer program. He can make my 40 hp into a 50 hp but LS monitors his computer and they will freak if he does that. I would not do it unless I find I need more HP but so far so good. I would wait until the warranty is over as well.

most modern engines are detuned in most things. For one doesnt stress the engine out, 2 allows the manufacture to say next year "new" upgraded engine with 10% more HP

 

[SSdoxie]

Quite common with today's electronic injection to have various HP ratings of the same engine, no internal differences. The ECM programming changes fuel injection timing, volume, & pressure to alter the available torque at RPM. Torques X RPM divided by 5252 = rated HP.

 

[ericm979]

With diesels, more fuel == more power, up to a point. It's not like gas engines where there's a narrow range of fuel:air ratios that are effective.

From a manufacturing and marketing standpoint it makes sense to have different tractor models that use the same engine with different injection tuning to get different power levels and thus model differentiation. It's fewer engines to make and keep in stock. For example the Kubota L3301 and 3901 are the same tractor with the ECU turned up on the 3901, for whick Kubota charges about $2000. I think there's one other small difference in the PTO.

It can be done on mechanical injection too. The Branson 3725 and 4225 are the same tractor with the same engine model number, but one has 5hp more. I asked my dealer and they said the difference is the fuel injectors. I can see how on a mechanical FI system the injector size would limit the amount of fuel.

 

[finn1]

Back in the eighties and before, manufacturers would design and produce engines in small displacement. Off the top of my head, International made a 155 and 179 three cylinder engine, 206, 239, and 268 , plus a 239 turbo engine, and 310, 358, 402, and 358 turbo six cylinder engines, all the same family, and all made on the same line.

Deere had a similar lineup.

The complexity and logistics were mind boggling, and very expensive.

Today, manufacturers understand the cost of this complexity, and, with modern electronic common rail fuel systems, can offer one basic bore and stroke in three, four, and six cylinder versions, and cover the same power range.

Remember, the manufacturer is selling power. Without the different displacements, it was easy to buy the lowest power engine, and turn the pump up, cutting the manufacturers profit.

With modern electronics, it’s not so easy.

Remember, although we all like cheap tractors, the manufacturer needs profit to develop new products and keep investors happy.

Without profit, it’s a race to the bottom.

 

[ovrszd]

The road grader I run even has different HP output depending on what gear it's in. The lower the gear, the lower the HP. The higher the gear, the higher the HP. Ranging 175Hp thru 255HP in 8 gears.

 

[Industrial Toys]

When we bought our JD 6200, there was a 6300 and 6400, all identical except for HP and Injector pumps. I figured buying the lowest was the BEST deal and meant buying a tractor and drivetrain that was heavier than required for the given HP. Rather then the other way around.

 

[nybirdman]

Just as common in the marine outboard motors of all manufactures.

 

[PILOON]

In many cases it is RPM and timing that make the difference.
Generally the higher RPM is higher HP but usually at the loss of torque.
Then also compression ratio as well as stroke contributes.

All told for the same basic block, the lower the HP the better the longevity to be expected.

 

[PILOON]

Just as common in the marine outboard motors of all manufactures.

Yep, when I was into outboards I discovered what started as a 16 hp became a 25, then that went to 30 and onto 40 HP. all on the same engine block with the majority of major parts interchangeable. (other than housings grips mountings etc) perhaps carb and stroke changed and fuel consumption went up.

 

[Industrial Toys]

My Dad always told me, you buy the next higher tier product but entry level. So you don't buy a Chev with all the bells and whistles but buy an Entry Level stripped down Caddy. Better value and quality.

 

[stuckmotor]

-snip- I figured buying the lowest was the BEST deal and meant buying a tractor and drivetrain that was heavier than required for the given HP. Rather then the other way around.

Probably a good idea. I recently watched a video about the International Tractor model that had a transmission that wasn't strong enough for it's engine. The company spent millions trying to fix the problem and never outsold John Deere again. I can't remember the tractor model or relocate the video.

 

[TractorGuy]

Same deal on some of the big units. I have tried to figure how my New Holland 575E has less HP and Torque than a 675E. They have the same displacement, bore, stroke, compression ratio etc. I think they even have the same injectors and pump but I don't remember if I compared turbo size.

 

[WoodDuck]

Quite common with today's electronic injection to have various HP ratings of the same engine, no internal differences. The ECM programming changes fuel injection timing, volume, & pressure to alter the available torque at RPM. Torques X RPM divided by 5252 = rated HP.

This. It's common in most modern engines to use a common block with different fuel mapping for different models. Ease and cost of manufacturing. Rarely does a manufacturer tune a new engine design these days for max output right off the bat. They leave some room for future tuning in their engine design, so when their competitor launches a new model tractor, truck, UTV, snowmobile, jet ski, etc.... with more power than their top-shelf model has, it's only a matter of putting a more aggressive fuel map in the ECM to boost your HP number past the competitor again. (In some cases anyway.) Much cheaper than designing and building a whole new engine. Diesel engines respond particularly well to tuning; many people with diesel trucks have been doing this for years. Dramatic increases in HP,torque, fuel efficiency, etc... There's anything you want from mild to wild!

 

[CobyRupert]

When we bought our JD 6200, there was a 6300 and 6400, all identical except for HP and Injector pumps. I figured buying the lowest was the BEST deal and meant buying a tractor and drivetrain that was heavier than required for the given HP. Rather then the other way around.

Hmmm...but on the other hand....

The tractor only supplies the horsepower that the task requires.

For my tractor, they made a 45hp/55hp/65hp/75hp versions, all using the same engine and drive (ignoring tire sizes differ).

Why not just buy the 75 hp and work it like a 45hp?

If hooked up to identical loads that (say) require 42 hp, both tractors will output 42 horsepower regardless of their model. Both drive trains will experience identical strain and torque. The 45hp engine will just be operating nearer it's maximum fuel delivery design.
...but the 75hp will have a lot extra in reserve for those moments you need it.

I guess your argument is for when you run it working a (say) 65 hp load all day, then yes, the drive train is working harder than the 45hp ever could and isn't "as heavy" (in the sense it's working closer to it's limits) .

 

[ovrszd]

Hmmm...but on the other hand....

The tractor only supplies the horsepower that the task requires.

For my tractor, they made a 45hp/55hp/65hp/75hp versions, all using the same engine and drive (ignoring tire sizes differ).

Why not just buy the 75 hp and work it like a 45hp?

If hooked up to identical loads that (say) require 42 hp, both tractors will output 42 horsepower regardless of their model. Both drive trains will experience identical strain and torque. The 45hp engine will just be operating nearer it's maximum fuel delivery design.
...but the 75hp will have a lot extra in reserve for those moments you need it.

I guess your argument is for when you run it working a (say) 65 hp load all day, then yes, the drive train is working harder than the 45hp ever could and isn't "as heavy" (in the sense it's working closer to it's limits) .

What is the price difference between the 45hp model and the 75hp model?

 

[CobyRupert]

What is the price difference between the 45hp model and the 75hp model?

I don't remember the specifics, or how it varied among the 55hp and 65hp too, but I seem to recall you got a lot more bang for a few more bucks.