Same Engine, Different Horsepower

[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.