HP differences out of same engine???

[azhfl56]

Ok, I have been wondering about this for some time. Across Kubota's engine range you will see many different hp figures. Most of the engines are different displacement. However some of the engines have the same displacement, bore, stroke etc and have hp differences of 10. For example the M6040 and M7040. How are they doing this? What are they doing? Just curious. Thanks,

Bryan

 

[SkyPup]

Injection pump pressure can easily be raised and larger injection nozzle orifices can be installed to deliver more fuel during the injection timing.

Just screwing on an injection nozzle with larger spray orifices onto the stock injector is good for 10-20% increase in power....

 

[N80]

why would they do that? I know that some auto makers have been accused of lowering the hp specs on an engine in a lower line vs the same engine in a luxury line when in fact they put out the same hp. Obviously I can substantiate such a claim but I'm not sure its any worse than intentionally lowering the hp in an engine just so hp figures line up across several levels of tractor. I guess they could be matching the hp to the deisng and strength of the running gear, etc.

 

[dgl24087]

It's for production cost efficiency. Manufacturing one engine and manipulating fuel flow for variations in HP is considerably cheaper than manufacturing a number of different engines to accomplish the same thing.

 

[SkyPup]

Any basic diesel engine design can be tuned to deliver more fuel per injector stroke for any variety of horsepower and torque outputs, including the addition of a turbocharger.

 

[dfkrug]

Look at the new JD 4000 series CUTs. Several have the same engine
displacement but different HP ratings. The FI is different and the JD
factory rep says they use some electronic FI controls. Makes me
wonder if they do more than just change the fuel delivery. Anyone
know?

 

[rswyan]

why would they do that?

Cheaper to make one basic engine but vary a few more minor parts ?

I guess they could be matching the hp to the deisng and strength of the running gear, etc.

I'd say that would be a good guess.

 

[OrangeGuy]

Good question azhfl56,

I looked at the JD 4X20 series tractors for a farm I am considering purchasing. I've been orange in the past but a JD dealer with a good reputation is near this farm. I too was puzzled by the engine specs, and for that matter all the specs on the JD 4X20 series tractors. The engine is 149 cu. in. and 2400 rpms for all 4 models. The hydraulics systems are identical as are the weights at 3,700 lbs. What's the difference in models?

Do they come down the assembly line, the last inspector looks at the dealer order and calls out the model, the final assembler adjusts the injection pump to the appropriate HP, and then puts on the appropriate decals for the model? Is there a price difference, and if there is, why?

OrangeGuy

 

[indianaEPH]

Good question azhfl56,


Do they come down the assembly line, the last inspector looks at the dealer order and calls out the model, the final assembler adjusts the injection pump to the appropriate HP, and then puts on the appropriate decals for the model? Is there a price difference, and if there is, why?

OrangeGuy

Why? Because people will pay more money for more power and JD, and any other manufactuer, can change the power with a calibration change (mechanical or electrical). The engine HP/Torque curve is called the rating. Engine manufactuers design the engine around the top (highest) rating and then derate the engine for the lower HP options.

As said before, this gives them the ability to sell a variety of engines ratings with the same engine (mechanical) configurations. This is very cost effective for the plant.

This can only be taken so far though. IF you derate to much you loose efficiency as you could get the same power with a smaller engine. You can't go to high of a rating as the durability of the engine will be comprimised. This is a workable strategy for a limited range of ratings.

Enigine rating

 

[N80]

Makes sense but I just hate the idea 1) of paying more for the extra hp when the engine itself cost no more than the de-rated one or 2) paying less for the de-rated engine but knowing that your engine makes less power than a virtually identical one.

I guess the next question is how hard is it to up rate a de-rated diesel?