How does the HP change?

[Northvale PA]

I picked up a JD utility tractor brochure. It lists 4 different HP for the exact same size engine. 2 questions: I assume the fuel is turned up to increase HP, yes? And, why bother buying the lower HP machine when cost is based on the engine size?

 

[MeanGene1]

It makes sense once you learn that rated "horsepower" is just a calculated number based on measured torque and RPM. Turn the governor down, rated HP goes down. I sold off and derated a lot of stuff when all the Tier this and that, 50 hp and 2500 hp stuff came in. John Deere and others had charts on their websites that told what RPM to turn the governor down to 49 hp to get under that limit. If you look up a 315 Cummins engine, you will find that it's just a 350 with the governor set to 1800 RPM. When the factory hot rod cars got hit with heavy insurance charges in the 70's, the HP claims went down, just by the RPM it was rated at. One of the more famous ones was the 428 Cobra Jet with a "rating" of 335 HP, when it actually made well over 400 when you revved 'er up a little more

 

[paul]

Looks like the comments so far are spot on.

In addition on other product lines, they can add a turbo, and then add a turbo and inter cooler to get 3 power levels from the same block.

At times they might change the bearings and such on the higher hp engines, and also a tougher transmission behind it, but often they don’t. Might be a better radiator, etc.

Paul

 

[495man]

I picked up a JD utility tractor brochure. It lists 4 different HP for the exact same size engine. 2 questions: I assume the fuel is turned up to increase HP, yes? And, why bother buying the lower HP machine when cost is based on the engine size?

If those are the Tier II ones with the flat top fenders the only difference was the fuel screw setting, number on the hood and the amount you paid.

The 45 and 55 were supposed to come on 13.6 and 14.9s and the 65 and 75 being on 16.9s, but every one I saw was on 16.9s.

I priced these new, seems to me it was about $2500-3000 between models. The 5045E was the real bargain other than the HP.

 

[MarkB_MI]

It makes sense once you learn that rated "horsepower" is just a calculated number based on measured torque and RPM. Turn the governor down, rated HP goes down. I sold off and derated a lot of stuff when all the Tier this and that, 50 hp and 2500 hp stuff came in. John Deere and others had charts on their websites that told what RPM to turn the governor down to 49 hp to get under that limit. If you look up a 315 Cummins engine, you will find that it's just a 350 with the governor set to 1800 RPM. When the factory hot rod cars got hit with heavy insurance charges in the 70's, the HP claims went down, just by the RPM it was rated at. One of the more famous ones was the 428 Cobra Jet with a "rating" of 335 HP, when it actually made well over 400 when you revved 'er up a little more

You will note that the horsepower for the different versions are all rated at 2100 rpm. So it's not a matter of speeding up the governor. And since the rpm is the same, the torque must be different. There are many different ways to increase torque, but with a diesel the simplest one is to increase fuel, so that's likely what was done. But what is unknown is what other changes may have been made to the engine to accommodate the higher torque. Various internal components may have been beefed up along the way. Going from 50 to 73 hp without increasing rpm is a whopping 46 percent increase in torque. It seems unlikely JD would have just cranked up the horsepower without beefing things up a bit.

 

[Mike(NEOhio)]

A lot can be done with just a different cam, carb jetting and compression ratios. Ford 3 cyl. 2000 and 3000 were basically the same engine. Early Cubs were around 13 hp and gradually upped to 18 with the same engine.

 

[cjunrau]

case tractors 2470,2290, and a lot of others have a 504 block I think that is the correct number.
The block itself is the same. I copied and pasted.

• Horsepower Range: Generally 108 PTO HP (2090) to over 180 PTO HP (1570/2590).
• Applications: Used in Case 1370, 1570, 2090, 2390, 2590, and some early 1470 models.
• Design Variations: Early models had smaller cranks and oil pumps, while later models (23/2590) featured larger cranks and high-volume oil pumps with piston spray cooling.
• Block Strength: Considered a "brute". While often used around 150-180 HP, they can handle higher performance with proper modifications, though they may require attention when exceeding 200 HP.

 

[RJKeith]

case tractors 2470,2290, and a lot of others have a 504 block I think that is the correct number.
The block itself is the same. I copied and pasted.

• Horsepower Range: Generally 108 PTO HP (2090) to over 180 PTO HP (1570/2590).
• Applications: Used in Case 1370, 1570, 2090, 2390, 2590, and some early 1470 models.
• Design Variations: Early models had smaller cranks and oil pumps, while later models (23/2590) featured larger cranks and high-volume oil pumps with piston spray cooling.
• Block Strength: Considered a "brute". While often used around 150-180 HP, they can handle higher performance with proper modifications, though they may require attention when exceeding 200 HP.

Same for the Case 430 (30HP), 530 (42HP) and 630 (49HP). All use the 188 ci engine, just different adjustment to the injector pump.

 

[JOCCO]

Not speaking to computer engines. In the old days many ways, RPM Change, governor change, Bigger carb, fuel injectors, or pump turned up. Internal different cam, stroke or bore and timing too. Compression ratio, heads, valve size. Lets not forget adding a turbo It made sense to have one block and change a few smaller things.

 

[Dingo3]

It makes sense once you learn that rated "horsepower" is just a calculated number based on measured torque and RPM. Turn the governor down, rated HP goes down. I sold off and derated a lot of stuff when all the Tier this and that, 50 hp and 2500 hp stuff came in. John Deere and others had charts on their websites that told what RPM to turn the governor down to 49 hp to get under that limit. If you look up a 315 Cummins engine, you will find that it's just a 350 with the governor set to 1800 RPM. When the factory hot rod cars got hit with heavy insurance charges in the 70's, the HP claims went down, just by the RPM it was rated at. One of the more famous ones was the 428 Cobra Jet with a "rating" of 335 HP, when it actually made well over 400 when you revved 'er up a little more

From what I recall part of the muscle car HP drop came from where it was taken. Previously the cars were rated at the flywheel on a stand with no accessories giving impressive numbers to sell cars to gear heads. Later it was measured at the rear end giving a lower number. Gross vs net. That, lower compression heads and available gear ratios were the main reasons for the lower numbers.

 

[moresmoke]

You will note that the horsepower for the different versions are all rated at 2100 rpm. So it's not a matter of speeding up the governor. And since the rpm is the same, the torque must be different. There are many different ways to increase torque, but with a diesel the simplest one is to increase fuel, so that's likely what was done. But what is unknown is what other changes may have been made to the engine to accommodate the higher torque. Various internal components may have been beefed up along the way. Going from 50 to 73 hp without increasing rpm is a whopping 46 percent increase in torque. It seems unlikely JD would have just cranked up the horsepower without beefing things up a bit.

On diesels, it is common to change the turbo and injectors. The rest of the internals typically stay the same. Externally, the cooling system and whether or not an intercooler is used may change between models.

Further, on a tractor you may find differences behind the engine, wider gears, bigger bearings, heavier axles and commonly more hydraulic capacity.

As to the OP’s question of why buy the smaller of twin models? To the manufacturer the cost is the same, but the buyer is paying a premium for the higher HP.

 

[Phill Tibbetts]

I'm waiting for Dieseltech to chime in.

 

[Brendon-KS]

With modern diesels it is just a software change. In fact, there have been Nebraska tractor tests run for multiple models within a family all using the exact same physical tractor - they just swap out the engine software between tests. The machine I'm responsible for at work is this way - the model number is determined by the engine software we flash on the production line, the corresponding decal we put on the hood, and what is stamped on the serial tag. All three models have exactly the same mechanicals.

Obviously the profit margin to the manufacturer is greater the higher up you go within a given tractor family. The customer is buying horsepower and so the more powerful models will naturally have a higher price even though the mechanicals are identical to the lowest powered model. On the flip side the warranty cost tends to go up with the power level within a family so that offsets some of the profit.

 

[MeanGene1]

From what I recall part of the muscle car HP drop came from where it was taken. Previously the cars were rated at the flywheel on a stand with no accessories giving impressive numbers to sell cars to gear heads. Later it was measured at the rear end giving a lower number. Gross vs net. That, lower compression heads and available gear ratios were the main reasons for the lower numbers.

The gross vs net was more the difference of bare engine with no accessories vs with all the accessories and their drag. What I was referring to was how easy the numbers can be manipulated by what RPM they are taken at. Dyno measures torque then calculates "horsepower"

 

[MeanGene1]

You will note that the horsepower for the different versions are all rated at 2100 rpm. So it's not a matter of speeding up the governor. And since the rpm is the same, the torque must be different. There are many different ways to increase torque, but with a diesel the simplest one is to increase fuel, so that's likely what was done. But what is unknown is what other changes may have been made to the engine to accommodate the higher torque. Various internal components may have been beefed up along the way. Going from 50 to 73 hp without increasing rpm is a whopping 46 percent increase in torque. It seems unlikely JD would have just cranked up the horsepower without beefing things up a bit.

Torque and hp will change with an engine's state of tune of course. But the dyno measures torque and calculates "horsepower" based on the torque and the RPM it was measured at. Usually referred to as "rated" hp @ xx RPM- which is easily manipulated by the RPM the rating is taken at. Test the same engine at 2000, 2500 and 3000 RPM and you get three different "ratings". When you see the formula for calculating "horsepower", you'll see what the torque and horsepower curves always cross at 5252 RPM.

Horsepower=Torque (lb-ft)×Speed (RPM) / 5252

 

[cumminstinkerer]

@MeanGene1 That is a formula I remember well, it was beat into our heads during engines class for diesel tech!

 

[MeanGene1]

@MeanGene1 That is a formula I remember well, it was beat into our heads during engines class for diesel tech!

 

[Dingo3]

The gross vs net was more the difference of bare engine with no accessories vs with all the accessories and their drag. What I was referring to was how easy the numbers can be manipulated by what RPM they are taken at. Dyno measures torque then calculates "horsepower"

Agree, the manufacturers had all kinds of ways manipulating the numbers up or down. A common practice to lower the numbers was measuring at the rear wheels thus net HP.

 

[cumminstinkerer]

how about using calculated, aka theoretical, based on displacement and VE? most auto makers still do the calculated, thank god the Ag world went to a physical test, Nebraska, even if they can manipulate the numbers as has been mentioned through RPM changes. It kept all of them pretty honest, most that I've checked after the Nebraska tests came to be tended to underrate their machines, there were a few and I wont name brands that tried to sneak through with bigger numbers but got their butts handed to them.

 

[Brendon-KS]

how about using calculated, aka theoretical, based on displacement and VE? most auto makers still do the calculated, thank god the Ag world went to a physical test, Nebraska, even if they can manipulate the numbers as has been mentioned through RPM changes. It kept all of them pretty honest, most that I've checked after the Nebraska tests came to be tended to underrate their machines, there were a few and I wont name brands that tried to sneak through with bigger numbers but got their butts handed to them.

There's enough cars and pickups strapped down to chassis dynos to give plenty of evidence that automotive engines are putting out the power they advertise. (If not more - the latest Corvette ZR1 measured over 1000 hp at the wheels in an independent test, only about 30 hp less than the crankshaft rating. Drivetrain losses would be much higher than 3%.) And this makes sense because they dyno those engines (per the SAE J2723 standard) just like in the ag world - it is certainly not true that they use just theoretical numbers in their spec sheets.