BHP vs HP (Agricultural)

AugustusMinimus

Anyone explain the difference to me.

Most Irish cars have about 100bhp or so.

Most Irish tractors are said to have 100 horse power.

After having a look on the net I actually can find much about it. Is this some sort of metric v imperial measurement system or something ?

CiniO

Here's some info
http://en.wikipedia.org/wiki/Horsepower

h3000

I think it's more to do with where the power is measured than different units of measure. Most of the pulling power of tractors comes from their gearing. That are geared at much lower ratios than cars would be.

I'm not 100% on the specifics and too tired to look them up :)

Neilw

Torque, it's for tractors and trucks.......and vw tdi's:D

Mr Benevolent

Neilw wrote: »

Torque, it's for tractors and trucks.......and vw tdi's:D

I heard that NASA are planning to spin up the Moon with a 1.9 TDI. VAG have assured NASA that it won't need a remap.

Terrible joke I know.

muckwarrior

Tractors may have similar HP to cars, but they have much more torque, so this combined with lower gearing gives them their massive pulling power in comparison to a car.

pajo1981

There is no difference. The peak power output of both a road car and a tractor is about 100BHP+

AugustusMinimus

pajo1981 wrote: »

There is no difference. The peak power output of both a road car and a tractor is about 100BHP+

OK.

Torque x RPM = Horse Power

If this is the case, if a car and a tractor had the same power, if the tractor revved at half the speed of the car engine, it would have double the torque.

What sort of size engines do tractors have and what sort of torque. From memory, they rev at, at least 2,000 RPM which isn't far off a diesel car.

Plug

OSI wrote: »

Aren't BHP and HP measured at different points along the drive train?

I'm not sure it of it all, but I though one was measured at the flywheel, and the other at the wheels or something along those lines...

BHP is measured at the flywheel with no load. No alternator, ac, ps, nothing. Its the true power output from an engine.

pajo1981

AugustusMinimus wrote: »

OK.

Torque x RPM = Horse Power

If this is the case, if a car and a tractor had the same power, if the tractor revved at half the speed of the car engine, it would have double the torque.

Correct, if the tractor puts out peak power at half the rev rate, then at peak power the torque output will be double.

Don't forget though that this only one point on the rev range.

Nonoperational

Confab wrote: »

I heard that NASA are planning to spin up the Moon with a 1.9 TDI. VAG have assured NASA that it won't need a remap.

Terrible joke I know.

The small silver bit at the end of your post should really be in huge bold font at the start :-)

Wossack

AugustusMinimus wrote: »

OK.

Torque x RPM = Horse Power

If this is the case, if a car and a tractor had the same power, if the tractor revved at half the speed of the car engine, it would have double the torque.

What sort of size engines do tractors have and what sort of torque. From memory, they rev at, at least 2,000 RPM which isn't far off a diesel car.

dont forget the magic number!

HP = torque x RPM / 5252

under 5252 rpm, torque figures are always higher then hp, above 5252 rpm, hp is always higher. At 5252 rpm, torque and hp are exactly the same

conneem-TT

Confab wrote: »

I heard that NASA are planning to spin up the Moon with a 1.9 TDI. VAG have assured NASA that it won't need a remap.

Terrible joke I know.

Well known fact, they have been testing for years

rocky112

AugustusMinimus wrote: »

Anyone explain the difference to me.

Most Irish cars have about 100bhp or so.

Most Irish tractors are said to have 100 horse power.

After having a look on the net I actually can find much about it. Is this some sort of metric v imperial measurement system or something ?

Hi,

BHP is Break Horse Power and it is used to measure amount of horsepower for machines like dynamo-meter.
HP is Horsepower is a mathematical definition of power.

When it comes to vehicle like car then BHP is corrector of accessories and HP is for net figure.

Plug

Heres a fact about the space shuttle, It pushes out about 20 million horsepower:eek:


Not quite as powerful as a Tee Dee Aye though.

Pique

Little known fact about BHP.
It stands for Brake Horsepower.

Also, the middle pedal is for the brakes.
The lever behind the gearstick in most cars is called the handbrake.

Please forward this information onto those who, despite driving for years, are still unaware of the difference between 'to brake' and 'to break'.

Plug

Pique wrote: »

Little known fact about BHP.
It stands for Brake Horsepower.

Also, the middle pedal is for the brakes.
The lever behind the gearstick in most cars is called the handbrake.

Please forward this information onto those who, despite driving for years, are still unaware of the difference between 'to brake' and 'to break'.

Pique

Plug wrote: »

om nom nom

dharn

average 100 bhp tractor would be about 4 litres they must be designed for more torque output as the average tractor engine is much bigger than 3-4 litre car engine

Plug

dharn wrote: »

average 100 bhp tractor would be about 4 litres they must be designed for more torque output as the average tractor engine is much bigger than 3-4 litre car engine

They would have a long stroke to give high torque output. Also a long stroke gives it the low RPM.

Solnskaya

AugustusMinimus wrote: »

Anyone explain the difference to me.

Most Irish cars have about 100bhp or so.

Most Irish tractors are said to have 100 horse power.

After having a look on the net I actually can find much about it. Is this some sort of metric v imperial measurement system or something ?

hitch your car to a tractor using a big, meaty chain, then have a tug of war between them. Nothing explains torque like a good auld visual demonstration. Unless you have a Daewoo Musso. (see youtube, daewoo musso v tractor, I'm way too thick to post a link, but it's a good watch. Well, I liked it anyway)

teednab-el

My understanding is of the terms. HP in a tractor is pulling power. BHP in cars is power output of the drive shaft on an engine, completely different concepts.

CiniO

AugustusMinimus wrote: »

OK.

Torque x RPM = Horse Power

That's not really correct.
To be exact:

Torque * Angular velocity = Power

SI units for above are:

Torque - Newton * Metre
Angular velocity - Radian / second
Power - Watt

So in other words:

1Newton * 1Metre * 1Radian / 1second = 1Watt

To have it in more understandable format, we have to convert Angular velocity from Rad/s to RPM, and Watts to BHP - we can leave Torque at N*m as this is most commonly used unit.

1 RPM = 2π/60 Rad/s
1 BHP = 745.7 Watt

So:

1 Rad/s = 60/2π RPM = approx. 9.55 RPM
1 Watt = 0.001341 BHP


So now we have:

(Torque of 1 N*m) * (9.55 RPM) will produce = (0.001341 BHP).

Then:
1 N*m * 1 RPM = 0.000140419 BHP

Calculate:
1/0.000140419 = 7121

In the end:

Torque (N*m) * Rev (RPM) / 7121 = Power (BHP)

That's the correct formula (approxime as calulus was only approx).

Assuming I made all calculations right

AugustusMinimus

Solnskaya wrote: »

hitch your car to a tractor using a big, meaty chain, then have a tug of war between them. Nothing explains torque like a good auld visual demonstration. Unless you have a Daewoo Musso. (see youtube, daewoo musso v tractor, I'm way too thick to post a link, but it's a good watch. Well, I liked it anyway)

Excluding the additional traction that a tractor has due to being heavier and having larger tyres, surely a car of the same horsepower as a tractor could pull a trailer equally as well as a car if you put a special gearbox in the car to gear down the RPM in order to increase torque to the same level as the tractor ?

Solnskaya

CiniO wrote: »

That's not really correct.
To be exact:

Torque * Angular velocity = Power

SI units for above are:

Torque - Newton * Metre
Angular velocity - Radian / second
Power - Watt

So in other words:

1Newton * 1Metre * 1Radian / 1second = 1Watt

To have it in more understandable format, we have to convert Angular velocity from Rad/s to RPM, and Watts to BHP - we can leave Torque at N*m as this is most commonly used unit.

1 RPM = 2π/60 Rad/s
1 BHP = 745.7 Watt

So:

1 Rad/s = 60/2π RPM = approx. 9.55 RPM
1 Watt = 0.001341 BHP


So now we have:

(Torque of 1 N*m) * (9.55 RPM) will produce = (0.001341 BHP).

Then:
1 N*m * 1 RPM = 0.000140419 BHP

Calculate:
1/0.000140419 = 7121

In the end:

Torque (N*m) * Rev (RPM) / 7121 = Power (BHP)

That's the correct formula (approxime as calulus was only approx).

Assuming I made all calculations right

And I thought Einstein was dead. My head hurts mum.Make the bad man stop.

conzy

AugustusMinimus wrote: »

Excluding the additional traction that a tractor has due to being heavier and having larger tyres, surely a car of the same horsepower as a tractor could pull a trailer equally as well as a car if you put a special gearbox in the car to gear down the RPM in order to increase torque to the same level as the tractor ?

Pretty much, just like if you put a tractor engine in a car and had a gearbox with longer gears it would accelerate at the same rate as a car with the same horsepower, obviously ignoring weight differences and the time taken to change
gear etc..

Gearing makes the torque generated at the flywheel irrelevant, a 300bhp car with 350Nm of torque will accelerate at the same rate as a 300bhp car with 150Nm of torque OR 900Nm of torque.. The are obviously geared very differently and are very different driving experiences

AugustusMinimus

conzymaher wrote: »

Pretty much, just like if you put a tractor engine in a car and had a gearbox with longer gears it would accelerate at the same rate as a car with the same horsepower, obviously ignoring weight differences and the time taken to change
gear etc..

Gearing makes the torque generated at the flywheel irrelevant, a 300bhp car with 350Nm of torque will accelerate at the same rate as a 300bhp car with 150Nm of torque OR 900Nm of torque.. The are obviously geared very differently and are very different driving experiences

Why then are tractor engines so large compared to car engines if they are putting out a similar power output ?

4L capacity has been quoted above for a mere 100bhp.

puzzle factory

Solnskaya wrote: »

hitch your car to a tractor using a big, meaty chain, then have a tug of war between them. Nothing explains torque like a good auld visual demonstration. Unless you have a Daewoo Musso. (see youtube, daewoo musso v tractor, I'm way too thick to post a link, but it's a good watch. Well, I liked it anyway)

http://www.youtube.com/watch?v=tzxxok-H08E

Fishtits

Cinio is dead right in his post.

Unfortunately not everyone has a degree in engineering so here's a simpler explanation:

Torque is a threat - here is what I think I can do - measured.

Power is a witness - here is what actually happened - calculated.

Power tells what torque did over a given time.

You can have a huge torque and not move - ie a guy pulling on a spanner.

Power incorporates the "work" torque has done once it moves a distance.

To put it to bed, power = acceleration.

Esel

In the good old days, wasn't there some rating system whereby a HP was 125cc? So, a one-litre car was classed as 8 HP, etc. I think this was for motor tax purposes.

AugustusMinimus

Esel wrote: »

In the good old days, wasn't there some rating system whereby a HP was 125cc? So, a one-litre car was classed as 8 HP, etc. I think this was for motor tax purposes.

Weird that. Cause a lot of farmers will tell you that most cars have around 10 HP.

AugustusMinimus

Fishtits wrote: »

Cinio is dead right in his post.

Unfortunately not everyone has a degree in engineering so here's a simpler explanation:

Torque is a threat - here is what I think I can do - measured.

Power is a witness - here is what actually happened - calculated.

Power tells what torque did over a given time.

You can have a huge torque and not move - ie a guy pulling on a spanner.

Power incorporates the "work" torque has done once it moves a distance.

To put it to bed, power = acceleration.

I always think that the link between torque and power seems to be the level effect.

You can put the same force on the end of two levers (akin to torque), but you'll lift more using a longer lever (akin to lower RPM), but you'll do it slower.

Hence, power governs the overall situation. The split between torque and RPM (or lenght of lever for instance) is used for a given situation. Hence a gearbox.