Can someone please explain the difference between the two engines and how they produce power and torque and the main differences. For example the 2.0 tdi 4 cylinder engine in my Audi produces 150HP and 230ft/lbs of torque while the engine in my JD 6930 produces 155HP and around 530ft/lbs from a six cylinder 6.8 engine. What are the main differences ? Thanks
The difference between a tractor engine and a automotive engine
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john432
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- Carmarthenshire
"Horsepower - Wikipedia" https://en.m.wikipedia.org/wiki/Horsepower
Have a read of this first then maybe @Cowabunga might explain
Have a read of this first then maybe @Cowabunga might explain
Suffolk Serf
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- Location
- Bury/Thetford
Power = Torque x speed. (engine speed)
Tractor has more torque and less speed.
Car produces it's power at higher engine speed, simple really.
Tractor has more torque and less speed.
Car produces it's power at higher engine speed, simple really.
DeeGee
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- North East Wales
I suppose it basically comes down to fuel efficiency and how to get power and torque at lower engine revs?
Cowabunga
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- Ceredigion,Wales
That article explains it perfectly in as much, or little, detail as one would wish to take from it.
Torque is related to many things, among which and apart from the obvious rotational speed of the crank and swept volume, there is the relationship between the throw of the crank, which is basically the stroke of the piston, to its diameter. The amount and timing of energy input also has a profound influence. It depends on how deep one wants to go but I'm not into the detailed engineering mathematics of how they plan these things and how they calculate, for instance, how heavy and of what material the crank needs to be and how stiff the block needs to be built. Even the professionals have been known to get these things wrong from time to time.
Some people might be interested to know that whether you are talking about motorbike engines, car engines, tractor, tuck or whatever, the mean piston speed of most running engines is remarkably close.
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76masseyman
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- Lincolncestershire
Horsepower = How fast you hit the wall.
Torque = How far you go through the wall.
Torque = How far you go through the wall.
and huge engines such as in boats, which rev at a rate in the order of 60 rpm
i hate this phrase - its commonly bounded around by people who really do not know what they are reffering to. See the more informative posts above.
Sorry.
Power is simply torque multiplied by speed.
You measure torque, and then calculate the power output.
76masseyman
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- Lincolncestershire
Ok. Torque = work done.
Horsepower = how fast that work can be done.
Two very simple phrases used many times years ago to help explain it simply to those just coming into engineering without scaring them.
GeorgeK
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- Location
- Leicestershire
Yes similar hp ratings but how long is the car engine expected to output maximum power for over it's life? Maybe 1% of the time will be spent really gunning it? A tractor engine should be able to produce it's maximum power all day every reliably for 10,000 hours
Exfarmer
Member
- Location
- Bury St Edmunds
The power of an engine is decided by several factors.
firstly cubic capacity.
then air flow
then charge
then revs, more revs more power strokes.
other factors are also in place.
as an engine speeds up so the efficiency of the air flow decreases, the cylinder does not get exhausted so well and air does not flow in fast enough.
to sort this turbo charger ( or superchargers ) are used.
turbos are very efficient at speed in enhancing air flow but not at low revs so we now find twin and even triple chargers on high performance engines.
this then gives a need for a wastegate to ensure the pressure does not get too high.
this boosting also heats the air, which thins it so intercoolers are fitted to condense it.
then comes the charge, the injection of fuel should be just before top dead centre so the explosion occurs at the peak point. However this gives starting issues
with old technology controlling this to maximum efficeincy was not possible, but todays chip controlled electronic injection means the engineers can do far more to get perfection.
all engines will have a peak pointof power production at a given RPM and air flow etc. Boosting air pressure can raise this point as will changing charge timing etc.
then comes weight larger enginesare obviously much heavier, irrelevant in a tractor but crucial in a car.
then the latest technology including triple chargers etc, bring cost, not popular with tight farmers.
The slower running tractor engine will have a very flat power curve useful for when the grunt is needed .
the car engine will have a curve rising sharply to perhaps 5.000 revs then dropping again.
in theory you could put a car engine in a tractor and gear it down but it would not sit well .
Tractors though have benefitted from these advances in technology too, the average engine size has not increased that much from when the first 6 cylinders appeared, but hp has gone 2-3 fold from that similar block
firstly cubic capacity.
then air flow
then charge
then revs, more revs more power strokes.
other factors are also in place.
as an engine speeds up so the efficiency of the air flow decreases, the cylinder does not get exhausted so well and air does not flow in fast enough.
to sort this turbo charger ( or superchargers ) are used.
turbos are very efficient at speed in enhancing air flow but not at low revs so we now find twin and even triple chargers on high performance engines.
this then gives a need for a wastegate to ensure the pressure does not get too high.
this boosting also heats the air, which thins it so intercoolers are fitted to condense it.
then comes the charge, the injection of fuel should be just before top dead centre so the explosion occurs at the peak point. However this gives starting issues
with old technology controlling this to maximum efficeincy was not possible, but todays chip controlled electronic injection means the engineers can do far more to get perfection.
all engines will have a peak pointof power production at a given RPM and air flow etc. Boosting air pressure can raise this point as will changing charge timing etc.
then comes weight larger enginesare obviously much heavier, irrelevant in a tractor but crucial in a car.
then the latest technology including triple chargers etc, bring cost, not popular with tight farmers.
The slower running tractor engine will have a very flat power curve useful for when the grunt is needed .
the car engine will have a curve rising sharply to perhaps 5.000 revs then dropping again.
in theory you could put a car engine in a tractor and gear it down but it would not sit well .
Tractors though have benefitted from these advances in technology too, the average engine size has not increased that much from when the first 6 cylinders appeared, but hp has gone 2-3 fold from that similar block
the Buick 215 v8 springs to mind
Cowabunga
Member
- Location
- Ceredigion,Wales
Except that it has been proven time and again that there is.
See posts above, which i don’t entirely agree with when it comes to torque curves, especially his [Exfarmer's] reading them from left to right when torque is the resistance to the twisting force on a shaft. This is why it is measured always on a dyno from full throttle with an increasing resistance applied and measured. It measures the force required to maintain revs. Therefore you do not desire a flat torque curve for a tractor engine. What you need and is oft commented on in the press, is a steep torque rise curve, reading from right to left, the peak being at least 30% and up to 50% higher than at rated [high] speed. You also don’t want the curve falling off a cliff from peak torque revs down to 1000 rpm or slower. This is often referred to as the start-off torque which should be at least as much as the torque at rated speed. This much is referred to as 100% start off torque. Ideally it would be higher than 100% but not lower.
Torque rise in this context is also referred to as the torque reserve of an engine, which is as important as the absolute maximum torque produced for a given engine.
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GeorgeK
Member
- Location
- Leicestershire
Performance wise yes, but for some there is a human element whereby no amount of forced induction will ever rival the guttural warbling of a large capacity v8
indeed- the best F1 engine ever made was 1.5 L. if i recall correctly
as i say.......... Americans !
not even forced induction always - take a look at the v10 era F1 engines
deleted user 837354
Member
Power is merely the rate at which work may theoretically be done.
Torque is a twisting force.
Two engines producing 150hp, be in in an Audi TDI or a John Deere tractor, both are capable of achieving the same work rate but how they deliver that result is very different.
Think hammer blows as an analogy. The Audi is driving in nails with 6000 little taps from little hammers per minute.
The John Deere is whacking down 2000 heavier taps from a sledgehammers. Either way, those nails are being driven in at quite a rate of knots, but how each method gets there is the difference.
Torque is a twisting force.
Two engines producing 150hp, be in in an Audi TDI or a John Deere tractor, both are capable of achieving the same work rate but how they deliver that result is very different.
Think hammer blows as an analogy. The Audi is driving in nails with 6000 little taps from little hammers per minute.
The John Deere is whacking down 2000 heavier taps from a sledgehammers. Either way, those nails are being driven in at quite a rate of knots, but how each method gets there is the difference.
Whilst we’ve got the engine boffs around- what makes some engines sound so good, and others not so? It’s not even to do with volume. What is mechanically different about a lumpy V8 (even a 100hp Rover V8) an 80’s V6 Alfa, a 90’s V10 F1 car, a group B Audi Quattro or even a 10 series John Deere that makes them so kind on the ear? Yet something that should sound extraordinary like a McLaren V8 just doesn’t do the same. So it’s not power related 
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