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Horsepower or Torque?

24567…13

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  • #32
    [Deleted User]
    Posts: 21,179 ✭✭✭✭ [Deleted User]


    Isn't it a case where Horsepower is a unit of measurement of power which means hp and torque ?

    If I compare our old CRV 2.0L petrol, 150 hp and 160 lbs of torque to the old VAG 1.9 TDI PD 130 hp and 220 lbs torque, the Honda definitely feels much livelier.

    While the TDI took off noticeably harder, I can spin the wheels a little in the crv on the open road when I drop a few gears to over take something the TDI couldn't do and the crv is a fair bit heavier.

    The crv has decent torque at low rpm but the difference is the power band, I got power most way to the limiter where the tdi runs out of puff far earlier.

    I can stay in 2nd much longer than in the TDI. and I got to tell you I love it much more than any tdi, especially the sound, I'd love a vtec.

    The TDI however would be much better for towing a trailer or caravan or climbing mountains (at slow speed)

    The Prius, well that's different altogether but it has a lot more grunt low (400 lbs) down than the crv which is great especially if climbing a mountain, if you come up to a hairpin bend in the prius and have a really steep hill after the bend the prius pulls off like a rocket, but it doesn't last long as the speed increases it feels then like a normal 110 hp car. But for those first few seconds it feels like it has a lot more power.

    The crv on the same stretch of road with the big hill means I need more revs for power and that can mean lots of wheel spin to give me the power for that big hill, but once I'm going the crv goes like a rocket but the power lasts longer than the prius, but it's got 40 more total hp.

    The tdi will climb from around that bend very well like the prius because the torque is much more than the crv at low rpm meaning much less wheel spin. But again the tdi runs out of puff far earlier than the honda in the rev range.

    on a normal road between the honda and the tdi, I prefer the Honda because I still have all the torque I need for relaxed driving but when I drop the gears the honda feels a lot faster than any tdi with around the same power.

    The main difference is the fuel consumption ! but if I want economy I'll convert to lpg.

    Full electrics, well they are completely different experience to any ice, 110 hp in a leaf will feel a lot more powerful than a 110 hp diesel/petrol. HP in an electric is deceiving.


  • #33
    [Deleted User]
    Posts: 21,179 ✭✭✭✭ [Deleted User]


    OSI wrote: »
    What you want is a nice turbo petrol. Best of both worlds.

    Indeed, or more cylinders ! ;)


  • #34
    Anan1
    Registered Users, Registered Users 2 Posts: 22,815 ✭✭✭✭Anan1


    Deleted User wrote: »
    Isn't it a case where Horsepower is a unit of measurement of power which means hp and torque ?
    Exactly. As conzy said, in a world without gearboxes torque might be king.


  • #35
    jimgoose
    Registered Users, Registered Users 2 Posts: 20,202 ✭✭✭✭jimgoose


    Deleted User wrote: »
    ...Full electrics, well they are completely different experience to any ice, 110 hp in a leaf will feel a lot more powerful than a 110 hp diesel/petrol. HP in an electric is deceiving.

    That's largely because the torque curve of an electric motor is like Table Mountain. Consider this'n, from a Tesla Roadster:

    122_0910_03_z+tesla_roadster+dyno_chart.jpg


  • #36
    [Deleted User]
    Posts: 21,179 ✭✭✭✭ [Deleted User]


    Does the roadster only have just over 200 lbs torque ?

    It's what this all translates to at the wheels though is the important part, I think most people that drive high power electrics prefer them much more to the ice.

    I know Tesla tried to make a gear box but they couldn't get one to handle the sheer torque of a leccy motor. A gear box might stretch out the torque curve more through the rev range.


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  • #37
    jimgoose
    Registered Users, Registered Users 2 Posts: 20,202 ✭✭✭✭jimgoose


    Deleted User wrote: »
    Does the roadster only have just over 200 lbs torque ?

    It's what this all translates to at the wheels though is the important part, I think most people that drive high power electrics prefer them much more to the ice.

    I know Tesla tried to make a gear box but they couldn't get one to handle the sheer torque of a leccy motor. A gear box might stretch out the torque curve more through the rev range.

    Best thing to use with 'lectric is some sort of CVT. I believe the Prius has one?


  • #38
    [Deleted User]
    Posts: 21,179 ✭✭✭✭ [Deleted User]


    jimgoose wrote: »
    Best thing to use with 'lectric is some sort of CVT. I believe the Prius has one?

    It does, but it's a very simplified version, the Prius box is a single speed driven by a chain. The torque of the motor eliminates the need for the lower ratios that are needed for an ice to get moving, so what effectivly would be gear (ratio) 1,2,3 for an ice is gone in the prius.

    The MK III prius is even simpler as it has no chain, gust a fixed gear.

    So if your looking for a 2nd hand automatic, the Prius is going to be one of the most if not (the) most reliable automatic you'll find.


  • #39
    [Deleted User]
    Posts: 21,179 ✭✭✭✭ [Deleted User]


    MK II on the left, and MK III on the right. Very simple indeed and a lot of the complexities of a normal cvt or automatic are eliminated in the prius. Which is one reason they last well over 350,000 miles.

    2010-toyota-prius-transaxle-at-right-with-larger-heavier-transaxle-from-2009-prius-at-left_100179713_l.jpg


  • #40
    jimgoose
    Registered Users, Registered Users 2 Posts: 20,202 ✭✭✭✭jimgoose


    Deleted User wrote: »
    ...So if your looking for a 2nd hand automatic, the Prius is going to be one of the most if not (the) most reliable automatic you'll find.

    Mmm. Except I'd rather Fred Flintstone it in a Hindustan Ambassador with no floor than buy a Prius! :D


















    Just kidding ML, don't kill me!! :D:D:D


  • #41
    [Deleted User]
    Posts: 21,179 ✭✭✭✭ [Deleted User]


    A cvt would be interesting in an electric, but I'm not sure it's necessary. I'm not sure it would improve efficiency enough but it may allow more efficient faster speed cruising.

    Unlike an ice, electrics are more efficient at faster rpm, so I'm not so convinced there would be a benefit.


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  • #42
    jimgoose
    Registered Users, Registered Users 2 Posts: 20,202 ✭✭✭✭jimgoose


    Deleted User wrote: »
    A cvt would be interesting in an electric, but I'm not sure it's necessary. I'm not sure it would improve efficiency enough but it may allow more efficient faster speed cruising.

    Unlike an ice, electrics are more efficient at faster rpm, so I'm not so convinced there would be a benefit.

    Probably give a more satisfying take-off as well.


  • #43
    jimgoose
    Registered Users, Registered Users 2 Posts: 20,202 ✭✭✭✭jimgoose


    OSI wrote: »
    I thought one of the big benefits of electrics was that they didn't need a gearbox

    They don't "need" them in the way an ICE does, but some sort of CVT does improve things somewhat.


  • #44
    [Deleted User]
    Posts: 21,179 ✭✭✭✭ [Deleted User]


    OSI wrote: »
    I thought one of the big benefits of electrics was that they didn't need a gearbox

    They don't, but they can in certain circumstances improve efficiency.

    Like an ice they have a range in their rpm where they're more efficient.

    But as battery capacity improves it would eliminate the need for the need to improve efficiency, as they are already pretty efficient.

    For torque, well I think most people will find that having max torque up until 40 odd mph and still pretty decent torque to the speed limit of 85 mph in the case of the Leaf would be more than enough.

    If you want to go much faster then yes a gearbox would make them more efficient.

    You see electrics are different to ice,

    If you want more speed you increase the voltage to the motor, if you want more torque you increase the current, all of this means more HP.

    Now this can be manipulated through the controller, software and the single speed transmission.

    Electrics need a reducer gear because the motor spins much faster than in an ice, (about 15,000 rpm or so) so you need to reduce this.

    There are also different types of motors with different windings which will translate to more or less torque or higher or lower speeds.

    I would love to see the power and torque graph of a leaf.


  • #45
    Paddy@CIRL
    Registered Users, Registered Users 2 Posts: 1,900 ✭✭✭Paddy@CIRL


    The numbers are irrelevant without context.

    Every car is different and should be judged on the sum of its performance, rather than what's on paper.


  • #46
    Jesus.
    Banned (with Prison Access) Posts: 4,794 ✭✭✭Jesus.


    dgt wrote: »
    Well tuned diesels have serious useable power and torque but are usually out of puff around 5k rpm.

    True but can't you just change down at that point? :P


  • #47
    Anan1
    Registered Users, Registered Users 2 Posts: 22,815 ✭✭✭✭Anan1


    Jesus. wrote: »
    True but can't you just change down at that point? :P
    Or up? ;)


  • #48
    Jesus.
    Banned (with Prison Access) Posts: 4,794 ✭✭✭Jesus.


    Anan1 wrote: »
    Or up? ;)

    Now THAT was embarrassing! :o


  • #49
    Dartz
    Registered Users, Registered Users 2 Posts: 4,425 ✭✭✭Dartz


    Torque and power really only tell half the story.

    The gearbox can also have a very strong effect on how a car feels because it's what determines the actual force at the contact patches of the tyres.

    If I have two engines that produce the same power output - but one revs much higher than the other - I can use shorter gearing on the faster-spinning engine to achieve the same force at the tyres. But it'll require a lot more effort to keep it in the powerband and careful gearshifting because if the rev's drop it'll feel gutless because it just doesn't have the sheer brute force to move the car.

    On the other hand, a big fat diesel engine will feel effortless. Put your foot down and it'll wind up and do something. But it runs out of breath at higher speeds. At lower speeds however, it produces much higher pulling force allowing you to carry larger loads. Also, at lower speeds the engine is under much less stress. This is why most trucks use big, high-torque engines.

    You can build a truck with an 18000rpm-spining 1 Litre engine. And with the right gearing it'll still move a load quite happily. But that little fast-spinning engine will be in such a high-state of tune and so massively stressed to do it that it'll just explode after a few miles. And you'll need some clever gearing to make it work.

    The best way to think of it:

    Power is a measure of your top speed. How fast you can ultimately go.
    Torque is a measure of how fast you get to your top speed. (Or how much load you can pull up to that speed). How easy it all feels.

    You also need to look at the power and torque curves.

    An engine with a lot of low-dow torque in the 1500-2500rpm range will feel lazy and effortless - but as you start to push it harder it will start to feel breathless and run out of puff. Much more relaxed for motorway driving or for cruising when you don't really give a **** you just want the car to 'work' when you put your foot down.

    On the other hand, an engine with all its torque somewhere in the 6000-9000rpm range (Or higher) will be ****ing manic. Lots of revs, lots of gearshifting, lots of noise and lots of fuel burn but a ****ing hoot to drive if you're into it. Or very, very tiring when you're not. And then there's the downshifting three gears to overtake a truck.


  • #50
    AugustusMinimus
    Registered Users, Registered Users 2 Posts: 4,591 ✭✭✭AugustusMinimus


    Cogsy88 wrote: »
    More horsepower increases top speed.
    More torque increases acceleration.

    This is simply not true.

    For a start, gearing is very important in determining top speed and acceleration.

    Simply put, if you have 2 identical cars, but one with more torque and the other with more horsepower, and give both cars optimal gearing, then the car with more horsepower will still accelerate faster and have a higher top speed.


  • #51
    [Deleted User]
    Posts: 21,179 ✭✭✭✭ [Deleted User]


    More hp is needed to go faster in other words.


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  • #52
    AugustusMinimus
    Registered Users, Registered Users 2 Posts: 4,591 ✭✭✭AugustusMinimus


    Deleted User wrote: »
    More hp is needed to go faster in other words.

    A car with more bhp will have a higher top speed and will accelerate faster than a car with more torque all else being equal.

    Top speed depends on a lot of things.

    1. Engine bhp
    2. Gearing
    3. Power loss between engine and wheels due to frictional loss
    4. Rolling friction of tyres on road
    5. Aerodynamic drag of car


    Engines with high bhp but low torque just need to be driven harder to get the bhp out of them. Diesel engines have loads of torque which is why people think they are so driveable. They have a narrow power band meaning you need more gears though to exploit this torque.


  • #53
    AugustusMinimus
    Registered Users, Registered Users 2 Posts: 4,591 ✭✭✭AugustusMinimus


    Here's a good question.

    If you have a CVT gearbox. In order for the car to accelerate as fast as it can, do you rev the engine to peak power or peak torque ?


  • #54
    [Deleted User]
    Posts: 21,179 ✭✭✭✭ [Deleted User]


    AugustusMinimus wrote: »
    Here's a good question.

    If you have a CVT gearbox. In order for the car to accelerate as fast as it can, do you rev the engine to peak power or peak torque ?

    If you want max power then they'll almost red line the engine until speed increases and you back off the accelerator. (called the rubber band effect) they hold high revs until speed increases or demand reduces.

    Though it's a lot more apparent in a weaker engine because you got to rev the nuts out of them. All auto's work much better with more powerful engines. Dumb electronics don't help the situation.

    The Newer VAG Multitronics shift ratios like a dsg and it works brilliantly.


  • #55
    [Deleted User]
    Posts: 21,179 ✭✭✭✭ [Deleted User]


    CVT works great with diesels, makes them very relaxing to drive.

    I could accelerate in the B6 multitronic at peak torque, albeit slowly at peak torque and the revs would not increase or decrease. It would hold say 2500 revs until speed increased or I backed off the accelerator.

    If I wanted to accelerate fast I planted the throttle and it would sit at 4k ish revs until speed increased or I backed off the accelerator.


  • #56
    Jesus.
    Banned (with Prison Access) Posts: 4,794 ✭✭✭Jesus.


    All other things being equal, would it be fair to say that a car with similar - or slightly less - bhp but more torque would burn less fuel, seeing that you have to push the high hp motor hard into the high rev range to get it up to speed quickly?

    I'm thinking of my car at around 110 hp and herself's, also with around 110 but a diesel with more torque. You rarely have to cane the latter because it seems to accelerate much more easily - albeit with more up-shifting.


  • #57
    [Deleted User]
    Posts: 21,179 ✭✭✭✭ [Deleted User]


    Jesus. wrote: »
    All other things being equal, would it be fair to say that a car with similar - or slightly less - bhp but more torque would burn less fuel, seeing that you have to push the high hp motor hard into the high rev range to get it up to speed quickly?

    I'm thinking of my car at around 110 hp and herself's, also with around 110 but a diesel with more torque. You rarely have to cane the latter because it seems to accelerate much more easily - albeit with more up-shifting.

    I would say that depends more on how you drive.

    The diesel is naturally more efficient and it not necessarily related to it having more torque.

    however, If you do lots of short trips and in the town city then the 1.0L petrol will be a lot more efficient than the diesel .


  • #58
    Joe 90
    Registered Users, Registered Users 2 Posts: 917 ✭✭✭Joe 90


    CiniO wrote: »
    I think the best measure of car performance is 0-62mph acceleration value.
    Maximum power or maximum torque on it's own doesn't tell us much, without knowing car weight, revolutions at which they appear, gearing, wheel size and plenty of calculations.

    I would reckon that the 0-60 or 0-62 time is outdated and has been for 30 years. The 0 to 40 bit is a measure of how well you can balance grip nand wheelspin if you have any worthwhile performance and the bit around 60 ish mph is very much affected by whether or not you have to change from second to third before you get there. I would reckon 40 to 100 mph to be a much more valid figure.


  • #59
    [Deleted User]
    Posts: 21,179 ✭✭✭✭ [Deleted User]


    For most people I think the 40-100 is far less important.

    For most people it's economy and motor tax.


  • #60
    AugustusMinimus
    Registered Users, Registered Users 2 Posts: 4,591 ✭✭✭AugustusMinimus


    In terms of efficiency, its all about balance.

    Lets say a petrol car. High revs are not very efficient. A car with a large engine will have a lot of torque. However, eventhough you'll be able to keep the engine revs low, this torque will be constantly wasted most of the time as the torque needed to push the car forward will be much less than what the engine is putting out.

    Car manufacturers obviously believed that 1.4 and 1.6L gave the best balance for fuel efficiency. Smaller, turbo engines may be even better due to be being able to reduce the torque the engine produces at a given amount of revs.


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  • #61
    AugustusMinimus
    Registered Users, Registered Users 2 Posts: 4,591 ✭✭✭AugustusMinimus


    Deleted User wrote: »
    For most people I think the 40-100 is far less important.

    For most people it's economy and motor tax.


    60 to 130 for me. Overtaking is why I need acceleration. Get it over with as fast as possible. Nothing more dangerous than a long, drawn out overtake.


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