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... but to go really deep, you have to realize that horsepower is just a marketing term that is mostly meaningless. It was used to sell vehicles to Americans al

by grecy 8y ago

... but to go really deep, you have to realize that horsepower is just a marketing term that is mostly meaningless. It was used to sell vehicles to Americans all through the 80s and 90s until now. It's torque you actually want - i.e. turning force. Horsepower is just torque X rpm. The best example of how meaningless horsepower is was the original Honda S2000, at the time, the world's highest specific-power engine (horsepower per liter of engine size). It was revvy as hell, and only developed power when really high in the rev range.. i.e. 6k-9k rpm, so many people hated driving it. You had to rev the crap out it to go anywhere. A few years later, the next revision had a bigger engine, with less horsepower. But it accelerated faster and was way better to drive. Why? The bigger engine had more torque. The horsepower figure is mostly irrelevant to drive-ability and acceleration. Interestingly, a steam locomotive has maximum torque at 0 rpm, a complete contradiction for an internal combustion engine.

mahesh_rm 8y ago
"you have to realize that horsepower is just a marketing term that is mostly meaningless" No it's not. Same torque on a single cylinder engine going up to 5000 rpm is a drastically different thing than on a 8 cylinders engine going up to 18000 rpm, and this makes your reasoning pointless. Race engines usually deliver most of torque at higher RPMs, and that's just how physics work. You might enjoy engines that yield torque early, but that's just a subjective personal matter that does not influence definitions and value of torque and hp as indexes of performance.
- grecy 8y ago
  > No it's not. Same torque on a single cylinder engine going up to 5000 rpm is a drastically different thing than on a 8 cylinders engine going up to 18000 rpm, and this makes your reasoning pointless. You're using examples that barely exist in the real world, so your reasoning is pointless. a) Show me a single cylinder engine that makes the same torque from idle to 5000rpm. No such thing exists. b) The only 8 cylinder engine ever made that revved to 18,000rpm was for Formula 1, and they have not used 8 cylinders for many years. I would propose there is not a single 8 cylinder engine being made in the world today that can rev to 18,000rpm. > Race engines usually deliver most of torque at higher RPMs, and that's just how physics work Can you link to a torque curve that shows that? I've never seen an engine where torque goes UP with rpm. It always falls off as volumetric (in)efficiency fails to get the air in and out of the cylinder.
  - mahesh_rm 8y ago
    "You're using examples that barely exist in the real world" No I'm not. I have a 110hp motorcycle with 4 cylinders (CBR 600RR), and a 30hp motorcycle with one cylinder (Royal Enfield Continental GT). They behave mostly the same, with comparable performance and torque, up to 6000rpm. Then the 1 cylinder reaches to top rpm. The 4 cylinders one starts to deliver the extra 3/4 of torque from 7000 rpm. I enjoy riding both, in different moods.
    - grecy 8y ago
      What's the displacement of the Royal Enfield? > They behave mostly the same, with comparable performance and torque, up to 6000rpm ...so , you are confirming what I said. A bike with 30hp performs similarly to a bike with 110hp. - UNTIL the Enfield hits it's rev limit, at which point you can't really compare them because one physically can't do what the other does.
      - mahesh_rm 8y ago
        What's the displacement of the Royal Enfield? 535cc vs 600cc of the CBR. "...so , you are confirming what I said. A bike with 30hp performs similarly to a bike with 110hp." Look bro, I don't want to argue indefinitely. They really do not perform similarly. My point is that HP is not a perfect index of performance, but being it TxRVM, it includes rough information about power snapshots (torque) and power range (RVM), and it is therefore more informative, and therefore more appropriate to describe engine performance that torque only. If you are arguing that before buying a vehicle you should take a look to its power delivery curve first, yep, that's what's more informative than torque, and hp. In absence of the curve, and being in need of indexing with a single number, hp (number) is more informative than torque (number).

by grecy 8y ago

mahesh_rm 8y ago

"you have to realize that horsepower is just a marketing term that is mostly meaningless" No it's not. Same torque on a single cylinder engine going up to 5000 rpm is a drastically different thing than on a 8 cylinders engine going up to 18000 rpm, and this makes your reasoning pointless. Race engines usually deliver most of torque at higher RPMs, and that's just how physics work. You might enjoy engines that yield torque early, but that's just a subjective personal matter that does not influence definitions and value of torque and hp as indexes of performance.

grecy 8y ago
> No it's not. Same torque on a single cylinder engine going up to 5000 rpm is a drastically different thing than on a 8 cylinders engine going up to 18000 rpm, and this makes your reasoning pointless. You're using examples that barely exist in the real world, so your reasoning is pointless. a) Show me a single cylinder engine that makes the same torque from idle to 5000rpm. No such thing exists. b) The only 8 cylinder engine ever made that revved to 18,000rpm was for Formula 1, and they have not used 8 cylinders for many years. I would propose there is not a single 8 cylinder engine being made in the world today that can rev to 18,000rpm. > Race engines usually deliver most of torque at higher RPMs, and that's just how physics work Can you link to a torque curve that shows that? I've never seen an engine where torque goes UP with rpm. It always falls off as volumetric (in)efficiency fails to get the air in and out of the cylinder.
- mahesh_rm 8y ago
  "You're using examples that barely exist in the real world" No I'm not. I have a 110hp motorcycle with 4 cylinders (CBR 600RR), and a 30hp motorcycle with one cylinder (Royal Enfield Continental GT). They behave mostly the same, with comparable performance and torque, up to 6000rpm. Then the 1 cylinder reaches to top rpm. The 4 cylinders one starts to deliver the extra 3/4 of torque from 7000 rpm. I enjoy riding both, in different moods.
  - grecy 8y ago
    What's the displacement of the Royal Enfield? > They behave mostly the same, with comparable performance and torque, up to 6000rpm ...so , you are confirming what I said. A bike with 30hp performs similarly to a bike with 110hp. - UNTIL the Enfield hits it's rev limit, at which point you can't really compare them because one physically can't do what the other does.
    - mahesh_rm 8y ago
      What's the displacement of the Royal Enfield? 535cc vs 600cc of the CBR. "...so , you are confirming what I said. A bike with 30hp performs similarly to a bike with 110hp." Look bro, I don't want to argue indefinitely. They really do not perform similarly. My point is that HP is not a perfect index of performance, but being it TxRVM, it includes rough information about power snapshots (torque) and power range (RVM), and it is therefore more informative, and therefore more appropriate to describe engine performance that torque only. If you are arguing that before buying a vehicle you should take a look to its power delivery curve first, yep, that's what's more informative than torque, and hp. In absence of the curve, and being in need of indexing with a single number, hp (number) is more informative than torque (number).