If the government thinks it can design cars better than GM, it should start it's own car company. You know, like in USSR, because we know how great Soviet cars were.
Originally posted by: senseamp
If the government thinks it can design cars better than GM, it should start it's own car company. You know, like in USSR, because we know how great Soviet cars were.
There is the IIHS, which is a private entity and does crash tests and safety ratings that are a lot more stringent and comprehensive than the government's test. Private sector does it better in that case. There is role for government as far as keeping automakers honest, so that they don't sweep problems under the rug and lie to consumers. But here it's not the case. GM puts it's EPA ratings on every vehicle they sell. Consumers are the ones who want big trucks and SUVs.Originally posted by: OS
Originally posted by: senseamp
If the government thinks it can design cars better than GM, it should start it's own car company. You know, like in USSR, because we know how great Soviet cars were.
not such a great analogy, federal crash test/ratings/laws do a lot for us.
No, in fact, *ALL* engines do as I purport since simple physics explains how an engine works. An "ideal" engine model would aspirate with 100% efficiency and would have a flat torque curve vs RPM. HP would increase proportionally to RPM because HP is proportional to RPM times Torque.Originally posted by: eos
Not all engines do as you purport.
Imagine looking a car from the side over the windshield. In a C15 Cat engine, the torque curve peaks at 900, holds to 1500 and then drops as it falls to max RPM of 2100. Like looking at the car from the right.
The horsepower is exactly the opposite. Lowest at 900, then peaks at 1500. Looking at the car from the left, IOW.
Max torque ranges from just above idle to halfway through the rpm range. get out of it and you're inefficient.
link to Cat .pdf
Originally posted by: JPSJPS
No, in fact, *ALL* engines do as I purport since simple physics explains how an engine works. An "ideal" engine model would aspirate with 100% efficiency and would have a flat torque curve vs RPM. HP would increase proportionally to RPM because HP is proportional to RPM times Torque.Originally posted by: eos
Not all engines do as you purport.
Imagine looking a car from the side over the windshield. In a C15 Cat engine, the torque curve peaks at 900, holds to 1500 and then drops as it falls to max RPM of 2100. Like looking at the car from the right.
The horsepower is exactly the opposite. Lowest at 900, then peaks at 1500. Looking at the car from the left, IOW.
Max torque ranges from just above idle to halfway through the rpm range. get out of it and you're inefficient.
link to Cat .pdf
But in the real world aspiration (air flow in/out) at high RPMS is restricted due to friction so torque is reduced. To overcome this methods like valve timing or turbocharger/supercharger are used gain airflow in/out at high RPMs.
In 1782 a guy named James Watt proposed a term "horsepower" (550 ft-lbs/sec) to define the power output of an engine. That term has now become an accepted standard although some manufacturers prefer to use KW instead. One HP is approximately 3/4 KW.
As I stated in an earlier post, "torque" alone means absolutely *nothing* to describe the power output of an engine unless RPM is also specified so that HP can be calculated. Torque is a term that is only meaningful to engine/drive train designers.
Answer the two simple questions that I asked earlier and you will understand James Watt's definition of engine "power" and ignore the meaningless term "torque".
Originally posted by: OS
Originally posted by: senseamp
If the government thinks it can design cars better than GM, it should start it's own car company. You know, like in USSR, because we know how great Soviet cars were.
not such a great analogy, federal crash test/ratings/laws do a lot for us.