Which is faster horsepower or torque?
Discussion
The question is lacking in detail. The OP has specified only peak power and peak torque but no engine speed as which these to parameters occur, therefore it has been assumed that they occur at the same engine speed.
So a poor question leads to (in the most part) poor answers and bickering due to different people interpreting the question differently.
So a poor question leads to (in the most part) poor answers and bickering due to different people interpreting the question differently.
Mr10secs said:
How come those diesel trucks in the states are so quick down a 1/4 mile they dont make a relatively large amount of hp just masses of torque, i would imagine gearing plays a rather large part.
I don't think I share your definition of "not a large amount of hp". The faster ones have four-figure horsepower outputs. 
Mr10secs said:
How come those diesel trucks in the states are so quick down a 1/4 mile they dont make a relatively large amount of hp just masses of torque, i would imagine gearing plays a rather large part.
CVT. Maximum acceleration is always at the peak torque figure so logically if you hold the revs under full load at those revs then your always accelerating at the fastest rate. (Or is this wrong?).
Welshbeef said:
Maximum acceleration is always at the peak torque figure
This is an oft-cited but highly misunderstood statement. Maximum acceleration for a given gear ratio comes at peak torque. Maximum acceleration for a given speed comes at peak power. So for a CVT where you have complete control over the ratios, you want to always be at peak power.
kambites said:
Welshbeef said:
Maximum acceleration is always at the peak torque figure
This is an oft-cited but highly misunderstood statement. Maximum acceleration for a given gear ratio comes at peak torque. Maximum acceleration for a given speed comes at peak power. So for a CVT where you have complete control over the ratios, you want to always be at peak power.
Welshbeef said:
So if you had CVT you'd want max power revs to be held but if the gear ratio was fixed ie 4/5/6speed box as your progressing through the rev range under full load for that gear maximum torque would give maximum acceleration.
If you only have one gear, the maximum G-force will be pulled at peak torque. If you can alter gears, you always want to be in the gear that puts you at the highest power figure possible. Basically, if you're in third gear, your car will accelerate harder from 40mph than it will from 80mph but if you're doing 40mph, your car will accelerate hardest in second gear not third.
kambites said:
Welshbeef said:
So if you had CVT you'd want max power revs to be held but if the gear ratio was fixed ie 4/5/6speed box as your progressing through the rev range under full load for that gear maximum torque would give maximum acceleration.
If you only have one gear, the maximum G-force will be pulled at peak torque. If you can alter gears, you always want to be in the gear that puts you at the highest power figure possible. Basically, if you're in third gear, your car will accelerate harder from 40mph than it will from 80mph but if you're doing 40mph, your car will accelerate hardest in second gear not third.
If you ignore the actual number of gear changes and time taken to change gear, you always want to be as close to peak power as possible.
ETA: The only difference with less gears, is that you're forced to be further from peak power more of the time, so the length of the power plateau is is more important. The converse, of course is a CVT where you can always be exactly at peak power.
ETA: The only difference with less gears, is that you're forced to be further from peak power more of the time, so the length of the power plateau is is more important. The converse, of course is a CVT where you can always be exactly at peak power.
Edited by kambites on Monday 13th January 22:09
Welshbeef said:
Does anyone have a power/torque graph for an EV
They tend to peak at 0rpm and gradually tail off as the revs rise. Some will be torque limited to protect the rest of the drive-train, so you get a flat bit at the start of the curve and then it falls off past a certain RPM. Don't turbos and superchargers make these calculations irrelevant? A fairly low powered turbo can produce huge torque and be in the zone in most normal driving conditions be on the power?
A 100hp turbo can produce torque that would require a much bigger NA engine.
One of the reasons most modern diesels can destroy a petrol car if you can't be arsed to change gear?
A 100hp turbo can produce torque that would require a much bigger NA engine.
One of the reasons most modern diesels can destroy a petrol car if you can't be arsed to change gear?
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