HP vs Torque Discussion (No Jokes, No bantering. Just facts and reality)
02-13-2009, 01:28 PM
#242
Rennlist Member
Thread Starter
I guess I wasnt clear enough from the beginning. Sorry about that.
Yes, based on the original question, that you note below, it would "Depend".
It would depend on the shape of the two HP curves. Yes, for a road race course, I could provide two equal HP curves from cars, with one having much less engine torque that would prove more performance at ANY vehicle speed. (i.e. coming off turns, down straights etc). Again, we have to look at torque that is produced at the rear wheels as multiplied through the gear box.
In theory, a peaky HP curve with higher torque vs low torque , high rpm flatter HP curve would be an example of this. It certainly is not as common, but a couple of the HP curve comparisons Ive provided in this thread show that it certainly is possible.
This why the best answer to Dez's question is to say that it depends on the shape of the HP hp curve. Generally, higher torque engines have flatter hp curves, but its certainly not the rule.
mk
One
Yes, based on the original question, that you note below, it would "Depend".
It would depend on the shape of the two HP curves. Yes, for a road race course, I could provide two equal HP curves from cars, with one having much less engine torque that would prove more performance at ANY vehicle speed. (i.e. coming off turns, down straights etc). Again, we have to look at torque that is produced at the rear wheels as multiplied through the gear box.
In theory, a peaky HP curve with higher torque vs low torque , high rpm flatter HP curve would be an example of this. It certainly is not as common, but a couple of the HP curve comparisons Ive provided in this thread show that it certainly is possible.
This why the best answer to Dez's question is to say that it depends on the shape of the HP hp curve. Generally, higher torque engines have flatter hp curves, but its certainly not the rule.
mk
One
02-13-2009, 01:46 PM
#243
I guess I wasnt clear enough from the beginning. Sorry about that.
Yes, based on the original question, that you note below, it would "Depend".
It would depend on the shape of the two HP curves. Yes, for a road race course, I could provide two equal HP curves from cars, with one having much less engine torque that would prove more performance at ANY vehicle speed. (i.e. coming off turns, down straights etc). Again, we have to look at torque that is produced at the rear wheels as multiplied through the gear box.
In theory, a peaky HP curve with higher torque vs low torque , high rpm flatter HP curve would be an example of this. It certainly is not as common, but a couple of the HP curve comparisons Ive provided in this thread show that it certainly is possible.
This why the best answer to Dez's question is to say that it depends on the shape of the HP hp curve. Generally, higher torque engines have flatter hp curves, but its certainly not the rule.
mk
One
Yes, based on the original question, that you note below, it would "Depend".
It would depend on the shape of the two HP curves. Yes, for a road race course, I could provide two equal HP curves from cars, with one having much less engine torque that would prove more performance at ANY vehicle speed. (i.e. coming off turns, down straights etc). Again, we have to look at torque that is produced at the rear wheels as multiplied through the gear box.
In theory, a peaky HP curve with higher torque vs low torque , high rpm flatter HP curve would be an example of this. It certainly is not as common, but a couple of the HP curve comparisons Ive provided in this thread show that it certainly is possible.
This why the best answer to Dez's question is to say that it depends on the shape of the HP hp curve. Generally, higher torque engines have flatter hp curves, but its certainly not the rule.
mk
One
02-13-2009, 01:51 PM
#244
Rennlist Member
Mark, in the interest of civility, I will merely say that you are incorrect, and that the higher TQ vehicle--all other things being equal--will be more useful on a road course.
02-13-2009, 02:08 PM
#245
Rennlist Member
Thread Starter
Can you explain why and where the advantages would be?
Keep in mind, you might be considering the "torque" after the gearbox mulitplication. If not, and are truely talking about disparate engine torques, Im not incorrect in saying that there are instances where a lower torque, higher rpm engine with equal HP migh be better suited for a road course. This would be true if it could produce more REAR wheel torque at any vehicle speed, and this is certainly possible. Even at not all speeds (some being equal) but some, it still would be a factor that could make the lower torque engine better suited.
Mk
Keep in mind, you might be considering the "torque" after the gearbox mulitplication. If not, and are truely talking about disparate engine torques, Im not incorrect in saying that there are instances where a lower torque, higher rpm engine with equal HP migh be better suited for a road course. This would be true if it could produce more REAR wheel torque at any vehicle speed, and this is certainly possible. Even at not all speeds (some being equal) but some, it still would be a factor that could make the lower torque engine better suited.
Mk
02-13-2009, 02:15 PM
#246
Rennlist Member
Thread Starter
Absolutely! Im not saying its always the case, becuase to VR's point, if a High Torque engine also has broader HP curve, then it would be better on a Road course. The point again, is that it just isnt always the case. it depends.
Here are two dyno runs, both being near 290rwhp where the lower torque engine ( 60ft-lbs less torque !!) would actually be better suited for a road course. at worst, even at any speed on the road course, both would have 250hp after a gear shift. any point faster than that, the lower torque engine would have the advantage. if you consider the use of close ratio gear boxes, the advantage would fall even farther in the low torque engines "court". (even if both vehicles could use it)
* note: both engines would be shifting at a 27% rpm drop. (pretty normal gear spacing) close ratio would be more like 20%.
mk
Here are two dyno runs, both being near 290rwhp where the lower torque engine ( 60ft-lbs less torque !!) would actually be better suited for a road course. at worst, even at any speed on the road course, both would have 250hp after a gear shift. any point faster than that, the lower torque engine would have the advantage. if you consider the use of close ratio gear boxes, the advantage would fall even farther in the low torque engines "court". (even if both vehicles could use it)
* note: both engines would be shifting at a 27% rpm drop. (pretty normal gear spacing) close ratio would be more like 20%.
mk
Last edited by mark kibort; 03-10-2009 at 04:53 PM.
02-13-2009, 02:16 PM
#247
Rennlist Member
Mark, I believe I have already tried to do so. While I do not use as many words as you, nor do I have a physics degree, ample real world experience stands behind the numerous examples I have already given--spread acress two threads--to illustrate my observations. Now, you may or may not be correct in the classroom & in the perfect world of infinitely-variable transmissions. Again, I have no physics degree; and in the end, it doesn't matter. However, in the real world, on real tracks, all other things being equal, I would rather take the extra grunt out of corners a higher level of torque can offer than not.
02-13-2009, 02:19 PM
#248
Absolutely! Im not saying its always the case, becuase to VR's point, if a High Torque engine also has broader HP curve, then it would be better on a Road course. The point again, is that it just isnt always the case. it depends.
Here are two dyno runs, both being near 290rwhp where the lower torque engine ( 60ft-lbs less torque !!) would actually be better suited for a road course. at worst, even at any speed on the road course, both would have 250hp after a gear shift. any point faster than that, the lower torque engine would have the advantage. if you consider the use of close ratio gear boxes, the advantage would fall even farter in the low torque engines "court". (even if both vehicles could use it)
* note: both engines would be shifting at a 27% rpm drop. (pretty normal gear spacing) close ratio would be more like 20%.
mk
Here are two dyno runs, both being near 290rwhp where the lower torque engine ( 60ft-lbs less torque !!) would actually be better suited for a road course. at worst, even at any speed on the road course, both would have 250hp after a gear shift. any point faster than that, the lower torque engine would have the advantage. if you consider the use of close ratio gear boxes, the advantage would fall even farter in the low torque engines "court". (even if both vehicles could use it)
* note: both engines would be shifting at a 27% rpm drop. (pretty normal gear spacing) close ratio would be more like 20%.
mk
To borrow from VR: Sofaking easy
02-13-2009, 03:25 PM
#249
Rennlist Member
The fact that this argument continues without anyone having conducted a simulation proves that none of you know WTF you're talking about. It's just a math problem, for goodness sake.
02-13-2009, 07:15 PM
#253
Rennlist Member
Thread Starter
I must have not been clear enough. In those two real world examples, there will not be a difference in grunt at any point , off any corner on any race track. Forget about an infinitely variable gear box. just standard gear boxes that either car came with. Use these two engines and there will not be any advantage for either one at any lower rpm range. unless you are in the wrong gear (and I guess that could be a real life situation for some 
)
Now, you mention possiblity of the higher grunt out of the corners that one can provide and the other cannot. You are probably talking about engine torque, where it is irrelevant if you are not comparing RPM. In the example, pick any speed, anywhere on the track, show me that the "extra grunt" will equal anything other than the same torque at the rear wheels. You are generally right for most situations where you have a "torquey" engine. generally, it will have a flatter HP curve. In real life, one of my car's advantage is its flat HP curve and high torque level, ironically enough. But its not the rule, as these two HP curves very clearly show.
both would operated from a range of rpm. 5500 to 8000rpm for one, and 4500 to 6400rpm for the other. the HP ranges for both go from an identical 250hp up to 290hp. At the low end of 250hp, both would produce the same exact rear wheel TORQUE at the beginning of the next gear . if you were mid rpm , at mid corner, based on the curves, the lower torque engine might have more torque, MORE GRUNT off the turn based on its flatter HP curve. This is just basic stuff and very easily to mathematically model. It follows reality. Ive race both of these cars, (against and in) by the way!
Mk
Here are the gear charts. this gives you the speed and gear ratio. check out the HP curve for the power or the torque. take the torque, multiply the gear ratio. wala! rear wheel torque!
NOTE: first one is the v8 928 gear chart, second one is the e36 gear chart, with a famed, 4.10 rear end!! alternatively, you can look at the stock 3.73:1 rear end and have still, near the same results of the comparison.
)Now, you mention possiblity of the higher grunt out of the corners that one can provide and the other cannot. You are probably talking about engine torque, where it is irrelevant if you are not comparing RPM. In the example, pick any speed, anywhere on the track, show me that the "extra grunt" will equal anything other than the same torque at the rear wheels. You are generally right for most situations where you have a "torquey" engine. generally, it will have a flatter HP curve. In real life, one of my car's advantage is its flat HP curve and high torque level, ironically enough. But its not the rule, as these two HP curves very clearly show.
both would operated from a range of rpm. 5500 to 8000rpm for one, and 4500 to 6400rpm for the other. the HP ranges for both go from an identical 250hp up to 290hp. At the low end of 250hp, both would produce the same exact rear wheel TORQUE at the beginning of the next gear . if you were mid rpm , at mid corner, based on the curves, the lower torque engine might have more torque, MORE GRUNT off the turn based on its flatter HP curve. This is just basic stuff and very easily to mathematically model. It follows reality. Ive race both of these cars, (against and in) by the way!
Mk
Here are the gear charts. this gives you the speed and gear ratio. check out the HP curve for the power or the torque. take the torque, multiply the gear ratio. wala! rear wheel torque!
NOTE: first one is the v8 928 gear chart, second one is the e36 gear chart, with a famed, 4.10 rear end!! alternatively, you can look at the stock 3.73:1 rear end and have still, near the same results of the comparison.
Mark, I believe I have already tried to do so. While I do not use as many words as you, nor do I have a physics degree, ample real world experience stands behind the numerous examples I have already given--spread acress two threads--to illustrate my observations. Now, you may or may not be correct in the classroom & in the perfect world of infinitely-variable transmissions. Again, I have no physics degree; and in the end, it doesn't matter. However, in the real world, on real tracks, all other things being equal, I would rather take the extra grunt out of corners a higher level of torque can offer than not.
Last edited by mark kibort; 02-13-2009 at 07:35 PM.
02-13-2009, 07:24 PM
#254
Rennlist Member
Thread Starter
a simulation is just a series of math elements. Ive been asked to produce an example of why one car vs the other will produce the same if not more "grunt" off a turn. Based on the two HP curves, you can plug the integrated curves into a simlulator with what ever resolution you want , or pick a point, a vehicle speed, and it will be easy to show in hard numbers.
For example. say, some gear coming off a turn at 60mph. both cars are in a gear that provides exit rpm, gear spinning 500rpm over the lowest rpm they ever see. Both cars will produce the exact same torque at the rear wheels after the gear box. If you want actual numbers, I can produce them. or , just follow the physics identy of :
Acceleration = power/(mass x velocity)
This basically means, if you are comparing two same cars both with the same HP at any speed, they both will have the same acceleration rate, even though one might have much less engine torque than the other.
actual numbers:
BMW 60mph , 5750rpm 3rd gear 243ft-lbs of engine torque 1.66 ratio x 4.1:1
928 60mph 4500rpm 2nd gear 293ft-lbs of engine torque 2.68 ratio x 2.2:1
Net winner???? any takers which is producing more torque at the rear wheels
mk
For example. say, some gear coming off a turn at 60mph. both cars are in a gear that provides exit rpm, gear spinning 500rpm over the lowest rpm they ever see. Both cars will produce the exact same torque at the rear wheels after the gear box. If you want actual numbers, I can produce them. or , just follow the physics identy of :
Acceleration = power/(mass x velocity)
This basically means, if you are comparing two same cars both with the same HP at any speed, they both will have the same acceleration rate, even though one might have much less engine torque than the other.
actual numbers:
BMW 60mph , 5750rpm 3rd gear 243ft-lbs of engine torque 1.66 ratio x 4.1:1
928 60mph 4500rpm 2nd gear 293ft-lbs of engine torque 2.68 ratio x 2.2:1
Net winner???? any takers which is producing more torque at the rear wheels
mk
Last edited by mark kibort; 02-13-2009 at 08:05 PM.
02-13-2009, 07:40 PM
#255
Three Wheelin'
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Geez guys. 17 pages?
One of those classic cases of most everyone being right, depending...
The real question is whether you want your HP torque-flavored or RPM-flavored. And, for the record, absent a plethora of curves (that's your queue VR), amateur racers on a road course are probably better served with torque--assuming Santa did not drop 19,000 rpm and a 9-speed gearbox down the chimney.
One of those classic cases of most everyone being right, depending...
The real question is whether you want your HP torque-flavored or RPM-flavored. And, for the record, absent a plethora of curves (that's your queue VR), amateur racers on a road course are probably better served with torque--assuming Santa did not drop 19,000 rpm and a 9-speed gearbox down the chimney.