HP vs Torque Discussion (No Jokes, No bantering. Just facts and reality)
02-13-2009 | 11:18 PM
#286
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From: saratoga, ca
Hey, you were talking about the turbofan on the roof, now its JATO rockets. You sure are a moving target!
RAM jets just try to approximate constant thrust, but never quite get there. They just lose a heck of a lot less than their turbofan cousins at the low speeds due to their design. incredibly inefficient at sub mach numbers. But yes, their Hp goes up even more than jets. thrust goes up with their speed too, similar but to a greater extent than turbofan engines.
Maybe in the lower gravity field you can break out the solar sails or use the photon rockets to try and get to the next galaxy at light speed
mk
RAM jets just try to approximate constant thrust, but never quite get there. They just lose a heck of a lot less than their turbofan cousins at the low speeds due to their design. incredibly inefficient at sub mach numbers. But yes, their Hp goes up even more than jets. thrust goes up with their speed too, similar but to a greater extent than turbofan engines.
Maybe in the lower gravity field you can break out the solar sails or use the photon rockets to try and get to the next galaxy at light speed
mk
Yeah, but F-16's are old and slow, just like the 928... what if JATO rockets were used instead? Or RAM jets? In the case of the latter, acceleration is NOT constant. Better yet, if you used both, it'd be like a 2-stage turbo setup... where you get the best of both worlds. Immediate and absolute thrust from a solid fuel rocket, and then the ever-increasing thrust from a RAM jet.
And what if it was done in a lower gravity field?
Just throwing some hypotheticals out there.
And what if it was done in a lower gravity field?
Just throwing some hypotheticals out there.
Last edited by mark kibort; 02-14-2009 at 02:56 AM.
02-14-2009 | 03:08 AM
#289
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From: saratoga, ca
Well, since we are at 20 pages , here is the answer:
BMW has 1650ft-lbs at 60mph at the rear axles
Porsche 928 has 1730 at 60mph at the rear axles.
Same speed, different reduction ratios, near the same HP at that speed, grossly different engine torque numbers.
BUT, the bmw has 24.5" diameter tires and the 928 has 26" diameter tires. SO, the porsche has a thrust force of 92% of its rear wheel torque in ft-lbs. that value is 1597ft-lbs. BMW wins at the low end and the high end. There is no place where the higher torque 928 would have an advantage. (even if the cars were the same weight or the cars were the same in all other reaspects)
(BMW with 24.5" diameter tires has 98% of its rear wheel torque in thrust force., or 1625ft-lbs)
Dez, and VR, there is your answer. It depends!
mk
BMW has 1650ft-lbs at 60mph at the rear axles
Porsche 928 has 1730 at 60mph at the rear axles.
Same speed, different reduction ratios, near the same HP at that speed, grossly different engine torque numbers.
BUT, the bmw has 24.5" diameter tires and the 928 has 26" diameter tires. SO, the porsche has a thrust force of 92% of its rear wheel torque in ft-lbs. that value is 1597ft-lbs. BMW wins at the low end and the high end. There is no place where the higher torque 928 would have an advantage. (even if the cars were the same weight or the cars were the same in all other reaspects)
(BMW with 24.5" diameter tires has 98% of its rear wheel torque in thrust force., or 1625ft-lbs)
Dez, and VR, there is your answer. It depends!
mk
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
02-14-2009 | 09:36 AM
#290
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I want to thank you all for the effort to make this happen! It couldn't have been done without you.
I want to particularly thank Mark for continuing to reach deep into his bag of questions that nobody asked, asking them himself, and then providing his answers without wasting the time it would take to see if anyone wanted to hear it. You are the best!
I want to particularly thank Mark for continuing to reach deep into his bag of questions that nobody asked, asking them himself, and then providing his answers without wasting the time it would take to see if anyone wanted to hear it. You are the best!
02-14-2009 | 01:13 PM
#292
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From: saratoga, ca
Well, then after 20 pages, i guess the answer that I provided, with actual values, is contrary to your "feel" of what would happen. It does "depend" because power at any given vehicle speed, determines acceleration, not engine torque. As someone that knows this stuff besides me, and see what they say. By the way, Newton agrees as welll and this guy was pretty darn smart! (i.e. Acceleration=power/(mass x velocity) and Power = Force x speed or Power in HP = Ft-lbs x MPH /375 which is a handy one.)
1. I provided two cars with idential HP
2..the two cars had one that had much more engine torque than the other.
3. I found a spot on the useable rpm curve where the high torque engine was at its peak torque!
4. I then calculated the rear wheel torque of both cars at that speed.
5. In this case, the LOWER torque engine actually had more accelerative forces.
If you disagree, lets hear why?
6. In the racing world, there are probably more instances where a higher torque 400hp engine would be better due to a broader HP curve, BUT its not the rule. And in the racing world, close ratio gear boxes can solve most of these disparities, at the cost of more shifting
Again, I dont think i was able to make my message clear enough, becuase it seems that you are still confusing engine torque with what is produced at the rear wheels THROUGH the gear box at any speed. maybe not, but It sure seems that way.
So, in the end, two idential hp cars that have different engine torque values CAN accelerate the same out of a turn, the lower torque engine , as I have shown, CAN accelerate faster, and more common, the higher torque engine CAN accelerate faster. WHY?? It "DEPENDS". (all other things being equal or not)
mk
1. I provided two cars with idential HP
2..the two cars had one that had much more engine torque than the other.
3. I found a spot on the useable rpm curve where the high torque engine was at its peak torque!
4. I then calculated the rear wheel torque of both cars at that speed.
5. In this case, the LOWER torque engine actually had more accelerative forces.
If you disagree, lets hear why?
6. In the racing world, there are probably more instances where a higher torque 400hp engine would be better due to a broader HP curve, BUT its not the rule. And in the racing world, close ratio gear boxes can solve most of these disparities, at the cost of more shifting
Again, I dont think i was able to make my message clear enough, becuase it seems that you are still confusing engine torque with what is produced at the rear wheels THROUGH the gear box at any speed. maybe not, but It sure seems that way.
So, in the end, two idential hp cars that have different engine torque values CAN accelerate the same out of a turn, the lower torque engine , as I have shown, CAN accelerate faster, and more common, the higher torque engine CAN accelerate faster. WHY?? It "DEPENDS". (all other things being equal or not)
mk
02-14-2009 | 02:30 PM
#293
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From: All Ate Up With Motor
Mark, it's not "feel". It's experience , in a lot of cars on a LOT of tracks.
And frankly, if you were as smart as you are trying to convince everyone you are, you would close this thread now.
And frankly, if you were as smart as you are trying to convince everyone you are, you would close this thread now.
02-14-2009 | 03:00 PM
#294
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From: Belgium
this is a hard to the bone statement friend, for someone just asking a opinion and starting a learning,instructing discussion. Don't be that harsh , even if you think you're on the right side. A forum is for open minds, not self-sure opinions and orders. Pitty, let the discussion open , don't get involved with personal demands. Please. Real world is hard enough, is a forum not for pleasant entertainment???
PS forgive my spelling, i'm a Duch , stupid , flamish guy from Belgium.
02-14-2009 | 03:06 PM
#295
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From: All Ate Up With Motor
this is a hard to the bone statement friend, for someone just asking a opinion and starting a learning,instructing discussion. Don't be that harsh , even if you think you're on the right side. A forum is for open minds, not self-sure opinions and orders. Pitty, let the discussion open , don't get involved with personal demands. Please. Real world is hard enough, is a forum not for pleasant entertainment???
PS forgive my spelling, i'm a Duch , stupid , flamish guy from Belgium.
PS forgive my spelling, i'm a Duch , stupid , flamish guy from Belgium.
Priceless.
02-14-2009 | 03:24 PM
#296
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From: Belgium
PS is it not appropriate to come in after 20 pages ? from what # do we have to chim in ?
Last edited by belgiumbarry; 02-14-2009 at 03:47 PM.
02-14-2009 | 06:15 PM
#297
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From: saratoga, ca
If you raced in that 928 with that hp curve, you would lose to the BMW in all areas of the track, even if the other variables were the same. You cant even grasp the simplicity of all this. When was the last time you reviewed HP or torque curves, driven them on the track and made such an assessment. Most of the results of such a test, are far beyond the human receptor capability.
Again, and for the 100th time, why not answer the question. based on those HP /torque curves of the V8 vs the M3, what possible logic do you have for us to show that at any point around any track, at any speed, that the higher torque of THIS V8 would have any advantage over the Inline 6 of 50ft-lbs less torque? Can you give us some hint of a reason for your logic? The real professionals have already shown very little difference in the new M5 vs CTSV test. You didnt test the cars we saw the dyno runs for , and I produced a couple of dyno runs of real life race cars for your review. still, you hold fast to your experience, making jokes along the way.
You will never answer the question and it is your right. But, based on your responses, you have left out a very powerful point..... reality. Reality, plus experience, can make your opinion worth something. But, disconting the obvious, is just silly.
You maybe the greatest driver, instructor, the world has ever seen, but to determine performance by only a difference in engine torque values, given equal HP levels, is , quite frankly, impossible without the high chance of error. (i.e. being wrong)
mk
Again, and for the 100th time, why not answer the question. based on those HP /torque curves of the V8 vs the M3, what possible logic do you have for us to show that at any point around any track, at any speed, that the higher torque of THIS V8 would have any advantage over the Inline 6 of 50ft-lbs less torque? Can you give us some hint of a reason for your logic? The real professionals
have already shown very little difference in the new M5 vs CTSV test. You didnt test the cars we saw the dyno runs for , and I produced a couple of dyno runs of real life race cars for your review. still, you hold fast to your experience, making jokes along the way.You will never answer the question and it is your right. But, based on your responses, you have left out a very powerful point..... reality. Reality, plus experience, can make your opinion worth something. But, disconting the obvious, is just silly.
You maybe the greatest driver, instructor, the world has ever seen, but to determine performance by only a difference in engine torque values, given equal HP levels, is , quite frankly, impossible without the high chance of error. (i.e. being wrong)
mk
02-14-2009 | 06:37 PM
#299
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From: KY
I haven't been in here for a few pages, but I can't resist.
If we had two identical cars (same tire diameter, same rear end, same transmission, in the same cars) and we had two 400 hp cars, but with radically different torque curves then it still depends:
The shape of the torque curve is critical, but let's assume that the high torque motor makes power sooner than the lower torque motor. Somewhere in there, the low torque motor will catch up in horsepower, let's assume that it's similar to the CTS and M3 curves Mark was using.
So, both motors have about the same range of equal power, about 2000 rpm. Now, it depends on the track because with identical everything else, only one of those cars is going to be in the power band at any given point. So, which one is better? Damned if I know, but I didn't have anything else to do for the last five minutes.
If we had two identical cars (same tire diameter, same rear end, same transmission, in the same cars) and we had two 400 hp cars, but with radically different torque curves then it still depends:
The shape of the torque curve is critical, but let's assume that the high torque motor makes power sooner than the lower torque motor. Somewhere in there, the low torque motor will catch up in horsepower, let's assume that it's similar to the CTS and M3 curves Mark was using.
So, both motors have about the same range of equal power, about 2000 rpm. Now, it depends on the track because with identical everything else, only one of those cars is going to be in the power band at any given point. So, which one is better? Damned if I know, but I didn't have anything else to do for the last five minutes.
02-14-2009 | 07:27 PM
#300
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From: All Ate Up With Motor
You cant even grasp the simplicity of all this.
Again, and for the 100th time, why not answer the question. based on those HP /torque curves of the V8 vs the M3, still, you hold fast to your experience, making jokes along the way.
You will never answer the question
You maybe the greatest driver, instructor, the world has ever seen, but to determine performance by only a difference in engine torque values, given equal HP levels, is , quite frankly, impossible without the high chance of error. (i.e. being wrong)
mk
Again, and for the 100th time, why not answer the question. based on those HP /torque curves of the V8 vs the M3, still, you hold fast to your experience, making jokes along the way.
You will never answer the question
You maybe the greatest driver, instructor, the world has ever seen, but to determine performance by only a difference in engine torque values, given equal HP levels, is , quite frankly, impossible without the high chance of error. (i.e. being wrong)
mk
Mark, even after all the warnings, is this level of condescension REALLY necessary?
Again and for the 100th time, you are changing the subject. We ARE NOT and WERE NOT comparing a V8 928 and an I6 M3, were we?
We were comparing 2 identical 400 hp cars with different torque on road courses.
And despite all your condescension and sanctimony, every time you try to change that to suit your predetermined conclusion, it speaks volumes.
And yes, Mark, I do hold fast to my experience, and also to my ability to actually compare apples to apples. And the car with the greater torque production--all other things being equal--will do better on a road course. Period.