Fair enough. With the RP that you suggest, we can construct 4 points on the HP and TQ curves. First graph below However, we can also propose somewhat different RPMs for the HP and TQ values and then construct comparative curves...which are not obviously anymore or less valid on appearance than the original suggestion. Second graph below Here is the LS1 curve as well. Third graph below Without knowing more about the full curves, how can one select a configuration that gives the best performance? One of things that made the 355 such a revelation was the very flat TQ curve from 2500 to redline. This led to a very flexible engine in that you didn't have to worry as much about keeping the RPMs up when shifting /cornering as in a peaky car...one of the worst of these is the Honda S2000. I recall 0-60 of 5.5s when shifting at 8500, but 0-60 of 11s when shifting at 5500. This illustrates my original point...without RPM data, voting for a preferred configuration is not too meaningful. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Two Web sites that discuss the topic of HP, TQ, ET are listed below. The first site is a very fundamental analysis of the mechanics and physics involved; conclusion: TQ matters, HP can be important. http://www.mustangsandmore.com/ubb/DanJonesTorqueVsHP.html It's a bit hard to read on the screen, so a Word version is attached. (55 kb) the second presents several EMPIRICAL equations for calculating ET when HP and weight are known. http://www.stealth316.com/2-calc-hp-et-mph.htm Here is a summary comparison of the Fox equations from the second site for road tests in recent R&T. The table suggests that the equation is not alway accurate...not surprising, since it is empirical. Chrysler Crossfire - 215 HP and 3340 lb ET @ mph Fox 15.6 92 Actual 14.9 96 Audi TT - 225 HP and 3560 lb ET @ mph Fox 15.7 91.6 Actual 14.8 94.8 Porsche GT3 - 380 HP and 3340 lb ET @ mph Fox 12.9 111 Actual 12.4 113.8 Cadillac CTS - 400 HP and 4070 lb ET @ mph Fox 13.5 106 Actual 13.4 109 I also dug up a road test on a 1962 Mercury Monterey Special to see how older cars did in the equations Merc- 405HP and 4208 lb ET @ mph Fox 13.7 105 Actual 16.5 94 I have a program called Desktop Dyno, which allows you build engine configurations to much detail (e.g. valve lift and duration, fuel/air flow, displacement) and it generates torque and HPO curves. It's been fun to tinker with it. I have been able to reproduce reasonably well several Ferrari engines where I was able to get the data. There are also packages which simulate ET, 0-60 etc from engine/weight data. Here is one. I have not tried it out to any great extent. http://www.cartestsoftware.com/cartest2000/index.html (free demo version) Image Unavailable, Please Login
To calculate Power you need to now the torque ... and as I said in my last post regarding this they show power for the reason you state, ie. they cannot tell you the torque the engine produces because they do not know the ratios ... but that does not matter for power. They still read the force, calculate the torque and then the power ... My last post on this subject. Some of you seem determine to prove that torque does not exist ... which is BS. Please remember that an engine simply produces torque. When the torque curve finally falls right off, that is peak POWER!!!!, when the torque curve reaches its peak that is peak TORQUE. Everything is about TORQUE, not power. Power simply is a way to describe mathematically the engines ability to continue to produce meaningful TORQUE ... because that is what an engine produces (as well as heat, noice and vibrations, etc.). If your car produces nothing but Torque it will move, power does not matter. It CANNOT produce any Power if it does not produce Torque. An engine that produces Torque over a wide rev range and at high rpm is king, because we can use gear ratios to multiple that Torque to produce good and sustainable acceleration. Pete
That would be good if this is your last post because what you are saying is not only not useful it is incorrect [/QUOTE] Some of you seem determine to prove that torque does not exist ... which is BS.[/QUOTE] Name one poster in this thread trying to determine that torque does not exist, you're the BS king about this one. [/QUOTE] Please remember that an engine simply produces torque. When the torque curve finally falls right off, that is peak POWER!!!![/QUOTE] A truly ridiculous statement that can't even be quantified. What defines a torque curve "falling right off"? Look at a Formula one power curve, as the rpm continues to climb, the torque continues to fall and the power continues to rise. By the way F1 cars have peak torque number that are only about ONE THIRD their peak horsepower numbers. Torque rules indeed! [/QUOTE] When the torque curve reaches its peak that is peak TORQUE. Everything is about TORQUE, not power.[/QUOTE] Another fundamentally ridiculous statement. "Everything" as you call it is about torque AND rpm. This is called HORSEPOWER. A max of 400 lbs ft of tq at 100 rpm wouldn't make for a very exciting car, yet you say "everything is about torque". [/QUOTE] Power simply is a way to describe mathematically the engines ability to continue to produce meaningful TORQUE ... because that is what an engine produces (as well as heat, noice and vibrations, etc.).[/QUOTE] Torque is only the measurement of a force. Horspower is the measurement of how much WORK the engine can do to accelerate the car. By the way, OF COURSE an engine produces torque, but only when you combine it with RPM to determine HORSEPOWER is that torque meaningful in relation to determining car performance. [/QUOTE] If your car produces nothing but Torque it will move[/QUOTE] This is just fundamentally stupid, I don't know what else I can say. [/QUOTE] Power does not matter. [/QUOTE] Only a true fool would consider that an honest statement, This statement is utterly ridiculous. It's like saying water isn't wet. [/QUOTE] It CANNOT produce any Power if it does not produce Torque.[/QUOTE] Of course not, torque combined with rpm determine HORSEPOWER. [/QUOTE] An engine that produces Torque over a wide rev range and at high rpm is king, [/QUOTE] Of course it is, because it makes more POWER Maybe your are so confused because torque is easier to visualize than horsepower. Of course TORQUE at the drive wheels is the force that moves the car, but only when combined with rotation of the wheel (RPM). Engines produce torque at the crankshaft, but it is meaningless without rpm. Gearboxes are great TORQUE multipliers. The more Horsepower and engine make the more torque you can produce at the drive wheels at a given speed. This is true of hp only not tq. Repeat after me: Maximum TORQUE at the drive wheels at ANY speed is determined by maximum engine HORSEPOWER. You can determine a cars max torque at the rear wheels at any speed by knowing the max hp. You cannot do this by knowing only the max torque. Only when torque is combined with rpm (THUS HORSEPOWER) can you determine max tq at the drive wheels at any speed. TORQUE WITHOUT RPM (THUS HORSEPOWER) IS MEANINGLESS IN DETERMINING A CARS PERFORMANCE. Don't let you stubborness get in the way of learning.
But to get the speed aligned with the RPMs of max HP you have to change the gearings for every speed. Thus operating like a CVT. Once again to connect the speed of the car to the RPMS which correspond with the RPMs of peak HP you require a CVT. we are not talking about CVTs I claim you can't even do it using HP! Go back to my three expample, your rule fo thumb fails to pick the winner, each and every time; Why? If you rule of thumb was useful at more than back of the enveope calculation accuracy then it would not be failing these cases. Why does it fail? unless you can answer why your rule of thumb fails, nobbody whould listen to why it works so well; with so many expamles of it failing! But HP has exactly the same problem when V=0 as in P/V = m*a, therefore, when V=0 you cannot use HP to determine acceleration. But notice when V=0 the equation F = m*a still works! while P/V = m*a does not. So, in the very typical situation of starting at a standstill, the equation based on TQ leads to solutioins while the one based on HP does not. TQ without RPMs is still a force, forces accelerate things, things that accelerate increase in velocity. Forces do the acceleration. In the process of acquiring velocity, the shaft obtains a rotational velocity, and thus RPMs. But for that split second when V=0, the equations of force lead to sensible solutions, while the equations based on power do not. Why? Do you even know why I am asking why? Don't look in the mirror
I keep trying to ignore teak360's response but he never understands my points. Yes I know that I went to the extreme on the last post ... but I need to answer this point: teak360, please have a look at an engine dyno chart. One you have reached peak torque the only reason the engine continues to 'build' power is if it can continue to make torque and can rev higher. If it cannot continue to make torque then you have reached peak power. That is what I was trying to say. Now in the real world most of the time the limit is mechanical, ie. revs dictate peak power, because of: P = 2*pi*n*T You can see that if you can still make more revs you get more power, as long as x1*(n*T) is greater than x*(n*T). But some engines do stop breathing because of poor porting/valve size, etc. Also teak360, remember gear ratios. We have over and over explained to you why revving high is a blessing, but you ignore us. A F1 car revving to 18000 rpm accelerates fast because of the fact that it revs so high and can then maximise the TORQUE multiplication through the gearbox by running very low ratios, ie. 80 mph in first gear at 18000 rpm is probably similar ratios to my Toyotas first gear that peaks at 20 mph. Thus imagine how much fast my Toyota could accelerate if it could maintain that same ratio all the way up to 80mph!!, but alas it cannot and I have to change up and thus reduce my torque multiplication, and thus slow my acceleration. Sorry did not explain myself clear enough. Everything about acceleration is about torque. That example of 400 lbs ft at 100 rpm would have a very impressive acceleration figure for a VERY short time Again you are wrong. Acceleration is calculated from uneven force balance ... thus it has NOTHING to do with now much WORK and engine can do ... remember F = m*a ... is correct for all masses and forces. Oh one more thing teak360, HP (Power) does NOT get multiplied by the gearbox ONLY torque. Remember P = 2*pi*n*T, and at the rear wheels the rpm is NOT the same as at the motor, but the Torque has increased ... Power infact at the rear wheels will be LESS than at the flywheel due to friction loses via the driveline. But you knew that I guess ... and just confused yourself and did not mean to post that Pete ps: teak360, I will try and explain how to do quotes correctly again. If you want to put text in a quote box, you put 'quote' inside the [] brackets at the begining and then '/quote' inside the [] brackets at the end. The / signifies the end of the quote ... have a nice day and remember acceleration is calculated from force and thus torque I promise I will ignore this post from now on ...
keep trying to ignore PSK's responses but he never understands my points. . A given basic. Not really needed in the basic discussion Ignored what? As I stated in my last post, gears are simply torque multipliers [/quote] Only if it made more POWER Because you're engine won't rev high and develop more power. F1 enginges rev high so that they can have MORE firing sequences per unit time. More explosions per unit time. Burn more fuel per unit time. See the point? But they don't make more torque! They do make MORE POWER, and through the torque multiplication of the gears get the increased power to the road and accelerate harder. Not true. Put a 24 inch breaker bar on a lug nut of your Toyota and stand on it with the car in neutral. You will be developing about 400 lbs ft of torque. And you will experience piddling acceleration for a very short time as the power you would develp would be minimal. In fact the power would be so minor that a wood block in front of the tire would probably stop your acceleration altogether. If you can accelerate your car without "doing work" to it you will be rich. Because you will have something on your hands that defies the laws of physics. P.S. Don't invest in any perpetual motion machines either. Of course it is and I never said it wasn't. As I stated earlier, of course I know that gears are just torque multipliers. Also, everyone knows of friction (and thus power losses). They are not really relevant to this basic physics discussion. Nor is wind resistance, the earth's rotation, etc. etc. Again I think you are letting minutia get in the way. Thanks, I hadn't seen this posted before. Right
MORE TORQUE. The V8 Ferraris really lack acceleration times in comparison to other cars on the market...My dad's Corvette runs 0-60 only 4 tenths of a second behind a 360..I think that is really sad. Ferrari is all about going around race tracks fast, and then hopping on the road and doing the same. If they want to continue doing this they must go for the torque increase. -Blair
I missed addressing this in you last post. I will convert 400 lbs ft at 100 rpm to horsepower: 400 x 100 / 5252 = 4000/5252 = 3/4 hp. That's three quarters of a horsepower! Who on this board with a shred of common sense would believe that would produce "a very impressive acclereation figure"? Even for a "VERY short time"? Let common sense prevail
Yes I realize an Enzo would get the job done. But we arent talking about an Enzo, or any 500,000+car with a nice V12 we are talking about the 360's replacement, a V8, that is going to run well under the Enzo's price. For the money I feel the 360 should be quicker off the line, and that that is what they need to fix with its succesor.
He does understand the underlying physics and underlying math. Perhaps you should listen. If his lowly toyota held onto its TQ as RPMs rose in 1st gear towards 80 MPH that engine would HAVE TO MAKE MORE POWER. That is what power is! power = TQ at RPMS. But lets go back: Why does your rule of thumb not work for the three examples given? If it does not work there, then why should anyone believe in your rule of thumb?
Of course it is, I think we all agree on that. TQ without RPM, thus horsepower, is what we need to accelerate our cars. I'll quote you again "power = TQ at RPMS." In other words, tq is merely a component of horsepower. What I have been saying all along. Thanks for finally posting it clearly and concisely.
By the way, the portion of your statement "HAVE TO MAKE MORE POWER" is ridiculous. Engines don't HAVE to make more power as the rpm rises. In fact most engines, if you look at their power curves, make peak horsepower BELOW redline. In other words, the rpm is rising and the power is DROPPING. Just the opposite of what you just stated.
No, you say that, we say TQ accelerates cars. No, HP is what happens when TQ is allowed to do its thing. But why does you rule of thumb not work in the three examples? I bet you don't know!
No, if the TQ curve is flat, or even slightly downward sloping with no abrupt serious downturns, HP will rise with rising RPMs. THere is simply no other way to compute it: See HP = TQ * RPMs / 5252. With TQ a relative constant, and noting that 5252 IS a constant; HP is proportional to RPMs. They do if the TQ curve is rather FLAT, no other way around it. HP rises until the TQ is dropping faster than the RPMS are rising. See its all about TQ. But why does your rule of thumb fail in the three examples? Or are you so stupid that you can't figure it out or are you so stupid that you can't respond in a meaningful way? Either way, you remain wrong in HP versus TQ. Why does you rule of thumb fail? Until you answer this, there is no reason to further this discussion. Why does your rule of thumb fail?
Rules of thumbs arent exact. In this case, the rule of thumb assumes a certain generalized power curve shape (i.e. a certain area under the curve). A car with a weak low end like a Ferrari probably wont match this assumed curve very well and has an overall lower area under the power curve. This discussion has been on par with what can be found at clubsi.com
Looks like 500/500 is the new benchmark with Ford GT, Viper, and Baby Lambo Sometimes your competition settles the argument for you. TR 390hp torque 490 Nm Dry weight 1600 kg 512tr 428hp torque 491 Nm Dry weight 1595 kg 512M 440hp torque 500 Nm Dry weight 1630 kg 355 380hp torque 363 Nm at 6,000 rpm Dry Wieght 1,350 kg 360 400hp torque 373 Nm at 4750 rpm Dry Weight 1,290 kg Gallardo 500hp torque 510 Nm at 4500 rpm Dry Weight 1430 kg Ford GT 550hp torque-500 or 677Nn, weight- 3,500 P.S. Mark it has to be closer to - "677 Nm of TQ as its 500 lb-ft (measured somewhere) weight is in the 3500 lb catagory" Thanks for the help Mitch TR (l x w x h) 4485 x 1976 x 1130 mm Gallardo ( l x w x h ) 4300 x 1900 x 1165 mm 360 (l x w x h ) 4,477 x width x 1,922 mm x 1,214 mm 355 (l x w x h ) 4,250 x 1900 x 1170 mm
Has to be closer to 677 Nm of TQ as its 500 lb-ft (measured somewhere) weight is in the 3500 lb catagory.
First of all I haven't called you stupid in a public forum, I would say since you have called me stupid this only reflects on your confidence in yourself. Which is it, a "flat" tq curve or a "dropping faster than rpm's are rising" tq curve? By the way, the statement "dropping faster than the rpm's are rising" is a meaningless statement in the context in which you have used it. Do you mean dropping by 2 lbs ft of torque per 1 rpm? You would run out of grunt pretty fast wouldn't you? When did I ever say I was talking about a "rule of thumb". I use basic facts and formulas, not "rules of thumb". I believe my statements to be meaningful. An example of a meaningless statement in regard to this thread is this: "HP rises until the TQ is dropping faster than the RPMS are rising. That's a meaningless statement from you, not me. I'll say it a different way this time; laws of physics are not rules of thumb. You may derive your conclusions from graphs, charts, feelings and cars of equal weight where the one with more hp loses the race, but I will stick with basic facts. The number of potential answers to your three posits are endless. I think these are the three questions you want answered : I'll assume ALL other variables are equal in the cars. Otherwise your posits are meaningless Car v has more area under the power curve Once again, I'm not using "rules of thumb". And of course this example is possible, I have NEVER implied that it wouldn't be. The answer is the same as above. By the way, if the cars both ran only at max hp, as in a CVT, car F would always win. Surely you can see that as you add more and more gears to a car (5 speed, 6 speed, 7 speed, etc.) You approach a CVT. There is no magic line where tq rules, then hp rules. HP always rules. Again, car v has more area under the power curve. Simple I would like to see the thumb you derive your rules from, Mitch. It must be quite interesting looking. P.S. Answer this question. All of the following statements are true, how can that be according to your statements? 1.You must do work to accelerate a car 2. Torque is defined as a force 3. Horsepower is defined as the ability to do a certain amount of work over a certain amount of time. 4. You can apply torque (or a force) to a car without doing work to the car. In other words, if the force is applied and the car doesn't move, such as you just standing there all day on your lug wrench, no work is done. 4. You CANNOT apply horsepower to a car without doing work to the car.
Mitch, Give up!, I have. He will never get it. He is wrong and always will be. As I said in my other post I am just concerned for others that may believe ... and thus I suggested they research elsewhere. Black is white for some ... and also some cannot think outside the real world and thus cannot grasp instaneous values, etc. Thanks for trying teak360 and 4sfed4, Enjoy your Ferraris and I wish you all the best. Pete
No offense taken here. This topic falls into the "politics and religion" category. It will be (and has been) debated ad infinitum on car boards acorss the world and no resolution will ever be arrived at. Some look at the "problem" being discussed in a "quasi-equilibirum" state (i.e. a series of instantanous "snapshots" of the vehicle moving forward). In that manner...of course the max acceleration will occur at peak torque. But, that instantaneous value is of little use in a real accelerative contest as time does have to be considered. As soon as time enters into the equation, then power (or torque, gearing and rpm if one wishes to look at it that way) becomes important. In the end, we are all looking at the same quantity. However, there is no Ferrari in my garage. They dont make enough torque and are therefore too "slow" for my tastes. LOL.
I don't know about you Pete, but I live in the real world. This is a telling statement on your part. The world we all live in, and the physics that define it, are all very real, but you and Mitch have taken things to a level where you resort to using graphs and examples where cars with the most hp get beaten by cars with the least hp to somehow support your incomplete understandings. You don't need all the graphs and silly examples if you understand the very basic concepts of work, hp, tq and rpm. Pete, I challenge you, or Mitch, to simply and elegantly disprove any statement I made in my previous post. If you can't, then you shouldn't really concern yourself with me confusing the rest of the world. Pete[/QUOTE]
