You misunderstand what happens at the contact patch. On the tire side the modified engine TQ becomes a direct force. On the road side a moving footprint of force travels down the road with teh contact patch. As seen by the road, it is a linear force. Forces cause accelerationi,..... This road force is often called THRUST. It just so happens when expressed as the linear thrust vector, that the equations of motion can be run in 3D and mimic the rocket or jet. These engines are actually not rated in HP although there are conversions, they are rated in thrust. Take the weight of the rocket pointing straight up to avoid sin() cos() geometry problems. The weight of the rocket is being pulled downward by the force of gravity, the thrust of the engines are pointing in the opposide direction. If the thrust is greater than gravity the rocket accelerates with the residual from thrust minus gravity as a force applied to the weight of the rocket. Rockets are special in the equations of motion ctagory. Cars do not apreciably change their weight durring an accelerations run, rockets do. So, while 6M lb of thrust can lift a 4.5M lb rocket at 1/3Gs, the rocket quickly looses some 3 M lbs in the first 2 minutes, so at this time that same thrust is causing 1 full Gs of accelerative force, but since ther rocket is now pointing almost at the horizon the acceleration is closer to 3 Gs from the cos() effect. As the final fule burns, acceleration can go higher. The HP/V = M*a is practically unworkable in this computational domain except by converting to energy and double differentiating to get acceleration. The other complainant thinks HP is useful in rocketry, it is not, Energy is important. Converting 4.2M lbs of fuel into 200K lbs at 1750MPH, At the end of the journey, the reentering vehicle has to disipate this energy, so we have a 200Klb vehicle dealing with the heat of 4.2Mlbs of fuel over 10 minutes or so. Power never comes up. ---back to the point---- So, the horse accelerates and/or pulls his load because he exerts linear forces at the road surface and the road surface pushes back. Newtons laws take it from here. No real difference except that the delivery means to the final contact point as seen from the car is rotational in nature. At this point I prefer to leave Teak360 ignorant.
Mitch, I did not notice that comment: No comment ... disbelief Anyway I thought Mr Ed could torque Pete
Mitch, you forgot to add that "on the tire side a moving footprint of force effectively rotates around the tire to maintain it's position at that portion of the tire that is, relatively speaking, at the bottom of the tire, or in layman's terms, "where the rubber meets the road" blah, blah, blah....... I wrote this in MY LAST POST Mitch. "Of course it is tq at the tire (thus a linear force at the tire to asphalt contact patch) that determines acceleration." What are you smokin, man? [/quote] It just so happens when expressed as the linear thrust vector, that the equations of motion can be run in 3D and mimic the rocket or jet. These engines are actually not rated in HP although there are conversions, they are rated in thrust. Take the weight of the rocket pointing straight up to avoid sin() cos() geometry problems. The weight of the rocket is being pulled downward by the force of gravity, the thrust of the engines are pointing in the opposide direction. If the thrust is greater than gravity the rocket accelerates with the residual from thrust minus gravity as a force applied to the weight of the rocket. Rockets are special in the equations of motion ctagory. Cars do not apreciably change their weight durring an accelerations run, rockets do. So, while 6M lb of thrust can lift a 4.5M lb rocket at 1/3Gs, the rocket quickly looses some 3 M lbs in the first 2 minutes, so at this time that same thrust is causing 1 full Gs of accelerative force, but since ther rocket is now pointing almost at the horizon the acceleration is closer to 3 Gs from the cos() effect. As the final fule burns, acceleration can go higher. The HP/V = M*a is practically unworkable in this computational domain except by converting to energy and double differentiating to get acceleration. [/quote] You sure talk a lot without saying anything useful to the issue at hand. HP is not the terminology used in rocket engine science. But it certainly can, legitimately, be used in rocketry. I was simply trying to point out that any time work is done, in ANY form, the amount of work per unit time can be described in horsepower. It can NEVER be described only with torque, and usually can't be described even with torque as a component. Actually, on re-entry its coming down Mitch......just kidding. Basically, your entire statement is so convoluted and lacking in useful content that it is meaningless. As an example "converting 4.2M lbs of fuel into a 200K lbs at 1750MPH". ??????? I won't even waste my trime trying to figure out what you're trying to say. Converting 4.2M lbs into 200K lbs? Maybe you can get rich with this magic weight loss formula. Duh Thanks Hey Mitch, here's a hypothetical challenge for you: We each build a 3,000 lb car. We can each define the gear ratios for our own cars. My car develops 200 hp. Your car develops 1,000 whopping lbs ft of torque. The only rule is that I get to define the rpm your max tq occurs at and you get to define the rpm my max hp occurs at. My car will win EVERY time. I'll even cut my horsepower max to a 100 measly hp, guess what.... I win EVERY time again. Mitch, will you put your money where your mouth is this time? A simple yes or no will suffice this time. ANY competent physicist, engineer, or just plain smart guy will see that I am correct. Too bad I am so ignorant though..... At this point I will still try to educate Mitch, I think he has potential.
Yet again you do not define you competition enough to make it worthy of listening to you. What, where, etc. are you going to race. I can tell you that Mitch could make his car accelerate faster than yours for certain distance (maybe 2 metres, but you did not specify) ... but you seem to think that specifying anything enough to make sense is not worth while. Sorry teak360 but it is more complicated than the most hp wins everytime ... and limiting Mitches torque to a specific rpm means you DO know that torque is important. Note: we never said that torque at high rpm was not important, we just said that you cannot calculate your potential acceleration ACCURATELY using just power. Now teak360, walk nice and close to a brick wall, move your head back and then forward really fast. Make sure your head hits the wall, and repeat a few times until you feel numb. The definition of an idiot (or someone that does not know what they are talking about) is the constant revaluation (sp?) of what they last said ... this is a feeble attempt to regain respect as they realise by the others reactions that they have said something stupid. You fit this bill perfectly. Sorry to say this but that is what you are doing. Goodbye, and again I wish you the best in the future. Pete
I can just hear you talking to Sir Isaac Newton now. "But Isaac, what type of apple tree was it? Were there lots of leaves on the tree? Were you sitting in grass or dirt? How did the apple taste" etc. I have specified PLENTY to make sense, you just insist in not seeing it. Of course it is, when you insist on bringing in any myriad of variables. QUOTE] and limiting Mitches torque to a specific rpm means you DO know that torque is important. [/QUOTE] Of course it is, I have never said otherwise. You're implication that I don't know this shows that you really haven't been paying attention. As far as limiting his rpm goes, Mitch says TORQUE rules, not TORQUE AND, OH YEAH, PLUS FACTORING IN THAT RPM THING RULES. Because then he would have horsepower, and it would be much easier for Mitch to say HORSEPOWER RULES than TORQUE AND ,OH YEAH, FACTORING IN THAT RPM THING RULES. Who's banging their head now? Of course you can't say that, because "torque at high rpm" is HORSEPOWER Engine torque without knowing rpm is USELESS in determining acceleration. Horsepower without knowing rpm is NOT. You are TOO SMART to disagree with this, aren't you? You can calculate the greatest potential acceleration PRECISELY knowing just hp. Stop banging your head for just a second and repeat after me: "This is a hypothetical discussion". Now, if you give me a car weight and max HP, I will simply calculate applying the hp continuously over any distance you like to give you the best ET. Surely you can see how simple this is Pete. Of course this implies a cvt transmission, so what? That does NOTHING to discredit this exercise. You and Mitch are so hung up on this when it is not necessary for this exercise, Mitch has spewed out so many rear end ratios it could fill a book. If I give you a cars weight and max tq you CAN'T do the calculation. Because TQ without RPM (that's hp remember?) is usless in this computation. Remove teak360, replace with Pete or Mitch, preferably both. Disregarding your incorrect definition and spelling I will say this: I do reevaluate most things I write or say, as I strive to learn. That is not the definition of an idiot. If you haven't noticed I have never waivered from my basic premise which is: Horsepower alone can determine the max acceleration poential of a car of given weight. Torque can not, unless you also know the rpm the torque is made at, then VOILA, you have something else. Guess what that something else is. It is HORSEPOWER
Actually, that is a waivering right there! In this case you just said "horsepower"... which could imply the whole horsepower curve; however, in your previous assertions you said "max horsepower"... in which case your premise is simply false (unless you are allowing a CVT). In contrast, the statement here is valid, assuming by "max potential" you mean ignoring the details of friction, air resistance, gearing, and so on; and by "horsepower" you mean the "horsepower curve".
I made a mistake in the last post, I meant to say "Max Horsepower" implying without needing to know the rpm. In other words, the maximum rate at which work can be done. In this case to accelerate a car. You need to do work to accelerate a car. You can do work with horsepower alone. You cannot do work with torque alone. When people say things like "good low end torque" they are implying there is an accepted range of rpm (thus again, torque and rpm to make horsepower) within which others believe they are speaking about (perhaps 1500 - 3000 rpm, again only implied). But, again, throwing out torque numbers without rpm renders them meaningless, they tell you nothing about what they can do to accelerate a car. This has become accepted communication and in a way it is valid. However, when someone says a car makes 600 hp. Then you know you have got a serious engine there, REGARDLESS of the rpm at which that power is made. You don't need to know the rpm to know the capability of the engine. Through torque multiplication (gearboxes) you can develop ANY torque at the rear wheels with ANY horsepower. With one horsepower you can develop 1,000 lbs ft of tq at the rear wheels! Wow. But so what? Without adding the component of rpm to the component of tq (and thus hp again) you don' know how much work you can do per unit time.
False, unless you are assuming a CVT... If your engine is 600HP at 5000 rpm, but 10HP at 4500 rpm and below, and redlines at 5001 rpm, and has a normal 5-speed tranny, you are going to have pathetic acceleration numbers in the 1/4 mile. You may argue that's extreme, but if you look at any of Mitch's examples of practical cars, you will see that what the HP curve looks like matters when you are talking about 1/4 mile or any other acceleration number that goes through the gears. In your quest to ignore gearing and such, you are making "theoretical" statements that are just flat out wrong. Further, you are interpreting automotive terms with strict physics definitions. The torque curve of an engine implies a power capability... nobody measures at engine torque NOT at an RPM... the engine must be spinning... and its ability to produce that torque at that RPM does not change as load is applied (as long as the engine is still able to turn at that RPM). So, your arguments seem inane... you are strictly theoretical when you want to be, and make practical assumptions when you want to... your resulting logic and statements are simply nonsense... and using that inconsistency, you talk around all the valid statements that other people are arguing. Quite annoying behavior, actually.
I official give up ... Amazing how somebody can accept that a Force accelerates a mass (actually not sure we have got this far), and that Torque is a rotational force ... but cannot accept that the force that accelerates a vehicle comes from Torque, just amazing to me. It is a real pity that P = F/V cause so much confusion. Rearranged thus F = P * V, thus it is easy to see how one gets confused. The problem with current 4-stroke combustion engines is that Power (er, Torque that produces power) is not constant, and thus saying that (and I quote): Is invalid because some huge percentage of time during acceleration the engine is no where near maximum HP. Now with a CVT or an electric motor this formula is 100% percent valid, until then it is not in the real world. Quite happy to accept: Anyway who cares. Pete
I was under tha assumption that you knew something about rocketry after making a comment about rockets. 200K lbs is the weight of the shuttle after you get rid of the SRBs and the fule tank. It end up moving at 17500 MPH while in orbit. The product of M*V represents the energy of the craft while in orbit. That energy came from 4.2 Mlbs of fuel. I will define the TQ curve decreasing from max TQ at 1% per 1000 RPMs. So even if you peg max TQ at 1 RPMs, I will have more than 200 HP by 1100 RPMs. By 2000 RPMs I have 390 HP and on and on and on. See its still all about TQ you vaccuous heap of parrot droppings! I happen to A) be a competent engineer, with 23 patents, and wolrd wide recognition of my contributions to computers, B) be a competent physicist in the non-relativistic realm C) pretty good in the relativistic realm. You have not demonstraited the ability to do either the math or setup the physics problem, let alone indicate why your rule of thumb fails so often and so miserably. And it really is too bad that you are so stupid that you cannot be educated. Were you born that way, or did you have to work at building such a thick skull?
Pete, reread what you just said above and then read the following. They are ALL things I have said in THIS THREAD. "Max acceleration in any given gear is at max tq" "Torque is defined as a force" "Engines produce torque at the crankshaft" "Gearboxes are great TORQUE multipliers" "Also, of course it is a force where the tire meets the asphalt that provides the thrust to move a car. The force x the distance to the center of the wheel can be calculated as a torque. " I can see one of only two choices: You aren't paying attention or you aren't telling the truth. Which is is Pete? So with a CVT my formula is 100% valid? Oh I forgot CVT's don't exist.
Your statement was incomplete and basically irrelevant to the discussion at hand. This proves you can't follow simple directions. I simply asked you to define the rpm where max tq occurs. Some people with analytical brains, like yours, are completely lacking in the ability to follow a simple command. And you are a Lemming, following the party line. Then why can't you honor a simple request? You have repeated this meaningless tome so many times that you are starting to look like the parrot. Your prose is so eloquent, Mitch.
I am assuming a CVT. Oh yeah, I forgot again, CVT's are just theoretical. Please, show me ONE that is wrong. Just ONE. And what is wrong with theoretical? Besides, remember when I asked this Brian? "It is very simple, and very clear that these questions can be answered YES or NO. Will you do it? 1. Knowing only a vehicles weight and max horsepower, can you calculate it's theoretical best 1/4 mile e.t.? 2. Knowing only a vehicles weight and max torque, can you calculate it's theoretical best 1/4 mile e.t.? " And yes I said "theoretical". I don't know why you would have a problem with that? They are really very simple questions. Here are the answers you posted: No and No. How anyone with even a basic understanding of physics can answer no to the first question is beyond me. And then you actually said this in a a prior post: "HP=ability to breathe freely at high RPM is true" What kind of nonsense is that? A totally meaningless statement. I think you have eliminated yourself from holding a credible position on this thread. And Mitch, our much decorated physicist actually said this: "TQ does the work, HP gets the credit.............." What the FU*#! A real physicist would never say that. He would look too stupid. So long to the Lemmings following the great Torque God.
I raised this before... and not once did you confirm you were assuming a CVT!!!! That changes everything! No, I posted this: "Well, we have to define some assumptions: your "vehicle" has normal gears (not CVT or other weirdness) when you say "max horsepower" you are referring to a single number that is the highest horsepower at any RPM (not a horsepower curve over RPMs) No and no." You NEVER said my assumption of "not CVT" was invalid! If you assume a CVT designed to keep the engine running at the RPMs where max HP occurs, then yes... we all agree that theoretical acceleration of the car can be computed from knowing max horsepower alone. BFD! Given we are assuming a normal Ferrari gearbox (not a CVT), the answer is no. Anyone with basic understanding of cars knows that. Dude, there's only one person in this thread looking stupid right now!
I've never said it was more than a simple physics exercise, and it does more easily help people to see that keeping the engine running closest to max hp provides best performance. Even THAT was argued against at the beginning of this thread. The point is to show that engine tq is not what defines a cars accelerative potential. And for your group to say something to the effect that "sure it is, its just tq at an rpm" is a cop-out. As if that were something different than horsepower. You didn't answer the simples questions correctly, and you didn't post the stuff above at the time you answered no and no. Your angry just because you can't think "outside the box". It is a BFD if you can get it through your head that this is the absolute HIGHEST rate of acceleration possible,(which I'm not yet sure you understand), and is precisely the point I am trying to make! This same engine could make a max tq of anything from 10 lbs ft to 1000 lbs ft and it would not change that max acceleration rate one iota. Do you really understand that, what the tq measures out at doesn't matter?! HORSEPOWER RULES - PERIOD. WIth gearboxes and ANY given engine tq, you can create ANY torque at the drive wheels. But that is all meaningless without rpm, which is HORSEPOWER. You all chant over and over that it is TORQUE that does the work. Again to quote your exhalted leader Mitch "Tq does the work,HP gets the credit". This is so ingrained in the car culture that you are acting like members of a cult. Torque is a force, torque itself CAN NOT do work. Only when combined with RPM can work be done. This is horsepower. And I don't care how many patents Mitch has, that quote of his is as fundamentally untrue a statemet as you can make in physics. Which begs the question, why would he lie like that and try to pass it of to support his position? You and the rest have all done your share to turn this thing into something much more complicated than it is. Repeat after Mitch: "Tq does the work,HP gets the credit". "Tq does the work,HP gets the credit". A physicist with ANY credentials should be highly embarrased to have uttered those words just to try and support an untenable position. Dude, there's more than one person in this thread looking stupid right now! And I'm not in the group. I don't mind standing alone when I'm the only one with legs to stand on. At this point you all have so much testosterone flowing in you posts I don't think you would change your positions if the Goddess of Enlightenment whacked you on your A$$es with her staff of truth! Well boys, off to the store, to buy a bag of horsepower. Seems they've put the torque our for free but no one's been taking it.
At the start of this thread, I asserted that most discussions such as these result from people reading too much or too little into terms... the above is a perfect example. Everyone arguing against you is stressing exactly that point... horsepower is just torque at an RPM... and it is torque at an RPM that causes acceleration. YOU are the one saying that HP is somehow superior... but we have been countering that with anything other than a CVT, you need to know horsepower over RPMs just as much as you need to know torque over RPMs. Only in the CVT special case is it good enough just to know max horsepower (because only in the case of CVTs can you actually keep a car at max HP over an acceleration run). The reason the automotive world quotes both max T and max HP is BECAUSE they don't have CVTs, and thus they NEED a picture of the curve over the range of RPMs... and max T@RPM with max HP@RPM gives you a simplistic picture of the overall torque (or horsepower) curve. BULL$#IT!!! Go back and look at the post before you call me a liar!!! That is EXACTLY what I said in the post where I answered no and no. Go read it. We agree in the case of a CVT... that was stated way back in this thread... but you insist on applying it to Ferraris... and in the case of Ferraris (or other non-CVT vehicles), its absolutely NOT possible... without a CVT, you need to engineer much more than max HP... you need to engineer a broad HP curve (or torque curve... same difference). Contrary to your assertion, it is absolutely NOT possible to accurately compute 1/4 mile ET using simply max HP for a non-CVT car. That's a stupid statement. As you yourself have agreed to earlier in this thread, "max acceleration rate" occurs in first gear at the point of max engine torque... not at max horsepower!! Even with a realistic (non-infinite) CVT... unless max HP is at max T, the point of max accleration will be with the CVT at its lowest setting and the engine running at max T... not max HP. Dude... listen for a change... we've said over and over that we're talking about CARS here... we're talking about how torque is quoted for engines in the automotive world... get your head out of your freshman physics book for a second and listen. Nobody on the planet quotes engine torque at anything other than an RPM... engines don't operate at zero RPM... nobody worries about an engine's torque at 0 RPM. You continue to completely miss the point here. The point is NOT torque vs. horsepower. The point is two-fold: 1) Other than the case of CVT, its not about "max HP" (or "max T"), its all about the HP curve (or T curve) over the range of RPMs you'll be operating in; and 2) In the automotive world, the torque curve and HP curve are interchangeable, with a simple unit-of-measure conversion: HP = T*RPM/5252. But rather than focusing on the real point, you continue to focus on twisting words: Well, I'd have never said that... BUT, any non-geek would realize that Mitch was not making a physics statement with that comment... he was talking about the physics vs. the common conceptions of things in the automotive world. But then, we can't expect you to understand that... given the above, you clearly do not comprehend the automotive world. While we are picking nits in what people have said, let's focus on your statements that have caused the whole mess in this thread. The downfall of this whole thread is that you are assuming CVTs without stating that... or even worse, you were assuming CVTs while stating that you are NOT assuming CVTs... that you are assuming normal Ferrari gearboxes. Your apparent lack of understanding of that FUNDAMENTAL difference, shows complete ignorance of automobile engineering... you are simply arguing using simplistic notions of two physics terms... with no real understanding of what we're talking about here... cars!!
Teak, let's at least wrap up the key issue here... you're into trying to simplify things down to a simple yes-or-no question... so, please, answer this simple question, if you dare... Do you agree (simple yes or no) that your statement "You can reliably predict a vehicles 1/4 mile trap speed and et with only two things: HP and weight.", while true in the case of a CVT, is false in the case of a typical 5-speed or 6-speed Ferrari gearbox, which forces the engine to operate at RPMs well away from max HP? Simple yes or no...
Ill dare (since I am bored at work ) and Ill most likely get blasted here...but here goes! I would say that--- Yes...trap speed can be fairly accurately predicted with HP and weight but that ET is much more difficult to predict. The "fairly accurate" qualification is based on a true power reading (from something like a Dynojet), not some manufacturer's power rating. The very typical formula used for years is-- hp = (trap speed / 234)^3 x weight A few examples--- My 1991 Dodge ran 115 mph. In that tune, it dynos right around 380 whp. By the above formula we get 391 hp. Close enough for me. My 2000 Maxima ran 96 mph. It dynoed at 211 hp. By the above formula, 217 hp is predicted. My 2002 C320 ran 91 mph. By the above formula, it would be predicted that it would make something around 210 hp. I havent dynoed it yet, but we shall see! 210 hp sounds realistic. I just read a road test of a Challenge Stradale. It ran 114 mph. I think these cars weigh something around 2950-3000 lb? If so, they should make roughly 340-345 whp. I think the dynos posted have been 325-330 hp. None of this is exact, but it gets one in the ballpark. It obviously ignores aero drag, rolling resistance, etc in favor of some "preset" assumption, but it generally gets realistic results within a small margin.
Check your physics. And read the following carefully: Acceleration in ANY given GEAR occurs at max engine TQ. Acceleration at ANY given SPEED occurs at max engine HP. ( The reason for this is that the greatest amount of work is always being done at MAX HP). Thus, in a CVT car max acceleration ALWAYS occurs at max engine HP. I know you don't understand this Brian, and it is is counterintutive. But I think even Mitch could could explain to you that this is true.
I understand it and do NOT find it counter-intuitive at all, as long as you explain that you are not assuming fixed gearing (those who assuming normal car gearbox will be very confused by the statement... since many given speeds can NOT occur at max HP given the possible gears). HOWEVER, note that you didn't say "at ANY given SPEED" in the statement I was declaring as stupid... you said simply the "max acceleration rate"... in that case, it'll be at max torque at the in the lowest possible gearing of your CVT.
For the record, I asked: and you properly answered: Thank you. Now we're getting somewhere. We've all seen that cleared up now... no argument there. We've also all seen your challenge: I submit your own statement above as a reputable physicist's truthful denial of the statement in your challenge, given that I can easily prove that "a Ferrari Modena" does not have a CVT. Thus, you owe me your 360 Modena. Pay up! Mitch, PSk, I'll toss some of the proceeds to you to compensate for your lost time on this thread. Oh, and Fchat will get a major donation from the proceeds to compensate for everyone else's wasted time reading this thread. Teak, PM me for delivery instructions.
