torque vs hp for 360 replacement | Page 7 | FerrariChat

torque vs hp for 360 replacement

Discussion in '360/430' started by 95spiderman, Feb 23, 2004.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

?

which choice for 360 replacement engine specs?

  1. 475 hp and 300 ft/lbs, 8500 redline

  2. 400 hp and 400 ft/lbs, 7500 redline

Multiple votes are allowed.
Results are only viewable after voting.
  1. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    9,252
    and to make things simple, the TQ outside the TQ band is zero.

    Ignoring air resistance:
    And not using the word faster in both an acceleration sense and velocity sense:

    Using the same rear tires, the same differential ratio and the same gearbox ratio, both cars will accelerate at the same rate when in the powerband of their engines. In this case, the low power band car would have to shift to a lower TQ multiplication ratio at 5000 RPMs, but the high power band car would delay shifting until 7000 RPMs. If the winner is decided before the shift is necessary, neighter car wins or losses, otherwise: notice that the higer powerband car wil loose if the race takes place between 2000 RPMs and 4000 RPMs where it has zero power, just like the low power band car looses in the band between 5000 and 7000 RPM.

    However, if the car with the high power band engine is geared such that it reaches 7000 RPMs at the same time the lower power band care reaches 5000 RPMs, the higher power band car will be acelerate at a greater rate of speed in the ratio of 7/5. In this case both cars would shift at the same time. In this case the higher power band car wins. all sensible encounters.

    Notice the concept of HP was never involved in the analysis of the problem. Only TQ, RPMs, and ratios. The same results are obtained, and with greater insight into what is going on than by using HP.

    At this point I can tell:
    A) you either can't understand
    or
    B) you think you understand but aren't properly prepaired in the mechanics
    or
    C) you are unwilling to advance your understanding when that contradicts your rule of thumb
    or
    D) you understand and are just argumentative
    or
    E) you don't understand enough of the underlying priciples for a web based forumn to be incapable of educating you to the point of any useful understanding
     
  2. PSk

    PSk F1 World Champ

    Nov 20, 2002
    17,673
    Tauranga, NZ
    Full Name:
    Pete
    Hmmm, thought about this some more and this statement is also incorrect. Fuel economy will not be the worst at peak torque. Anywhere above that point you are providing MORE fuel but NOT getting anything more out of the combustion process, infact you are getting less as torque is dropping (maybe slightly).

    Thus the worst position rpm wise for fuel economy has to be at the maximum possible rpm the engine will sustainably run at. In this case all the extra fuel you are providing is either being wasted, as the combustion shape design (cams, etc.) cannot turn the fuel into combustion OR is being consumed simply making the engine spin faster, and thus not producing any extra output in the form of an increased force/torque.

    Again a special place that peak torque, where everything comes together to work the most efficiently.

    Pete
     
  3. Aircon

    Aircon Ten Time F1 World Champ
    BANNED

    Jun 23, 2003
    100,524
    Melbourne, Australia
    Full Name:
    Peter
    That's pretty much how it works. It only ever revs as hard as it needs to to get the power necessary to do the work at the lowest possible revs. Geez...did that make sense?
     
  4. Aircon

    Aircon Ten Time F1 World Champ
    BANNED

    Jun 23, 2003
    100,524
    Melbourne, Australia
    Full Name:
    Peter
    Hang on a sec....please someone clarify....if best fuel consumption is at peak torque, then why aren't i running my car at 6200rpm on the highway? Sounds like i should be!
     
  5. teak360

    teak360 F1 World Champ

    Nov 3, 2003
    10,065
    Boulder, CO
    Full Name:
    Scott
    Gee, because it's making more horsepower? YES! The same torque, MORE HORSEPOWER.



    [/QUOTE]
    Notice the concept of HP was never involved in the analysis of the problem. Only TQ, RPMs, [/QUOTE]


    WHAT DO YOU THINK TORQUE AND RPM ARE! THEY ARE HORSEPOWER!

    [/QUOTE] The same results are obtained, and with greater insight into what is going on than by using HP.[/QUOTE]


    What the &%($! You are absolutely talking about HORSEPOWER The car with the same torque at higher rpm is making MORE HORSEPOWER. What is SO HARD about this. Torque is NOT THE HOLY GRAIL.
    [/QUOTE]
    At this point I can tell:
    A) you either can't understand [/QUOTE]


    LOOK WHO'S TALKING!

    Man you guys are too much with your holier than though attitude toward this guy.
     
  6. PSk

    PSk F1 World Champ

    Nov 20, 2002
    17,673
    Tauranga, NZ
    Full Name:
    Pete
    HAHAHAHAHAHAHAHAHAHA, teak360 you crack me up :D, thanks for the laugh.

    It is because there is more torque multiplication thanks to the higher revs and same speed. Anyway you continue believing that HP is everything and that Torque does not exist, and the Einstein and F = m*a are wrong. The site that 4sfed4 posted the link for very clearly stated how HP and Torque work and why a high HP engine is best ... because of the wide torque band at high rpm that enables you to use nice and low gearing. It is not just the fact that it produces high HP (remember HP is the engines ability to produce TORQUE at high rpm).

    BTW I do not have a holier than thou attitude to Mitch ... but he has been proved right many times, and I have always agreed with Torque moving my car as I debated last time.

    Pete
    ps: It is nearly weekend time for this lad ... so I am about to go and get into my gutless Toyota and drive home. Hopefully teak360 has not had a go at it and eliminated Torque from the equation ... otherwise I won't be going anywhere :(.

    Over the weekend teak360, think about the fact that it is a force that moves your car, that has instantaneous values ... and where does that force come from.

    Think about that piston going down in the cylinder ... and that force acting on the crankshaft ... what is that?

    Does that actually move your car?

    If power did not exist would your car still move? ... yes

    If torque did not exist would your car still move? ... no

    Thus how can power be the FORCE that moves your car.

    Also think about what happens when you hit the brakes in your F360. The brake calipers clamp the brake disc. When I last looked at a brake disc (it has been a while), it was a round thing. This thing spins around on the wheels stub axle.

    Lets do a force balance equation:

    The car slows when the clamping force on the disc provides enough resistence to counter act the vehicles momentum that is rotating the wheel and thus disc.

    This is a negative rotational force ... and thus again a torque.

    You are going to say it takes power to slow a brake disc. And I will say yes, because rpm and time are involved, but it is the torque that equates to the negative force that actually does the slowing of the disc. Power is just a factor of how much torque at x rpm ... again if you believe in F = m*a? ... which you do not so you won't believe this comment either.

    This force balance equation was (I think) the first leason in Physics ... and it has never been proved wrong, so I strongly believe it.
     
  7. teak360

    teak360 F1 World Champ

    Nov 3, 2003
    10,065
    Boulder, CO
    Full Name:
    Scott
     
  8. Brian C. Stradale

    Brian C. Stradale F1 Rookie
    Lifetime Rossa

    Mar 17, 2002
    3,612
    Dallas, TX, USA
    And you know this how? You've examined my college and graduate education and determined this?

    So, EFWUN, how about giving the necessary credentials for your "competent physicist"? How about an automotive engineer, would such qualify? How about a software engineer that coded the simulators used by automotive design houses?

    Or how about a public domain simulator that has been scrutinized and developed by physicists the world over? A simulator that lets you see the math at work... the math that is approved by not just one physicist, but hundreds of physicists, engineers, and automotive experts.

    This isn't about "punching buttons"... this is about having the math and physics codified and debugged to precision that has then been empirically checked against experimental data of thousands of actual cars and actual acceleration runs.

    Oh, and by the way, that's how modern physics is done... at least when you get beyond the freshman year of high school. It is coded in simulators and then tested empirically.


    You are an idiot. The point I was making is that this is an EXTREMELY accurate simulator. But you can set all that stuff to zero if you don't want to factor it in. The real point is that it does NOT work off of a simple HP number for engine power. It works off a torque curve; but it will interpolate one from max HP and max T... but it will not even try to use just max HP. That is NOT adequate for any accurate calculation.

    Similarly, I can easily show you two cars with identical max HP and different max T and they will have different 1/4 mile times and speeds. This is a simple real-world proof that your statement is utter BS. No physicist is needed, unless you want one to explain why the measured reality is not reality.

    Think about it (I know that's asking a lot for you)... if your car only spends a few instants at max HP, but 10-15 seconds running a 1/4 mile, the rest of the torque curve is going to be pretty important.


    I have done better... I am offering the math of hundreds of physicists and engineers codified in a way that you can plug in numbers and see the results for yourself... and has been verified by thousands of experiments.

    But if you insist on a single qualified physicist to write a 100-word statement, then post for me acceptable qualifications and hand your Modena's title to a neutral third party and I'll go get your "qualified physicist". I work in and around research labs and have hundreds of connections in universities and the real world... I'll have no problem getting this done. But there's no way I'm going to bother any of them to do this just to get some high school freshman troll's 1/64th Matchbox Modena.
     
  9. teak360

    teak360 F1 World Champ

    Nov 3, 2003
    10,065
    Boulder, CO
    Full Name:
    Scott
     
  10. teak360

    teak360 F1 World Champ

    Nov 3, 2003
    10,065
    Boulder, CO
    Full Name:
    Scott
    Your resorting to a childish diatribe really exposes your true character. You insist on calling me EFWUN, but I am not. By the way, the Modena is real, and the fact that you can't meet the challenge in a simple way shows your true insecurity, or inability to understand the very basic challenge. Perhaps you have overeducated yourself to the point that a simple challenge can't be answered by you without many meaningless references to your associations, with no substantiation. You, sir, are the real troll.
     
  11. Brian C. Stradale

    Brian C. Stradale F1 Rookie
    Lifetime Rossa

    Mar 17, 2002
    3,612
    Dallas, TX, USA
    Others asserted you were EFWUN long ago... you did not deny it until now... so, I assumed it true. My apologies... but you sound just like him.

    Nobody can meet your challenge as you refuse to be specific about it... you have stated that I am not an adequately "competent physicist", but have given no other details on what qualifications you will accept.

    I am not insecure... I simply am not going to waste someone's time responding to you if you're just going to declare them not a "competent physicist". My point regarding my associations is simply a challenge to you:

    If you precisely define the qualifications necessary to be "a competent physicist" and if you substantiate your 360 Modena is on the line by placing the title with any of the independent dealers on this forum, THEN I will be happy to and fully capable of meeting and exceeding your challenge.

    And further, if you fail to do the above, then your "challenge" is just a load of BS. A bunch of hot air meant to obscure the fact that you have no idea what you are talking about. (Note that there's a bunch of people asserting you have no clue; the long lost EFWUN is your only possible supporter, but I think even he would now disagree with you.)
     
  12. 4sfed4

    4sfed4 Karting

    Dec 22, 2003
    231
    If you have the ability to data log your car, watch the injector pulsewidth values. They will generally be the largest at the peak torque rpm.
     
  13. 4sfed4

    4sfed4 Karting

    Dec 22, 2003
    231
    I have the Dynojet owners manual and in the section on "Theory" it explains the measurement process. I am not smart enough to have thought it up myself ;) It is enough to say that the dyno knows:

    1) The velocity of the drum at any instant
    2) Time

    With those items (along with drum specific ifromation), it has all it needs to make its calculations for power.

    The first calc it makes is for the force at the drum surface. From here, one will say......AHA! It has the force and now can calculate torque since it knows drum diameter! But, why couldnt the dyno instead use that force value along with a velocity and come up with power first? It makes no difference as the force value is fundametal to either power or torque in the dyno's calculations. The reason it doesnt do torque first is that if it doesnt have an engine speed input, it does not know the effective gear ratio. Thus, the force as measured at the wheels would be something along the lines of "tractive effort" and not particularly meaningful to the average user (although some dynos do seem to report this).
     
  14. 4sfed4

    4sfed4 Karting

    Dec 22, 2003
    231
    I guess I am just stupid. Or, I am looking at the elephants tail.

    In any case, we are all describing the same thing. Some just prefer to use power and some torque and rpm. Power is only one quantity and thus less effort is needed to find the answer. Why worry about all these gear ratio calcs, etc? Do the dyno test I mentioned by overlaying power vs speed and youll get the same answer more easily.

    But, since this thread has been reduced to personal attacks, I bid this thread farewell.
     
  15. teak360

    teak360 F1 World Champ

    Nov 3, 2003
    10,065
    Boulder, CO
    Full Name:
    Scott

    I'm not EWFUN and don't even know who he is, apology accepted. Maybe you are a physicist, if you are I apologize. I also may have made some errors in posting in the middle of the night, if so I was wrong and should placed before the Fchat firing squad.....red bandana please.

    My entire point in entering this thread was to show that torque is a component of horsepower, and it is horsepower that determines a cars performance. A car with good "low end" torque for example simply means it has relatively higher low end horsepower than a car that doesn't.

    People tend to look at torque as an entity in and of itself when talking about cars, as if it were unrelated to horsepower. That is simply incorrect.

    Torque and torque alone is not capable of doing work. Horsepower is, and work is what is being done to your car when you are accelerating it.

    Brian, let me ask you two simple YES or NO questions: (please don't answer like my wife does, with a minimum of 200-300 words for a yes or no question)

    Also, we don't need graphing software, high res. interpolation, coeficients of any kind, etc. etc. Newton didn't confuse himself with apple skin texture, the relative effect of Mars gravity or any of that when the apple fell on his head and he came up with his simple, but brilliant, formula.

    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.?
     
  16. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    9,252
    TQ causes acceleration, acceleration causes velocity to accumulate, velocity causes distance to accumulate. TQ is a force. Force through a distance is work. Therefore TQ causes work to be performed.

    What is so hard about this concept?
     
  17. Brian C. Stradale

    Brian C. Stradale F1 Rookie
    Lifetime Rossa

    Mar 17, 2002
    3,612
    Dallas, TX, USA
    Here you are talking about the horsepower curve rather than just the max horsepower number... and as such, I agree with that latter sentence. The former sentence makes me uncomfortable... it is true that horsepower curve determines performance... but it is also true that the torque curve determines performance. Why? Because in the case of a car, torque at an RPM is a measurement of how much torque an engine can maintain at a particular RPM... which implies an ability to do work. In that sense, although torque and horsepower are wholly different concepts in theory, in the sense that the terms are used in automobiles (always associated with an RPM; always implying a torque that can be maintained at that RPM), the two are just different ways of measuring the same thing. Hence the formulation HP=T*RPM/5252, which is not a universal physics conversion... but rather a relationship between engine torque at an RPM and engine horsepower at an RPM.

    Using general physics definitions, true. Using the automotive definition of torque as "the torque that can be maintained by the engine at a particular RPM", then it actually implies a horsepower by HP=T*RPM/5252... thus, they are mathematically identical... just different units of measure.

    Well, we have to define some assumptions:
    1. your "vehicle" has normal gears (not CVT or other weirdness)
    2. 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.
     
  18. teak360

    teak360 F1 World Champ

    Nov 3, 2003
    10,065
    Boulder, CO
    Full Name:
    Scott
    Well, you got the second one right.

    I am just refering to a simple physics exercise. This is concept we're talking here. The hp curve, the type of gearing, the color of the car, the wind direction, etc, etc, do not matter.

    Brian, you give me a cars weight and its max hp AND NOTHING ELSE, no curves, ratios, blah blah blah and I will calculate its best potential et in the 1/4 mile. Any hp and any weight, that's all I need.

    I will give you a car's weight and its max tq AND NOTHING ELSE and you CAN NOT calculate its best potential et in the 1/4 mile. Without knowing the rpm that the peak tq occurs at (thus the HORSEPOWER) you CAN'T do it.

    Is that a simple enough challenge to prove my very basic point? Anyone else is welcome to try this also.
     
  19. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    9,252
    We tried this;

    Car V: 3000 pounds 400 HP
    Car F: 3000 pounds 400 HP

    Yet car V out 0-60s, out 1/4 miles car F all the time.

    But lets try a different expamle:

    Car V: 3200 pounds 350 HP
    Car F: 3200 pounds 380 HP

    Once again car V out runs car F, your rule of thumb indicates this is impossible. A demonstrable example shows your rule of thumb is wrong.

    Lets try a third example:

    Car V: 3400 pounds 300 HP
    Car F: 3200 pounds 300 HP

    Once again car V out runs car F. Why?
     
  20. teak360

    teak360 F1 World Champ

    Nov 3, 2003
    10,065
    Boulder, CO
    Full Name:
    Scott
    Simple: Because I am driving car V and you are driving car F
     
  21. teak360

    teak360 F1 World Champ

    Nov 3, 2003
    10,065
    Boulder, CO
    Full Name:
    Scott
    Seriously, what part of the following statement is so difficult for you to grasp?

    "I am just refering to a simple physics exercise. This is concept we're talking here. The hp curve, the type of gearing, the color of the car, the wind direction, etc, etc, do not matter"
     
  22. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    9,252
    Yes, but you don't seem to understand the mechanics of this particular physics problem. You may or may not understand the math used to
    find solutions to problems like these.

    The whole concept of physics is the solution of differential equations,
    this requires calculus. The underlying math can integrate up to energy,
    and differentiate down to acceleration. Power is just one step along
    the path. The underlying math indicates that it is forces at "play" here
    as in Newtons first law. At certain points in the operating region it
    is impossible to obtain solutions when using power. There are no such
    regions when TQ is used to solve the problem.

    But try to come up with an answer why all three examples I gave are contraindicated by your rule of thumb?
     
  23. Bryan

    Bryan Formula 3

    As noted:

    Power (in hp) = Torque (in lb-ft) multiplied by rpm divided by 5252

    Using this equation power is only calculated not measured, using measured torque and measured RPM in a dyno. The reason we get so keyed up on torque is that it's easy to measure on a dyno.

    However, we also have another HP equation

    HP = velocity (in ft per s) x acceleration (in ft per sec squared) x mass (in slugs)

    Slug = Weight in pounds divided by 32.2


    I can see how to calculate HP if I know a car's mass and acceleration AND speed, but not with just two of these. Estimating speed, based on ET after 1/4 mile is not sufficient, I would think.
     
  24. Bryan

    Bryan Formula 3

    Since the poll didn't state what RPM the two sets of values were at, I am going to take some liberties.

    Below 5252 rpm any engine's torque number will always be higher than its horsepower number, and above 5252 rpm any engine's horsepower number will always be higher than its torque number. At 5252 rpm the horsepower and torque numbers will be exactly the same.

    So, let's look at the two choices in the poll and assume that the measured value for each choice is at the same RPM.

    475 hp, 300 lb-ft. By the above rule, we must be above 5252 rpm; in fact, we can calculate the RPM as 8315...almost the engine peak.

    400 hp, 400 lb-ft. We must be AT 5252 rpm.

    It's possible to construct a torque/HP curve with these characteristics in a single engine. So, there isn't a way to differentiate between the two choices without more RPM data. <g>
     
  25. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    9,252
    I'm quite sure he is postulating an engine with a peak TQ of 400 lb-ft near 4000 RPMs and peak HP of 400 around 6,000 RPMs for the second. As evidence, the original C5 LS1 engine had 350 TQ at 4300 and 350 HP at 6000.
     

Share This Page