For Inquisitive Gearhead and Vortech Pro
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For Inquisitive Gearhead and Vortech Pro

  1. #1
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    Default For Inquisitive Gearhead and Vortech Pro

    Both you gentlemen wanted to discuss Dyno's, and the math that makes the dyno work. As you said that we needed to know the math that proves that the dyno works. So lets have a no pissin match discussion about that.

    As IG is the Superflo/dyno expert here, Question goes to him.

    We have all the numbers on the 496 with iron heads that VP built. Some of us have questioned the HP that motor produced with the parts it was built from. Using some of the formulas you showed, and even more if you would like or need to, Can you show us how the math proves the dyno is correct? I'm not just talking the correction here, but the airflow, rpm engine size etc etc. that equals the HP that VP says he got.

    As a general statement to myself and others here. No BS name calling etc on this thread. Lets look at the math, and the proof that the math shows, and work from that. Ask questions. Lets try and keep statements that are based on know facts or facts we can prove.

    To Mr IQ. Can you fill in the formulas, not just say what they are? IOW, not A2+B2=C2, but show the numbers for A, B, and C.

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    Default Dyno 101 - Is that for real???

    Mr User,

    I have gone through many things on this forum to try and show where numbers come from so that folks could have an appreciation (at least a better understanding) of how dyno numbers are derived and some of that has been in detail. As a result, some were interested and at least one dude (or dudette) has questioned my integrity and openly accused me of defending VortecPro Mark instead of how dynos work!

    So having stated my few experiences thus far on this forum I am not only reluctant to dance to this tune but highly suspect of the unknown agenda behind it.

    As an example, the index finger on the left hand would type a G and the little finger on the left hand would type a Q.....You typed IQ not IG so I assume that was on purpose and not a mistake.....ends up spelling a slip of the agenda perhaps? You also typed both to IG and VortecPro at the same time.....Why is that? Saving yourself typing strokes?

    However, in view of the potential to present and sensibly discuss where dyno numbers come from (which is why I started posting here instead of just lurking anyway), I will accept the general framework of what you have proposed with a few additional caveats of my own. Once the BS starts flying (and I am convinced it will) I will simply not tolerate it and will not participate in the game. Adult conversation? You bet. Also, I will start at the basics and go forward from there. SO, I would suggest that folks park their egos outside the door and let the process begin. I wish to stay on the issue of how dynos work (or should work) to produce numbers and THEN discuss specifics of how to analyze an engine as an add- on if necessary.

    Last is the issue of time to address questions - There are lots of folks out there and only one of me (my wife is glad of that) so as time permits I will try and answer each question or series of questions in a timely fashion.

    Regards,
    IG

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    Quote Originally Posted by Inquisitive Gearhead View Post


    So having stated my few experiences thus far on this forum I am not only reluctant to dance to this tune but highly suspect of the unknown agenda behind it.
    Please do not buy into what you may or maynot have read/heard here. When I ask a question, I don't have hidden meaning. I'd really like to see the math that proves the dyno numbers.


    As an example, the index finger on the left hand would type a G and the little finger on the left hand would type a Q.....You typed IQ not IG so I assume that was on purpose and not a mistake.....ends up spelling a slip of the agenda perhaps? You also typed both to IG and VortecPro at the same time.....Why is that? Saving yourself typing strokes?

    Honest, I really didn't see that. Not a freudin slip, not on purpose. Just a typing error. my fingers don't always work on the keyboard correctly. I put VP in the title, because its his engine build. Figured he should know what I was asking you.

    a few additional caveats of my own. Once the BS starts flying (and I am convinced it will) I will simply not tolerate it and will not participate in the game. Adult conversation? You bet. Also, I will start at the basics and go forward from there. SO, I would suggest that folks park their egos outside the door and let the process begin. I wish to stay on the issue of how dynos work (or should work) to produce numbers and THEN discuss specifics of how to analyze an engine as an add- on if necessary.

    Pretty much what I said, and I agree with it. Start where ever you feel needed,(its your show) to get to showing us how the dyno HP numbers equal the math, or how the math proves the dyno numbers, which ever is the right way to say it.

    Last is the issue of time to address questions - There are lots of folks out there and only one of me (my wife is glad of that) so as time permits I will try and answer each question or series of questions in a timely fashion.

    More than fair

    Its all yours

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    You like that 700+ HP 781 headed 496 dont you Bill, 10.4 compression, 248 @ .050 roller, ported air gap intake.

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    Default Dynos 101 - The basics and some history

    Readers of On the Dyno - Dynos 101 begins now,

    Dynamometers are devices to measure force and the word dynamometer comes from the Greek dunamus metron (force measurement). The earliest dynamometers were built to measure the capabilities of windmills and used ropes (Smeaton -1758). There are many ways to use a dynamometer and for the sake of time and clarity I will restrict this presentation initially to engine dynamometers but the principles that started out are still prevalent today (even much of the arithmetic is the same). A Scottish engineer by the name of James Watt coined the term horsepower in 1780 and ever since then the term has been associated with bragging rights and even intones a level of emotion.

    By definition, the term horsepower (force x distance) / time is also Work / Time. The basic calculation for horsepower with most dynamometers (dynos) is Hp = T x RPM / 5252 Where T = torque in lbs-ft (NOT ft-lbs) and RPM = engine revs per minute. Note that the constant 5252 is derived from 33000 / 2pi = 5252.113

    Note that a dyno measures Torque and calculates power (horsepower).

    Although there are several types of absorbers, the most common in racing or performance venues is the water brake absorber.

    Questions????

    Regards,
    IG

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    Quote Originally Posted by Vortecpro View Post
    You like that 700+ HP 781 headed 496 dont you Bill, 10.4 compression, 248 @ .050 roller, ported air gap intake.
    Excellent Results.
    If you ain't the lead dog the view is always the same !

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    Default Dyno 101 - Calibration

    Anyone interested in this stuff, try to read and respond as it rolls along or someone will ask a question that was covered at the git-go. These comments apply to all dynos and certainly not just superflow dynos. The calculation of horsepower is the same in that it is Hp = (T x RPM) / 5252 yep that is a repeat of the intro info.

    The basics of sound testing is more than can be described quickly on one of these threads, but I will try and breeze through some things to look for or be aware of in order to know how numbers are generated and we should be able to even cover some of what the numbers mean.

    One of the first things to be aware of about dynos and dyno numbers is calibration. As an example when you go to the doctor and they weigh you in, it is on his scale and that will be the baseline they use - They do not care if your scale at home shows you to weigh 20lbs less. It is much the same with a torque system on a dyno. It becomes important to make sure the calibration for the torque scale is the same as someone else's dyno when you want to compare numbers......That is where the oddities begin - with the torque system. The torque system on most modern dynos use strain gages but some use pressure transducers. It is imperative that the exact length of the torque arm or calibration is known. In the case of sf 901s (like VortecPro has) the effective length is 3.00ft and its effective torque from hanging it on the absorber (thus the strain gage system) is 17.5lbs-ft. Any weight that is placed on the calibration arm would be multiplied times the length (ie: 150lbs x 3.00 = 450 + 17.5 = 467.5lbs-ft of torque). The weight can be any amount but should be precise as it affects the accuracy of the torque system. Sure you could use a sack of sand or an old engine block but both would vary in actual weight with the accumulation of dirt or loss therof - not to mention changes due to atmospheric water on the sack of sand....

    The tachometer on most modern dynos is connected to the mainshaft and it is common that the number of teeth are counted by a counting circuit (electronically triggered by a magnetic pick up). The most common tach counts are 60 times per revolution and that sets one element of the resolution of the measurement system.

    Questions???

    Regards,
    IG

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    Default Tachometers - an interdictive comment with some torque too

    Folks of the forum,

    Do you use a tachometer? Most would respond yes. Most use electronic tachs but mechanical units are also used. What is the accuracy of these devices? VERY good (even the more expensive electrical tachs) are typically +/- 5% full scale devices. Do the math and see what happens: 10K tach face means +/- 500rpm. 8K face means +/- 400rpm. SO if you get accurate dyno data that indicates your engine made peak power at 6500 and you are seeing 6500 in the boat or car, what is the real number????
    Eventually I will tie this right together with timing lights too.

    The accuracy of dynamometer tachometers is substantially more accurate than the normal instrument that folks buy to place in service on their boats, autos, trucks, or other mobile floater. More often than not they will be much tighter than .5% (depends on many things but that is close enough for now.

    Oh yeah, the torque system described before is typically +/- .2lb-ft in its reading but for the sake of argument and demonstration we will use +/- .5lb-ft. As you get out your $9 calculator multiply .5 times 6500rpm and divide by 5252. IF you got .62Hp at least you are paying attention.

    Questions???

    Regards,
    IG

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    Default done for the night

    I am folding it up for the night.

    Regards to all,
    IG

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    Quote Originally Posted by Inquisitive Gearhead View Post
    I am folding it up for the night.

    Regards to all,
    IG

    Lazy.

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    Default errata and update on Dyno 101

    Mistake in post #5: spelling of the Greek dunamis metron... my apologies

    I should have also listed another important point for dynamometer history. The first use of Brake Horsepower (BHp) as a term in power measurement was in 1822 by Plobert and Faraday referencing their work with a Prony brake (Gaspard de Prony 1755-1839).

    Because there have been no questions posed overnight, I assume that either this stuff is of no interest to you or you knew all this already.....

    IF you pose a question, please refer to the posting number for everyone's clarity.

    Regards,
    IG

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    Default How can you tell if the torque system has been calibrated?

    How can one discern if a torque system has been calibrated? This question in not only important to address as an operator but also as a party having their engine tested on a dynamometer (dyno).

    There is a rather detailed procedure to go through for verification of calibration on units that use a strain gage. On 901s it is called calibration procedure and involves verifying several things such as power supply voltage, and the zero, balance and gain of the strain gage. Once that is done the system is checked for hysteresis. Mr User says he is a EE so that would make sense to him I would think.

    The system is verified by removing weights and/or adding weights to make sure the system output (torque) is linear.

    Now how can you easily check a system that is supposedly calibrated if you are a customer getting your engine tested????
    Quite easily you would ask to see what results are produced if you had a known weight and had it hung on the calibration bar or lever of the torque system. A shop of integrity will gladly show you and even explain the system of calibration.

    A system typically cannot be calibrated by using a single point on a calibration curve, but some systems can if they have that type of software. The best way is to check the torque system with several different known and verified weights.

    Questions????

    Regards,
    IG

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    Harold,

    I am just reading and attempting to digest all this.
    Now to make it clear in my mind post seven states that HP is Torque times rpm divided by 5252. Is this correct?

    And the dyno does not measure HP, rather calculates HP derived from the TQ produced..is this also a correct statement?

    This is interesting because I and many others have incorrectly assumed that the dyno measured HP or in my mind HP and TQ were both measured on a dyno.

    Looks like it is time for me to order your book and do some reading.

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    Quote Originally Posted by Carl View Post
    Harold,

    I am just reading and attempting to digest all this.
    Now to make it clear in my mind post seven states that HP is Torque times rpm divided by 5252. Is this correct?

    Correct

    And the dyno does not measure HP, rather calculates HP derived from the TQ produced..is this also a correct statement?

    Yup, HP is a math number derived from the Tq
    ...

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