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Old 03-05-2013, 03:25 PM   #521
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I mean, the dyno obviously measured something, but it didnt measure Ft-lbs of TQ and/or Nm of TQ.

therefore we cannot accept the HP numbers.
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Old 03-05-2013, 03:30 PM   #522
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Quote:
Originally Posted by 18psi View Post
Here's the thing: I would believe what you're saying if it didn't specifically state: " 498ft/lb " meaning its not just a screwed up chart that was distorted onto the HP graph, but the dyno "spit out" the tq figures incorrectly in the 1st place.

Therefore there is no method to this madness.

Therefore its about as legitimate as......can't even come up with something witty at the moment


PS: we're all waiting for Dan to chime in and its all speculation at this point (as is his dyno plot). Just in case its unclear.
What I think is that the horsepower curves appear to be consistent, with both the before and after numbers that Dann provided. The units of measure shown in the combined printout are also consistent with the horsepower numbers Dann's provided and with the stand alone horsepower chart of the new setup Dann provided.

The issue is with the torque curves, no matter how we look at it, something is definitely off about the torque numbers provided, they clearly don't match up with the units indicated on the printouts or with the horsepower numbers. What we don't know, and can't determine from the printouts, is if the shape of, and relative measurements between the two torque curves, is accurate but the units are off or if both are off. I am simply suggesting that the curves themselves may be accurate but the units shown, for whatever reason, are clearly wrong.

Jim J
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Old 03-05-2013, 03:32 PM   #523
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Originally Posted by jimj64 View Post
I am simply suggesting that the curves themselves may be accurate but the units shown, for whatever reason, are clearly wrong.

Jim J

we said that like 5 hours ago and you argued the wrong tq plots were being presented...or the "scaling" was off.
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Old 03-05-2013, 03:39 PM   #524
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The dyno looks to be a standard one (no space materials) and the units looks to be the normal non SI ones
Mainline DynoLog Dynamometers
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Old 03-05-2013, 03:41 PM   #525
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Quote:
Originally Posted by Braineack View Post
we said that like 5 hours ago and you argued the wrong tq plots were being presented...or the "scaling" was off.
Actually, I never once said the wrong torque plots were presented, but you don't read very carefully so I can see why you would say that... I think the "curves" are quite posibbly accurate (but I don't know that for sure), but the scaling/units of measure are clearly off. I offered a possible explanation and you went all ape **** cause you thought I was disagreeing with you about the torque numbers being off, I said in my first post about the dyno sheets that he was only making 304lb/ft of torque and not 498.

Jim J
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Old 03-05-2013, 03:43 PM   #526
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I cant tolerate you any longer. this is the first time you've used the term "unit of measure" btw
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Old 03-05-2013, 03:44 PM   #527
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Quote:
Originally Posted by NiklasFalk View Post
The dyno looks to be a standard one (no space materials) and the units looks to be the normal non SI ones
Mainline DynoLog Dynamometers

In this case, i'd like to request that Dan make a video of his 500ftlbs-equipped turbo 1.6 car ripping some gears on pavement. In4massivewheelspin.
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Old 03-05-2013, 03:45 PM   #528
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Note: SAE J607 is an older standard which did not attempt to include any of the engine's internal friction losses. Consequently, J607 gives higher values, which fail to include the friction losses. SAE J1349 is a newer standard which does specify various ways to include the engine's internal losses, and therefore presents a more accurate indication of engine power.

From:Equations: Dyno Correction Factor and Relative Horsepower

What is Corrected Horsepower?

We have all seen and made claims of an engine’s horsepower. However, this stated horsepower is almost never what the engine actually made for power. How can that be? Most of the stated horsepower numbers are “Corrected” values. The correction standards were developed to discount the observed horsepower readings taken at different locations and weather conditions. It is obvious that an engine builder in Colorado could not produce as much horsepower as a shop at sea level. There is just less oxygen for the engine to burn at the higher altitude. What are less obvious are the other weather condition effects on the engine. So in order to compensate for this all advertised horsepower is “corrected” to several different industry standards.

Most of you know about Atmospheric Correction Factors that are used to compare an engines power output for one day or location to another. However, these factors can be rather confusing and even deceptive. Everybody seems to declare there engine’s horsepower as “etched in stone” number, however we also know that the engine will make very different power on different days. Excluding other factors like engine temperature and quality of fuel used, the engine output is very dependant on the amount of oxygen in the air. So the only way to compare an engine’s horsepower is to correct the output on a given day to some standard.

The most common are the SAE standards. The older J607 standard considers that the engine was run on a 60F day with 0% humidity and a barometric pressure of 29.92 in-Hg or the newer SAE J1349 standard of 77F (25C) day with 0% humidity and a barometric pressure of 29.234 in-Hg (99 KPa). Also the ECE standard is the same as the SAE J1349, but does not use mechanical efficiency in the calculations. The DIN standard which corrects to 68F (20 C) day with 0% humidity and a barometric pressure of 29.92 in-Hg (101.3 KPa) and the JIS standard corrects 77F (25 C) day with 0% humidity and a barometric pressure of 29.234 in-Hg (99 KPa), but uses different correction curves than the others (as a substitution for using mechanical efficiency factors). Further, we have the J1995 corrects 77F (25 C) day with 0% humidity and a barometric pressure of 29.53 in-Hg (100 KPa).

Since very few engines are actually run in these conditions we apply these correction factors so that it is possible to compare the results taken on different days. First lets just look at the weather correction, we will see the second section dealing with mechanical efficiency later. Consider if you take a baseline run of a normally aspirated four stroke V-8 engine on a sultry day in late August, say 85F and 85% humidity and 28.85 in-Hg and the engine produced 400 Hp. Then after you finished making all your modifications you retest the engine in late September when it is 55F and 35% humidity and 30.10 in-Hg, the engine now makes 442 Hp. That’s almost an 11 percent increase in Hp, however the engine is actually producing the exact same amount of horsepower according to the J607 correction values of 400 Hp * 1.1005 ≈ 440 Hp and 442 * 0.994 ≈ 440 Hp. If you had retested the engine in the same weather conditions it would have made 400 Hp again.

There are many different correction “Standards” out there, but here is the SAE J1349 formula:



cf is the final correction factor multiplier
Pd is the pressure of dry air in hPa
(990 hPA = 99 kPa)
Tc is the air's temperature in degrees Celsius

One more source of confusion about the SAE J1349 is all the different values quoted for the Barometric Pressure in inches of Mercury. If you search around you will find the base values are different. Some will quote 29.234 in-Hg and others 29.318 and others 29.380. How can they all be correct? Well the calculations are done in KPa or millibars. These units are all true pressures, however inches of mercury, although considered a pressure unit, changes with temperature. This is because mercury expands as it gets warmer. Therefore 99 KPa at 32F is 29.234 in-Hg and 99 KPa at 60F is 29.318 in-Hg.

Now this may sound confusing, but these formulas were developed to attempt to allow standardize advertised hp ratings and comparisons. The formulas are based on the amount of oxygen that is found in the air that the engine is breathing. The greater oxygen the more fuel can be burned and thus more horsepower. However, these formulas are not perfect. They were developed empirically and are a good approximation for the variables of humidity, temperature, and absolute pressure. However, internal combustion engines develop power on many other variables and although it is possible to have the same correction factor at high temperature and pressure as low temperature and pressure, the engine will make different power. The wetting effect and temperature differences are not perfectly compensated for. This gives rise to the “purist” touting that all engines must be tested at the same atmospheric conditions or else the results are useless. In a prefect world this would be true, but this would be ludicrous. The cost of building an environmentally standardized test cell is well beyond the capabilities and cost of even large OEM companies and would give rise to even more deception in horsepower advertising.

Now lets consider the next effect on the SAE standard that some other industrial standards do not include, the “Mechanical Efficiency” of the engine. Which is basically the amount of energy the engine got from the fuel versus how much energy actually was produced at the flywheel. This is a measure that includes the frictional torque, viscous effect, etc. required to rotate the engine. If we take the SAE standard that a four stroke normally aspirated engine consumes 15% of its’ developed horsepower to rotate the engine. This is another huge point of debate, but it does make sense. If we want to correct the observed horsepower to a standard condition, it make sense that the friction required to rotate the engine does not change with added oxygen in the air. So in the last example the engine produce 400 Hp on that hot August day. This time consider the SAE J1349 correction standard which has a correction factor of 1.0634. According to the SAE 15% standard it took 70.58 Hp (400 / 0.85 – 400 = 70.58) to overcome the friction from ring drag, bearings, valve train, etc. Since this is a constant value no matter where the dyno test was taken, we know that the energy produced by the engine was actually 400 + 70.58 = 470.58 Hp. Now if we want to compensate for the atmospheric condition then we should use the amount of energy that the engine got from the fuel supply. So we take the 470.58 Hp * 1.0634 = 500.42 and then subtract out the constant Hp reading of 70.58. 500.42 – 70.58 ≈ 430 Hp.

Now it does make sense that the frictional torque is almost constant no matter how much oxygen was in the air, but the SAE flat rate 15% does not accurately cover all internal combustion engines. It is a compromise. In the example above we used a normally aspirated 4 stroke V-8 engine, but what if it were a two stroke V-8 outboard engine. It is quite obvious that the two stroke has much less frictional drag. It has no camshaft, timing chain, valves and springs, oil in the crankcase, etc. Comparing these two engines with the same 15% friction losses does not work. That is why some higher end dynoing software calculate the friction losses on many different variables, like the displacement, stroke for piston speed, type of aspiration, number of strokes, type of fuel, and RPM. Using this information will yield much greater accuracy in calculating a mechanical efficiency and therefore a much greater accuracy for in house comparisons between pulls. However, in order to advertise the value as SAE J1349 compliant you must usually use the SAE mechanical efficiency number.

Another way to get accurate mechanical efficiency is to use a dyno that can “motor” the engine, like an AC dyno. Just measure the amount of power it takes to drive the engine and then use those values for your own custom mechanical efficiency. Once again though, you will need a high-end software package that will easily allow you to use the new efficiency or else you will be doing a lot of tedious and time-consuming hand calculations. But once again, this solution is not perfect either. Many will argue correctly that motoring the engine is not the same because there was no heat, bearing loads, metal deformation, etc.

Some companies who are working on a particular engine family will actually test the same engine under many different conditions and develop their own correction table. To these companies it is vital to know how their engines will perform under specific varying conditions. Consider snowmobiles that will operate at many different altitudes and temperatures, but they can pretty much discount the effects of humidity because the engine will almost always operate at temperatures below freezing. However, it is critical that their engines perform well at extremely different barometric pressures. An exhaust designed to run at sea level will not perform well at all in the mountains. Further, the opposite is true for marine engines. These engines are run most often at sea level, warm temperatures, and high humidity. Or a waste gated turbo engine that is pretty much impervious to even large barometric pressure changes. Thus the one size fits all SAE approach does not work well.

The debate over the validity of correction factors still lingers on, but they are the only way to make realistic comparison of your engines on different days. There are, and always will be, unscrupulous competitors who advertise inflated horsepower gains by manipulating the correction factors, however they are eventually exposed at the races where it counts to the customer. In order to perform accurate and credible results you must use some factors and try to conduct your tests under “similar” test conditions. In fact, SAE requires that the corrections be less than 7%. So in the example above we would not be allowed to use the STD or standard J607 SAE factor of 1.1005 because it is correcting by more than 10%, however the SAE J1349 factor of 1.0634 could just barely be used.


From:Corrected Power
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Old 03-05-2013, 03:50 PM   #529
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Jim: I think the bottom line is that **** aint right brah! By trying to explain it and it not being anything any of us had any hand in is ridiculous. It just straight up makes no sense.

although I was tarded about the IM (it's cool though, I'm a pilot now). Both of the threads regarding this subject of the 2560 and such have really left me feeling disappointed and irritated. Any kind of scientific evidence or knowledge that could have came from this has been tainted. The dyno ish was drawn out and so was the plot posting.

It's like if someone goes to the drag strip. You just want to see the time slip. They don't have to say a word. All they have to do is scan it and post it.
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Old 03-05-2013, 03:52 PM   #530
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want to break records?

fudge numbers.


WINNING!!!!!!!!!!!!!!
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Old 03-05-2013, 03:54 PM   #531
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Quote:
Originally Posted by sixshooter View Post

i understand how CF works.


his first 290.5HP dyno has a .63 CF or -37% (with only a disappointing 251 ft-lb)

this latest has a 4.27 CF or +427%
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Old 03-05-2013, 03:59 PM   #532
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I guess the moral of the story is regardless of whatever record. the 2560 is pretty shitty above 16 psi. Aren't you all glad we learned that? If 335-350 was obtainable on e85 It would have been useful information... I was skeptical of course but anyone with half a brain would be.
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Old 03-05-2013, 04:12 PM   #533
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I see Dann lurking this thread, what do you have to say?!

Honestly I'm tired of seeing these strange inaccurate dyno plots. Do a 3rd or 4th gear pull in the car on a flat road and post it here so that we can plot it in the virtual dyno. I'd trust that more than whatever the hell backwards aussie dyno you are currently using.
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Old 03-05-2013, 04:30 PM   #534
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I wasnt lurking, I just woke up, its 7:25am here and Ive awoken to 3 or 4 pages since I last checked last night, been reading it.

Its interesting you point out the torque figures are wrong, Ive always had the impression that torque figures on rolling roads were absolutely BS every time.

My uncle called me when i was at the dyno and asked how it was going, and I said we had just pulled 325, he said **** that, tell me the important stuff, how much torque did it make, the dyno operator said thats irrelevant because he can make the torque figures say whatever he wanted.

This was my understanding also.

The car will always make X horsepower regardless of gear, but a stock NA in makes like 900ftlb in 1st gear, thats why you can hillstart 1st but not 4th etc

Ill go speak to the dyno owner this morning about this and ask what he says about his dyno, and Ill do whatever you guys want me to do not because I want to prove it has x HP but because i want to better understand the current debate.

My understanding was that the dyno recorded rate of change and got HP from that, and back calculated torque based on whatever diff ratio the dyno had inputed at the time, and if the operator doesnt change that ratio then torque numbers will always be wrong.

This is why I personally dont ever trust torque figures.

To the "why does it hold 22psi" crowd, the wastegate was wired closed, its got a pretty good manifold with an exhaust that you can literally roll a tennis ball through and its on E85. I cannot give other reasons, Im just glad the stuff i built is doing the job.

Dann
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Old 03-05-2013, 04:32 PM   #535
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You dyno actually outputs the actual torque from the wheels.

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Old 03-05-2013, 04:32 PM   #536
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HP numbers are still beyond magical.
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Old 03-05-2013, 04:33 PM   #537
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HP is a function of torque.

You can solve equations in "either direction." Whether HP = X, or Torque = X.

This equation is not solvable in a way that makes sense.




This really sounds like your dyno operator was a total moron.
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Old 03-05-2013, 04:36 PM   #538
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Seems like input gearing ratio is wrong or something.

As far as I can tell this type of dyno uses a measured force ("Motive Force" on the dyno sheet) and then back calculates the WTQ or engine tq using the Final Drive and gear ratio.

If the wrong ratios are put in the torque numbers could be way off but the shape of the curve is still correct.

I'm not sure what coversions were done to convert 6198N to 498.3ft-lbs but it seems there in lies the mistake.

Anyway this thread went from fairly awesome (peaking with my ANZAC cookie reference, which went completely unnoticed) to fairly crappy, drudging on about shitty dyno charts.

Cliff notes:

Stupid dyno chart is stupid

Laggy 1.6 is laggy

Fake record is fake

fael

***EDIT : Apparently Nitrodann posted the gearing stuff while I was writing this post.

Last edited by Efini~FC3S; 03-05-2013 at 05:00 PM. Reason: add edit comment
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Old 03-05-2013, 04:40 PM   #539
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Thank you. Now I'll just sit back and watch this bs unfold to the tune of this violin that Dann so conveniently called me out with a couple pages ago.

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Old 03-05-2013, 04:50 PM   #540
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Lol, First off, I sure didnt fake anything.

Lets get that straight, I dont operate the dyno I dont know how to, and I cannot imagine the owner of the dyno just going and doing it.

Ill ask him how his dyno calculates torque and power.

Perhaps we can simply imput the correct tire size and diff ratio and it will spit out a proper torque number.

What do you want?

Dataloged and video'd pulls? Different dyno?

Standing mile?

What.

Im loving how worked up everyone is, the dyno took a week cos the local guy was busy, and the sheet took from friday arvo to monday cos I had to run a family member to hospital (mother in law just started chemo and she isnt coping well) and so I went and got it first day i was free this week.

Dann
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