hi

good question

i have ages ago just wanna see what peoples thoughts are

cya

I reckon its all in the software. Not so much shootout software but the entire software package that enables to power to be read and shown on the screen as a series of numbers.

I've done some proggramming subjects at university in C and C++ and there are an infinite number of ways to tackle a problem.


Also try and see if you can have a look for the instruction manual of both brands of dyno. Make sure you do this first before you make any assumption. If they have different operational instructions then bingo they've hit the nail on the head for you.

hi

yes u r right about the final calculation on the screan

but my question is why the difference , if we are using the same car all the time as a test vehicle the we should see very little variaton on the final horsepower between dynos

DTS has a different algarithm to make there calculatio to dyno dynamics
which intern gives a different horsepower reading for the same car they claim there correct yet dyno dynamics claims there correct so who do u believe

so what does this tell us about the accurace of dynos in general

so whos following STANDARDS makes you wander now

we know how fast the rollers are spinning
we know how much load is being placed on the load cell( strain gauge) so the software calculates a horse power figure there is some compensation in the software but differences of 20 %
and we always using the same car to test
the only difference is the dyno manufactures
Doesnt it make you wander now whos right or wrong or who is close to the correct reading within plus or minus 2% , 3 % , 4% , and 5 %


cya

My quote above directly from DynoDynamics, says they don't say their numbers are correct at all (no dyno manufacturer should be stupid enough to claim that). Here it is again.

"The fact is, a (quality) dynamometer is fundamentally a diagnostic tool. So the accuracy of power measurement in an absolute sense is generally not critically important. "

And broken down:
"diagnostic tool" does not equal a scientific measurement device (a set of calibrated scales is).
"accuracy of power measurement" when combined with "absolute" equals correctness, which they then claim is not "critically important", in other words, they can't guarantee the correctness of their equipment. Because in the software there are known guesses being made (by the software and/or the operator). A set of scales doesn't take any guesses, a micrometer doesn't make guesses. A Dyno does.

Leave it at that. You obviously don't comprehend the depth of the physics required to make these sort of calculations with accuracy (due to the sheer number of variables involved some of which have been detailed by myself and others previously).

The formulae I posted above are simple - approximations. The formulae Dynos use are more complicated (and proprietary between manufactureres - closely guarded secrets), but still do not approach what is required for scientific accuracy.

hi


LOL PMSFL

so you are happy to roll upto a petrol station and put fourty dollars of fuel in ur thank at $1.20 cents a litre remember this a complictaed equation "You obviously don't comprehend the depth of the physics required to make these sort of calculations " just quoting someones words here how many litres should u be getting for ur money LOL im sure you would be a happy customer if you got 10litres in ur tank for fourty dollars but at the same token im sure the petrol seller wouldnt want to give you 70 litres in ur tank so have a think what im saying but im sure u would be happy if you did recieve exactly what you have paid for say 33.3 litres

now another hypertheticle situation

you go to safeway and purchase 300grams of nescafe blend 43 for 10 dollars with conficence you expect to get 300grams of coffee for your ten dollars

I'm not a bean counter but do u get the picture

with you analogy FORD Motor company and GMH holden release a new car they advertise there engine produces so many kwatts im sure you wouldnt be a happy camper if it didnt produce what they claimed

Remember Ford and Holden both use engine and chassis dynos for there RND work so to say its juat a diagnostic tool think again

LOL

have fun

cya

PS no need to get into a heat arguement aand to insult other peoples intellagance well thats another thought to think about

we are all on a equal playing feild in here

I don't mean to insult you, and I apologise if that is the case.

You two examples are actually very good and I'll argue thus:

Your 300gram MASS (I choose the term wisely) of Nescafe is nice and easy to quantify, and there arwe laws and standards as such to ensure consumers don't get ripped off. Here on earth that 300g MASS will also WEIGH 300g. But on the moon it'll WEIGH about 100g, and on jupiter it'll WEIGH several kilos. The point, variables, in this case gravity. On earth we assume gravity is 1 so an objects weight and mass are the same.

Now for your tank of petrol. The volume of petrol you buy relies on several factors, the main ones being pressure, temperature, volume, quality, density. The servo charges you on volume - in Litres. Problem is petrol can change in volume with changes in the other variables. When petrol is hot (ie. hot summer day, fresh from the refinery) it is less dense, thus larger in volume. But the specific energy remains the same, so you're getting less bang per litre. One thing which doesn't change with temperatre and/or density is petrols MASS. You'll find in Europe petrol is sold by MASS, not VOLUME. Use you and I are getting rippe doff at the pumps on a regular basis - whenever there's hot fuel in the tank. This has been covered on the 'current affairs' programs in the past.

So I reiterate, there's just far to many variables involved between the engine, and the printout to be able to determine with scientific accuracy, and in many case even any sort of repeatability, dyno readings.

I don't claim to know it all, Physics isn't something I've done in many years.

FPV_GTp It all comes down to precision vs accuracy. Dyno's are instruments that have an extremely high degree of precision. But are they accurate? Going by the above argument and many similar arguments Its safe to say that they are not all that accurate. Infact they, as a measuring instrument, they are probably the least accuracte device developed within the last 50 years or so.

what the hell the programming language has to do with dyno variance ill never know

Because chassis dynos are computer controlled. Not like engine dyno's 50 years ago that were all analogue and had no electrics in them whatsoever.

You used to load the car with a water brake, rev it out and whatever the needle reads is your hp. Things are very different now days.

lol - If two companies are writing dyno software using the same formulas and assumptions, it doesnt matter what lanuage they use they should get the same result.

If different brands of dynos are getting varying results, then obviously they are not using the same formulas or assumptions

Bingo, and they're not going to share, because they each think their' sis right. But none can prove it (at least not with current technology).

hi

LOL at least someone is on the ball

cya

hi


lets have a look at this vehical

a CD ford cortina with a 351 cleveland 2V closed chamber heads C10 auto 9 inch differential 4.11:1 ratio

this car fuelled up and driver in it weighs 2640 pounds
this car runs consistant 10.8 seconds a quarter mile all day long at night fall it runs 10.737 to 10.771 seconds at 122 miles per hour

what horsepower at the flywheel is this car producing

what horsepower is it producing at the wheels ????

cya

122mph in 2640 car takes 374 ponies at the wheels, 10.8s in same car takes 414 ponies.

mph is more reliable power indicator so according to forumulas around 280rwkw using

whats the dyno say?

You didn't take into account the reduction in weight as that thristy donk chews trhough the petrol.