Y2KZX12R
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posted August 25, 2003 05:05 AM
 Edited By: Y2KZX12R on 25 Aug 2003 06:43
This is an actual dyno. Its called a "water brake" dyno. Its the real deal. Its made by DTS and can handle blown alcohol engines with mega hp, under a continious load. Its similar to a superflow water brake dyno except for a few things that dont matter here. Two good friends of mine each own them.
This is the type of dyno that kawasaki would use to develop the zx12r engine. The Winston cup teams also use this type of dyno for engine development and testing. They can give you an almost uncomprehendable amount of data that can take days to pour over and decipher if you want it to. I have seen engines that have come off the superflow and go right on the DTS and show hp within a few % of the other dyno.
They do vary just as the Dynojet and Factory eddycurrent type dynos do.
The eddy current dynos are a brake dyno like the waterbrake but instead of pumping water and heating the water, they run a generator and usually send the power produced to a carbon pile or "stack" that turns the power to heat and disapates it.
The eddycurrent dynos have a linit of how long they can sustain a load by the rate of heat disapation they can handle.
The waterbrake dyno has a 1500 gallon tank of water that recirculates and can also be cooled, so it can run continiously for days.
My buddy did some testing for Ford on a prototype engine and they ran it at 80% power for days and days.
As stated before the DJ150 is an inertia type "dyno", that isnt really a dyno at all.
The known drum mass and moment of inertia etc. are dialed into an algorythem in the software and its known exactly how much hp it takes to spin that actual drum in THAT dyno up to a given speed. Lets just say from 100 rpm to 1000 rpm in 10 seconds.
Then the computer compares to the known data and calculates what hp it actually took to do that work in that amount of time.
Superflow also makes a chassis inertia "dyno" similar to Dynojets one but for cars etc. Some oval track teams prefer it because it also takes into account the power losses in the drivetrain and can show if a particular setup on the car is robbing power to the ground.
Heres some pics of the DTS dyno.
Heres the control room. Trust me you dont want to be near a big V8 that making alot of power on the dyno. Its not even just the noise, but you could be killed if a connecting rod, flywheel, or blower etc. let go.
The actual water "pump" housing and chassis.
The engine stand and coupler. It gets hooked right to the pump solid as solid can be. The rotational torque on the crankshaft wants to rip the engine from the stand in the reverse direction.
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Y2KZX12R
CompetitionCNC.com
   
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psycho1122
Pro
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posted August 25, 2003 06:37 AM
Nice hardware!
My point on the MJP (and others that perform like it) is that it can MEASURE h.p. and torque while the break is ON. This allows you to adj a/f on the fly, UNDER LOAD. This is something that the DJ250 cannot do, and on MODIFIED (i.e. high compression) engines, the 250 will usually set it up too lean.
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You say PSYCHO like it's a BAD thing!!
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frEEk
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posted August 25, 2003 10:58 AM
damn Y2K, that's a pretty serious setup. i read about a hydraulic dyno once too. ti bolted staright to the wheels of the car. an interesting take on the chassis dyno, but i dont know that it makes me feel very safe. looked unstable.
psycho, u'v touched on yet another point of confusion. many people seem to take the name Dynojet as synonymous with inertia dyno, but the 250 (a 200 with the eddy current retarder attachment) is not an inertia dyno far as i know, or rather it doesnt have to be used as one. i understand it should be able to do the same as the MJP or any other brake dyno. or is the DJ250 not capable of the same thing because it's a RETARDER and not a BRAKE? either way, i have read complaints about the DJ not being able to control the RPMs very well, tho that would surprise me as the high intertia drum should make RPM control easier (less fluctuations).
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Y2KZX12R
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posted August 26, 2003 12:55 PM
Yea its about $80,000 and thats installing it yourself. The installation wound up costing several thousand. The varriable motor drive on the wall to the right in the control room was big $$$ and doesnt come with the dyno.
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Y2KZX12R
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Tearinitup
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posted September 16, 2003 03:05 PM
Edited By: Tearinitup on 17 Sep 2003 13:48
Wow. Lots of stuff here. Hmm where to start.
The applications of a engine dyno and a chassis dyno are vastly different and are used for very different purposes.
Engine dynos are great for doing extensive and precise R&D work on a motor. Almost guaranteed that every engine manufacturer has one or uses one. Nice dyno setup Y2KZX12R. Would love to have one of those here. 
Now with chassis dynos...
We produce loaded inertia and pure inertia dyno's for R&D work for some big name companies and race teams, but that isn't really what you are asking. In the aftermarket tuning world our goal is to produce a simple to use and long lasting tool for measuring real world performance from Bikes, Atvs, Midget Cars, 2wd/4wd cars, and snowmodiles. Our first dyno was the model 100 bike dyno, pure inertia very simple to use and maintain. After the success of the model 100 we did some mechanical updates and released a model 150 to supercede the 100. Now comes the model 200 motorcycle dyno. The model 200 is still based off the inertia dyno concept but added some updated electronics and the ability to measure AFR and control an eddy current brake. The eddy current brake is used to disipate energy as heat and provide variable braking for the dyno, this brake does the exact thing that hydraulic brakes do on other dynos. The reason that we picked the eddy current brake over other types was (among other things) portablity, performance and price. First we wanted a design that was somewhat self contained and didn't rely on extensive installation efforts to operate the dyno, the price of an air cooled 500-1000 hp eddy current brake is a very small fraction of the cost of a fully installed and operational hydraulic brake.
As it sits our 250 is capable of pure inertia dynoruns still as they are and will probably always be very useful and simple to perform and load controlled tuning. When the Tuning Link was developed we tried to capture the standard tuning process for a fuel injected bike and provide a TOOL for tuners to use that would both help them in accuracy and speed. This tool uses the capabilities of the model 250 dyno to accomplish several things in tuning. First the "Warmup" mode lets a user exersize the bike especially handy for bringing a cold bike up to operating temp. The "Steady State" mode is used for complete step tuning of the bike. I use this when tuning generally for the lower throttle positions and anywhere in "cruise". Steady state is useful for these lower throttle positions but steady state tuning at or near redline and higher throttle positions generates a TON of heat in the bike (cooling nightmare). This is where the "Roll-On" tuning mode comes in. This mode allows the operator to select a limited acceleration rate and tune the bike while the bike is constantly accelerating and then returns the bike to a lower rpm range for the next test. This software is configurable to tune to ANY air/fuel ratio that is required by the user and can be set to optimize the fuel on the bike in 3 ranges. These are mostly used to build maps that both get good mileage when cruising down the road and to provide an optimal power area when you are racing. The tuner has the ability to configure the software to tune the power ranges to any value (usually somewhere between 11.5 and 13.5 depending on your motor setup). You can then set the software to tune the cruising part of the map to a leaner setting (11.5 would get pretty poor mileage).
We feel that the 250 dyno provides what a end user and tuner would need without the extensive setup and complexity of other systems. Pure Inertia runs, limited acceleration and pure steady state tuning.
We also are constantly researching other methods and other applications in the field. We have provided a duration test and race simulation setup to some big name NASCAR teams. This setup uses eddy current brakes to disipate up to 1000 hp virtually indefinately with the proper cooling. We also have a mobile auto dyno that travels to NASCAR events for support and testing. We also have provided custom setups for Visteon's mobile trailers that are used for NVH testing. http://www.visteon.com/portabledyno/index.html And as always we have new products and invovations on the horizon.
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kcadby
Pro
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posted September 16, 2003 04:10 PM
Didn't get to read it all right now so...don't slam me if I missed something 
I was going to mention what Tearinitup said about setting the A/F ratio...
I'm NOT saying what psyco said is wrong but...the PERSON on the dyno (with Tunning Link) can set the A/F to whatever they WANT the A/F to be...13.8 (for cruising mileage)...13.2...13.0...12.8...whatever you want for best power...
I have mapped Harleys at 13.8 up to 40% throttle and 3,000 to 3,500rpm for cruise and 13.2 for 60%-80% and 3500rpm-up then 13.0 for power (100% throttle)...
It's cool when you can actually FEEL the bike pull harder when you get past 40% throttle!!! 
Just had a guy come in last week just to tell me...he went from 130miles per tank to 190miles per tank AND pulled away from his buddies when they screwed it on
I LOVE how the "Link" can map this way with proper use...
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frEEk
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posted September 16, 2003 06:34 PM
hey tearinitup, thanks for the info, but if i may further pick ur brain on one more point, which is what is the reason for the numbers dynojet uses via the lower numbers most others use? what is the reason for the numbers? which is to say how do the calculations differ, not why did u decide to use those numbers. that's somethign that i have never seen answered. plenty of people argue which is better or more correct etc, but never seen WHY they are different.
and for those that don't know and didnt get it from his post, tearninitup is part of dynojet, hence he has some idea of what he's talkin about
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Tearinitup
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posted September 17, 2003 12:57 PM
Now frEEk. You know that I can't discuss specifics about the implementations of any of our products.
For those who are wondering. I am a full time 5 Year Software Engineer at Dynojet. Feel free to flame me about all the bad shit in our software here at Dynojet (it was probably me).
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k bryant
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posted September 17, 2003 01:58 PM
You are a brave man to make a statement like that on this site. I give you a lot of credit. But what could anyone have to flame you about, you guys make great products. So hopefully the flameing you may get, will be in jest or "constructive".
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entropy
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posted September 17, 2003 04:21 PM
Tearinitup!!!!!!!!!!!!!!!!!!!!!
GREAT post! Thanks for taking the time to educate us.
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frEEk
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posted September 17, 2003 06:58 PM
wasnt sure if u could share that or not. figured what exactly the calculations measured wouldnt be secret material but i guess it is  so the question lives on unanswer... oh well, i tried.
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Grinder_Smith
Parking Attendant
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posted October 17, 2003 10:14 PM
My late input.
You guys that build/sell/use dynamometers have great input and are to be respected, thanks. My data is purely from my own extensive research over decades and from my extensive discussions with other engine mad scientists.
*Inertial dynomometers and absorption dynomometers anre both real. You can hold an RPM with an absorption (brake) machine, but not with an inertial.
*One obvious major failure of inertial units is the absolute lack of understanding that too many operators have. I have read published statements about how much a car engine's power increased by putting on a light flywheel . . .
(1.000 HP = 550 # X feet /second)
*Please pardon the Camaro input . . .
If the big block Camaro had 500 HP at the wheels, and had 25% more at the crankshaft (500 HP X 1.25 = 625HP) - like the magazines always lie - there would be 125 HP disipated in the drivetrain: the transmission absolutely would melt, after the lubricant caught fire. Some few real men admit that this old 25% loss is just BS - the Camaro never had 625 HP.
*Yes, many EFI systems use AE, Acceleration Enrichment.
*Any dynomometer would be very useful for tuning _your_ engine. To try to tune your one engine by measuring each modification on some other magazine's machine would work poorly.
(Me, I am more amazed at the considerable consistency in ZX-12R magazine dynomometer curves!)
*I really got off on this!
Some go-kart, jet craft (Jet Ski, Super Jet) and model aircraft guys have built their own machines. They build a flywheel(!), and use a commonly-available data logger system with a special PC program that makes it read out as a dynomometer.
Grinder
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I am designing a 3749.551cc 60* V-12 engine.
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frEEk
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posted May 06, 2004 12:12 PM
after a little more thinking and reading, plus talking to a couple more people, here's some final conclusions that I think accurately describe the different numbers we commonly here. this is probably just a pipe dream, but i hope this will end arguments over HP numbers and lead to more descriptive, if not consistent, numbers being posted.
There appear to be 3 things that affect how a dyno reads (not to be confused with how the bikes power output, that comes later):
1. where in the drivetrain the power is measured
2. inertia dyno run versus steady state dyno run
3. correction factor for environmental differences (SAE vs STD, etc)
#1 is pretty simple. You can measure the power at any one of several places, the most common being at the crank (which the manufacturers publish) and at the rear wheel (includes losses thru the transmission, chain, and the rest of the drivetrain). Rear wheel numbers is what everyone other than the manufacturer publishes.
#2 seems to be largely unknown or misunderstood by the public at large. An inertia run is where you start at a low rpm and spin the drum faster as teh rpm go up. Since the dyno software knows the weight of the drum, it can calculate the power required to spin it to a certain speed within a certain amount of time, and this gives you your HP number. In a steady state dyno run, you choose the throttle % and rpm you want to measure at (usually 100% throttle at peak HP rom is what you'd publish) and the dyno adjusts the resistance of the drum till it stays steady at that rpm. There is no calculation required to measure power in this mode as you are litterally measuring the power directly. The difference in readings between these 2 modes are that spining up the crank, tranny, chain, and most importantly wheel in inertia runs takes up some amount of power and this leads to a lower reading. From what i gather through reading all the material I have come across, is that the DynoJet numbers we are used to seeing (being the accepted standard) are steady state numbers. On inertia runs dynojet estimates the power robbed by spinning up the drivetrain and adds this to the calculation to estimate HP numbers from a steady state run. Dyno jet can't confirm this but most seem to claim as such and judging by the numbers i'v seen it makes sense. of course, if you are running a DJ250 in steady state mode there is no estimation happening, as you are measuring the steady state power directly.
#3 is the smallest factor in most cases, since using one correction factor over another only seems to make a few HP difference in most cases. however, using uncorrected readings at a high altitude vs corrected readings of any type will make a HUGE difference, but in my experience pretyt much everyone seems to use corrected readings. the problem is that rarely dop people say whether their numbers are SAE or STD or what. Also, i understand that some correction factors don't work well at extreme altitudes.
Now, the second factor that effects dyno readings: the power output of the bike itself, regardless of how you measured and calculated it. The condition of the bike can make a HUGE difference in the power the bike outputs. Get this: a stiff, dry, old chain vs a properly lubed chain in good condition can be 5hp+ in itself. That's huge. Add in other factors like manufacturing tolerances, how the bike was broken in, how many kms are on the bike, which oil is being used, and other items. John Doe and Mr Smith may have have bought identical bikes but doe to how they maintained and rode them, their power outputs could vary significantly.
I suppose I should add a third factor which is dyno operation. How much air is in the tire and the weight of the rider on the bike or if the bike is strapped effects dyno readings. The quality of the air in the dyno room (good/bad ventilation) can make huge differences. Where are the measurements for the correction factor (air temp, humidity) taken? If the environmental sensors are badly placed the correction factor will be calculated on incorrect information and give credit the run with too much or too little power, though these differences would generally be fairly small.
So that's it. I am finally at peace within my own mind as to what the deal with HP readings is. Hopefully this will help other people understand what's going on too, and alleviate some of the debate over incompatible HP readings. The final conclusion is of course something we've always known: dyno readings are only really accurate/good for comparing back to back runs. If there was full disclosure on every dyno reading and every dyno was properly setup and every dyno operator knew their job really well, then comparing dyno run A on this dyno on this day to dyno run B on that dyno on that day could probably be used as a fair, if not perfect, comparison. but unless all of the variables are closely matched, comparing readings is a fool's exercise.
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