So, DynoDynamics are dissapointing becuase the end user has control over adding a 'correction factor' ?


Seriously?

 

No, what I said, or typed, is that I dont think you can manipulate it to read 2 or 2 1/2 times what it should be.
Skewing the weather station may net a few, but you aint gonna double it.

 

So, then the problem is there is to much ability to control the correction factor even tho every single run made on a DD saves the factor and weather info (just like a DJ) and thus is just as easy to catch a 'liar' on?

 

Ed is that you?

 

Yeah, whos askin?

 

sent ya a pm

 

All these people get excited about nothing. You can change the measured tq on any load controlled dyno. A 150,000 engine dyno is no different. It is not a negative or a problem with any of the dynos, it is just that you have dishonest people or misunderstood test methods available with a load cell or absorber dyno.

We have been over this a bunch of times, but the problem is there is no standard in testing. Again the same with engine dynos, one shop may use a 100 rpm accell rate and the other may test at 300 rpm. That is what most are adjusting or have set different from shop to shop with the loaded dynos.

True, it makes no less. But it will accelerate faster in the lighter car and you are using up some "measured" power due to the faster acceleration. That is why a 100 rpm pull on a engine dyno will read higher than a 300 rpm pull. And back to the varible loads on the chassis dynos, this is why you will get a higher tq/hp number with more load, higher tq/hp number with a heavier vehicle weight entered if running in "vehicle simulation" mode, or a higher tq/hp number with a slower acceleration rate if using rpm or mph/sec controlled pulls. Btw.. all of this is to a point then it will not be much of a change, but you get the idea.

 

Alvin,

I came across this thread randomly while researching some unrelated info. Yes, I called you by phone after hearing of your experience. From our previous conversation, your gripe was the low test number, followed by the operator's ability to change a correction factor, and last, the difference in test results between your runs.

There is a bit more involvement with loading dyno operation than an inertia dyno. Inertia dynos are considered to be fairly (generically speaking) dummy proofed. On Dyno Dynamics, the dyno is based around the eddy current retarder and not just an add-on. Attached to it are low inertia knurled drums on the driven side. The other set of rollers are idlers only. The front and rear rollers are not belted together purposely to keep inertia as low as possible. Keeping the rollers separated promotes traction as well.

There are two ways to use this dyno. When doing WOT sweeps in the Graphing screen (live to screen I should add), a ramp rate is applied (how quickly do we expect the vehicle to accelerate the rollers). This is based on power output.

The other area of the dyno software is operated within the Bar screen. This is where the majority of a tuner's time takes place When in the Bar screen, you can load the vehicle at a given speed, hold it there without wandering around from that number regardless of how low or high the RPM. It calculates very quickly how much duty cycle needs to be applied to hold it steady-state. By holding and advancing throttle position, you can see your calculated WHP, WTQ, and more importantly, Tractive Effort (ft-lbs). When mapping out these areas, a tuner realizes its value 10 fold on how much easier it just made his life

As far as the correction factor (CF), sure, manual changes can be made by the operator but not as you suggested. The weather station is either on, off, or manual. When conducting training, a shop should be taught to use the dyno properly and not how to shift the numbers. Out of the box, there's just one recommended CF called ATMC2 for the newer digital dynos or ATMC1 for the older Analog units. There's also SAEJ1995 and ATM. Setting it to Manual is just that. By default, all of the newer digital dynos are ATMC2 and that's recommended.

Again, you can't just click on a CF button. There's a display for CF, which is what you saw. The operator must have been changing either ambient temp, baro, or humidity. Most likely temp but baro affects the numbers even more when set in manually. Then there's also a temp probe that should be placed in the intake air stream for an additional reference. Anyway, I would venture to guess that you seemed unhappy with the numbers so he may have been playing into that.

As an answer to tampering with CFs, there's an option in place so no one can ever argue that the CFs were manipulated. This option is called 'Shootout'. It sets the CF to a fixed set of variables that can not be edited including ramp rate, etc. There are Shootout groups for NA - 4cyl/6 cyl/8 cyl, FI- 4cyl/6cyl, 8cyl, and AWD. Once completed, the graph will show "Shootout".

And finally, Dyno Dynamics is considered extremely repeatable. Once a shop is properly trained on vehicle setup, similar numbers should come from that vehicle run after run. Some variance could be from ignition timing being pulled from heat soak, det, etc. If these aren't occurring, then I would suspect tire pressure or the way it was strapped down.

On a Dyno Dynamics, various strapping methods can be incorporated depending on a cars power output. But always, we are pulling the car into the rollers and not holding it from the front and the back. Tire pressure needs to be 50psi for standard tires and 40psi for low profile. Some truck tires need even more. This prevents the tire from deforming, which keeps it repeatable. If the straps are too tight, it will make the numbers lower than expected as well. On higher powered cars, the tires will actually climb up the roller. This is how traction can be held at very high levels as the tires are forced to bite into the knurled rollers. Lower powered vehicles do not need so much force when ratcheting them down though.

Resolution - I did say that you need to 'smooth' your graphs to get them to look nice. Is this not true? What happens when you smooth that graph? All of your important details are gone. On the Dyno Dynamics, you don't need to do that. It either looks good or the tune is off. You can even spot minor detonation on the graphs.

You also mentioned that you can hold load steady-state. The inertia dynos that I've seen wander from the target RPM when fitted with a retarder. Try and hold a fixed speed for example and it has trouble keeping it there. Additionally, prolonged loading steady state will over heat the coils in the retarder making the problem worse. Heavy drums will do that. It's a compromise in design. And, correct me if I'm wrong, but I've also heard that the DJ doesn't produce hp and tq while holding load. If this is the case, I would find it incredibly difficult to tune like that.

You say on the DJ that the numbers are always repeatable. Try strapping a vehicle to the front of the rollers and then to the rear. My experience has been that it'll change the test results.

That's not what this objective study found.
http://www.factorypro.com/magazine/m...ojet_dyno.html

Again, I wouldn't be so hung up on the numbers. Besides, you were testing that vehicle in AWD right? You can't possibly know what the drivetrain loss is and the fact that you're use to seeing higher numbers. I would bet that drivetrain loss on a truck is far higher than a full-time AWD Subaru for example. I always say take it to the track and look at the trap speed That'll tell the tale.

 

All this thread does is further prove that dyno numbers don't mean a damn thing when it comes to actual speed, and it's ultimately pointless to have a dyno queen unless you have a 4 inch killer and two grapes between your legs. I say, your money is better spent on a gun if you're lacking in that area.

 

Interesting thread.
The Dyno argument is analogous to the flow bench argument. When comparing different benches, you end up looking at variation in set up, instrumentation, environmental, and operator influence. Then you can start looking at the differences between the benches that you are comparing. I go through this argument often in the aerospace industry as a Test Engineer.

As brought up multiple times in this thread, the delta on what you start out with vs. what you end up with is all that matters for performance. Unfortunately, the "human" influence is very strong and the public wants to see a large number for all of the cash (and ego) they have spent on their combination. This is a given, that most dyno shops have to deal with. I happen to tune on a DJ and I like the repeatability when dealing with something as simple as a big inertia wheel. There's good arguments for doing part throttle "loaded" tuning on a Mustang or DD or a loaded DJ for that matter, but since I'm on a dyno tuning for WOT performance I havent been inclined to experiment with the others.
I have had the opportunity to run a couple of drag engines on an engine dyno, followed by the dynojet, and then to the track. What I have seen on these two engines was a 22% and a 25% loss at peak horsepower. Both had high stall converters and both had predictable times (from the RWHP numbers) at the track. Street cars, or cars that will take time to get into there power band are much more difficut to predict (as you would expect).

 

Manual weather correction? Are you serous? I saw what I saw and the operator clicked up until we where seeing a 1.14 weather correction. No place on earth would give that weather correction that I know of except for maybe the mountains in the sinai.
So I don't get it.. are you argueing that it is or isn't ok for the dyno operator be able to tune his correction factor to whatever he would like to see. One way or another he went from a correction that seemed normal and reasonable to a correction factor of 1.14


I don't know know where you get that from.. You can definately run a car on smoothing zero and it will produce a nice graph. If you would like I'll gladly post a smoothing 0 run on a smooth 5 run. And yes we have outstanding resloution which is nice to diagnose spark knock, belt slip, weak ignition, etc.



I usually set the steady state to MPH to rule out torque convertor slip and clutch slip but it will hold the hell out of the car. You will feel like you are going to break the car if you try to power above it. Yes you can make a torque gauge to watch while doing steady state tuning. I've never done it like that because you'd haev to be awful consistant with your throttle position to see if your makeing a power increase at a certian cell all while changing the tune and fighting heat soak.

So your saying try strapping it down WRONG and see if you get consistant results? FYI I haven't seen any better or worse power strapping them down on different sides of the drum. It doesn't take a rocket scientist to be able to strap one down consistantly.

Wheres the subjective study on your companies dyno? I bet that would be a interesting read if it wasn't first paid off by your company like so many magazine articles are.

I know this.. An AWD dynos about 10 rwhp lower than a 2WD trailblazer. With your dyno I have no idea if the operator isn't using it right, if he had a hell of a "manual" weather correction, or if theres something wrong wtih the car. If i put a car on my DJ and i know it should make 335-345 stock than I know when it makes 280 I need to go back and see what the hell is up.

Bottom line.... NOTHING seems accurate with close to a 40% drivetrain loss on a GM LSX vehicle which are UNDERRATED from the factory anyway.

A dyno that reads low in my opinion is not even in the same book as a dyno that reads 244-255 WHP on a vehicle that typically dynos 290-310 on awd dynojets and mustang dynos across the country.

 

I for one like the option that the operator has to change the ambient temp and such. On the main one I have used, there was a weather station setup on the dyno itself. Every hour when the temps would change, we would adjust the correction to ensure it was accurate. If you can't trust the operator to be consistent in the numbers, then I'd probably suggest you wouldn't try them to tune your car. Not everyone is dishonest. I know of one DD that did read lower then the dyno-jets around that area. It was adjusted after several cars were ran on the dynojet to show the same numbers. This was done not to "fool" customers, but for them to not think their car made any less HP. After this adjustment it has been left alone and tested several times with cars going from one dyno to the other and showing consistent readings.

Once again, who cares about the numbers. For a TUNING tool, IMO the DD dyno can't be beat. You can't hold a mustang dyno last time I checked at a certain RPM, only MPH. Maybe you can with a dyno-jet. That to me is useless when trying to tune in a certain cell or have a problem in a certain RPM range.

 

How many threads on here do you see that say guess my track times?Very few,its always guess my dyno numbers. Everyone wants to post here and tell there friends "my car made 500 horsepower with the newest, coolest heads or cam".Thats why dyno numbers are important and frequently bullshit,dare I say here especially.If a h/c car doesnt make 480 theres something wrong with it apparently.Its just stupid!

 

Would you like me to post a screen shot? What you saw was one of the CF variables being changed in manual mode. There is NO botton for "CF" per se. Again, I would bet the operator was buying into your need for big numbers.


No it's not a good practice. I can't say what he was doing since I wasn't there.


Really? Please show me this. Not on just one vehcile. I'll even drop by some time to check it out. I have not seen any other dyno do this. Generally they look pretty bad at '0'.

So you have to make something to read torque? So probably like 0.1% of all DJ owners have something like this. Even then, it will WANDER from the point of hold. It gets worse the longer you hold it.

You talk about heat soak being a problem? I just tuned a car over the weekend for one of our customers on their Dyno Dynamics unit in basic ATMC2. A little 2.0L 4cyl that ended up making 582.2whp - yes on a Dyno Dynamics! This was just a street car and I pushed steady state tuning on this little motor past 5500rpms Heat soak? What's that?

You just proved MY point. It's pretty easy to see that it's simply to skew the DJ numbers via the position of the wheels. Not to mention, what if you use lighter wheels/tires or something in the drivetrain changes? WOW! On a Dyno Dynamics, you can also change inertia compensation in the case of race set ups or those who want it all.

Come on man. No dyno company had anything to do with that article. Why even suggest something like that? Why would you even say such a thing?

So a 2WD vs AWD should read 10whp difference? I think most folks here would know that this is not the case.


Your last comment is interesting as well. I have seen some of the other loading and inertia dynos read way off . There are some shops here in the U.S. that have the "heart breakers", but others read MUCH higher numbers. That's why Dyno Dynamics is at the very least -consistent! It's always a low reader regardless of where you are

 

You absolutely can hold a mustang dyno to a given speed or rpm, that's half the reason I bought one. Beyond that you can accurately simulate load for weight (vehicle or towing), grade, and they even have a way to calculate drivetrain loss for a vehicle. Toyota uses mustang dynos at the shows like sema and pri to simulate their commercials for the trucks. They set 3 up next to each other put their tundra on one and 2 other manufacturers' pickups on the other. They then go on to simulate what they do on their commercial when they pull the 10k lb load up a grade. Governments, military, and transit authorities all use mustang dynos to test their vehicles, tune for the given situations of their vehicles, and perform diagnostics. I'm not getting into a back and forth but rather stating just some of the capabilities of the Mustang Dyno. Dynojets are much more common and much simpler, therefore their capabilities are more well known. I constantly make it a point to educate my customers to the abilities of the machine. I also educate the people about the lower numbers shown by a mustang dyno and how it uses torque feedback from the car to provide accurate data.

You better have some information to back yourself if you're going to make a statement like that. Otherwise your professionalism should be questioned the way you're questioning this dyno.

 

Why havent any of the dyno companies done a simple test:

Taken a car, removed the engine - dynoed the engine at a number of engine dyno facilites and got an average engine dyno number.

Then bolted the engine up to a car, and then done a back to back chassis dyno test using a number of vendors dynos.

This way you might be able to practicaly observe the differences between the setups and perhaps even get an average between different vendors and check repeatability with in the same model of dyno.

Thos would also answer the "drive train" loss for that particular car, and provide actual results for customers to observe.

Seems like a great marketing and promotional opportunity to me

 

I'm sure you did!

 

Dyno dynamics in australia a bad rep for dial your horsepower and there are many shops notorious for it. Im not bias but user can alter horsepower with a few key stroke is open for people to quote unrealistic gains. A simple weather station with auto capture is all that is need like most decent dyno companies. but the fact that you can make credabiltiy debatable. i have included a real life unbiased facts testomonial of someone who tested it.

"Interested in hearing a little story about dyno figures? If so, read on, if not (because you are inclined to believe the hype surrounding chassis dyno marketing), don’t bother reading any further!

The following is fact, having taken place literally minutes prior to me penning this ditty. And for the record, all dyno sheets are available for reference if proof is required.

Scenario; We take a turbocharged six cylinder vehicle and place it on an unnamed dyno (this info comes later), a dyno whereby the software makes it impossible for the operator to in any way fudge the figures, with the only variation being temperature correction (via an inbuilt weather station that automatically corrects in relation to the ambient), which is of course to SAE standards, and once again can’t be played with.

1. Said Test Vehicle produces 282.1 rear wheel kilowatts @ 14 psi boost.
2. Said vehicle is then driven approximately 300 metres to another workshop where it is placed on a current model Dyno Dynamics chassis dynamometer equipped with the latest Dyno Dynamics Shootout Mode software. Software designed, we’re told, to ensure an absolute level playing field between every Dyno Dynamics dyno in the country (when fitted with the Shootout Mode software).
3. Once said vehicle is strapped onto the dyno and the software is set to the ‘Shoot6’ Mode (for six cylinder powered cars), a power run is performed for a relatively consistent result of 288.5kW @ 14 psi.
4. Said vehicle is now run with the ‘Shoot8’ Mode (designed for V8 powered cars), with the power run resulting in 304.9kw @ 13 psi.
5. Said vehicle is finally run on ‘Shoot81’ Mode (designed for turbocharged/supercharged or nitrous facilitated V8 powered cars) with the power run resulting in 317.8kw @ 12.5 psi.

Okay, so we have the very same car producing more power with each run but with a lower boost output. Interesting huh! The bottom line is that the bigger the engine (4 versus 6 versus 8 versus forced induction 8), the faster the ramp rate, hence the potential for a turbo to achieve maximum boost is lessened. In other words, the run is so fast it’s hard for the turbo to come on boost.

So the question is this: Why should a V8 benefit from a faster ramp rate (hence vastly improved power output)? Could it be that the more the power, the more potential there is with a Dyno Dynamics dyno for the car to spin the tyres if a ‘real’ ramp rate was allowed?

Another thing to consider with these fast ramp rates is that they are far from ‘real world’. A ramp rate that sees an engine achieve maximum power and rpm in say five seconds is simply ridiculous. A concern here is that the slow ramp rate allows a tuner to go with greater boost, greater ignition advance et cetera because during a five second run this may not be a problem. In the real world it is.

The bottom line is that using the same car on the same dyno, and run after run it produced almost an additional 40 rear wheel kilowatts by simply changing the Shootout Mode."

I personaly have seen this many times personaly when i have hired another brand dyno (dynolog) and have only yeild a repeatable 230rwhp (5 times over 4 weeks) with autoweather correction. then the same car went to a dyno comp held locally using a mobile dd and the car pulled 307rwhp using the shootout mode. and there is noway as long as you butt point to the ground would a standard skyline running stock boost yeild that power. so at the end of the day a dyno dynamics is only reliable as the operater.

 

the vette doctors just UPGRADED to this dyno from the dynojet...
will keep you updated on how they like.. Ill see them soon.
Ive ONLY heard raves about this DD dyno, just until now in this thread have I heard complaints.


btw mustang dyno's dyno 40rwhp LESS than dynojet. I know from experiences on various ones. So for the guy saying how all LS1 cars make 290-310 on a MD and a DJ thats not true. DJ most make 300-320rwhp and on MD hey make 270-290rwhp.
Anyway a dyno is just a tool for tuning, which the DD is far superior than the others.

 

The fact that it reads lower doesn't matter to me since it'll show gains, but I'd never go to a place where the operator asked me what numbers I wantred to see and then started changing them at the push of a button.