LpBevoEvo

iTrader: (9)

Thanks for the input Tim. That cleared up alot of my questions.

SloRice

iTrader: (8)

Any dyno that doesn't connect the tires together somehow is bad for transfer cases and center diffs especially with today's high tech. cars. The reason being is because you don't have a 50front/50rear torque split. So when the rollers (or hubs) and tires are spinning at different speeds, you are putting undue stress on those components.

Take my car for example. It has the DCCD (driver controlled center differential). Most of the time I leave it in automatic and let the computer do its thing. So when you are on the street, the computer is always changing what the front to rear torque split is.

First, let's put it on the Dynojet. The front and rear rollers aren't connected together. So the rear is going to spin up before the front does because there is more power going to the rear. Well the computer sees this and thinks the rears are slipping. So it puts more power to the front, now the fronts are going faster and the computer thinks the fronts are slipping. And this goes on and on throughout the run. You are now putting more stress on the center differential to try and keep thousands of pounds of inertia going the same speed because you are trying to control the front and rear wheels/tires AND the rollers, not just the tires as you would on the street.

Now lets put it on the Dyno Dynamics. The front and rear rollers aren't connected together on this dyno, but they do a better job of keeping the front and rear tires going at the same speed due to the PAU's. But at the same time, you are still causing stress on the center differential because the car's ECU and center diff. are fighting the dyno's ECU and PAU's to come to a common balance between the front and rear. But when you have a car like mine where the ECU is always changing the front to rear bias, it's very difficult to control the speed of the front and rear.

Finally, lets put it on the Dynapak. This dyno has the same problems as the Dyno Dynamics, but it's multiplied by two because you have all four tires going at four different speeds.

Tim
Mustang Dynamometer

RallyRedEVO

iTrader: (5)

So, the Mustang Dyno doesn't do this to the car? How does the Mustang avoid this problem?

I find it odd that he DynoDynamics would cause a problem, I know that it has a setting so that you can tell the dyno you are running a car with this type of drivetrain. I would assume that this setting is so that the dyno wouldn't cause this problem, but would use the PAU's to keep the same speed on both front and rear to keep this problem from occuring. Is that an incorrect assumption?

GreedMOTO

iTrader: (3)

I read somwhere to just pick one dyno, be it a Mustang, Dyno-jet, or Dyno-pac, and do all your tuning and pulls on it.

Switching from one dyno to the next can yeild confusing results and be hard on the ego.

RallyRedEVO

iTrader: (5)

You can take the same vehicle to all the different types of dynos and get a different number from each, and even a different number from different dynos of the same make and model. Sport Compact Car did this.

Everyone pretty much will agree that there is no way to get the same HP number from different vendors currently. But in terms of accuracy, if the DynoDynamics can project flywheel HP within 7HP of the factory spec it has to be pretty dang accurate.

SloRice

iTrader: (8)

The Mustang doesn't have this problem because the front and rear rollers are belted together so they spin at the same rate. You are correct, the Dyno Dynamics does a much better job of keeping the front and rear rollers at the same speed due to the PAU's. But the car's center diff and ECU are still fighting the dyno's computer and PAUs. That comment was mainly directed at the Dynojet because they don't have any loading capability to keep the front and rear rollers going the same speed.

Correct! Just be aware that all dynos are different and will yield different results and have different tuning abilities.

Az3ar

iTrader: (18)

DynoDynamics is by far the best tuning dyno out there. I am driving 600 miles to get my car tuned on DD instead of 200 miles to get tuned on Dynojet.

LilJapnBoy

iTrader: (6)

Tim what the freak are you doing on the evo board!!! j/k :-)

When are we getting an awd locally? There was talk about it months ago and the topic just faded away....

D1_EVO8

iTrader: (9)

Actually Dynojet has a Eddy Current PAU option on there dynos now.. they called "Load Control" it can be used on a 2wd/4wd dynos.. anyone have any experiences with dynojets PAU?

D1_EVO8

iTrader: (9)

i agree.. the dyno operator could "swing" #'s to his favor or make a car dyno really low , if he doesnt like you

BadazzCR

iTrader: (5)

This was only seen on the earlier dynojets and not their newer model 424x. The dynojet can measure power at each axle and if what you were saying was true you would see and increase or decrease during the run from the DCCD transfering power to one wheel which is not the case. We have dyno'd many STI's and evos and have never experienced this problem your talking about.

RallyRedEVO

iTrader: (5)

I think you're probably mistaken. The car would still be sending out the same amount of power, the dyno would just be reading it from different rollers. You would however get a skewed graph, and inaccurate readings. But, that's what a DynoJet does.

BadazzCR

iTrader: (5)

I don't think you understand what I said. With the dyno jet you can read the hp for the front wheel seperate from the back and visa versa. So you would be able to see on the dyno graph how much power is being transfered to the frt and how much goes to the back. That is all..... and if the dyno was causing some problem you would see a change between the two during the run.

RallyRedEVO

iTrader: (5)

Either way, a DynoJet isn't even in the running here.

They are so grossly inaccurate; they're flawed from the ground up in design and methodology. The part mentioned earlier about measuring HP and then calculating torque is one of the largest flaws of the DynoJet, not to mention the use of the drums.

Porter

Wow, lots of opinons flying around on here with very little fact.


All the dynos currently commercially available in the US are very good at what they do. Some have particular features that make them better for a particular style of use, but there is no "best" dyno.

I have used a DynaPack extensively at a previous job in addition to working with the DynoJet 424x that we have here, and I have to tell you I have been impressed with the new design from DynoJet. We're seeing resolution and repeatability that previously I would have thought reserved for direct-axle connection dynos like the DynaPack.

Our dyno also seems totally free of the center diff and drivetrain issues that plagued us with the DynaPack. It is VERY obvious when a center diff is not happy on a dyno, the vibration alone is enough to cause most people to stop a run and exclaim, "what the hell?" I saw a lot of that with the DynaPack.

And also, as Doug said, our graphs of rear vs. front output show absolutely ZERO torque transfer problems. It's reality, folks. If you want the graphs we will post them.


I would like to point out that many people have an irrational distaste for the DynoJet based entirely on experiences with the previous model which is no longer made. It was a 2WD dyno with a 4WD attachment and was a "limited solution" at best. Please, do some real research on these topics before screaming superlatives like "XXX is best! YYY brand sucks!" It'll help keep the signal-to-noise ratio down on the forum.



Jason Porter
TopSpeed