1UZ-FE dyno day, 127 to 180 rwkW N/A

[CHOKE ON THE SMOKE RACING]

<Sigh> This is the kind of BS that always seems to happen when people express their opinions in the form of an attack. Keep it civil, or we'll lock the thread.

Yep same old **** just a diffrent forum.

Ps sorry for retaliating.

 

[rms]

A couple of things re Dynojet v Dyno dynamics dyno's.

From what I believe the Dynojet is an 'inertia' dyno and calculates power from the acceleration rate of a known weight (roller). There is no direct measurement of wheel rpm or torque. Physical calibration of this dyno would be very difficult - there is no practical way to verify the calibration.

The Dyno dynamics dyno uses a load cell to measure load at the roller. The load cell calibration can be physically verified.
Now the 'fudge' factors.
To calculate wheel torque and speed needed to calculate bhp YOU MUST ENTER WHEEL DIAMETER into the dyno. I have yet to see an operator measure the wheel diameter and enter this into the computer.

The Dyno dynamics specifications re max torque ASSUME a 23.5" wheel dia. I assume that this dia is their default setting.

I think this is the main reason we see wildly different figures.

 

[V8Datto]

What about if you left the car in first gear/low gear? wouldn't this be able to turn the dyno easy and give out a higher figure?

Eg: A mate of mine had the same car as me (V6 holden 5spd manual's) a few years back, His car recorded 110kw atw, and mine on a different dyno recorded 85kw atw.
Yet mine pulled harder from a set of lights.

ofcorse peak power has nothing to do with drivability but we could never figure out how the dyno's could put out such odd and wrong numbers.

For this reason alone Id more use a dyno for tuning a car or finding more power with mods.

 

[rms]

That is exactly my point.
Did you or your mate see them measure tyre diameter and input that figure into the dyno?

The higher figure in a lower gear at the roller is only the TRACTIVE force (lb or Kg) at the roller, it is NOT TORQUE. To calculate torque lb/ft or Nm from this force you MUST know the diameter of the tyre.

You MUST also know the tyre dia to calculate the wheel speed in RPM from the roller speed.

Only when you know the torque (lb/ft or Nm) at the wheel and the rpm of the wheel can you calculate rwkw or rwhp.

On top of that you have atmospheric changes and what the figures are corrected to.

 

[turboandrew]

Makes a negligible difference what gear you are in. They measure HP by seeing how long it takes to go from X RPM to Y RPM for the roller, then they calculate torque, using your RPM logs from your engine. No need for tire diameter whatsoever. You need to log roller RPM and engine RPM (with adequate resolution) and that's it.

http://www.bristoldyno.com/info/whatis.htm

 

[4000GT]

A couple of things re Dynojet v Dyno dynamics dyno's.

From what I believe the Dynojet is an 'inertia' dyno and calculates power from the acceleration rate of a known weight (roller). There is no direct measurement of wheel rpm or torque. Physical calibration of this dyno would be very difficult - there is no practical way to verify the calibration.

The Dyno dynamics dyno uses a load cell to measure load at the roller. The load cell calibration can be physically verified.
Now the 'fudge' factors.
To calculate wheel torque and speed needed to calculate bhp YOU MUST ENTER WHEEL DIAMETER into the dyno. I have yet to see an operator measure the wheel diameter and enter this into the computer.

The Dyno dynamics specifications re max torque ASSUME a 23.5" wheel dia. I assume that this dia is their default setting.

I think this is the main reason we see wildly different figures.

I doubt it. Most of the Dyno's are hub dynos in NZ...

Also if this difference was to be explained by not entering the wheel diameter, then you are also assuming every time someone here doesnt enter it, somehow the value not entered over your way is less than here. Donest really seem plausible does it?

 

[rms]

Turboandrew,
If you use an 'inertia' dyno you can not measure power at a constant (fixed) speed, rpm, or throttle setting. They are useless for mapping an engine over the range of throttle and rpm.

e-solver,
Please read the heading - 'Dynojet v Dyno Dynamics'.
Nothing about hub dyno's.
The dyno sheets I have seen from NZ are headed 'Dyno Dynamics'.
I am not assuming that MOST NZ dyno's are one or the other.

On a rolling road dyno you must know wheel diameter to calculate torque,wheel speed and power - agree?

 

[cjsupra90]

A couple of things re Dynojet v Dyno dynamics dyno's.

From what I believe the Dynojet is an 'inertia' dyno and calculates power from the acceleration rate of a known weight (roller). There is no direct measurement of wheel rpm or torque. Physical calibration of this dyno would be very difficult - there is no practical way to verify the calibration.

The Dyno dynamics dyno uses a load cell to measure load at the roller. The load cell calibration can be physically verified.
Now the 'fudge' factors.
To calculate wheel torque and speed needed to calculate bhp YOU MUST ENTER WHEEL DIAMETER into the dyno. I have yet to see an operator measure the wheel diameter and enter this into the computer.

The Dyno dynamics specifications re max torque ASSUME a 23.5" wheel dia. I assume that this dia is their default setting.

I think this is the main reason we see wildly different figures.

Not saying that you are backwards cause I dont know much about dyno dynamics products, but I do know that dynojet units are brake (load) type dyno's, not inertia type.

 

[cjsupra90]

Ok, sorry I am wrong, according to dynojets website, they are inertia type. I was wrong in what I thought.

Now where I am confused is that how can a inertia type unit such as a Dynojet be used to simulate road / driving conditions for testing and diagnostics as Dynojet states? I thought that inorder to do that that you need a brake / load type dyno so that you can simulate a load.

 

[Damien]

On a rolling road dyno you must know wheel diameter to calculate torque,wheel speed and power - agree?

I asked the guy who dynos my car about this - he said that the dyno can calculate the power to turn the roller because it knows the tractive force measured on the load cell, the diameter of the roller and the speed of the roller. This is on a Dyno Dynamics so in that case tyre diameter isn't needed.

They then get the relationship of roller speed to RPM by running the roller to 100km/h and then input the engine RPM into the dyno at that point.

If you dig through Lextreme you'll find a few other threads about the differences in measured power on NZ dynos compared to Aus. I think we should forget about the numbers altogether unless someone in NZ can dyno a bog stock Soarer or Celsior so we can compare the baseline data. A stock V8 Soarer in Aus will get somewhere between 120 and 130rwkw.

 

[4000GT]

Turboandrew,
If you use an 'inertia' dyno you can not measure power at a constant (fixed) speed, rpm, or throttle setting. They are useless for mapping an engine over the range of throttle and rpm.

e-solver,
Please read the heading - 'Dynojet v Dyno Dynamics'.
Nothing about hub dyno's.
The dyno sheets I have seen from NZ are headed 'Dyno Dynamics'.
I am not assuming that MOST NZ dyno's are one or the other.

On a rolling road dyno you must know wheel diameter to calculate torque,wheel speed and power - agree?

So you are left with everyone here overestimates configuration settings when compared to those in Aussie?

 

[Damien]

If most of the NZ dynos are hub dynos and most of the Aussie ones are Dyno Dynamics there must be something in that to explain the differing figures.

 

[4000GT]

If most of the NZ dynos are hub dynos and most of the Aussie ones are Dyno Dynamics there must be something in that to explain the differing figures.

Thats what I suggested, but RMS explained every comparison he made sure the sheets for from the same brand of dyno.

I think there is one or two rolling road dynos in the south island, not sure about north.

Most people are understandably using Dynapack dynos given they are made here...

 

[striker]

A couple of things re Dynojet v Dyno dynamics dyno's.

The Dyno dynamics dyno uses a load cell to measure load at the roller. The load cell calibration can be physically verified.
Now the 'fudge' factors.
To calculate wheel torque and speed needed to calculate bhp YOU MUST ENTER WHEEL DIAMETER into the dyno. I have yet to see an operator measure the wheel diameter and enter this into the computer.

I think this is the main reason we see wildly different figures.

I don't know what the tuners and dyno owners are like at your side of the globe, but one won't get away with that in europe....

Even in rolling road mapping very acurate figures are taken, that's very popular in the UK,
I had both done and altough the actual dyno time (and additional mapping) yielded a little better curves and more torque in the lower parts of the band, the startpoint measurement taken on the dyno was within 2hp of the values that the rolling road (absolute weight versus G-load and distance) so even that can be very acurate when opperated right.

grtz Thomas

 

[rms]

For a rolling road if you do not know the wheel speed and torque you can not calculate bhp.
A hub dyno knows the axle speed and torque.

If I have not done the maths correctly, please show me the error of my ways.

The roller speed is the same
The force at the roller is the same
The only difference is the wheel speed and diameter
BHP = (torque x rpm)/5250

 

[4000GT]

How does the calculation help determine the difference between NZ and AU figures you find?

 

[striker]

you can determine how much force is needed and for how long to move a certain weight over a certain distance, when you know the G-load things get really interesting with also accel ratio etc etc

from there you can determine just about anything you want.

so not all is nessecary if the car is actually moving...

grtz Thomas

 

[rms]

How does the calculation help determine the difference between NZ and AU figures you find?

You seem to be pushing an OZ v NZ thing here. Sorry, won't bite.

ALL rolling road figures (from wherever) are suspect as shown above, unless the operator takes all the variables into account and they are stated on the dyno results.

 

[4000GT]

You seem to be pushing an OZ v NZ thing here. Sorry, won't bite.

ALL rolling road figures (from wherever) are suspect as shown above, unless the operator takes all the variables into account and they are stated on the dyno results.

Mate you said all NZ figures are higher than AU ones... The only offering you seem to be making is that the settings we use make our HP higher. Im not trying to make you bite anything, I am trying to understand why you think our figures are always higher as you dont seem to have a plausible explanation in my opinion.

 

[Death By Bass]

Mate you said all NZ figures are higher than AU ones... The only offering you seem to be making is that the settings we use make our HP higher. Im not trying to make you bite anything, I am trying to understand why you think our figures are always higher as you dont seem to have a plausible explanation in my opinion.

cos you're a bunch of waynkers...

sound fair? haha