Dyno Cheating / How to create false figures with incorrect strapping | Roller Climbing

Ever wondered how certain companies see magical numbers, higher than everyone else? More often than not it is a simple case of dyno cheating!
Numbers sell, however, this does not mean your car or tune is any better than someone else.....
The Method:
You'll see how the car is moving a lot to start with when shifting gears, once loaded at the start of the power run, torque builds allowing the car to climb all the way to the top roller - during the power run as torque starts to drop the car will naturally try to drop back into the dyno bed fully. All this is from having loose rear straps, simply tightening the straps will prevent this from happening.
The Theory:
On a two roller dyno such as dyno dynamics, dyno developments etc the rear idler (not gripped) roller is part of the calculation for final HP.
When the wheel 'climbs' up onto the front roller the inertia of the wheel is no longer turning the rear roller, therefor the rotating mass of this idler is no longer spinning but the dyno calculation for this is still present. This method gained ~30HP/30LBFT over correct strapping method.
Check out our M2 Tuning video to compare strapping / car movement on the dyno!
Full Blog write up - wp.me/p9G7fa-1dm
Rolling Road / Dyno - Dyno Dynamics, Dyno Tech
Location - South East, Kent, near Sittingbourne
Check out our online HP Calculator to see what we can offer for your car @ wgmotorworks.co.uk
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[@gnkVLCT]

AT and IT differences being far as well....

[@Scouse.Malinois]

This is true and false, you can cheat a dyno this way but there is also some tuners who purposely dyno this way and its not to cheat you, weather its the type of dyno or the way its calibrated I don't no but I've had my car dynoed both ways, at one dyno where it doesn't move and a different dyno where it climbs the front roller and the figures where basically the same

[@MotortunePhoB]

This video is relevant only for twin roller dynos, where these rollers are not mechanicaly connected/linked. Otherwise doesnt matter. Just potential traction issues will make the difference.

[@ARDEN440i]

Very interesting. Great video Warren. What kind of dyno do you use? Is it a Mustang or a Dynojet?

[@WGMotorworksYouTube]

Its a Dyno Dynamics - Dynotech :)

[@ARDEN440i]

@@WGMotorworksTH-cam Ah nice. These kind of dynos usually add a bit of resistance to simulate driving on a road, so they tend to read out slightly lower, but more realistic power and torque figures. By far the best dyno available 👍🏾 In the US they refer to it as a "Mustang" dyno.

[@WGMotorworksYouTube]

Yeah, they are more accurate in our eyes, especially when making stock figures! - Dynojets that read WHP only read a lot higher, in fact - dyno dynamics has a 'comparison feature' to compare their WHP to Dynojet WHP

[@tunedbyrabbid]

DynoJet or Mustang is a separate brand of dyno not a type.
You have three dyno types Inertia Dyno's, Braked Dyno's or a Hybrid of both.
Inertia dynos just rely on a larger heavy mass and measuring the rate of change in speed of the mass people love to say how they're accurate as you know the mass of the roller but that not true..The roller isn't all the rotating mass, there is also wheels, shafts, gears clutches etc. This is the drive line mass which has inertia.
DynoJet's are complete rubbish in the USA, rather than properly calculating drive line inertia they just added a fudge factor to increase the numbers on their original bike dyno. (Google DynoJet fudge factor) I think it was they measured 90WHP on a bike that was meant to be 120WHP with a brake. So the 33% fudge was input into their software so it popped out 120WHP.
This fudge carried on to all their car dynos too. The problem with inertia dynos is they don't keep a constant acceleration rate so your error changes up and down with acceleration rates depending whether you've over or under calculated the total inertia of the dyno. As you add more powerful vehicles they accelerate the roller faster and end up with huge errors.
All rolling roads have error but Dyno Dynamics gets as close as you can get to the real number.
What you're seeing here is the amount of inertia assumed by the software is changed from what is rotated by the car. By removing the rear roller the inertia it has is no longer part of the total inertia of the rotating mass the car is pushing. The software still includes this as it has no idea the car has lifted and the extra power from the car is being transferred to the brake. So it's effectively counted twice.
Dyno Dynamics hold a fixed acceleration rate whether you're 100 or 1000WHP and have a drive line inertia locked into the calculation. If the drive line inertia is wrong you'll get a the same error at 100WHP or 1000WHP whether it be 1HP or 5HP its comparable regardless of the power and the more power you make the smaller the error gets as a percentage.
On a DynoJet there is no drive line inertia they just under read the rotating mass then fudge it with a percentage so the error is a percentage so if you have a 5% error at 100WHP that becomes 50HP at 1000WHP
On a dyno dynamics you measure as much as you can with the brakes load cell and minimise the amount of inertia involved by restricting the acceleration rate with the brake.
If you measure at steady state there is no inertia power reading and their is only brake power reading which is accurate WHP. If your power increases or decreases when you use a ramp or sweep test your total inertia is wrong.
During a power run you're running a hybrid between a brake dyno and an inertia dyno.
If you did a step test where you step at 100 or 500RPM intervals you could measure the vehicle at every single point in steady state with no inertia but that would be stressful and very heat intensive for the vehicle.
And that's before we even begin to talk about fly wheel calculations.

[@leehearsey]

nice motor that ;)

[@WGMotorworksYouTube]

Could do with some more power though :P

[@leehearsey]

@@WGMotorworksTH-cam I'm sure it'll get some in the future 😋

[@robertolombardi3698]

Lovely M2 Lee, I had one in the beautiful Long beach blue.

[@leehearsey]

thanks mate, it is lovely shade :)

[@WGMotorworksYouTube]

@@leehearsey Not quite San Marino, but still up there :P

[@230JS]

I also use Dynotech(Dyno Dynamics) at my workshop. Never miss a beat. Love it!

[@WGMotorworksYouTube]

Ours has been running for 4 years without any issues also! And consistent results