How To: Setup and use Virtual Dyno

[Lex]

Vdyno is a very powerful tool and we love using it. However using it properly is essential to getting repeatable and meaningful results. So how do you go about this?

First of all, remember Vdyno just like any dynamometer is used to show you differences in performance from one tune to another or from installing different components. Always keep this and consistency in mind.

1. Find a flat stretch of non populated (safe!!) road. This road should allow you to run in both directions.

2. When you take your car there keep your running weight consistent. That means no extra stuff in the trunk, passengers, etc. Try to keep fuel levels the same. All these small variables matter.

3. Wind resistance matters. So if it's windy that day, it's not a good idea to take logs.

4. Temperature matters. This however can be compensated for while wind can't. Remember though that all turbo cars lose power in the heat. So if you made 310whp in the winter and you added a big intake and are logging in the summer and you lost power, it's not the intake, it's the temperature. So before making tuning or part swaps, take a baseline run on the same day or close to it. Don't compare runs between winter and summer as it will skew results.

5. Logs in 4th gear are probably best in the MS3/6. The higher the gear, the more load you place on the motor. So the higher the gear the MORE power you will make. Do all pulls in the same gear - whichever is safe for the area you are logging.

6. When taking the log, always start in the same section of road, Always start at the same RPM (3000 RPM is recommended) and just punch the throttle straight to the floor. Don't hesitate. Keep it to the floor until redline.

7. Now, this is very important. Take ANOTHER log going the opposite direction on the same stretch of road. Why? Because you want to make sure your measurements are consistent. If they overlay like the one below, you're doing it right . If they don't overlay, the road is not flat, there is wind, or something else is going on and the data can't be trusted. Remember to take at least 2 runs for every change to make sure there is not error in the run or data until you have the process down and can really trust the data.

8. When setting the dyno type, it doesn't matter what you set it to (Dynojet, CF1.01 etc.) AS LONG as you always set it the same way. The same goes for smoothing. Setting of 3 seems to be optimal.

9. Remember to estimate the weight inside the car, and to accurately calculate your tire size.

10. Finally, Vdyno updates frequently and some versions have calculated power differently. Make sure you are comparing logs using the same version of software.

That's pretty much it. If you're lucky to live in an area that has some flat rural roads with little traffic, you can take some very repeatable logs and results and use Vdyno just as you would a regular dyno. Look at the back to back runs taken below in opposite directions on the same road with the same tune and on the same day.

More importantly - remember to be SAFE!!

[jdmage_mx5]

Thank you @Lex; for the write up.

[jbmazda6]

Good to know that I've been doing it right. Question though.. ever since I've started using your ots maps my vdyno graph doesn't start til ~3800 rpm but when I go back to my logs from cobb ots maps it shows the whole graph. I'm definitely going WOT before 3800 rpm.

[Lex]

Originally Posted by jbmazda6 Good to know that I've been doing it right. Question though.. ever since I've started using your ots maps my vdyno graph doesn't start til ~3800 rpm but when I go back to my logs from cobb ots maps it shows the whole graph. I'm definitely going WOT before 3800 rpm.

This is a very good point.

Vdyno uses the column called Throttle Position (%) to determine when you are going WOT. Depending on the tune, the ECU uses the throttle to hit load targets. This means that the throttle plate will close slightly during spool. This actually promotes spool but it fools Vdyno into thinking you are not WOT yet.

So, just make a copy of your log and set the Throttle Position (%) to 100 during the entire time that your Pedal Position is at to the floor (99% or so)

This is shown below.

[jbmazda6]

Got it. Thought it'd be something that simple. Thanks

[Dimenus]

Great write-up. Also, you make me jealous w/ that BNR

[ms3blackmica]

If you log Accelerator Pedal Position, then you do not have to worry about TPS hitting full throttle values. Virtual Dyno will take the APP column for TPS instead.

On a gen 1, APP will go to 99 and remain so until you let off.

On a gen 2, you may need to manual set them though as it does not lock at a single value sometimes.

[Lex]

Another thing to keep in mind when looking at a vdyno plot - does the curve look realistic? I see a lot of Vdyno plots with a hump or bump in the middle of the power curve bumping the peak numbers. However, often this is caused by a bump in the road and is not representative of the car's power.

To get an idea of what the average DISI K04 power curve looks like - look at dyno sheet as show below. Notice the smooth shape of the curve with peak torque being reached early and falling off in the upper RPM.



When a bigger turbo comes into play or the engine has been reworked for flow, the torque curve is flatter and is usually shifted to the right. However notice again the smooth shape of the curve:

[Lex]

Came across this article regarding logging rates and the AP V3.0. Best to turn off the following display gauges when logging:

First Gen MS3/6

USDM 2006-2007 Mazdaspeed 6
USDM 2007 Mazdaspeed 3
USDM 2009 Mazdaspeed 3
WM 2004-2007 Mazdaspeed 6
WM 2007-2008 Mazdaspeed 3

Accel. Pedal Pos
Battery Voltage
Coolant Temp
Equiv. Ratio
Fan Duty
HPFP Desired Press.
HPFP Sensor Voltage
Throttle Duty Cyc.


Second Gen MS3

USDM 2010 Mazdaspeed 3
USDM 2011-2013 Mazdaspeed 3
WM 2009-2012 Mazdaspeed 3

Accel. Pedal Pos
Battery Voltage
Coolant Temp
Equiv. Ratio
Fan Duty %
HPFP Desired Press.
HPFP Sensor Voltage
Throttle Duty Cyc.
Throttle Duty Desired


Cmd. EGR
Cmd. EVAP
MAP Voltage

https://cobbtuning.zendesk.com/hc/en...-V2-Accessport

[Snip]

Hi Lex,

Sorry to bump your old topic.

great writing, very useful for me as a starter in this.
Just one question, maybe for noobs it's worth adding to the opening post;

What are the channels that are really needed for virtual dyno to make a good dyno sheet?
I'm asking this here, since after a lot of searching I couldn't find a clear answer on the forum, just a lot of opinions of what channels may be deleted to improve the logging rate.

Thanks in advance, and my respect for all the effort and time you guys put in this.

[Lex]

The bare minimum you need are:

- Boost
- Actual AFR
- Engine RPM
- Throttle Position

[Snip]

Cool,

Thanks a million Lex!
Now I don't have to worry i'm forgetting anything needed for a virtual dyno run