Hi,

First double check that your Pulses per dyno rev is correct, then do the Gear ratio setup in the Run... window. Gear ratios are now saved per Session, so you need to do it there. I will remove the Gear Ratio from the normal Options menu.

• Thanks for your response..How do I know what pulses per Dyno rev is correct? By gear ratio in the run window you mean the Rpm/ gearing setup page?

Posted by: admin

Hi,

First double check that your Pulses per dyno rev is correct, then do the Gear ratio setup in the Run... window. Gear ratios are now saved per Session, so you need to do it there. I will remove the Gear Ratio from the normal Options menu.

Please dont remove that window in the options, Its what I use for Speedo calibrations using a gear ratio setting of 0.093,
Could you instead just rename it to something like Speedo calibration and change the RPM to KPH and keep it saving its own setting.

(Maybe put in the notes as well about setting it up. I cant remember the forumlar I used for roller size. But easy way is just use a car with 100% accurate speedo. Then set it like you would the RPM gear ratio)

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Open a run,
Then next to where the buttons for brake setup and stuff there is gear ratio.
Use that to set your RPM up.

I got it! Thanks guys for the help!

I have another question..when setting up the Rpm/gear ratio like this would it work on a cvt transmission that the ratio is constantly changing? Is there something I can get to show rpm without going through this process?

Wouldnt work using the roller gear ratio. Since as you said there is no fixed gear box ratio.
Better option with a CVT car would be to tune by speed since the CVT will try and keep the car at its peak torque RPM so RPM would mostly be a flat line while power falls as the speed goes up. But then only way you can truly tune a engine being fitted with CVT is to tune the engine only on a bench dyno.
Then tune your CVT seperatly using the graph you got from the bench dyno for the motor.

Software doesnt have speed feature yet.
You can sort of fool it like I do with speedo calibrations. But your torque readings going to be massively wrong since the software still treats it as RPM instead of KPH.

• So if I run a Cvt on it peak power will still be correct it just won't show with Rpm? And it seems like once I can use a Rpm adapter with the software I should be able to use it correctly with a CVT?

YourDyno expects a fixed gear ratio. A continuously changing gear ratio is possible to support, but it is not straight forward. I will look at it to see how it could be done. 

I would think taking a true engine rpm reading would fix this issue instead of using a caluculated rpm reading..if not could you please explain?

The biggest problem your going to have is the cvt is going to try keep rpm at peak torque the whole time so rpm is going to be a straight line.

Welcome Mrs_Blobby!

The software today calculates the torque and HP, taking into affect brake torque and acceleration of the moment of inertia. This is measured and calculated at the brake, then converted using the fixed gear ratio to engine numbers. What needs to be done when the gear ratio is changing during the run, is to for each sample calculate the gear ratio and use this when converting to engine torque/HP. So it is definitely possible, just a bit of software work. 

OBD2 for engine RPM reading may be too slow when the gear ratio is constantly changing. Updates are slower than the other data (it varies with the ODB unit) and the synchronization in time is not as accurate as when using the RPM2 input (where the timing is completely under YourDyno control). It may still be semi-ok as the gear ratio does not change that much over a short period of time, but it is not as accurate. 

Automatic brake control may be tricky with a CVT, as the CVT tries to keep the engine RPM constant. I don't see how you can get a nice RPM sweep. But it is possible to measure the power in the sweep. 

We ran a Cvt on this dyno tonight and locked the variator to only open up so far but keep low gear and did our Rpm readings there.. We are still getting very inconsistent readings.. tomorrow I'm gonna turn a couple more spacers to lock the front variator in one postion  (without low gear) and try again..I will keep you guys updated!

Hi,

The option to use the second RPM input as spark plug signal is almost ready. It will support wasted sparks. Setting the gear ratio then is just a matter of pressing 1 button. But it is not really difficult to add support for continuously changing gear ratio too, so while I am at it I may just as well do that. This will then only be supported for the second RPM input, not when OBD2 is the source for engine RPM, as the delay and update rate is not fast enough. The update I am working on now is quite large, with OBD2 support for the first time, so I might break this into two releases.

That said, you should stick to a specific gear and do all your tests in that gear for a given car. Moment of Inertia changes with gear ratio as well as drive train losses.