Hi,

Nice dyno. 

The brake is the master. So number of pulses per brake revolution is what we are after. So if the trigger wheel is on the brake axle (which it looks like here), then it is easy; the pulses per revolution is the same as the number of teeth on the trigger wheel.

In terms of speed, you need to calculate from the brake's point of view. In this case, the roller diameter divided by the gear ratio.

Cheers,

Thanks J.....

so from playing with the software it seems you have a bit of "calculations going on in the background based on my choices in the options...I have attached a pic of the SF documentation and these modes shown in the image were a choice you made in the software depending on car placement on rollers and if front load cell and rollers are connected.. mode 5 and 6 are my first priorities, the difference between the two is if the front rollers are connected. disconnecting the front rollers reduces the inertia from 3800 lbs to about 1800. lbs..

I am assuming I will need a profile for each of my modes...any guidance on options choices would be great!....my thought was to start with mode 6 as it is the simplest...using that mode now in a sweep run(0% brake) is pretty accurate, when we add load the HP numbers go way high..

Thanks for the help!

Yes, the best is to use different profiles for the different modes. If you disable an RPM sensor (set it to Not Used), then this wheel pair is ignored, including its load cell and associated inertia.  

thanks for the timely response.. 

so...... I understand the concepts but am a bit confused on some of your verbiage..

as the above video shows, I only have one RPM sensor so I will never be disabling an RPM sensor. 

and also note....my eddy currents are connected to each other in the middle of the chassis, they are not attached at the axle like the 4wd dynos shown in the documentation

and YES....sometimes I will need to ignore the front load cell, but NOT the inertia(see difference between mode 5 and 6 on attached file)

AND...please confirm, Is the inertia established by the MOI tests?

I am trying to get a grasp on what you are doing behind the scenes. for example: if I change the number of teeth on the RPM sensor my HP results change.....??

if you need any other pics or vids let me know

Bart

If the dyno has permanent 4WD setup (no clutch or ability to disconnect front and rear) and brakes are connected together in the middle, then you only need 1 profile. You should not need to turn off one of the brakes, right?

Hi J...

The brakes are permanently attached, they can never be disconnected( see video) and they are mounted 90 degrees to the rollers.

there are 4 modes that will be used

light RWD mode......front rollers and front loadcell are detached

heavy RWD mode....front rollers attached, front load cell ignored

FWD mode.....front rollers attached, rear load cell ignored

AWD mode...front rollers attached, both load cells contributing

I do not know of any manufacturers that make this type of dyno, it weighs 12,000 lbs.

I think the video on the beginning should be helpful, if you need more details let me know 

my big struggle is the load cell data is not being incorporated into the equation properly. As I said before in "light RWD mode" with NO brake being added the numbers are OK.....if I add brake the 400hp car will now be 1200hp...after running your MOI test  with only the rear rollers attached the MOI was 108

Bart

OK, so there is a clutch to disengage the fronts or the rears.

You can do 4 profiles to match that if you prefer. I would expect the AWD mode to work well on all cars though, unless the rollers are very heavy.

Since you only have 1 RPM sensor, it will either be configured as:

Load cell 1 RPM (for only Brake1) 
Load cell 1+2 RPM (both brakes)

I assume there is no difference whether you use the front or the rear brake when you only want one of them operating, since they are connected together. If you have to only enable either front or rear, then you need 2 RPM sensors. 

Leave the number of load cells as 2 for all configurations. Any load cell without an RPM sensor assigned will be ignored (e.g. Load cell 2 is ignored if RPM1 is configured as Load cell 1 RPM and RPM2 is configured as Not used).

Set the brake outputs that are in use to Brake Control, and the output(s) that are not used to Not used. 

Yes, you can use the MOI wizard to measure the MOI. I prefer checking it manually first though. There are some good tips on how to do that in the software manual.

THANK YOU!

this gives some great insight to configuring the setup....I will implement all of this and get back to you soon.

Bart

OK after taking some time to study your response I have a couple clarifications...

facts: both brakes are always engaged and they are both getting commands from output 1. output 2 is NOT USED. I only have one RPM sensor, RPM 2 is NOT used. Loadcell 1 is assigned to rear loadcell, and loadcell 2 is assigned to the front load cell

profile 1: front rollers are disconnected and load cell 2 info is not needed...so I set option/ RPM1 to "LOADCELL 1 RPM" 

profile 2: front rollers are connected but loadcell 2 info not needed....so I set option/ RPM1 to "LOADCELL 1 RPM"..........AND the only difference between profile 1 and 2 is the MOI will be different.

profile 3: all rollers and load cells are connected and needed....so I set option/ RPM1 to "LOADCELL 1+2 RPM"........AND MOI would be the same as profile 2

Other than the differences listed above, I should not need to change any configuration settings than those listed above, correct?

theoretical question.......remember my rollers and the brakes are rotating at different speeds. the brakes spin 2.2 times faster than the rollers. Does this not have an effect on the power output? or is resolved with the MOI?

Thnks again....Bart