Q&A Forum
I have a DJ 250i motorcycle dyno and after having suffered countless problems with the EX+ electronics (DJ’s older gen) I’m going to update it to YourDyno.
As I want to get rid of all DJ electronics, I’ll go for the Standard V5 instrumentation unit + eddy current brake power supply.
i know I have to order a load cell but I’m not sure about which one. In the picture attached (no picture, this is my first message and I can’t find how to do it) you can see the load cell placement in this dyno is not vertically placed but at an angle of about 30 degrees (yet to be accurately checked) So, I think the maths for the load cell will include a factor of about 15% (1/cos(alpha)) but I’m not sure of the right load cell to order.
The dyno is rated at 750 hp but I can’t foresee testing bikes of more than 200 hp. As the cylinder diameter is roughly 50 cm, at a max speed of about 300 km/h the max rpm the drum will reach is around 3200 rpm. Considering a 200 hp bike the calculator in the site and the angle increase factor I’d need a 172 Kg load cell, so, I guess a 200 Kg load cell in on the safe side.
I’d like someone more experienced to confirm this value is correct
Besides this, the retarder in the dyno is from Frenelsa but I don’t know it it’s rated at 96V or 192V. Does someone know how to verify this (or what DJ uses). In some of their documemtation I’ve read that wiring is different for 120 V vs 240 V mains, but I don’t know if this has some influence to connect the YourDyno power supply.
I have more questions related to the use of a Zeitronix ZT2 and ZT3 combo I use for datalogging on twin cylinder (Ducati) bikes but now it’s a bit early for more questions!
Hi,
The load cell should be placed 90 degrees to a line from the middle of the brake. The load arm (or more accurately, the line from the middle of the brake to the connection point of the load cell) does not need to be horizontal, although this is the most common.
The normal way to calculate the correct load cell is Load cell size (kg) >= Max brake torque (Nm) / 9.81 / Torque arm length (m)
If the brake is never over say half the capacity then you can use half the capacity when calculating the load cell. But in that case you should limit the max voltage output of the power supply in the software to make sure there is no risk that the brake will go to higher load.
You can measure the resistance of the brake to determine if it is 96V or 192V. 96V is around 5 Ohm while 192V is around 20 Ohm. You need 220-240VAC input to the YourDyno PS, and 192V is better than 96V (lower current, less noise).
The problem is that I haven't found any spec on the retarder, so I don't how to find out the max Nm spec for the retarder
To be on the safe side, fitting a 500 or even 750 Kg load cell would be a safer option? I prefer not to worry about max braking if there's no adverse side effect when using a higher capacity load cell.
By the way, how can I attach pictures to my posts?
I think the picture is now added!
Maybe that helps: https://www.dynojet.com/motorcycle-chassis-dynamometer-model-250i/
The Retarder is: Frenelsa model F16-120
500kg is good.
Thank you both Marco and Jostein. Now it's crystal clear for me!!!
Standard V5 Instrument kit, brake power supply and load cell ordered!
Can't wait to have it all set-up and working!
As we're in the high riding season, I don't have much time to spend working on updating my Dyno to YourDyno.
I've decided to fit both the V5 instrumentation and brake power supply in the original Dyno electronics cabinet.
I've built a small aluminum holder to place the power supply just in from of the cabinet fan to ensure proper cooling. The V5 instrumentation is fitted at the bottom of the cabinet so that the base is free for DJ'a original power supply to feed a Zeitronix ZT-2 and ZT-3 combo I plan to use both as Oxygen sensor controllers and datalogger. This first question is about this.
And this is how the basic layout inside of the cabinet looks like...
Now comes the question about my Zeitronix oxygen sensor controllers.
I'll be using two oxygen sensors as I'm a Ducati (V-twin) specialist and in my experience, both cylinders must be tuned independently.
The ZT-2, besides being an oxygen sensor controller, is a datalogger. This unit is very useful for my as I can record rpm/TPS/AFR1/AFR2.
Each session can be exported into .CSV format and then loaded into EFI analytics' MegaLogViewer and converted into an AFR table. Fast, straightforward and easy!
My first question is if this can be done straight into YourDyno software or if I have to keep on using Zeitronix's application (which is simple and works flawlessly for me).
I'm planning to use my Zeitronix combo both for the Dyno and for the datalogging software. This is why I've fitted the original SJ power transformer which outputs 15V, well within range of the 10 to 18V input Zeitronix accepts.
BUT, when I need to use it as a datalogger, it needs to get power supply and earth from the bike itself as the reference for both TPS and RPM.
I'm planning to install a DPDT switch in such a way that I can choose between the 15V power supply in the cabinet or 12V from the bike.
I might consider using a DPDT relay but I don't know if there's a simple way to control this from YourDyno software. This is my second question about this topic.