Q&A Forum
I am using YourDyno V5 to upgrade an old Stuska water brake.
The old data logger system PowerPro is rapidly approaching end of life.
We have a long history of running Ford 2000 pinto engines in a race class called Sports 2000.
The old PowerPro returned torque numbers very much inline with the numbers from the engine builders we work with.
The boss likes to use our dyno to keep the engine builders honest.
4000 to 7000 average torque of 130 to 140.
We have installed the load cell in series with the old Stuska transducer setup.
We have YourDyno water brake valve in series after Stuska manual valve.
we calibrate with load for 110ft/lb and check with added weights to simulate 130 and 150ft/lb.
Both systems (PowerPro and YourDyno) show nicely matching values.
0-2 no load 110-112 at calibration and 148-151 at max load.
However recorded data on YourDyno software shows 7 to 20% lower values.
We are still playing with settings and may be missing something simple.
We have been using Load Control 4000-7000 and manually starting Run.
Also seeing same values using the old hand load control valve with YourDyno valve set wide open.
I have attached a file showing three runs, all (PowerPro and YourDyno) are using J607 correction factor.
I would appreciate any input or thoughts anyone might offer.
I would really like to be able to offer the boss reports with similar outputs.
Thank you Chris
Hi,
The difference is likely in the Moment of Inertia. To double check this theory, do a test at steady state. The two systems shall read the same.
If the difference is only during acceleration, make sure "Compensate for inertia effects during acceleration" is on, and adjust the MOI number so they match.
Jostein, a question about MOI, does it need to be reset for each engine that is run or will the MOI from the rotating assembly not affect it enough to change it?
This question is for an engine dyno water brake setup in particular.
Thank you
@james-meyers MOI varies a bit from engine to engine. Most people don't change it for engines of reasonably similar type, but if you have very different engine and fast sweeps, then you need to change a little. If you are unsure about the MOI, do a ramp up then ramp down, or do two runs, one fast and one slow.
Thank you, I will work on that.