DIY Kart Dyno Using a Mychron - Rear Axle Mounted

GoKart Projects & Restorations
21

I don’t think you need a servo. Just by using a needle valve in line with the pressure output side of a hydraulic motor would work. Closing the needle valve would create the pressure drop for the increasing the load on the hydraulic motor. This would be similar to a water brake dyno operation. Not sure why hydraulic dynos are not popular but there must be a reason.

Also, it’s likely that these lightweight systems are very unstable or difficult to control RPM because there is no inertia (the weight of the kart is the “inertia”) to filter higher frequency pressure changes.

22

Hydraulic dyno always recycle the media, so without a large quantity of oil, the oil gets hot and the viscosity drops. With water you can just let it go down the drain. Keep a cool supply fresh water going to the absorption unit. I think that explains it. If anything starts leaking, no problem with water, big problem with oil.

23

Oh yeah, water brake dynos don’t recirculate the water.