Engine dyno with Eddy current brake
I'm looking into building an engine dyno by myself. But with an Eddy current brake instead of waterbrake.
I am restoring classic cars and i'm doing quite some engine rebuilds. I want to run them in and tune them before they go to the customer. I'm prefer an engine dyno with Eddy current brake because you don't have all the water stuff. I have seen that ie. a KLAM-CFK300 has a max RPM of 6200, which is perfect.
My question: Why are for engine test dyno's the water brake more common? And is overheating an issue with eddy current brakes?
A water brake is the most common brake for engine dynos. The reasons are mainly as you say max RPM and no run time limit as long as there is water available.
The Klam brakes are special in that they tolerate quite high RPMs. Water brakes can go higher still in RPM (to at least 10.000 typically) but 6200 is enough for some applications. Klam brakes can also be had with copper wires, instead of alu wires. The resistance of Alu wires is more impacted by heat than copper wires, so copper wire brakes have less reduction in the brake's torque capacity for long runs (it is still fairly significant).
Klam can give you a torque capacity vs run time that you can check out and compare with your needs. There is no problem to use an eddy brake as an engine brake if the braking spec is acceptable for your application.
I got in touch with KLAM and got my answers. Seems they are quite suitable for engine dyno's. For example a CFK500 can absorb 160 hp at around 2000 rpm continuous.