Mike!
Is this Dyno stand in your garage? You called it a stand so I kinda assume so, and it goes with the statement about " they told me".
Mike, this is not normal.
Your stand has to be set up just as it would be in a car, but even more importantly is the fan. Since it can pull air anywhere it wants to. It absolutely needs a fan shroud, and the fan needs to get up inside it. I would make sure the filler spout is the highest point in the system, install a gutted stat,and straight water. Now fire it up with the rad cap off,and immediately check for water circulation across the top of the coretubes. This will prove that the water is circulating; Or not. If you can't see the water rushing away from the top hose, the pump is not working. Go find out why. It could be that the bottom hose is plugged, or the coretubes are not passing the water down, or the pump impeller is not turning or it has lost it's fins.While you are staring down into the filler hole, look for bubbles. Bubbles could mean a blown headgasket, so if you see 'em, take a little whiff. If there is exhaust gasses coming out of there, you will be able to smell it.
To be sure, there are a couple of other reasons why the engine might spew its coolant, but get this sorted out first. Then you can chase the little things; like timing.
But Mike, If your engine is spewing in the DYNO ROOM, under load during a run, the dyno shop will have most of this bugged out already. So then you will want to show up with good headgaskets.
To that end, you will want to pressure test the system. I would test the cooling system first, to 15/20psi, and make sure it holds that, with no internal leakage. If that shows any sign of trouble. I would do a cylinder leakage test. I would try to test at 80/100psi, and watch for pressure escaping from the open rad. You can test with a 7/13psi cap, listening for it to blow off.
But above all make sure your waterpump is working.And if you can'tmake the filler spout the highest point in the system, then you will need a special recirculating reservoir, placed up high and plumbed in with a special cap on the rad.If you do not do this you will be stuck trying to burp the engine. This is not always easy.
Good luck!
