Got my "Save a Drop" water meter in the mail yesterday. Unfortunately it only shows accumulated flows and no gal/minute mode. That means I could not insert them in the running engine system to measure flow rate there.

Claims +/- 1.3% at 6 gal/min, 70 psi and 68 deg F. Max pressure 116 psi. (Sounds like there is a rotating "wheel" inside when water flows.)

So I did two one-minute runs that gave 18.1 and 18.5 gal/min (varies by pump pressure as you can see from the calibration spreadsheet). But the calculated flow rate in the spreadsheet (in zip file) comes out to about 16 gal/min average.

For some reason the 0.807" ID homemade flow sensors (with 1/16" OD pitot and static tubes) appear to produce lower pressures than predicted by the formula referenced in earlier recent posts. I calibrated the differential pressure sensors I use (MPX10) with a water manometer, so I'm fairly sure that my measured inches of H2O (head?) pressures are accurate within a couple percent.

That means that the Renesis total flow (see the other attached spreadsheet) could be as much as 12% higher or 53 gal/min at 4,800 engine RPM.

Again, I have two radiators in parallel, with as low as 1/2" ID restrictions in fittings and welded tubes.

Calibrations were done with pure water. Engine (system) runs with 50/50 antifreeze. At running temps (180+ F) the specific heat difference should be about 12% (only changing the 0.186 to 0.203 in the spreadsheet formulas).

What I don't know and hope one of the experts here (Steve Boese) can clarify is if zero system pressure (calibration flow of water emptying into the air) vs system pressure (varies with RPM and temps; couple of psi to as much as 8 psi in some of the runs) in the engine runs would make a difference.

In any case I'm now fairly sure that coolant flow rate and flow balance between the two rads is not a factor in my cooling issues.

Finn