You cannot answer the question as asked for the simple reason that flow rates are not static. Flow rates change with rpm and system restrictions. The rates are plotted on a curve and flow rates will vary all along the curve. Different engines seek highest flow rates at prescribed rpms and certain systems are designed for the highest efficiency.

Furthermore, the person asking the question has a unique cooling system which has likely been modified to affect flow. Comparing it to any other is perhaps fine for the coffee shop crowd but its rather... unscientific.

The reality is that most people are simply asking us this question because they heard a sales person say our pump pumps "x" gallons per minute and they want to find a pump that pumps "x+1" gallon per minute.

What we cannot understand is why a company would provide a gpm flow rate for any other reason than marketing. Admittedly, if you bench test a pump and run the pump until the curve peaks and write down the number you could make the marketing claim that this is the flow rate and some will accept it. Unfortunately, we won't do that because it is at best an oversimplification and at worst misleading.

To honestly answer the question you must to test one pump against another pump in a controlled environment to get an unrestricted number. Then you need to put the pump on an engine in a controlled system and test the two pumps against each other again.

Thirty eight years ago, we did just that this when we created the first high flow water pumps. Our goal then was outperforming OEM pumps and the self professed performance pumps. When we make any design change to further improve the flow rates, we test internally and, if warranted, test on dynamometers. Our goal is to achieve twice the flow rates at idle and maintain a 20% advantage along the curve.

What we find is that as rpms approaching 3,000 the flow rates are maximized in most systems and it is here that we see the ancillary benefits of higher system pressure.

If you read all of this and are still not satisfied. The answer is 42.  If we have to explain that too; uncle.