285 whp!

[longassname]

Tony,

If I'm reading you right you are saying the eg33 and 4 cylinder suby water pumps have the same output but the 3.0 6 cylinder water pump has a higher output.

The svx water pump pumps
20 liters per minute at idle
100 liters per minute at 3000 rpms
200 liters per minute at 6000 rpms

While charging ac systems after engine installations I've observed that coolant temps go down above 2500 rpm's so I'm comfortable saying that 100 liters min is about the minimum flow rate you would want. I don't have any information to indicate an upper limit where cooling performance drops back off. I imagine you either have that or can get that with your rig by forcing your fans on high and going for a drive at increasiningly high rpm with an already fully warm engine and monitoring the difference between the temp of the coolant entering and leaving the radiator (watching for a drop in the difference). If the difference continues increasing as you raise rpm's then it would be plausible that a higher flowing water pump like the 3.0 liter's would improve cooling performance--otherwise, identifying the upper limit of coolant flow where cooling performance drops off will identify how much you should try to underdrive the water pump by.

Originally Posted by Dessertrunner

A couple of people suggested that we need to find out the coolent flow rates of other Subaru engines. I was at Subaru today so I looked up the work shop manuals on the different engines. As they say a "Picture paints a thousand words".
- Checked all the different four cylinder engines and the water pump put out 200l at 6,000 rpm. Sound familiar.
- The best news was the next thing I checked was the 6 cylinder H6 and it surprisped me. It pumps 320l at 5,500rpm.

So my guess is our engines are cooking from lack of water flow.
Tony