greenman43 wrote:That said, some engines need to have the coolant stay a bit longer in the rad - if it passes through too quickly, it doesn't shed enough heat ...
Mmm, I've heard comments like this before, and I'm no expert, but it does not sound feasible to me. Passing through the rad slower to shed more heat would have the equal and opposite reaction of passing through the engine more slowly and gaining more?!
I suspect that the orifice plate is more to provide some back pressure to the pump to prevent cavitation at high revs. That's the exact reason that I fitted a water pump from an Integra Type-R engine to my track car. It is driven by the cam belt and has 21 'teeth' instead of the normal 19 and requires a longer cam belt to suit.
(-8'