[Dessertrunner]

Your point is interesting Joe, what I have noticed is that if I am driving the car at a constant speed but have it in 4th gear (6 speed box) when I should have been in 6 th gear the engine runs hotter. The moment I change to 6 th the tempreture of the engine drops. This is part of the reason that I agree with Tom on the top pipe. Somewere in the system when you increase flow the restriction in the left bank must get worse. Clearly there has to be a flow problem some were.
I am going to jump in at this point before I get every one coming out and saying this is a clear indication of cavitation of the pump. I AGREE THEY COULD BE RIGHT but it is best to stop this problem by reducing the restrictions in the pipe work and heads to enable the pump to handle higher speeds.
To explain at my work we have 3 by 500hp diesel pumps that each pump 300l of water per second. If we increase the speed on them to pump 400lps the suction pipe feeding the pump is to small and we get cavitation at the pump. This happens inspite of the suction pipe being 600mm in diameter. To solve the problem we changed the suction to 800mm and the problem went away.
Sorry to get off topic but I want to make the point we still have a lot of things to do such as increase the suction pipe from the radiator before we try to reduce the flow of the pump. It may turn out that we have to do that as well later but not now.