Coolant flow

Bewy said

Saying higher coolant temps looses power as an absolute is simply incorrect. It may or may not.

It will depend on what results from higher coolant temps. If it is a 'looser' engine that has increased the internal clearances, then there is a power gain from less friction. The oil thins out as temps increase & can reduce friction, increase hp. The power output of an engine like a 383/440 is far less likely to be affected by coolant temps because there is no coolant in the intake manifold to heat up the incoming air.

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All true. But I say cool(er) engine temperatures and THIN(er) oils.

You need to run a quality synthetic oil (not Group III oils) which BTW, makes more power.

I can easily run a 0w20 oil and still carry 75 psi hot at 7,000 RPM. On 160 degree coolant temperatures.

A big mistake is dropping your coolant temperature and continuing to use heavy grade oils. Which BTW using thinner oils allows for tighter clearances. Which reduces oil flow demand which means you can use a smaller oil pump and that saves some power.

That adds up to win, win, win.