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Joe K · 06-12-2019, 10:03 AM

Um. The reason for pressurized systems in modern cars is to raise the combustion cylinder temperature and achieve measurably greater gas mileage. Also to provide amenity like effective cabin heat - but that is an "after advantage."

As far as heat transfer goes, in a non-pressure system, heat transfer would be less. A higher radiator temperature will cause a greater delta T with the air and greater heat flow in proportion to the delta Ts.

A pressurized system might be of advantage if you're running very close to saturation temperature (i.e. 212) and you want to prevent cavitation in your pump (its called "net positive suction head" NPSH for pumps) where pulling a vacuum at the eye of the pump cuts severely into flow.

That said, there is no reason NOT to stay pressurized since you're already there - assuming the radiator was designed for it.

This radiator may have been an "adaptation." As in no rolled seam at the upper connection juncture?

Joe K
I like the part about one "getting his hood up!." Very apropos.

06-12-2019, 10:03 AM	#37
Joe K Senior Member Join Date: Jul 2010 Location: Cow Hampshire Posts: 4,188	Re: radiator failure Um. The reason for pressurized systems in modern cars is to raise the combustion cylinder temperature and achieve measurably greater gas mileage. Also to provide amenity like effective cabin heat - but that is an "after advantage." As far as heat transfer goes, in a non-pressure system, heat transfer would be less. A higher radiator temperature will cause a greater delta T with the air and greater heat flow in proportion to the delta Ts. A pressurized system might be of advantage if you're running very close to saturation temperature (i.e. 212) and you want to prevent cavitation in your pump (its called "net positive suction head" NPSH for pumps) where pulling a vacuum at the eye of the pump cuts severely into flow. That said, there is no reason NOT to stay pressurized since you're already there - assuming the radiator was designed for it. This radiator may have been an "adaptation." As in no rolled seam at the upper connection juncture? Joe K I like the part about one "getting his hood up!." Very apropos. __________________ Shudda kept the horse. Last edited by Joe K; 06-12-2019 at 10:08 AM.