Why did that new thread on engine cooling disappear ? I thought the article was very informative and I learned a few things . Did it violate something ? It certainly was about cars and cooling. Don
No, one was posted for only a short while this morning and after I read it and went to post it was gone. It discussed how a cooling system really functions and was written by someone in the business for 30 years. The one thing it pointed out was that it is a myth that removing a thermostat altogether makes an engine run hotter. I agree with that point. I am running no thermostat in my 27 because I am running a bored out stroker with a chopped radiator, and when I removed it the temp went down 10-20 degees and stays there now. I hope he reposts the article without the offending ads. Don
I agree as well. For a properly set up cooling system, increasing the water velocity cannot possibly cause the engine to run hotter. Here's the formula for basic heat transfer using a 50/50 mix of water/glycol as the heat transfer media: BTU/hr (this is the rate of heat from the engine transfered to the coolant) = gpm (coolant flow rate, gallons per minute) x 400 (conversion factor) x temperature difference in degrees F (water temperature leaving the engine minus the water temperature entering the engine). Radiators are designed for a specific BTU and temperature difference, so they behave according to the same formula. By increasing the flow rate, you can see that the temperature difference decreases. This is basic thermodynamics and the physics of "energy in equals energy out minus the energy stored". "Energy stored" equals zero for a properly set up cooling system. When "energy stored" becomes greater than zero, the engine goes boom.
I agree that increasing the coolant flow will not cause an engine to overheat. That said; in some situations when the thermostat is removed the increased flow can reduce the pressure in the eye of the pump impeller to the point that the pump begins to cavitate. When that happens the coolant flow drops to near zero. And as we all know lack of coolant flow is a bad thing. This happens most with stock water pumps running at high speed. I had a Pontiac that the internal baffle plate in the water pump had rusted through. This caused the engine to over heat at a specific RPM. I believe that the missing baffle plate was causing a cavation issue. It was interesting to watch because dropping below that point the temperature dropped instantly; above it was like no cooling at all. Fixing the pump cured the whole problem.
"It’s amazing sometimes to talk to an individual who thinks factory engineers don’t know much.Thing to recognize is that factory engineers know a helluva lot more than we do and get into sophisticated areas that the great majority of us know nothing about.What I’m talking about is the stubbornness and unwillingness to learn from those who’ve been down the road before us. Keep in mind too, factory engineers are constrained by the bean counters, and the necessity to build a vehicle that is useful to the majority ... " quoted from our very knowledgable late friend ... C9
Increased flow will not cause a pump to cavitate. The Net Positive Suction Head available (get your minds out of the gutter, this engineering speak)....or positive pressure at the pump's impellar inlet will INCREASE when the thermostat (a flow restriction) is removed. Cavitation is primarily caused when there is LOW pressure at the inlet, usually due to too much of a flow restriction. But this issue usually does not come into play in a closed system. Open hydraulic systems are more prone to cavitation issues.
A side note: My truck with a 350 sbc was running hot. I pulled the fail open style thermostat out and found that it had failed open on one side with the other side wedged shut (the prongs had contracted on one side and not the other). I put a regular Stant thermostat back in and it is running fine now.
The Jalopy Journal
