[QUOTE=trackbird] The problem is, a water pump not only moves water, it pressureizes the block. Water under pressure will have a higher boiling point. So, you will be less likley to boil water that is pressurized by a mechanical water pump.


The pump doesn't pressurize the coolant. That happens when the coolant expands due to heat. There is just as much pressure in my system now as before with the mech. pump.

 

[QUOTE=slimdawson]
You are incorrect. The pump is pushing water into the block. The thermostat resists letting it out. You will generate "pressure" in this situation. When the pump has more capacity than the "leak" at the other side, you will have pressure.

Think of the thermostat as a door. Go lean on a closed door. You can put several hundred pounds of force (body weight) against that door. The door is closed so you are not moving (no flow), but you have pressure.

Make sense?

When these belt driven pumps are using 7 hp or more (you gain 5-10 hp with an electric pump?), they are using enough energy to pressurize the block against the thermostat and the return lines. That HP is being used somewhere. Any that is not going into flow, becomes pressure (or essentially so).

 

This is also why you need to run a thermostat,without that resistance the water flows too quickly through the radiator to cool properly. I do have a question though. What about these electric motor kits that hook to a stock pump if the motor was big enough it could be ran on a rheostat type activator to spin faster as you increase in RPM's,and in princible this should work,right?

 

I still disagree with the pressure theory. Let's say you have a 15lb radiator cap. Obviously it opens at 15lbs. I will bet money that no mech. water pump is going to make anywhere near 15lbs of pressure. Therefore, any pressure it is capable of is useless. The only pressurization in your cooling system comes from the expansion of water. I know that the thermostat blocks water when closed, but the pump isn't efficient enough to pressurize water to the point of raising the boiling point.

 

Water is a incompressable fluid. The pressure comes from the water expanding and compressing the little bit of air that is in the system that can't get out because of the radiator cap.

 

okay guys, when it comes down to it, which is better, electric or mechanical....there are some very good points here, its hard to tell..

 

Again a electric water pump is not for a daily driven street car. Period

 

the waterpump doesn't pressurize the system, it is the heat expanding the water and the radiator cap regulates the pressure..
http://auto.howstuffworks.com/cooling-system7.htm

 

Has anyone ever put their finger over the end of a hose with the water running? I may be wrong ,but I would say that is pressure. Pressure can be brought on by many things including heat.

I also don't think that electric pumps are meant for the street,don't think they are meant to run full time,that is why most are run on a on/off/on (tic toc) switch which turns on when the engine water gets hot ,then off when cool ,etc.,etc.

 

I know several people running them on daily driven cars with no problems.

Also, people always say that you need to have a thermostat or your car will overheat from the coolant flowing through the system to fast. BS I ran a 355 with no thermostat for a summer and into the start of winter with no problems at all (until winter time, it kept the coolant so cold that my heater didn't work very well).

Have you ever been to a demolition derby or figure 8 race? Every one of those cars that I have worked on, we take the thermostat and knock out the center, so it is just a restrictor. I am sure those cars run in way more stressful conditions than your daily driven car.

Martin

 

Key word here is "RESTRICTOR "! That is exactly what a thermostate IS.

 

Yes I am aware of that, but I also said that I ran a 355 for several months without the thermostat all together. No restrictor plate or anything. No problems at all, temp gauge hovered at 160ish all the time. I guess if you want to say not to do something because you heard it won't work instead of actually knowing it won't work, thats cool.

Martin

 

Then again if you have a really good radiator and get the coolant temps down farther you won't need that pressure.