TO DO OR NOT TO DO ELECTRIC WATER PUMP

how hot you getting? I was about to put an electric water pump. on my 351.

Why are you putting a restrictor in the thermostat??? You think the hole is too large allowing the water to move thru the ratiator too fast??? Where do you think the rest of the water resides? The engine temperature gradient is way steeper than the ambiant/radiator temperature gradient, you want to get the heat out of the engine, not keep it in. Take it out, regulate the waterpump speed to the temperature.

Wallzy said:

Why are you putting a restrictor in the thermostat??? You think the hole is too large allowing the water to move thru the ratiator too fast??? Where do you think the rest of the water resides? The engine temperature gradient is way steeper than the ambiant/radiator temperature gradient, you want to get the heat out of the engine, not keep it in. Take it out, regulate the waterpump speed to the temperature.

Click to expand...

You just do not have enough information to make that statement.

1.
You have a restrictor in your car, it is called a thermostat. Your thermostat is a flow restriction, and it limits how fast coolant can flow through your radiator .

2.
Engine temperature gradient is way steeper than the ambient/radiator temperature gradient, but this is only because engine coolant has a high thermal capacity. This means engine coolant can absorb a good amount of heat energy, before dissipating it. This is why "engine temperature gradient is way steeper than the ambient/radiator temperature gradient"

3.
This is where you missed the boat
The radiator can only exchange so much heat energy, for a given surface area and rate of air flow. Temperature gradient, and rate of heat exchange do not directly coenside. If the engine releases a spike of thermal energy, It is absorbed into the thermal capacity of the engine coolant. You must thermally saturate the engine coolant, before you see a chance in temperature.

Bottom line: You do not want a coolant to flow at a rate that exceeds the rate of heat exchange of your radiator.

OK

So HOW do we determine the required flow rate?
Water Pumps are rated in GPM, usually...

How would one determine the needed coolant flow rates for the coolant?


We can decide what flow rate is required by experimentation or by calculation.
But how do we quantify the needed flow rate?

jason

Personally-I'd stick with a regular W/P. Preferably Edelbrock, i dont like relying on an electric motor for my cooling. Thats just my .02 cents.

Ant

Electric water pumps suck for street cars, and are even worse for a Daily driven street car, it's not if but when the cars going to overheat or the pump is going to go and leave you stranded.
Every person i know with one has had some type of issue.
Besides the waterpump doesn't soak up that much power.
Stick with a normal pump, the FMS replacement is pretty cheap and reliable.

enyawix
Quote:
Originally Posted by Wallzy
Why are you putting a restrictor in the thermostat??? You think the hole is too large allowing the water to move thru the radiator too fast??? Where do you think the rest of the water resides? The engine temperature gradient is way steeper than the ambient/radiator temperature gradient, you want to get the heat out of the engine, not keep it in. Take it out; regulate the water pump speed to the temperature.



You just do not have enough information to make that statement.

1.
You have a restrictor in your car, it is called a thermostat. Your thermostat is a flow restriction, and it limits how fast coolant can flow through your radiator .

2.
Engine temperature gradient is way steeper than the ambient/radiator temperature gradient, but this is only because engine coolant has a high thermal capacity. This means engine coolant can absorb a good amount of heat energy, before dissipating it. This is why "engine temperature gradient is way steeper than the ambient/radiator temperature gradient"

3.
This is where you missed the boat
The radiator can only exchange so much heat energy, for a given surface area and rate of air flow. Temperature gradient and rate of heat exchange do not directly coincide. If the engine releases a spike of thermal energy, It is absorbed into the thermal capacity of the engine coolant. You must thermally saturate the engine coolant, before you see a chance in temperature.

Bottom line: You do not want a coolant to flow at a rate that exceeds the rate of heat exchange of your radiator.

Click to expand...

Actually, I can make that statement.

1) A thermostat is used to keep the engine at a constant temperature (within a certain design range) by opening when the temperature gets too hot, and closing when it cools. You are correct that a thermostat will restrict the flow, but it's primary function is to maintain constant temperature in the system under a variety of "driving styles" and wether conditions.

2) The temperature gradient between the engine vs. the coolant inside the engine (block/heads) and the coolant in the radiator vs. the ambient air has nothing to do with the engine coolants thermal capacity. Its thermal capacity is dependant on the additives to the coolant and the pressure at what the system operates. These things are what prevent regular water at atmospheric pressure from boiling inside the engine. Point is, when you look at a heat transfer curve, for delta temperature over time (assuming heat loss to a stable heat sink, such as the outside weather conditions of a particular time and day), it is a parabolic curve with your highest amount of heat loss to ward the beginning of the curve, thus by keeping the water inside the radiator (in a free flowing system, not a thermostat controlled system) you are not rejecting heat to the atmosphere as fast as you can.

3) Missed the boat...hmmm - "A radiator can only exchange so much heat energy,"

--Yes, but it is also dependant upon what is going on in the flowing system, not only what happens outside of the system.

"Temperature gradient and rate of heat exchange do not directly coincide"

-- This statement is completely incorrect, the temperature gradient between the radiator and the air around it most definitely does...this is why cars have a greater tendency to overheat in the summer than in the winter.

"If the engine releases a spike of thermal energy, it is absorbed into the thermal capacity of the engine coolant"

--This is correct.

"You must thermally saturate the engine coolant before you see a change in temperature."

--This is not correct either, saturating means that the coolant can not hold any more energy in it, by thermally saturating the coolant you are creating a state change within the system, aka nucleic boiling. Ultimately changes in temperature are caused by differences in temperature gradients.

Bottom Line: Your rate of heat exchange is determined based on a set flow rate, but changing the flow inside the system - while holding everything else constant- one can increase or decrease the rate at which heat can be extracted from an engine.

Here is the real problem, and it is hard to see unless you look at the entire system:

A radiator exchanges heat, BTUs, and the faster they can be extracted from a system, the cooler the overall system becomes. You can't look at only what is going on in the radiator. By slowing down the flow into the radiator, you are rejecting more heat from the radiator per given time, but your heat rejection rate is actually lower because of the dependant factors heat transfer. At the same time that you are absorbing way-way-way more heat from the engine per given time. This becomes a circular problem. By capturing the heat, and getting rid of it as fast as you can, you can reach a steady state that is lower than if you slow your flow down.

I have a few thermodynamic books I can recommend to you if you want to check them out.

Walz

monte87 said:

Personally-I'd stick with a regular W/P. Preferably Edelbrock, i dont like relying on an electric motor for my cooling. Thats just my .02 cents.

Ant

Click to expand...

I have found several guys with the Meziere pumps who run them on the streets and the track, over several years without problems.

Buy a cheap e- pump and you may have issues.
Good e- pumps will be just as reliable as mechanicals.


Why does everyone freak out about the 'reliability' of e- pumps?

2000xp8 said:

Electric water pumps suck for street cars, and are even worse for a Daily driven street car, it's not if but when the cars going to overheat or the pump is going to go and leave you stranded.
Every person i know with one has had some type of issue.
Besides the waterpump doesn't soak up that much power.
Stick with a normal pump, the FMS replacement is pretty cheap and reliable.

Click to expand...

Isn't this the case with many 5.0's running mechanical pumps?
How often do you find threads here with guys who can't keep their coolant temps under control?
Not one that I can think of was running an electric pump...

I suppose a mechanical pump has never failed on you...
leaving you in the middle of nowhere...



I'm not going to try and convince you guys that e- pumps are the greatest thing since sliced banana bread,
I'm just throwing out my perspective on it.

Take it for what you think it's worth.

Wallzy said:

I have a few thermodynamic books I can recommend to you if you want to check them out.

Walz

Click to expand...

Please do!
I have been wanting to pick one up for a while.

PM if you like


jason

You do want to maintain some level of coolant flow while getting the motor up to temp.

Stagnant coolant will cause localized 'hot spots'

i've been running a Meziere (WP373) water pump on my 94 GT for 2 years, 180* T-Stat, Stock radiator, 50/50 coolant mix in Phoenix, AZ. i do not have any overheat problems.

if you run a Meziere w/ idler WP373 (94-95) or WP312 (pre 94) you have a bypass just like your stock water pump.

jason89gt said:

I've got a CSR pump with no bypass How would I run a bypass or do I need to if i go back to a thermostat? Thanks Jason

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I'll go against the grain here .. .. ..

I have recently installed a CSR Billet electric water pump. Best money I ever spent!!

I'll tell you why this works great for my application.

The reason your taking your thermostat out? ( For me anyway ) Because your CSR pump like mine, runs at a LOW CONSTANT SPEED. Regardless of what your engine rpm is.
What's the use of closing a thermostat, if your water pump will never increase the flow amount of coolant. ( This is why I like it---> ) I can be buzzing around town all day long and hanging at 200 degree's. Get stuck in rush hour? Boo Hoo. An electric water pump cools your car down fastest while sitting idling at the lights! ( or wherever ).

Even faster if your like me and have a manual override and can run the fan and water pump while the car is sitting shut off! ( Another thing a belt driven pump can't do )

My car was at 220 degree's one day when I shut her down, now me a few buddies sat and watched her this time. From 220 to 140 degree's in 6 1/2 minutes!
I love it!

My application could use a bigger rad. ( I have a Griffin aluminum, but it's stock configurations, so it's limited in my car, and I have a big cam and turbo sitting on top my baby, so I need all the cooling I can get.

And the story about: Oh, you can't tell if it craps out on you? ( cause it's electric )

Boo Hoo again. Been there, done that. How about you do what I did ( besides the manual override ). Put a little red or green light in the cockpit! Water pump shuts off .. .. .. Light goes out. ( you watch your gauges right ) Problem solved.

- Put a light and a manual override switch in the cockpit

- Put the 1" washer in ( Your CSR needs minimal resistance, but some, or according to them, you can burn the pump )

- Someone else here said it too, make sure you have a proper size rad. ( Prob the most important )

- Go Hard

Like I said, this is what works for my Foxbody, and I've been dealing with overheating issues since the first day we fired her up with the big cam.

Then again, maybe it's just me


P.S.

If you check out my Gallery, you can see the newer pics I put up.
Check out my water pump install. I have great heat in the car, great cooling, and no hassles!

( And the cool pic of my cockpit! )

Strange it is over a year later and I do not over heat. Actually I have a hard time getting to 180 on hot days.

The main reason I don't want electric besides for the huge price tag, I haven't seen any you can use with heat, or can you? I figured you could but just haven't seen fittings coming out to go to the heater lines.

Black1987Stang said:

The main reason I don't want electric besides for the huge price tag, I haven't seen any you can use with heat, or can you? I figured you could but just haven't seen fittings coming out to go to the heater lines.

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i spy heat on mine