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Old 11-10-2009, 02:00 AM   #21 (permalink)
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you forget 1 problem.
the energy from the alternator , is wasted converting rotational power to electric.
lose 25% , then the electric motor , back to rotational. Double losses !!
so you'd have to have a very smart electric pump to compensate for that loss.
huge conversion losses.
no free lunch on that. ( no engine alternator creates free energy either )

you also under estimate the huge amount of wasted energy the engine expels as heat.
Even at idle , and cruise.
The water temp(coolant) must never drop below 150F. or the ECU will drop to warm up mode and while go rich AFR. Defeating the whole purpose.
so you must keep the temp between 150 and 195F.
there is a latency for this , you must not let it overshoot.
so long as you maintain good circulation, you will be ok.

I think the mfg wants to shorten the length of the car by taking out the pump on the front RWD. or on FWD cars a bigger motor fitting between strut towers.
lots of reasons, but efficiency? , sorry im just a skeptic,
show me. with hard data.
Lots of ideas, few , hard facts.

Those inefficiencies above are darn hard to overcome.
SALUD !

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Old 11-10-2009, 08:17 AM   #22 (permalink)
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The key is to control the temperature of the coolant after it has passed through the radiator.

Thermostats control the flow based on the temperature of the coolant exiting the engine, but they do not control the temperature of the coolant exiting the radiator.

Radiator capacity is based on the "worst case scenario" of operation. In every other case it has too much capacity. As you reduce heat losses through hypermiling techniques, you will encounter lower coolant temperatures of coolant exiting the radiator.

When this happens the thermostat will restrict the coolant flow, but that will exacerbate the situation.

Test the temperature of the exit coolant hose in the summer and winter and you will see a huge difference in temperatures, as much as 100 degrees in coolant temperature.

One way to compensate for this is to reduce the effective surface area of the radiator, a radiator block, which has the effect of increasing the exit coolant temperature to bring it up to the temperature of the same coolant in the summer when its hot.

Two ways to fix this would be to have a thermostatically adjustable radiator block, or a thermostatically adjustable radiator bypass. Either solution would make the temperature of the coolant entering the engine constant regardless of ambient temperature or loads applied to the engine.

Basjoos does this by monitoring his coolant fan activity and adjusting his fresh air opening to allow more air flow when the coolant fan operation becomes more frequent.
Making this operation automatic by either adjusting the grille opening or bypassing the radiator would accomplish the same objective of controlling the coolant temperature as it enters the engine.

In his case since air flow through his engine compartment is much less than normal, he also benefits from warm air intake from the higher temperature of the under hood air available to the engine. This is recycling the engines radiated heat for higher efficiency.

I have personally used a radiator block on my Insight and seen a significant mileage improvement in the winter. I Have also completely blocked the lower grille openings on both my Insight and Echo, and it seems to have made a fairly significant difference in maintaining higher mileage as the weather cools down here in the fall.

I know this might seem off topic in relation to electric water pumps, but to me the real problem is not the water pump, but the inconsistency of temperatures of coolant entering the engine and its effect on mileage and thermal stresses.

regards
Mech
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Old 11-10-2009, 06:02 PM   #23 (permalink)
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all well and good.
the thermostat controls the flow of the coolant based on the temperature of the fluid as it just exits the motor. "out of the book" and controlling the flow controls the temperature at the same point. It will never control the temperature of the water temp. as it leaves the Radiator. By Design.

nothing else need be worried , so long as the Radiator has cooling Overhead

Thermal shock? are you cranking blocks?

you forget to state the problem.

you must be discussing , living in the extreme North. in super frigid temperature.
it is SOP to block the Radiator in these locations. since the tin lizzy days. (im 62 just retired,mech)
std.op.proc.

i guess we need a variable displacement radiator.
but a computer controlled bypass is the only solution. and one more thing prone to fail.
cardboard works great. as do the variable louvers on MACK trucks.

my friend (heavy equip. op , mech) in Prudhoe bay AK , they spray the whole motors with instant foam insulation. Extremes have not limit , it seems.
most their equipment never gets shut off ( speaks volumes, no?)

If you have cold operation prob. post them.

thanks for your clear issues.
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Old 11-11-2009, 02:11 AM   #24 (permalink)
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I work on a road race car with an electric water pump. with a 2.0 Liter ford OHC engine the pump runs at about 10% most of the time. and We take the thermostat out because the controller controls the speed of the water flow to the preset temperature. It takes surprisingly little water to cool the engine at speed. Oh, and the car has no alternator, we charge the battery between races, our sequential shifter solenoids use more power than the water pump. (We have full data logging on just about every part of the car....) I can correlate the battery charge at each turn...

Dave
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Old 11-11-2009, 03:53 AM   #25 (permalink)
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Quote:
Thermostats control the flow based on the temperature of the coolant exiting the engine, but they do not control the temperature of the coolant exiting the radiator...

Two ways to fix this would be to have a thermostatically adjustable radiator block, or a thermostatically adjustable radiator bypass. Either solution would make the temperature of the coolant entering the engine constant regardless of ambient temperature or loads applied to the engine.
Is "too cold" coolant temp variation incoming to the block an issue?

Cuz if the thermostat says brrr I'm cold, it closes, then flow incoming to the block is restricted/stopped. The net result is pretty consistent coolant temp in the block pretty much whatever the coolant temp leaving the radiator is... right?
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Old 11-11-2009, 07:29 AM   #26 (permalink)
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Sounds right to me. I'm interested in this thread because my block heater is an externally mounted one with connecting pipes to the engine. I have no choice in that. However, my temps never get up to much while the heater itself is piping hot. If i had a low wattage mains driven pump then i could heat the engine more evenly.

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Old 11-11-2009, 10:29 AM   #27 (permalink)
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All depends on the run time of the pump AKA how much waste heat you have.
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Last edited by dremd; 11-11-2009 at 10:40 AM.. Reason: can't spell
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Old 11-14-2009, 12:36 PM   #28 (permalink)
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race car , i wonder how that race car does in N,Dakota. in the winter?
Most ppl here?,expect it to work full time all the time. not on some track.

sure as i said, the temperature can be controlled at all times with flow and the rate of flow and with more than one sensor, when its really hot and when very cold.
a PIC processor and some tables. nothing more. ( with elec.pump)


Thermostat is a very reliable device and is gosh darn dirt cheap.
it regulates fully linear from closed to open (wax expansion)

one can argue that having simple system is better.
relying on the STAT and the belt. ( few parts)
the early rage for electric fans was.
low hood line.
and too small radiator was used for same, and now motor overheats at a engine kill.
so it kicks on ,parked key off at 225F or higher.

it for sure saves lots of fuel , when driving on a highway, that is for sure.
if the duty cycle is low. 10%
if the DC is high, it uses more energy (fuel) because of it's poor efficiency.(double conv)

keep in mind any extra piping is just more that can freeze.
same with external pump. (mind that antifreeze)

there must be this huge list of pros and cons
engineering is a compromise and must include bad weather.
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Old 11-14-2009, 01:01 PM   #29 (permalink)
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The 81 Horizon I had the electric water pump that I drag raced was also my dailey driver. I even used it several times a year during the winter when the cars the USPS used would not start....I never had a problem in the years I had it and neither did the second owner. I left so early for work back then that my car was the first out into the snow nearly every day...our area would never get plowed until later in the day....my car was the plow!
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Old 11-14-2009, 02:07 PM   #30 (permalink)
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I think it is safe to say that an electric water pump on a thermostat will save energy on just about any ecodriven vehicle. BUT if you are operating in conditions which create lots of excess heat, then the mechanical pump will win out.
However the time for the pump to pay for itself is very long.

I had a short talk with a manufacturer of an electric cooling pump last week at SEMA ad they estimated that run time was between 5% and 20% on a SBC depending on conditions.

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