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Message
All,
Been following the EWP thread with interest....
Sooooo...., actually knowing little, but suspecting
much:
I'd suspect that Mazda designed the water pump and flow
characteristics to provide adequate cooling for an idling engine in Phoenix in
the summertime. I'd also bet that the majority of time, a car is sitting
at idle, as opposed to cruising down the freeway at 70 mph.
My suspicion is that the water pump is designed for some
arbitrary flow rate that will be adequate at idle - and at normal cruise
(with it's attendant increased airflow). I'd guess that the pump
is flowing a much greater volume of water at high RPM's than is really
necessary, because the pump impeller is not variable. The engine
temperature does not remain cold, because the thermostat closes, either
completely or partially to keep the block temperature at 180-deg.
Have ya-all ever driven a car with a stuck-open
thermostat...? The engine never warms up. Runs OK, but builds-up
sludge and carbon inside.
Therefore (if all that's correct) an EWP will
not have to pump a correspondingly greater volume of water as engine speed
increases. I agree that it will take more flow for a higher horsepower,
the question remains: "What MASS of water per unit measure of time will cool 180
HP...?"
Here's a suggested test for someone with an engine:
Run a rotary with an EWP and radiator combination (no temp
regulator) (may need a fan).
Run the engine at idle, until the temperature stabilizes at
(say) 180-deg.
Measure the flow rate required.
Increase the RPM's to 2000, and increase the flow rate (if nec) to
stabilize the temperature at 180-deg.
Measure the flow rate required.
Increase the RPM's to 3000, and increase the flow rate (if nec) to
stabilize the temperature at 180-deg.
Measure the flow rate required
Jack Beale
----- Original Message -----
Sent: Monday, November 08, 2004 3:31 PM
Subject: [FlyRotary] Re: EWP Info- Lynn?
As I’ve suggested
before, I don’t see saving power consumption as a reason for considering an EWP,
especially considering the losses in converting mech energy to electrical and
back again.
I think the
biggest chance to save power on cooling is if Mazda is providing way
more than is necessary at our cruise rpms. I have to suspect that's the
case, since Todd is running just fine with only 9.X
gpm.
Al (I swear I will not say another
word about EWPs; that beheading thing is just too scary)
Ha. Don't
worry, my wife would kill me if I stained the carpet
:-)
As for EWP's
saving power, you'd think that the first people to jump on that would be the
racers. I know that these pumps are sold to drag racers, but I can't say
that I've heard of other types of racers using these pumps.
Hey Lynn,
-Are EWP's
against the rules?
-Has someone
determined that they don't save any HP?
-Has someone
determined that they won't cool the engine in racing
conditions?
Cheers,
Rusty (just can't
have any fun on this
list)
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