scootz
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| posted on 19/12/08 at 03:24 PM |
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Electric Water Pump
Does anyone use one?
I have the facility to use the mechanical drive pump from my existing engine, but it's going to involve a bit of fabrication... might be easier
to block up and just use an electric one... anyone have any opinions on these?
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02GF74
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| posted on 19/12/08 at 03:29 PM |
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pretty sure Razman (he of the blue aeaon) has one fitted.
other than expense (pump + controller) not heard anything bad about them; also not sure how long they've been around so cannot comment on
longevity.
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BenB
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| posted on 19/12/08 at 03:32 PM |
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Are you thinking of a Davies Craig water pump?
They have a reasonable reputation. But not perfect- I know some of the people on the Sevens list have them fitted and have had some failures. Whereas
a mechanical one will slowly break (usually as the impellers wears away) an electrical one can fail suddenly. Then you're left with convection
as your only way the coolant will circulate, and unless you keep a close eye on the water temperature, possibly a cooked engine....
They also take quite a bit of juice which might be an issue if your alternator isn't the most powerful in the world....
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scootz
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| posted on 19/12/08 at 03:46 PM |
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Was thinking about the 'Stewart' type.
I'll stick with the mechanical one if it's financially viable to convert it (the audi pump has a spaghetti junction of pipes coming out of
it for air-con and ancillary rads, etc... I just want it to pump ONE pipe - not 5!) 
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mr henderson
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| posted on 19/12/08 at 03:51 PM |
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If it's a question of avoiding complexity, and it can be done without causing any other problems, then I would say go for it.
There are no other advantages to electric water pumps, though
John
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matt_claydon
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| posted on 19/12/08 at 03:55 PM |
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There is one additional advantage. When you come in after a track session and switch off, the pump and fan can continue running and your engine will
cool down nice and quickly ready for the next session.
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mr henderson
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| posted on 19/12/08 at 04:30 PM |
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quote:
Originally posted by matt_claydon
There is one additional advantage. When you come in after a track session and switch off, the pump and fan can continue running and your engine will
cool down nice and quickly ready for the next session.
Well, if you are having an overheating problem then I guess that would be a good thing. Can't see the advantage otherwise, especially when the
thermostat closes.
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mark chandler
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| posted on 19/12/08 at 04:43 PM |
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Ah but there are advantages running an electric pump, that's why some race series have banned them as its a simple way of getting more power out
of what could otherwise be a standard engine.
CEC pumps are designed to run most efficiently at the normal engine speeds so once you go above say 3000rpm they are pushing water around too fast and
costing you BHP.
You can also get the problem of the water cavitating, I think that’s how it’s spelt but all it means is that its going so fast the water starts to
froth around the blades.
The solution here is fit a smaller pulley, but now we have lost flow at low revs so an electric pump again is ideal.
Regards Mark
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mr henderson
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| posted on 19/12/08 at 04:46 PM |
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quote:
Originally posted by mark chandler
Ah but there are advantages running an electric pump, that's why some race series have banned them as its a simple way of getting more power out
of what could otherwise be a standard engine.
CEC pumps are designed to run most efficiently at the normal engine speeds so once you go above say 3000rpm they are pushing water around too fast and
costing you BHP.
You can also get the problem of the water cavitating, I think that’s how it’s spelt but all it means is that its going so fast the water starts to
froth around the blades.
The solution here is fit a smaller pulley, but now we have lost flow at low revs so an electric pump again is ideal.
Regards Mark
OK, I will grant that for racing the electric pump may well be advantageous. For a road car, though, would you agree that an electric pump does not
have any particular advantages over the standard unit?
John
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scottc
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| posted on 19/12/08 at 05:53 PM |
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I understood, with the 'right' controller you can configure the pump output dependant on temperature.
so for example <60 degrees off
>60 <100 at 50%
etc
That way pump only runs when its needed, only consumes power when its needed and the car can warm up quicker.
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iiyama
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| posted on 19/12/08 at 06:02 PM |
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Ive removed the stat as Im using an electric pump. The pump controls the engine temp via the pump controller. Engine will generally heat up quicker
and have a much more stable temp when using an electic pump. Ergo they will be better in a road car as youll probably get better mpg.
If its broke, fix it. If it aint broke, take it apart and find out how it works!
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mr henderson
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| posted on 19/12/08 at 06:24 PM |
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quote:
Originally posted by iiyama
Ive removed the stat as Im using an electric pump. The pump controls the engine temp via the pump controller. Engine will generally heat up quicker
and have a much more stable temp when using an electic pump. Ergo they will be better in a road car as youll probably get better mpg.
Hmm, not too sure about that. I reckon more coolant coud get past a stopped impellor than it could a closed thermostat.
In any case, it makes you wonder why the original manufacturers don't use electric pumps, most of them would do if it would improve their
officially tested mpg figures
John
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mark chandler
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| posted on 19/12/08 at 06:29 PM |
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For a road car covering many thousands of miles an electric pump is overly complex, its all about the application.
For a kit car then it has advantages, for example a rover V8 water pump sits above the block, chopping this out would allow you to reduce bonnet
height, beyond the BHP returns
Horses for courses, lots of things on this site are also not applicable to normal road cars, throttle bodies and mappable EFI immediately springs to
mind but we still use them.
With regard to economy, the belt driven pump is designed to work most efficiently at cruising engine speeds so no advantage to economy, its all about
BHP flat out.
[Edited on 19/12/08 by mark chandler]
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austin man
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| posted on 19/12/08 at 11:08 PM |
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I was told not sure if its true that the newer Volvo's run electric pumps may be worth looking into as this may be a cost saving option
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Richard Quinn
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| posted on 20/12/08 at 08:46 AM |
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quote:
Originally posted by mr henderson
quote:
Originally posted by iiyama
Ive removed the stat as Im using an electric pump. The pump controls the engine temp via the pump controller. Engine will generally heat up quicker
and have a much more stable temp when using an electic pump. Ergo they will be better in a road car as youll probably get better mpg.
Hmm, not too sure about that. I reckon more coolant coud get past a stopped impellor than it could a closed thermostat.
In any case, it makes you wonder why the original manufacturers don't use electric pumps, most of them would do if it would improve their
officially tested mpg figures
John
Read the first part of this post again and maybe part of it will become clear. A mechanical pump runs all of the time and requires a
thermostat to control flow. The water is still flowing around part of the circuit. Why, apart from a little convection, would the water be flowing
past a stopped impellor? An electric pump can be off or on and can run at variable speed. A thermostat is therefore not required. They are, however,
expensive and quite complex and probably don't warrant being included in production cars for this reason.
[Edited on 20/12/08 by Richard Quinn]
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nike5
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| posted on 1/1/09 at 02:07 PM |
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Works well on my V8.
Pros
- always working at maximum, so is good in traffic (ie places where max cooling is needed but mechanical pump would be idling at slow speed).
- can be used to avoid heat sink if left running after engine turned off
Cons
- Idea that you are gaining horse power, because you are reducing mechanical loss from crank pulley, is offset against the extra electrical drain on
the alternator.
(unless you are an engine builder trying to massage the power output, by putting the engine on the dyno, without using an alternator and using a
separate battery ;-)
- If anything goes wrong, you can not go to local shop to buy another one, especially if you buy it from America.
- In 5 years I have had one fail. If going to a trackday or driving holiday I carry a spare to get me out of trouble (just in case).
I am happy with mine, but aware of the cons too.
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