Electric water pump

[chrishewett]

Has anyone fitted an electric water pump to a twincam?
They seem like a good idea on the surface - fitted in an afternoon, easily serviced or replaced and supposedly more efficient. How would the standard waterpump be disconnected and would there be any resultant increase in bhp?
Your thoughts please gentlemen.
Chris

[v7slr]

I strongly disagree with the way most EWP's are marketed. The manufacturers' intentions are always to run the EWP with their temperature-controlled PWM controller and no thermostat. The controller alters the flow of the coolant depending upon coolant temperature and this is where I part company with their intentions.

In theory you want the smallest temperature gradient across the head, particularly across an alloy head, so surely the best idea would be to retain the themostat and just run the EWP flat out all the time? I now a few people in the Se7ens community who have implemented EWP's and all, except one, have implemented them according to my philosophy (although not because of me specifically, they arrived at the same philosophy independently).

Cheaper this way too because you won't need to buy the controller.

Just make sure you buy one with enough pumping capacity. There are a few that look insufficient to me.

Another benefit is that you can leave it pumping after you switch the engine off, so it continues to cool the engine and prevents heatsoak.

[forfenderjazz]

If it were my car I woudn't consider going to an electric pump. I think for drag racing they are good, but to run on the street? The electrical drain would be hard for most alternators to keep up with. The reliability??? No way, not for me. They are a neat sounding idea though.

[v7slr]

I previously spoke out on another forum about their reliability, only to be shot down by some facts, like:

An EWP MTBF is higher than a traditional water pump.

A normal water pump is spec'd to work at both idle and max revs. At max revs it has normally gone beyond its ability to pump any more water than it did at 3/4 revs, so it cavitates. Run an EWP flat out and it will pump water without the losses associated with cavitation, so while I agree that at low revs it may be working harder than it needs to, the fact that it is always running at its optimal speed means that little wastage is felt. Your alternator may be working harder than before but you will have no water pump to turn. I am led to believe the savings are greater than the losses.


As I said, this was pointed out to me by other people. I have no personal experience but if I were building an engine nowadays, I would certainly go down this route.

Other benefits occur when, in the far future, you have to replace your EWP. It is usually positioned in a far more accessible place than the traditional water pump and won't require the removal of drive belts to get at it.

[john.p.clegg]

With an electric pump fitted externally(in the top or bottom hose)you will only get a minimal flow of hot water through the heater matrix wether the thermostat is open or closed-maybe no problem to yourselves but here in the chilly U.K. I like my heater hot in the winter.
John

[v7slr]

Why?

[Hamish Coutts]

I would also say that replacing or servicing an electric pump would also take away the need to remove the sump and head to service the bearings on a standard water pump. That is a bitch of a job!

I will be looking at using an electric water pump next time I have to 'play' with the existing pump, hopefully many 1000s of miles from now.

Hamish

[john.p.clegg]

Why?

The pump where it is circulates water round the engine block,out through the top hose,round the heater matrix and back in the bottom hose at all times.When the thermostat opens this carries on but with the additional (larger) path via the radiator...
With an external pump,water is being forced into the bottom union trying to circulate through the block and return via the radiator-no path to flow,when the thermostat opens you have flow from the pump through the engine block and returning via the radiator.
At no time is there any force acting on the water to drive it through the heater,unless the block is blocked!!!!
John

[chrishewett]

trying to circulate

I must be missing something. Why is it any different with a pump in the bottom hose than with the standard setup? A pump is a pump, surely. The water doesn't know if it is mechanical or electric. I have read what you guys are saying and I havn't yet heard anything that has convinced me that it is not possible to use one of these.
I shall continue to research.
Please keep the comments coming in.
Chris

[v7slr]

Right, I think I understand. It's more to do with the location of the pump rather than the fact that it's an EWP per se?

[M100]

If you consider where the existing mechanical pump fits into the block then any external replacement would have great difficulty in getting much, if any water into the engine block unless the mechanical pump was removed and a suitable blanking arrangement fitted.

By that time you may as well have fitted a new mechanical pump.

[v7slr]

Ah but I believe the proper implementation of an EWP is to remove at least the traditional pump's impellor, if not replace the whole caboodle with a blanking plate. As you're likely to require the pulley on the outside of the block, it's normal just to remove the impellor.

[john.p.clegg]

No,no,no,no,no.....
The position of the pump(in the block)pushes the water to the output(top hoses-heater and radiator)it will flow through these if possible and return to the input(bottom hoses)
So you have continual flow through the heater matrix.....

And flow through the radiator only when the stat opens.....

Wheras if the pump is external it is pushing water into the bottom hose and if the thermostat is shut there is nowhere for it to go-it will not circulate through the heater matrix.....

Thanks
John

[chrishewett]

Right! Now I begin to understand. Seems a shame that it looks like we are stuck with the old 105E pump
Back to square one.
Chris

[john.p.clegg]

Chris
There's nothing wrong with the pump if you don't overload it,try using a toothed belt with not too much tension.
John