Electric Water Pumps.

[lisalex]

Originally Posted by Matthew Ferguson

But now it seems that "air bubbles" are the enemy these = steam (created by localised boiling) and are the worst conductor of heat and we must remove bubbles. ?? Swirl pots, additives, whats the answser.

I was discussing (my) cooling system problems with another rally guy over here recently, and he said that he'd tried everything for his car, but the one thing that made a dramatic difference was the installation of a separator tank.

The tank was designed to prevent steam bubbles from reaching the radiator. It was placed on the inlet to the radiator, at a location that was physically higher than the top tank.

I'm not totally sure what was inside it, I got the impression it was like a perforated plate. Since it was now the highest point in the cooling system, it had a radiator cap installed in the top of it.

(He didn't have the car there at the time, so I don't have any photos of it, nor have i seen it in person)

Anyone else come across this before?

Alex.

[Ben Wilson]

Originally Posted by lisalex

Anyone else come across this before?

I've seen swirl pots hooked up to cooling systems before. It's a vertical tube with the coolant inlet mounted tangentially at the top, an outlet at the bottom and a radiator cap on the top. The theory is that the coolant spirals inside the tube forcing the air bubbles to the center and any bubbles will vent through the cap while you get pure coolant feeding back to the engine.

The radiator cap should be the highest point in the cooling system anyway, so for most cars the radiator should eliminate any bubbles in the coolant,

[Art Clarke]

That arrangement was standard fitting on '50s & '60s Vanguard and TR3 / 4 cars for much the same reason.
Improved cooling performance of the radiator, apparently the secret is that the coolant flowing into the tank slows suddenly which then causes it to give up dissolved air and any trapped steam.
It would be interested to see any factual data to support the factory explanation!
I reckon it's more that because the tank is the highest point in the system and dissolved air is collected there instead of being trapped elsewhere.

[Mark]

On a neutral note, sounds like the Focus WRC uses electric water pump:

WRC Ford Rally Live Development continues on Focus RS WRC ahead of Portugal rally

From 2009
The newly-homologated power plant available to drivers Mikko Hirvonen and Jarmo Lehtinen and team-mates Jari-Matti Latvala and Miikka Anttila includes an electric water pump and a lightweight flywheel. During a comprehensive testing programme, the drivers have reported a slight improvement in outright engine performance from the upgrades

Mark

[scooter]

Originally Posted by Mark

On a neutral note, sounds like the Focus WRC uses electric water pump...

And at the other end of the spectrum, one of my customers reported that one completely cured the cooling woes on his '36 Wraith (which is a truly beautiful thing). The original waterpump was so badly corroded that the impellor vanes were ineffective and it's not like they have them on the shelf at Repco, or anywhere else in the world for that matter....

[scooter]

Originally Posted by Warpspeed

I suggest all you non believers actually fit a water pressure gauge to your engine and see for yourselves what is actually happening in there at high engine rpm.

Did this earlier this year. 302w with Std serpentine belt water pump. Two brand new Pricol mechanical Oil pressure gauges, one into the inlet manifold water jacket (upstream of the thermostat) and another down stream of the thermostat. I also swapped the gauges around and got identical results because....

Water pressure downstream of the thermostat never moved, but engine water pressure increased more or less linearly with revs to a max of about 50psi at 5500rpm. Factory redline is 5800, so that makes sense. At that point the gauge wavered at 50 PSI. Clearly this is where the pump is running so fast that it's no longer efficient. This is commonly called cavitation by nearly everyone, but it's not actually cavitation and falls into the same category for discussion amongst engineering nerds as polar moment of inertia.

[Buerckner]

Originally Posted by Ben Wilson

While Warpspeeds arguments are vaild, I ran an EWP on the mr2 and it worked perfectly, it would reach operating temperature by the end of my street and the gauge would never budge after that.

Does the MR2 or similar mid/rear engine + front radiator juts use the same water pump as the Corolla?

I was thinking that an electric pump inline with the std water pump would boost cooling system performance, especially on a system with long radiator hoses and increased capacity.

[Ben Wilson]

Yeah, the mr2 pump is exactly the same as a Corolla pump.

It does use a really big radiator, but long standard size hoses.

[scooter]

Originally Posted by Buerckner

I was thinking that an electric pump inline with the std water pump would boost cooling system performance, especially on a system with long radiator hoses and increased capacity.

This was suggested to me by one of the tech-heads at PWR for possibly solving my cooling issues - it boosts the performance of the mechanical pump when it's not running at peak efficiency (which is most of the time!) like at idle and at the top of the pump curve near max revs. I never got to trying it as the huge ****-off radiator we made and a few other mods got things under control.

[Matt Dyne]

I bought one of the BMW pumps mentioned below. For some stupid crazy price.

And I never used it...brand new in it's packet.

If somebody wants to make me a sensible offer I'll most likely accept.

Specs are as per DSM's post. Except I think it's made by Pierburg...not VDO. But could be wrong.

It's a beautiful looking, high quality pump though...makes Davies Craigs look like a kids toy.

M

[spike]

it depends on the application in my oppinion

in a rally car, semi standard radiator up the front and that then you wouldnt need one.

but

when running an offroad or a drifter with major modifications an electric water pump makes sense to me. drifters cause some (uknown why) put the radiator in the boot and the electric pump pushes harder and more consistently.

i can see the for and against side of this but right now i cant afford one and havent got anything i need it for

[Mk1_Oz]

The ONLY time a water pump can pressurise the head is if the termostat is CLOSED. Once it opens the pressure through out the cooling system (a closed system) will equalise........

[Warpspeed]

Originally Posted by Mk1_Oz

The ONLY time a water pump can pressurise the head is if the termostat is CLOSED. Once it opens the pressure through out the cooling system (a closed system) will equalise........

Then you have never actually fitted a pressure gauge to your head, and run the engine up to high rpm, have you ?

There is far more going on here than you probably realize.

When you have tried this yourself, and you can honestly say, that at 8,000 water pump rpm, your water pump only produced 0.01 extra psi in the cylinder head, then your experience will be unique.

[Mk1_Oz]

I have not fitted a gauge no. I am applying fluid dynamics theory.

I would love to have the time and money to fit a pressure and flow gause to an engine though and examine what the pump does. I would hypothesis that the pump will cavitate at high revs.

It's all an interesting discussion......

[Warpspeed]

Fluid dynamic theory, huh ?

Well, if you restrict the outlet flow of a pump, then the pressure up stream of the restriction rises. Have you ever noticed how small the actual fully open flow area of a water flow thermostat is, compared to the flow areas everywhere else in the cooling system.
Why do they deliberately do that ?
That deliberately sized flow restriction is there for a VERY GOOD REASON.

Any water pump will cavitate on the suction side, if the pressure falls below the vapor pressure of the particular fluid. Even fully exposed marine propellers can do it.

Restricting the discharge side will not produce cavitation, just a massive pressure increase. If discharge back pressure produced cavitation, very high pressure hydraulic pumps would simply not be possible.