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Author Topic: What is EWP?  (Read 16035 times)
michaltalbot
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« on: May 04, 2007, 09:40:08 pm »

Krede and Anders? You've spoke about it in other section, what does it mean?
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Anders Dinsen
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« Reply #1 on: May 04, 2007, 11:19:07 pm »

Heh, good question, sorry for keeping it private.

EWP is just short for Electrical Water Pump. There's a company in Australia that manufactures a selection of eletrically powered water pumps for engine cooling, the idea is that you can run them instead of the belt driven pump - or as a booster pump.

http://www.daviescraig.com.au/

One of the things you can do with an electric pump is to eliminate heat soak - the effect where your engine actually heats up (and may even boil) after you switch it off. This can happen because the exhaust manifold is heated up far more than the head, so when the coolant flow stops, there is nothing stopping the temperature from rising. I've noticed it a couple of times on my car, especially if I have been driving slowly in city traffic and then turns off the car. Turning it on a few moments later, the water temperature gauge will be higher that when I turned the car off!

My idea involves using the EWP as a booster pump only - fitting it in the return circuit from the radiator and controlling it using a temperature controlled relay in the other hose to the radiator so that the pump is activated when the thermostat is fully open. It should be run directly from the battery, so it will maintain a coolant flow after engine shutdown - to prevent heat soak.

I did a crude drawing here:



The more advanced solution is to remove the water pump entirely, AND the thermostat, and run a computer controlled cooling system using a digital controller from the above company. For that, Krede needs a water pump assembly without impeller, and probably a secondary pump to run the cabin heating circuit?

- Anders Cool
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krede
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« Reply #2 on: May 05, 2007, 12:22:13 am »

I got the waterpump for the turbo of a late 80'ies vw passat turbo diesel... ... I salvaged it from a car (military) before they dragged it away and blew it to kingdom come with a couple of heavy machine guns... thus i got it for free... Might work if placed in the heater hose and wired up to the  ventilator fan, or just with an on off switch... Smiley

Btw you can leave the thermostat in if you want, if used with a controller the pump wont start before the engine reaches a certain temperature.. It would actually help in regards to the cabin heater
« Last Edit: May 05, 2007, 12:40:29 am by krede » Logged
Anders Dinsen
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« Reply #3 on: May 05, 2007, 07:01:46 am »

I got the waterpump for the turbo of a late 80'ies vw passat turbo diesel... ... I salvaged it from a car (military) before they dragged it away and blew it to kingdom come with a couple of heavy machine guns... thus i got it for free... Might work if placed in the heater hose and wired up to the  ventilator fan, or just with an on off switch... Smiley

Btw you can leave the thermostat in if you want, if used with a controller the pump wont start before the engine reaches a certain temperature.. It would actually help in regards to the cabin heater

I guess you liked watching that...

This will be your booster pump for cabin heating, right?

- Anders
« Last Edit: May 05, 2007, 07:06:29 am by Anders Dinsen » Logged

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gizmo
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« Reply #4 on: May 05, 2007, 03:30:22 pm »

Hi Guy's,

A cheap source of electric water pumps will be the Volvo 400 series turbo cars, they have them fitted to continue the circulation of cooling water to the turbo after the engine is switched off. They are controlled by a thermostat and the object is to prevent heat soak from killing the turbo.

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gizmo
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« Reply #5 on: May 05, 2007, 03:38:55 pm »


Is cooling a problem with murena's?
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« Reply #6 on: May 05, 2007, 03:44:33 pm »

Hi Guy's,

A cheap source of electric water pumps will be the Volvo 400 series turbo cars, they have them fitted to continue the circulation of cooling water to the turbo after the engine is switched off. They are controlled by a thermostat and the object is to prevent heat soak from killing the turbo.



I have just acquired one of these as my daily driver. I have also bought a "spares" car, so if anybody wants this pump and it isn't too hard to access, I can supply one.
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krede
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« Reply #7 on: May 05, 2007, 06:30:57 pm »

Hey Gizmo..
The Murenas seem have a reputation for overheating.. as has most mid engined cars come to think of it..(mr 2's for instance) but weather this has any truth to it Im not sure.
My car runs an "s" spec cam, and twin dellorthos.. gets a good thrashing on a regular basis and gets to drive 10-15 minutes through city traffic right afterwards, and it has NEVER shown even the slightest signs of overheating.. sure it gets hot, but only very rarely does the ventilator fan kick in... I actually sometimes let it run hot enough for the fan to start simply to check that the thermo switch IS working.
Thus any reputation for overheating Is IMHO highly exaggerated, Indeed I have spoken to a few guys who have run a 505 turbo engine (with the water cooled T3 turbo) in a murena with standard radiator etc.
I think most of the faults people have regarding the cooling is due to poor maintainance... they are old cars now.. and most people seem to be ok with just topping up the coolant tank when it gets too low....a little more is needed on 25 year old Murenas Smiley

The reason that  Anders and I are considering the EWP has less to do with faults in the cooling systems design... and more to do with our irrisistable urge to pamper and spoil.... the prrrreeeeecious ... Grin
 
   
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gizmo
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« Reply #8 on: May 05, 2007, 07:19:31 pm »


Krede,

I tend to agree that neglect is a powerful enemy of the 'old car' and the mid engine/front radiator layout could lead to problems if not regularly maintained. My MR2 runs rather cold and I think the thermostat my be stuck open (another job for the list). As cylinder heads seem to be the biggest casualty with overheating perhaps using the EWP just to circulate extra water through it might be a good option. What about fitting an oil/water intercooler (easily sourced from a modern car) to help to moderate the oil temperature.

I recall reading in a book on racing car design that a radiator only requires an intake 1/6 the size of the radiator to function correctly, perhaps some of the air feeding into the murenas over large intake could be stolen to cool the brakes, also less air taken into the radiator will mean less air to exhaust from the radiator cavity which should reduce the aerodynamic drag.

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krede
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« Reply #9 on: May 05, 2007, 07:35:35 pm »

As Anders Wrote, the main reason for the EWP is to keep cooling the engine even AFTER it has stopped!
This is possible with an electric pump and fan.
I have considered fitting an oil/water cooler, but, Im not too keen on adding more strain to the cooling system, be it in ok shape.
However, as soon as I find out what adapter to use, I will be fitting an oil cooler.. possibly one from a 911 as they are designed for rear engined cars.

While on the subject of cylinder heads you are on to one of the Murenas real trouble spots!! (the 2.2)
The cylinderheads on these cars (indeed on most older aluminium heads) are prone to cracking if overheated.
I know of many that have had to replace them.. mine too has had a new head not long ago. Matra Hans too I belive

While reading up on intercooling etc, I came across some similar pages about air ducting to the radiators... after seeing the front of the Murena, I believe that some thought have gone into the designing the "mouth" to increase the air speed onto the radiator.. if this is the case , its very high tech for a 1982 car.. but then again.. its French. Smiley     
« Last Edit: May 05, 2007, 07:46:12 pm by krede » Logged
gizmo
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« Reply #10 on: May 05, 2007, 09:14:21 pm »

 
Yes, heat soak after switching the engine off is the potential problem, especially in the aluminium cylinder head. The point I was making (not very clearly, after rereading my post) is that primarily it should be the cylinder head that is kept cool by the continued flow of water. The coefficient of expansion of the aluminium is much greater than that for the cast iron block and this is where the stresses of the heat soak will be greatest.

Check out this link for oil coolers and components  http://www.thinkauto.com/

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krede
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« Reply #11 on: May 05, 2007, 10:42:58 pm »

Hmmm....Yes.. using different materials can be a problem... but I believe to ahve read that aluminium has the capacity to dispose of heat 4 times quicker then cast iron... so maybe for this reason it would be advantageous to get the engineblock cooled faster? just guessing here.
 
Cooling the oil after the engine has stopped wont make much of a difference since it isn't circulated by the oil pump.
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Anders Dinsen
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« Reply #12 on: May 05, 2007, 10:53:32 pm »

While on the subject of cylinder heads you are on to one of the Murenas real trouble spots!! (the 2.2)
The cylinderheads on these cars (indeed on most older aluminium heads) are prone to cracking if overheated.
I know of many that have had to replace them.. mine too has had a new head not long ago. Matra Hans too I belive

My car failed the head some years ago due to overheating caused by a failing water pump.

In ideal state, the cooling system is adequate for the car, but running a tuned engine and a stainless manifold that doesn't dissipate heat as well as the cast iron, there's really a good chance that sooner or later, it will boil and risk destroying the head.

Another thing that can cause overheating (I've learnt this only recently), especially on tuned engines, is the ignition being retarded too much in idle. The workshop manual instructs the static idle timing at 10 degrees, but Des Hammill in his book on ignition systems recommends up to 14 degrees for a cam like the S-cam (279 degrees period) and even 16-18 for a Holbay (296 degrees period). Otherwise the engine will simply run too hot in idle!

Quote from: gizmo
Check out this link for oil coolers and components  http://www.thinkauto.com/

Tey also carry the Davies Craig EWP's in the range, though the price seems slightly higher than Demon Tweeks.

Quote from: krede
so maybe for this reason it would be advantageous to get the engineblock cooled faster? just guessing here.

Water cooling will cool both, but as the exhaust manifold heat enters through the head, that's where the cooling needs to be, I think.

- Anders Cool
« Last Edit: May 05, 2007, 10:57:04 pm by Anders Dinsen » Logged

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michaltalbot
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« Reply #13 on: May 07, 2007, 12:26:35 am »


In ideal state, the cooling system is adequate for the car, but running a tuned engine and a stainless manifold that doesn't dissipate heat as well as the cast iron, there's really a good chance that sooner or later, it will boil and risk destroying the head.


Well, this is big true!!! I bought my Murena S very cheap, because the engine was totally damaged, and I┤ve got the second engine which had the same problem - hole in the cylinder, and terrible damaged cylinder head



But the rest of the engine (timing chain with wheels, 3 pistons, bearings) looked very very new. Do you know where I found the reason of all problems? Yes - the car was equiped by 4 - 1 Devil exhaust. And many other Murenas with damaged engine had this exhaust tuning... Heat from this exhaust is so big, that the carpet in my trunk was burned right in the place where the exhaust pipes are.

I agree with that if everything is O.K., original cooling system is sufficient, but you must calculate, that it is middle engined car, so for sure, everytime when I came from the way through the city, and temperature is on the 90 or a little bit more, I turn on the heating system, then I stop the engine, but turn on the ignition till the wind from the heating is cold and than I turn on the engine again. Then the temperature goes under 90 degrees.
« Last Edit: May 07, 2007, 01:31:53 pm by Lennart Sorth » Logged

Anders Dinsen
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« Reply #14 on: May 07, 2007, 08:57:06 pm »

Hi Michal

But the rest of the engine (timing chain with wheels, 3 pistons, bearings) looked very very new. Do you know where I found the reason of all problems? Yes - the car was equiped by 4 - 1 Devil exhaust. And many other Murenas with damaged engine had this exhaust tuning... Heat from this exhaust is so big, that the carpet in my trunk was burned right in the place where the exhaust pipes are.

That's an interesting finding you have there, but I don't think the exhaust is the only source of the problem: The thing is that stainless steel has less heat conductivity than iron, so the amount heat dissipated from the cast iron manifold will actually be higher than from a similar stainless one.

I think there's another source - when you fit a free flowing manifold like the devil, the cylinder filling will improve significantly, especially to an S-cam with its overlap of 56 degrees. It will therefore develop more heat. Further, if ignition suffers on one or more cylinders, the energy produced in the cumbustion will not be extracted mechanically (since the combustion will be slower or delayed), and even more heat will develop. An ignition problem could be the reason why your engine had one broken cylinder, and three fine ones?

My car has been running with a stainless 4-in-1 manifold (similar to the devil) for years - there's nothing to see in the trunk, so I think something was seriously wrong on your car, and that's why it blew the cylinder.

Heat soak is different, though - since the manifold is not dissipating the heat efficiently, it will transfer to the head and cause boiling after ignition is turned off. I experienced that about a week-and-a-half ago - cooling system had a small leak so pressure coulnd't be maintained properly, and stop-and-go city driving combined with very hot weather one morning caused serious boiling almost immediately when the engine was switched off. The leak is fixed now and I'm very careful to keep the gauge below the 90 point, but this is why I want the electric water pump!

It seems we are equally paranoid with our temp-gauges Wink

It's a magnificent photo, by the way - do you still have the blown up block?

- Anders Cool
« Last Edit: May 07, 2007, 09:02:05 pm by Anders Dinsen » Logged

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