Electric water pumps?

[trdee]

i didnt dispute the electric water pump, nor did i dispute that the car overheated once you removed the thermostat. i just dispute the reason you give for the car overheating because, as much as "jibby jabber and calculations" might seem foreign to you, i actually have designed heat exchangers before and know how they work...

[toyota1515]

If you don't mind, what type of heat exchangers you design and for what kind of work?

[TERRA Operative]

No pictures of the impeller but i know it is all Stainless hardware inside that thing, they guarantee it for 2 years unlimited mileage,

here is a link!
http://www.meziere.com/ps-1148-0-WP336S.aspx

Nice, stainless is good, unlimited kilometre warranty is better.



I had always assumed that the reason for an engine overheating without the thermostat was due to the coolant flowing too fast (even on a non-bypass system). I'd be interested to learn what other factors are involved instead.

[trdee]

If you don't mind, what type of heat exchangers you design and for what kind of work?

when i was working in the only hydrogen peroxide plant in australia i did the working calculations on their shell and tube heat exchangers to make sure that they would cope with the extra heat duty going through them after their planned expansion. I can send you the excel files if you like

did i mention im a chemical engineer?

[trdee]

I had always assumed that the reason for an engine overheating without the thermostat was due to the coolant flowing too fast (even on a non-bypass system). I'd be interested to learn what other factors are involved instead.

if that were true then running no thermostat in an oil cooler system would make your oil overheat too??

I think not....

Think about it, the engine is constantly full of water, flowing or no. The engine is constantly rejecting a given amount of heat through the engine block into the water system irrespective of the flowrate of the water. The only thing the water does is "take" the heat away to the radiator. If it's flowing faster then that means that each specific unit of water is taking away a smaller amount of heat yes, but there is more water flowing through there so it makes no difference to the total amount of heat that the water is taking out of the engine per unit time.

HOWEVER, the fact that each specific unit of water isnt getting as hot means the temperature difference between the engine and water is higher for longer, which increases the rate of heat transfer, which will make a car run cooler. Not all cars overheat with a removed thermostat. How do you explain this then??? In some cars removing the thermostat does indeed make them run cold (this happens in AE92s, have seen from experience)

Now I dont know why some cars will overheat with a removed thermostat, but I do know its not from water flowing "too fast"

Also, increasing the flowrate of the coolant will increase the heat transfer coefficient of the coolant (smaller boundary layer) which will also aid in increasing the rate of heat transfer

[mullett]

Well i done it before many times and worked better than the factory system, temperatures where more consistent troughout the whole range of the powerband plus in the best case it did gain 8 whp,

All your jibby jabber and calculations are just speculations cuz every case is different, when you guys does what i did and get the results i am getting you will umderstand that formulas are for books and papers i dont stop there i have to try everything and maybe thats why puertoricans have the fastest rotarys and 4 banggers,

Only thing and the last i will say is i have done it many times and each and every one worked awesome, my dodge will have one and my Celica too, also remember that it will work better on high performance engines,

A good advise is, do not give up without even trying, think out of the box and you guys will be surprised!

Good luck.

Thinking outside the box is fine...but you have to understand what you're dealing with. All the jibby jabber and calculations? That's how the world works. Without a thorough knowledge of the physics occurring, you're just guessing (which is, incidentally, speculation). When you get down to it, most cases are very similar, except for a few variables. Once you understand the variables and the situation, you can make an informed decision. Keep in mind that people train for many years to get a good understanding of the driving principles behind engineering, and after that they'll often specialise in one tiny field. Most likely there's a guy (or more than one) in Toyota who simply designs radiators, or waterpumps, who has spent his whole life understanding cooling systems. Could I take a guess that was better than his judgement? I doubt it. And I'd be surprised if you could.

In most situations the factory system is designed, calculated and tested over hundreds of hours by people with a lot of experience (especially the case in Toyotas!) Removing something because it 'doesn't seem necessary' is an exercise in futility and demonstration of a lack of understanding.

I'm not saying that electric water pumps aren't a good thing...just that you've totally missed the point. They're a good thing because they draw the minimum amount of power at higher RPM. (if they're set up correctly). A factory belt driven pump needs to flow enough at idle to prevent hot spots and uneven cooling (as well as stopping it just plain overheating). As the engine speed is increased, you're pushing more water than you need to be (although...not as much as you might think. It's not a direct linear relationship). So an electric pump gets around this by not being mechanically driven, so the speed (which relates to power loss) is independent of the engine.

Reliability is how you define it...most people would be upset if they bought a new car and it didn't do 100,000km without needing anything except basic servicing...but I bet there's very few people who've done that many km on an electric waterpump. We're enthusiasts, and modifiers, and when you mess with something that's been so carefully designed, there's drawbacks. On the plus side, we probably pay more attention to our gauges and listen out for something that sounds 'off'. So we've got a better chance of catching something and fixing it before it all goes pear shaped. I ran a Davies Craig EWP in my MR2 for 2 years and 30,000km without ever having to worry about it, but I'd still rather have a factory one if I was going to drive across the nullabor.

[JDM hachi]

trdee.....toyota1515...... I read a lot of posts from both of you and i respect both of your abilities in so many different and varied ways, and am of the opinion that the both of you are awesome car fiends willing to go to great lengths to achieve your goals....can you guys turn this argument into a debate? would be really great info, cos at the moment it feels like mummy and daddy are yelling at each other......

After that, i will state a fact that may prove both of you correct....

Think about it, the engine is constantly full of water, flowing or no. The engine is constantly rejecting a given amount of heat through the engine block into the water system irrespective of the flowrate of the water. The only thing the water does is "take" the heat away to the radiator. If it's flowing faster then that means that each specific unit of water is taking away a smaller amount of heat yes, but there is more water flowing through there so it makes no difference to the total amount of heat that the water is taking out of the engine per unit time.

"surely a cooling medium has an optimum operating temperature, for the transfer of heat? "

While a formula has been posted to examine/explain the cooling ability of a slower/faster moving cooling system, there are a few constants to every equation, that if we lived in a vacuum at 25 degrees celcius would hold true.
If the cooling medium has a best/ultimate/awesome operational/heat transfer temperature, then that is an important detail i believe....

just sayin...
matty.

[mullett]

The bigger the temperature difference, the faster the heat transfer. That's the main reason cars run pressurised cooling systems, to increase the boiling point (and thus the maximum potential heat transfer). So coolant will transfer at maximum efficiency right before it boils (in fact, as it boils it will use a huge amount of heat without increasing temperature). This has an added advantage, that for any given air temperature on the radiator (below the coolant temp obviously ), the hotter the coolant, the faster it will expel heat.

[trdee]

Also we all got a by sidetracked here. Removing the thermostat doesn't really make the water run faster though the block anyway, it just allows more water to flow through the radiator, thus removing more heat from the system

[toyota1515]

I think you guys are missing one point, as mullet says these factory cooling systems has been engineered very well for years of trouble free duty and they do so, but they do son in factory and mildlly modified trim some are so good that can live in a very extreme modified engines, i never said a factory system is not good, cus it is good but a modified electric pump system is better on most cases when an engine is modified, cuz its ability to mantain a more stable and predictible performance, plus giving you some extra hp to spare.

Also the thermostat in an engine is not designed to restrict the cooling fluid flow, is to mantain a specific temperature in the system (talking motor vehicles) some systems are way diferent than others and work completly diferent, in a honda crx (and i have test it) you took the thermostat out and it will overheats, in a TE72 you do the same and it will stay cool to the point of a thermo choke carburator wont come out of the cold start circuit,

In my ol race CRX i went to the option of use flow restrictors in the cooling system to achive a more stable system,

I know things need to be calculated and caerfully designed and there is no other way buddy, but sometimes things just dont like to work that way, and you need to rely on your guts and experience (that only come with years of doing what you do) to overcome some obstacles,

I am no engeenere by any means on nothing, i am a tech who got 30+ years of experience working with high performance race cars, and i can tell you i have seen it all, but there is always something new around the corner,

[mullett]

Honestly I'm yet to see a system that is more stable than that controlled by a thermostat (it's a very neat and efficient way of controlling temperature, and does work by restricting coolant flow). Even with an EWP, I'd still run a thermostat, and PWM control the waterpump speed based on operating temperature (say a starting point of 20% for below 50 degrees, 40% by 70 degrees, 50% at 80 and ramp up to 100% as you pass 90 etc...which would take some fine tuning). You never want zero flow through the engine, even the thermostat won't block completely, usually the coolant will circulate back through the engine, and a small amount will pass through a hole in the thermostat to allow it to have an accurate indication of engine temperature.

-RM

[toyota1515]

hey now! i never suggest to eliminate the thermostat, i always enforce the use of it, on street cars and road race cars, regardless what kind of cooling system chosen, electric or OEM, i do sometimes eliminate the termostat but replace it with restrictors but only in Drag race cars, that wont see street at any time!

Just clarifying (^_^)

[aus jd 2703]

ok ive been keen to try an ewp when i finish my forged engine.
whats the price of a meizere pump? because u can get allow ewp110 for under $200. and ive been told the latest gen ewp's are alot more reliable than previous.
my under standing to is there is no such thing as flowing coolant to fast. but u need turbulence as this increases thermal conduction on the surface. this is why pwr use dimple tubes in their race radiators and why u need a flow restrictor. you need velocity to create turbulence.
and just so you dont think im pulling this out my ass im a mechanical engineer and studied fluid and thermal dynamics as part of the course so i have a basic grasp. but i could be wrong.
personally though ewp makes more sense especially in turbo cars as the pump and fans can run after the cars off thus preventing hot spot nucleate boiling which is a major reason 3sgtes crack blocks

[trdee]

more turbulent flow does indeed facilitate better heat transfer, but it also increases pressure drop (pump has to work harder)

[Toy77]

back to the original poster.... lol

i have this set up on my 1j - only running alternator of the harmonic balancer.
I removed the tensioner as well.
Moved the alternator to the passenger side of the motor.
mounted the pump between the bottom radiator hose and the thermostat houseing.... i have removed the thermostat.
the waterpump housing - i left in place, removed the impeller off the shaft, as well as the pulley etc

now i have had dramas with the waterpump controller - i rushed to get my car ready for the nats and haven't sorted the bugs out yet.
i cant comment really as to its effectiveness as yet.

Cheers
Stew