Whats everyones thoughts of running a electric waterpump? I know Meziere makes the block plates to do it. Ive been really thinking of doing this as I know it would help in driving around in town and I noticed on 3rotor.com they decided to run it that way.

 

You will probably hear a lot of negative things about EWP's, and a lot of arguments from people who know nothing about the properties of pumps.

I will say this much: there's at least two advantages to having an EWP:
1. More power.
2. No chance of water pump cavitation.

 

 

I actually have a ewp but after everything Ive read Im scared to put it on so I went and bought a meziere pump instead. After lots of talks I felt the electric waterpump was a win win situation. now I can sit in traffic on those hot days with a water pump at a constant speed. Hopefully eliminating any chance of overheating. So if anyone feels confident with a ewp I have a brand new one with controller I would be willing to sell.

 

I have the Meziere remote mount 55gpm pump for my car. Its the only way to go, no worrying about getting parts from japan, cheaper than buying a new one from the dealer.

 

I will start by saying that I have not studies pumps, but I don't see how this is much different from running a mechanical/electric fan.

How do you get more power? People seem to make this arguement about E fans, but the reality is that it takes energy to push the water/air. So from a power perspective a mechanical pump is a direct couple to the engine with some loss from the belts that are driving the pump and then pump efficiency loss.

If you run an electric pump you have the belt losses, then converting mechanical to electrical in the alternator there is an efficiency loss, then converting that electrical back to mechanical in the pump another efficiency loss, then the efficiency of the pump blades.

So in order to save power, the efficiency of the electrial pump (the blade part) would have to be SIGNIFICANLY higer than the mechanical pump to overcome the losses of converting to electrical power and then back to mechanical.

Don't get the no chance of cavitation part either? Just b/c the pump maintains a constant speed I guess? (I don't know what electic pumps are advertised to do)

Am I missing something on the power part? It it's related to the speed that you are driving the pump then that's just pulley's in which case the electical pump would still require more power b/c of the inefficiencies in the system.

-Chris

 

here's what I found.. its no rotary.. but same principle

After looking at all this you may ask " hey, does it take that much power to turn the alternator and other accessories ? ". Yes, it does, if you ever tried turning a stock alternator under load, you almost can't with your bare hands. As much as 10-20HP is used up by accessories, but there are some accessories that we can't do without, like: alternator, power steering and water pump. If you are willing to do without power steering and air conditioning you can gain even more power. With everything in place, you can expect a 5 HP gain on a stock Mustang by using underdrive pulleys.


WP316
55 GPM high flow rate
3000 hour life expectancy
Single in, double out bulkhead design
1.75 welded inlet port standard
#12 female outlets with o-ring seal design
Replacement center sections available
11-12 amp draw typical
4130 mounting bracket included
WP336
55 GPM high flow rate
3000 hour life expectancy
Single in, single out inline design
Modified #20 inlet and outlet accept Meziere "WN" style fittings
11-12 amp draw typical
4130 mounting bracket included
WP337
55 GPM high flow rate
3000 hour life expectancy
Single in, double out inline design
Modified #20 inlet accepts Meziere "WN" style fittings
Modified #16 outlets(2) acceplt Meziere -16 fittings for #12, #16, 1" Hose and 1.25 Hose
11-12 amp draw typical
4130 mounting bracket included


doing the math.. the electric water pumps take about 0.19 hp to operate.

12V * 12A = 144W (144 W) / (746 W/hp) = 0.19 hp

 

No impeller to turn within the pump creates less drive train loss. Also the power inefficiencies you are talking about can easliy be over come with a higher amp alternator.

 

Im not looking at it as a power advatage but for the reliability of being in stop and go traffic and having a water pump moving as much water as if I was cruising down the road. That and if I like I can set it up kind of as a turbo timer and use it to continue to circulate the water on shutdown. aiding cooling.

 

Pump laws, guys.

Volumetric flow rate is proportional to pump speed.
Pump head is proportional to speed squared.
Power is proportional to speed cubed.

These are universals for any given centrifugal pump. The EWP maintains a constant rpm (and thus cannot cavitate like a belt-driven pump at high rpms). It's power draw is always the same. Sure, it may be less efficient at idle having the pump maintain that speed, but that's not really what most of us care about. When you begin to turn the belt-driven pump at twice the speed of the EWP (which most likely you will, given that it's probably a slightly less efficient design), you're now using 8 times as much power just to turn the pump. That's where you're gaining power.

It just makes no sense to me to use a centrifugal pump are variable speeds. Running a certain blade design at a certain rpm HAS to be more efficient. It's like running a turbo at it's sweet spot. A certain vane design is calculated for a certain rpm and a certain flow rate. So why not use an EWP that's designed to stay at that rpm all the time.

I'm not saying there isn't downsides to EWP's and certainly they don't fit every situation, but I get tired of hearing the same power arguments from people that don't know anything about pumps. By the way, a fan is an air pump as well, so those same pump laws will roughly hold true. But of course, in the belt-driven fan's case, it's got the clutch working well in it's favor.

 

I don't disagree with the laws of physics. What I don't get is all the assumptions that go into people stating as a "fact" that EWP's use less power. Does anyone have actual numbers to show how much power a factory pump takes to spin?

So a EWP takes .19HP to spin... With alternator efficiencies at 55% that's .34HP from the engine.... ok, I'll buy that. Doesn't tell me that the EWP takes less power. The size of the alternator doesn't matter, it only changes how much power it can output. An alternator capable of 200AMP is going to require the same power input to run a .34HP pump as a 150AMP alt.

To me, a centrifugal pump makes great sense when you consider that the engine is going to be making more heat at higher RPMS. More heat needs more cooling and this can be accomplished with a higher speed. Futher, nobody knows anything about what the efficiency of the factory pump is, or at what RPM it was set to run max efficiency.

What RPM is the EWP running? Sure running it at the optimum blade speed may make the pump itself more efficient. But what about the fact you are flowing 300% (<- I made that number up) more coolant than you need around town, off idle, mid RPM range you pick anything but full load (b/c you have to size the EWP to always flow the coolant needed to cope with the highest heat load) So yeah, the electic pump is pushing 300% more than I need but it's running at 90% efficiency as opposed to the mechanical pump running at 50% efficiency flowing what I need.

Point being, I have not seen any hard facts that show that a EWP actually makes more power and there are WAY too many assumptions going on to be stating such a thing as a fact. I can make enough assumptions to show it the other way around too. So what.

If you want the pump as Power Hungry suggested to just flow tons of water and keep the temps down great. To help ensure excess flow at idle fine. But I'm tired of seeing people claim power gains as a fact who have zero abilty, or information to prove it. I'd love to see the hard numbers if someone has them.

 

That I dont know nor really care about power being made. My only thoughts are they are always used in drag racing so my guess is they must free up some power, but again I have no proof and nor do I care about making more power. Just my 2 cents

Did a google search on the subject and this is what super chevy came up with on a 350 chevy.
Test 1 Test 2 GAIN Test 3 GAIN
O.D. U.D. U.D. Electric U.D. vs. Electric
RPM TQ HP TQ HP TQ HP TQ HP TQ HP
3000 390 223 393 224 3 1 396 226 3 4
3200 404 246 409 249 5 3 412 251 3 2
3400 415 269 418 271 3 2 421 273 3 2
3600 418 287 421 288 3 1 424 291 3 3
3800 419 303 423 306 4 3 425 307 2 1
4000 417 317 421 321 4 4 423 322 2 1
4200 416 332 419 336 3 4 422 338 3 2
4400 416 348 420 352 4 4 425 356 5 4
4600 415 364 419 367 4 3 424 371 5 4
4800 412 377 414 379 2 2 419 383 5 4
5000 405 385 407 387 2 2 411 391 4 4
5200 393 390 398 394 5 4 401 397 3 3
5400 383 394 387 398 4 4 389 400 2 2
5600 371 396 375 400 4 4 378 403 3 3
5800 359 397 363 401 4 4 366 404 3 3
6000 345 394 348 398 3 4 356 406 6 6

MAX 419 397 423 401 5 4 425 406 6 6
AVG 402 335 406 338 4 3 409 341 3 3

I know its not a rx7 water pump but it does free up HP on a chevy

 

Can't you just leave it off (or at least run it at a lower speed / voltage) until the temps come up?


-Ted

 

If you run the ewp controller it has a built in temp control that pulses the pump on and off when needed.

 

Those HUGE SS AN hoses and fittings scare my wallet!


-Ted

 

I know what you mean but I was able to score all my needs on ebay
everything for under 100.00. Hoses and fittings.

 

I like ted's thinking. What about having lower voltages at idle so that pump doenst wear as fast? For instance, something like the Aeromotive Fuel Pump controller for the A1000? Any ideas?

AN fittings scare my wallet too...

 

Im running a craig davis water pump controller. It controls voltage on the pump from 3 to 12 volts depending on the temp of the coolant.

 

can any one tell me how many gallons per minute i would need?

 

Been running a Davies Craig ewp for maybe six years, periods of down time in between . Ah the sacrifices we rotary heads make, lol. Never overheated on 100 degree days in traffic. Used a 12v speed controller for constant duty and a bypass hooked up to the temp switch for full speed. With a relay of course. This way also allowed me to have heat in winter, �� I purchased two pumps because I was unsure of the pumps durability, extra pump still sitting in my garage. Plan to use it on my three rotor build feeding each housing directly. I spent an insane amount of time mapping coolant flow through engine. Trust me the rotary engine does. Of give a crap about gph! There I said it. Most critical is capacity, and if u understand heat transfer u know what I mean.

 

50 gpm universal Mezzier was recommended to me by a big name pro rotary race engine builder