I brought up the idea of the EWP (electric water pump) for our car a few years back. At that time it was really kinda a new thing and I was not completly sold on it and sure couldnt debate the issue with any hard data.
1st of all--this is not an idea to increase the power available by decreasing the parasidic lost of a mechanical pump. Yes it does give the car a little more power to the wheels but I think the other advantages far outweigh the power increase.

Why now?
This morning I was on my way to work. Going up the parking garage (5 floors) I notice my coolant temps (at the top radiator hose) slowly climb from 180F to 190F.
Yes decreased air flow is part of this, but also the low rpms of the engine in this situation really affects the water pumps ability to pump the coolant through the system. It was ironic, I thought, that at the time the coolant needs good circulation (low air flow) the water pump cant deliver?
Then I had a thought --wait a minute--this situation happens a lot. Street driving, traffic, etc etc and the different metals in the engine are being asked to tolerate fairly fast temperture changes. Thats not a real good thing? So how can this be fixed? How can this be addressed?

Bingo---the EWP! It just makes so much sense. Think about it. The ability to circulate the coolant during low speed situations, the ability to continue to run after the engine is shut down to advoid heat soak issues etc. A more steady state coolant temp would also mean a more steady state oil temp, it would mean less stress on the metals etc. This could be a real good thing--right?
Whats the problem then---why has no one done this? Is there a problem we dont know about? Is there an appropiate pump is available?
Well one thing is some people believe that the ewp doesnt have the power to pressurize the cooling system to the point it needs to be?
I dont know about that. Many big block cars run them on the strip and on the circle tracks. Now I do know that the reason the coolant system is pressurized anyway is to increase the boiling point of the coolant and we all know why we dont want the coolant to boil ---right? Thats right--hot spots---detonation---overheating the seals--yada, yada, yada. Real bad stuff.

So I had another thought-- what about a no pressure set up? One which the pump doesnt have to build pressure--just circulate? Sounds like Evans coolant could fix that!No pressure needed--or very little. 3 or 4 lbs?
In my mind that should work toward having a more steady state coolant temp during low speed driving? I dont think high speed driving is a problem?
Is a pump available? Yes there are EWP's out there that will pump 55gal per minute which is enough for us.
So an EWP in a system that uses Evans?
Recips race boys already doing this?
Why are us rotards not looking at this?
thoughts and discussion?
Is olddragger demented or just crazy?

 

I personnally love the idea. The electric water pump could run consistenly at the same rpm regardless of the rpms associated with the motor. The heat soak issue could also be addressed as you mentioned. The EWP could be linked to the relay for the electric fans. This sounds like a project for Mazmart. I'd buy one in a heartbeat.

 

Electric water pumps are definitely more efficient at moving water and minimizing drag on the engine. However, most EWPs I've seen look like mini turbos, and I"m not sure where that would mount in our engine bay. Also, they seem to have a high failure rate, at least on the newer (2006+) BMWs that use them. I think it would be great if there was a way to get them working in the renesis, but I still would trust a mechanical pump more than an electric one. Especially a plastic electric one. Has anybody used an overdrive pully to make the pump spin faster at low RPM? This is a great topic btw!

-Lawrence

 

I too have thought about this and messed with them in the past on a Honda. My experience on the B series Honda was positive, my friend never had any problems with it that I know of.

But, as with anything electric, there is a chance of failure. A mechanical pump lets you know when it is failing. What safeguards are built into an electric pump? How do you know when it is not working due to electric motor failure? Obviously you will know when you overheat but that may be too late.


And, EWP's typically are replacement pump in the OE location or remote mount.

 

Like everyone else mentioned, I think the common norm is to stray away from the electric pump on DD cars due to the maintenance and the failure rate. I too used to drive a Honda and at the time there were some cooling issues (some of the 02 civics came with half radiators and such) and people switched over to electric pumps. I remember horror stories of the pumps failing and not knowing it failed until it was too late.

 

with the major manufactors I dont electric motor failure is a problem? The seals and etc are well done. Wiring harnes's also.
I think electric motors last a long time?
Every one of our cars needs a true temperture gauge anyway and if for some rare reason it did quit, you would know very quickly.
Heck some gauges have a signal function in which you could wire in a fail safe for a certain temp.
The some ewps for the fords have just the motor mounted on the front plate of the water pump with the shaft going through the pump and driving its own impellar.
And how about this---if you get a computer control for the pump then no thermostat is needed? That would really be nice with the Evans coolant.
I need to speak with Paul?
OD

 

i have also thought about this as well because coolant temps can be a mf when crusing and then going high speeds. 1 min you ok next u listing to your exhaust and your temp is up way to high. it would be ok if it had a fail safe of some sort but i know most dont use them becuase if your temps get to high you f-ed.

 

Couple of thoughts on EWPs

1 the pump does not create the pressure in you cooling sytem, the heat does. the pump only needs to circulate the coolant. does not matter how much pressure there is, the pump needs the same amount of power to circulate.
2 Can't conect it to the fan relay the pump needs to run all the time but should vary the speed
3 ideally ou would have a temp controlled motor, the hotter it get the more it circulates.
4electric motors can be very reliable but not the typical brush type 12 volt motors. You need a brushless motor for reliability. reliability is going to cost $
5 EWP really is the ideal set up. But the devil is in the details. You would have a hard time matching the reliability of the stock mechanical setup without lots of time and money.

 

OD ... dude ... 190f won't kill your engine ... I can push my engine to 210-220f anytime I want to.

you're starting to act like 9K too much ... too afraid of water temp ...

if you really want to go E-pump, a lot of people has gone thru that path in the past rotary, and at the end most of them went back to stock pump.

sure E-pump saves some weight and it pumps water even if you switch the engine off (flip switch usually, some installed with e-thermostat) but its really not big of a deal.

 

I have had one in my car for a couple of years....I think it is another step in the better cooling scenario. I think it adds complexity to the system and that needs to be considered..so maybe not a NA non-track mod...

I think with a bigger rad and this pump...and oil cooling mods that the temp problem will mostly disappear. I really like the ability to leave it running with the car off...cools off after a track session very nicely....I'm still installing some of my solution....so stay tuned..I will have better data this spring

 

just lower the fan-on temp in the ECU will prevent most of the water temp spike. Trust me on this one. even tho the fan and fan shroud kinda suck.

 

I think most of us are way past that fix Wish it was that easy

 

very true dan and thanks for the feedback. I think the ewp is going to make it into production at some point --just like electric power steering
Curious as to what type you are using--the davis or a remote mount mezeire? The radiator mount meziere looks good to me?

nycaps--i think you might need to reread my post?

i wasnt concerned in the 190F temp. That scenario of the rapid 10F degree rise just got me to thinking. We all know what kinds of mess's i get into when I start thinking. he. So I posted my thoughts to help keep me out of trouble.
My main point is "steady state temps" as much as possible. We have an engine composed of different metals--old subject--right? Rapid temperture swings in therory should not be good for it. Little here, little there and it all adds up to decreased engine life expectancy etc.
More and more evidence is pointing to the corner and side seals as a real weak points in the S1 motor. People have identified that heat is causing problems for them in that area. I do agree with that. But, I am thinking of taking that, a step further. Not only is it the heat, but it is also the rapid temperture swings this engine has to tolerant?
It seems to me that this engine has a rather narrow tolerance in coolant temperature. 180f-210 coolant at the top radiator hose seems to be what all major builders say is the range of normal operating temps. Now I know tracks guys in the summer are above that, but professional teams arent. They dont get over 200F. There is a reason. Its been discussed many times.
Now let me be clear --the above temps are with water and maybe some antifreeze. If Evans is thrown in there then those figures are not applicable. It really is not about the higher temps at all. It is about "hotspots" that cause detonation/knock. Actually the higher the operating temps, the more efficent the engine. So an evans coolant engine may see 230F without any problems at all.
If the engine can be made to operate at 230F constantly without any hotspots/detonation it would be much better than an engine that swings from 180-210 all the time. Does that make sense?
So my thoughts are this... Computer controlled EWP with evans coolant? Best cooling package for the rotary engine-----period?

 

*argh*

I know what you mean in the original post. should've made myself more clear

hot spots exist since the original 10A. not much you can do about it. during rebuild you can add some extra "fin" around the spark plug area and it will cool the hot spot a lot better, but this is only needed when you are pushing everything to the limit.

E-Water pump --- gotta buy/fab your own adapter, wire it yourself, find a location for the pump, and check it every so often to make sure the pump still works.
Evans - $$$$ is one thing, another thing is you have to flush your system with PG at least 3 times before you can switch over. Actually make that 5. its also $$$. in case of emergency you have to fill it with Evans, nothing else.

It is probably the best, but 99% of the people don't need it.

 

Move to south Texas and run your car hard in the summer. You too will be worried about temps I am just worried about temps because I don't want my car dieing of heat stroke when I am making 275WHP Proper Prior Planning

 

we got 104 last summer I think thats hot enough

You should get RB flash or whatever you can to lower the fan-on temp (cobb access port can do it too)

it solves 99% of the problem.

 

In order for an EWP to be consistently more efficient, either in cooling or in reduced power requirements from the engine, than the mechanical, it would have to incorporate a rather sophistacated electronic control system to decide when to come on and with what strength. In terms of hp delivered to the pump vs. hp taken from the engine, the engine-->belt-->pump method will always deliver more than an engine-->belt-->alternator-->battery-->electric pump method. Simple physics there. The power efficiency gains possible with an EWP will come in ranges where the mechanical is delivering more than necessary flow. Cooling gains will come when an EWP can deliver more flow than a MWP for the given rpm. For a track car running consistantly over 6k rpm, I suspect that neither situation will be improved going to an EWP; for a street car it will probably happen more often. Worth it? Only maybe, but certainly not without automated control of the pump motor. This would be a major engineering effort, likely out of reach to most hobbiests. On the OEM front, the conversion to electric fans was very swift, conversion to electric steering is ongoing and slower, conversion to EWP's has been rare so far. There's a message in that.

 

I have lowered the temps VIA the Cobb and it seems to work but it's not very cold right now so the real test will be during the statewide meet in April. Last year during the long sections I got coolant temps in the 230F section. In certain sections of the canyons we (fast group anyway) pretty much stay in second gear near 8,000 RPMS for quite a while so the temps rise quickly.

 

the davis ewp already has a computer controlled pump that has been available for a few years now, variable flow --in essence just like a water methanol injection system.
No thermostat needed with it and that in itself takes a big restrictor out of the picture.
Agreed that track only cars may not see a benefit with temps, but there would be a few extra hp available from the non parasictic nature of the ewp and no, the alternator does not have to work that much harder. Dyno results have proven hp gain time after time. Plus if they could run Evans the engine would be more thermaly efficent .

Everyone please remember it is not overall high temps is not want I wanted to discuss. It is the rapid rise and fluctuation of temps and localized hotspots that is my subject here.
EWP should give a more steady state engine temp and Evans should take care of the hotspots?
The combo of the two seems perfect to me. Evans doesnt require any pressure in the system. The EWP that is allowed to operate in a free flow manner will flow even more gpm.
No thermostat restriction.


Cost----yep. Every damn thing that is done to this engine cost money. Is it worth it? That depends on the individual. I would think those that are pushing the car with FI or hard driving
may would want to look into this option?
Many many recip guys run there system this way.

My imaginary perfect system would be the ewp/evans and engine reworked to a single pass system with cool coolant passing equally to the intake side and the exhaust side exiting the rear of the engine.
I need to get out more---dont I?
OD

 

I like the idea and it would be easy to install a fail safe. I have seen a lot of set ups with EWPs and heres a couple of them.

-Install the EWP with a led lighted on switch. If the pump fails and is not running the led will go out.

-Computerized EWPs were sometimes set up with warning lights when temps reached X point or when the pump failed(changes in electrical currents can denote a pump failure)

-Most importantly having a gauge to read the water temps, once you reach your limit as to how hot you want to push the car, you shut it down.

 

Interesting. What are the parameters read for the computer to base flow decisions on? How is the appropriate feedback strength determined? If this is not done correctly, the temperature fluctuations could easily be worse than stock. As an example, think of a home central A/C system. Suppose it's 90F outside and you want 70F. In terms of min temp fluctuations within the house, it's best under those circumstances to have a A/C system just powerful enough to keep that temp difference without cycling on/off. Of course, it's helpless if the OAT goes above 90F. If one increases the cooling power of the system to be able to maintain 100/70, then it's too powerful to maintain 90/70 and thus requires an on/off cycle. Further increasing the size of the unit to be able to do 120/70, means that those fluctuations get worse at 90/70.

You see where I'm going with this? A variable-flow EWP system has the potential for keeping fluctuations smoother than a MWP, but only if the programmed feedback response is appropriate to the application or if the system is "smart" enough to figure out that optimal response on its own. Certainly, a MWP + thermostat is not optimal either, but that alone does not automatically imply that a EWP w/o thermostat is better. In my day job, we couldn't function without automatic feedback control in a bazillion different roles. However, it's very difficult to engineer them to behave sensibly in real-life conditions. "Computer-control" can make things much better - or much worse. The devil's in the details and I still question whether even the skilled eyeball engineer can make an add-on EWP work well through the range of conditions a street/track car present , though I certainly won't mind if an early-adopter proves me wrong.

 

At least for you, "out" doesn't mean 0 deg F. Winter makes me:

 

I think this is a great idea. Here are some things off the top of my head:

Cons:

-Reduced pumping efficiency. Converting the mechanical energy to electrical energy and then back to mechanical energy results in lost power.

-More significant alternator requirements. Our electric power steering already places large demands on our alternators. The constant drain from an electric water pump would increase that, and such drain would likely be enough to require a larger alternator to ensure proper operation.

-Increased change for failure. Yes, electric motors are becoming more reliable, but the fact is, if you make the system more complex, it is more likely to fail.



Pros:

-Dynamic cooling control. The rate of coolant flow could be a calculated based on a variety of factors, including ambient temp, engine temp, engine speed, AC usage, etc.

-Ability to run when the engine is off. For the hotter climates, this could be a big plus to help the fans cool the engine evenly after shutting down from some hard driving.

-Water pump failure detection. While the electric motor would likely have a higher change of failing, any reasonably intelligent motor controller is able to detect if the motor connected to it is running within expected specifications. A detected failure could trigger not only a check engine light but also could intervene with the throttle to reduce engine power and thereby reduce overheating proactively.

-Increased peak engine output power. A mechanical pump has a pump rate directly proportional to the engine speed, which means that there must be a balance between pumping power at idle versus power loss at redline, despite that such a balance may give more pumping power, and therefore power loss, at redline than what is needed. Having the ability to dynamically control the power consumption of the pump could increase peak engine power output, despite the pump having lower pumping efficiency.

-Better throttle response. Fewer components connected directly to the engine gives less rotational inertia to deal with.

 

This would be true only if the EWP controller would be programmed to "unload" during acceleration. The bad thing about rotational inertia is that it represents a drag to the system as the engine "spools up", however the energy put into that rotation while spinning up is recovered while spinning down. Also, any increased electrical requirement which could be expected to normally happen during acceleration in anticipation of higher heat loads (it's always easier to prevent an engine from getting too hot, than cooling it off once it already is) also represents a drag on that acceleration - and one that is not recovered during decelleration.

Otherwise, your list seems valid to me, as a good idea in prinicipal. The in practice part may not be so simple to achieve. It's instructive that even though OEM companies are taking all kinds of measure to eek out a few more 0.1 mpg's, with one exception in one model (that had problems apparently), none that I'm aware of, have gone to EWP's.

 

I think the ability to set a maximum rpm of the ewp that is just below cavatation speed allowing the most efficeint cooling while increasing peak hp would be the biggest advantage of running an ewp. the ability to run after engine shut down would be the second.

setting up a failure warning light shouldn't be too difficult.