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olddragger 02-07-2011 09:54 AM

discuss the electric water pump
 
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?

terch1 02-07-2011 10:07 AM

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.

tigersilhouette 02-07-2011 10:23 AM

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

9krpmrx8 02-07-2011 10:34 AM

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.

paimon.soror 02-07-2011 11:06 AM

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.

olddragger 02-07-2011 11:19 AM

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

sauceyI986 02-07-2011 12:12 PM

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.

Third-Reef 02-07-2011 09:43 PM

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.

nycgps 02-08-2011 01:08 AM

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.

dannobre 02-08-2011 01:09 AM

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

nycgps 02-08-2011 01:12 AM

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.

dannobre 02-08-2011 01:18 AM

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

olddragger 02-08-2011 08:17 AM

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?

nycgps 02-08-2011 09:21 AM


Originally Posted by olddragger (Post 3874650)
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.

9krpmrx8 02-08-2011 10:14 AM


Originally Posted by nycgps (Post 3874536)
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.


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 :)

nycgps 02-08-2011 10:23 AM


Originally Posted by 9krpmrx8 (Post 3874760)
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 :lol:

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. ;)

HiFlite999 02-08-2011 10:39 AM

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.

9krpmrx8 02-08-2011 10:58 AM


Originally Posted by nycgps (Post 3874770)
we got 104 last summer I think thats hot enough :lol:

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. ;)


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.

olddragger 02-09-2011 08:09 AM

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

DocBeech 02-10-2011 04:53 AM

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.

HiFlite999 02-10-2011 09:51 AM


Originally Posted by olddragger (Post 3875684)
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.

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 :dunno: , though I certainly won't mind if an early-adopter proves me wrong.

HiFlite999 02-10-2011 09:57 AM


Originally Posted by olddragger (Post 3875684)
I need to get out more---dont I?

:rock:


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

rjon17469 02-10-2011 10:31 AM

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.

HiFlite999 02-10-2011 10:51 AM


Originally Posted by rjon17469 (Post 3877169)
-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.

usnidc 02-10-2011 10:57 AM

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.

rjon17469 02-10-2011 11:04 AM


Originally Posted by HiFlite999 (Post 3877197)
Also, any increased electrical requirement which could be expected to normally happen during acceleration in anticipation of higher heat loads also represents a drag on that acceleration

I completely agree, however you are talking about drag (amount of energy loss per unit time), not inertia (resistance to acceleration due to mass). While there would be an increased electrical load present due to the water pump running, this has very little to do with how much energy it takes the engine to change speeds and more to do with how much energy it takes to keep the engine spinning at a constant speed.

The reason I say better throttle response is because you could completely remove the water pump from the pulley system, thereby reducing the engine's rotating mass and consequently provide better throttle response. A beefier alternator would be required which would likely impose additional rotating mass, but should not be equivalent to the amount of rotating mass eliminated.

*Edit* But I also completely agree that in theory, this all sounds nice. In practice, things can be quite different.

HiFlite999 02-10-2011 11:22 AM


Originally Posted by usnidc (Post 3877209)
setting up a failure warning light shouldn't be too difficult.

I'm not so sure this is true. Essentially the only fast failure mode for a MWP is the drive belt breaking - which also fails the alternator and lights up the normal dash display. MWP slow failures are generally preceeded by squeaking, or leaks around the bearing seal. An EWP could also have a bearing failure, but additionally, a motor failure, controller failure, or failure of one of the sensors used to adjust pump rotation. All of these could easily result in limited flow but still have current going through the motor power wire. Certainly, if there is no power to the motor with the engine running, it's easy to trigger a warning light. Not having proper flow isn't so easy to monitor. Adding an overtemp warning is also rather easy, but won't always save you. Why? Without flow, temps on the inlet or outlet of the engine may show normal while the engine is cooking. (One might argue that a thermostat problem in a MWP system could do the same thing, but thermostats always have a little burp hole, so as long as the MWP is at least partially functioning, there is always some flow even with the thermostat fully closed). Probably the sensor at the OBDII location will show rise in the no-flow condition, but then one has to get that signal out and into your interlock system; Tee-ing off the port won't work very well either, because it pulls the sensor out of the coolant flow stream.

usnidc 02-10-2011 11:22 AM


Originally Posted by rjon17469 (Post 3877220)
I completely agree, however you are talking about drag (amount of energy loss per unit time), not inertia (resistance to acceleration due to mass). While there would be an increased electrical load present due to the water pump running, this has very little to do with how much energy it takes the engine to change speeds and more to do with how much energy it takes to keep the engine spinning at a constant speed.

The reason I say better throttle response is because you could completely remove the water pump from the pulley system, thereby reducing the engine's rotating mass and consequently provide better throttle response. A beefier alternator would be required which would likely impose additional rotating mass, but should not be equivalent to the amount of rotating mass eliminated.

*Edit* But I also completely agree that in theory, this all sounds nice. In practice, things can be quite different.

Another part of it is that the ewp is running a constant speed based on the temp of the engine, not the rpm of the engine, so reving the engine would not have a direct effect on the ewp rpm. the electrical draw from the ewp would be more constant, thus not having as big of an effect on the electrical demand as some might think and could be accounted for.

usnidc 02-10-2011 11:40 AM


Originally Posted by HiFlite999 (Post 3877241)
I'm not so sure this is true. Essentially the only fast failure mode for a MWP is the drive belt breaking - which also fails the alternator and lights up the normal dash display. MWP slow failures are generally preceeded by squeaking, or leaks around the bearing seal. An EWP could also have a bearing failure, but additionally, a motor failure, controller failure, or failure of one of the sensors used to adjust pump rotation. All of these could easily result in limited flow but still have current going through the motor power wire. Certainly, if there is no power to the motor with the engine running, it's easy to trigger a warning light. Not having proper flow isn't so easy to monitor. Adding an overtemp warning is also rather easy, but won't always save you. Why? Without flow, temps on the inlet or outlet of the engine may show normal while the engine is cooking. (One might argue that a thermostat problem in a MWP system could do the same thing, but thermostats always have a little burp hole, so as long as the MWP is at least partially functioning, there is always some flow even with the thermostat fully closed). Probably the sensor at the OBDII location will show rise in the no-flow condition, but then one has to get that signal out and into your interlock system; Tee-ing off the port won't work very well either, because it pulls the sensor out of the coolant flow stream.

But like a fan controller on a computer motherboard, you could get pump rpm data and then with a couple of temp sensors work out "expected" rpms at various temps and be able to set up a warning system. basically, if temps are rising, the controller keeps boosting ewp rpms until temps pass a certain fail point then it throws the warning light/engine limp mode or whatever. also, if the pump is failing (i.e bearing failing), the draw (amps? ohms?) on the electrical system would be greater than expected for a given rpm and that could be seen also.

HiFlite999 02-10-2011 11:40 AM


Originally Posted by rjon17469 (Post 3877220)
I completely agree, however you are talking about drag (amount of energy loss per unit time), not inertia (resistance to acceleration due to mass). While there would be an increased electrical load present due to the water pump running, this has very little to do with how much energy it takes the engine to change speeds and more to do with how much energy it takes to keep the engine spinning at a constant speed.

The reason I say better throttle response is because you could completely remove the water pump from the pulley system, thereby reducing the engine's rotating mass and consequently provide better throttle response. A beefier alternator would be required which would likely impose additional rotating mass, but should not be equivalent to the amount of rotating mass eliminated.

*Edit* But I also completely agree that in theory, this all sounds nice. In practice, things can be quite different.

Picking nits perhaps, but with the belt off sometime, grab the waterpump pulley and see how fast you can twist it back and forth, then do the same with the alternator pulley. There is very little rotational inertia in the water pump by comparison. Going to a bigger alternator will add much more rotational inertia to the system than removing the MWP will take away. The pulley/shaft/impeller might weigh a pound or so, an alternator armature weighs 10x that, plus that mass is located much further from the rotational axis. Don't forget too, that if you increase the rotational speed of the EWP, you are also fighting the rotational inertia of the impeller/shaft/motor - which again will be more than the equivalent MWP. Acceleration (of the car) comes from the power in excess of what's needed to maintain constant velocity motion. Drag in any form, takes always from that excess power, no matter where it comes from. I agree that there are several potential advantages of an EWP, but not that there is much to be gained by elimination of that represented by the MWP. (Unless, like for drag racers, the pump is shut off entirely for the duration of the acceleration run).

rjon17469 02-10-2011 11:51 AM


Originally Posted by HiFlite999 (Post 3877241)
An EWP could also have a bearing failure, but additionally, a motor failure, controller failure, or failure of one of the sensors used to adjust pump rotation.

Very true. My thinking is that most of the sensors used to control the flow rate of the pump would be sensors that are already in place. For example, use the air intake temperature sensor for ambient temperature, use the throttle position sensor to perform the engine load calculation, use the RPM sensor for engine speed, etc. A failure of any of these already-present sensors would have significant impacts on either the ability to drive or overall operation of the motor and therefore are worth checking for errors.

However, I agree that there are a variety of ways in which a system like this could fail and it is impossible to account for them all. Therefore, a temperature sensor close enough to the core engine components such that it would be heated in a no-flow situation would be a requirement.

Given that, I don't think it's impossible. Years ago people had a similar debate with electric power steering, yet here we are.


Originally Posted by usnidc (Post 3877242)
Another part of it is that the ewp is running a constant speed based on the temp of the engine, not the rpm of the engine, so reving the engine would not have a direct effect on the ewp rpm. the electrical draw from the ewp would be more constant, thus not having as big of an effect on the electrical demand as some might think and could be accounted for.

True, but I think a properly implemented EWP system relies on more than engine temperature to calculate coolant flow. Take warmup - the engine is cold, so if the flow was based on temperature, there would be little to no flow. However, this isn't what you want. Higher flow during warmup could help to spread the heat from the combustion side of the rotor housing to the intake side, providing a more even warmup process. And likewise, if the engine is at operating temperature, the flow would need to be much different if the ambient temperature is 40 degrees compared to 100 degrees.

And like HiFlite999 said, it is much easier to proactively cool an engine as it produces excess heat rather than cool it off after. For a short burst up to 9k, the thermal mass of the engine along with moderate cooling could somewhat handle the temperature spike in an effort to provide peak power to the wheels, but spending any significant time in the upper RPM range under load would necessitate higher coolant flow. Doing this before the engine begins to warm substantially would help reduce thermal runaway.

rjon17469 02-10-2011 11:53 AM


Originally Posted by HiFlite999 (Post 3877272)
Picking nits perhaps, but with the belt off sometime, grab the waterpump pulley and see how fast you can twist it back and forth, then do the same with the alternator pulley. There is very little rotational inertia in the water pump by comparison. Going to a bigger alternator will add much more rotational inertia to the system than removing the MWP will take away.

But the MWP and the alternator have different load/RPM functions, and therefore comparing their relative loads at low speed isn't significant. Try turning both at 3,000 RPM and the story is much different.

*Edit* But I see your point here. I guess it really depends on the final implementation, but my hope is that the marginal increase in inertia from the larger alternator would be less than the reduction from having the entire pump assembly, pulley, etc on the engine directly.

olddragger 02-10-2011 12:13 PM

great discussion.
No truer words have ever been said than "The devil is in the details". Totally agree with that.

With the EWP's that are on the market now---no alternator upgrade is required due to sole addition of the ewp.
To simplify the arguement--just look at the dyno results of before / after installations in recip engine cars?
Wouldnt it be nice if the ewp controller could be individually set?
If things continue to progress as I anticipate (God laughs) then this spring I intend to more seriously pursue this idea.
Throwing all therum asside---this just makes a lot of common sense.
Who knows---it may end up being a supplimental pump for low rpm and shut off use?
OD

rjon17469 02-10-2011 09:40 PM

My next question is about the thermostat. To my understanding, the only reason the thermostat is there is because there is no other ability to control the flow of the coolant with a MWP. However, given an EWP, it seems like a conventional thermostat would reduce the functionality of the EWP. Two ideas come to mind from this.

The first is to operate without a thermostat. In this case the EWP would pump at the desired rate of coolant flow through the radiator. This slightly reduces the complexity of the cooling system but imparts a critical disadvantage. That disadvantage is that during warmup, there would be very little to no coolant flow. This is bad because it eliminates the possibility of using the coolant to help to evenly heat the exhaust and intake sides of the rotor housing, and reduces or eliminates the possibility of using the coolant to warm the throttle body and cabin until the engine is completely warm.

So my preferred option would be to use an electric thermostat. In this case the pump can run at high speeds during warmup to aid in evenly heating the rotor housings while not running the coolant through the radiator. This would aid in engine warmup significantly. Also, I've noticed during highway cruising in cold weather, my engine cannot always maintain full temperature, likely due to coolant passing through the radiator and being excessively cooled. An electric thermostat would prevent this and aid the engine in maintaining a proper temperature in a variety of ambient conditions.

However, an electric thermostat gives another piece to fail.

Thoughts?

DocBeech 02-10-2011 10:57 PM

electronic thermostat as in computer controlled? I would want to add a manual override to control it myself when on the track. This would allow me to warm up the engine faster.

olddragger 02-12-2011 08:06 AM

believe it or not there are ewp with a built in bypass for warm up!

dannobre 02-12-2011 10:31 AM

Believe it or not...all this discussion about regulation of EWP speed etc seems a bit overkill :)

What in hells name would you want to electrically regulate it for.....the thermostat does an amazing job of keeping the engine at a steady temperatre .....if it is closed you circulate the coolant in the block...if it is open it goes to the rad ;) The more circulation through the block the less chance of fluctations in temperature between the hot and cooler side

Having an electrical pump is complex enough.....

DocBeech 02-12-2011 06:44 PM

because sometimes you want the thermostat to stay closed a little bit longer, like to rapidly warm up a car for the track.

olddragger 02-13-2011 08:58 AM

i really dont like the bypass in this engine--i dont believe that the thermostat is fully sealing it Dan. Now with pressureless coolant (evans) --then yes it probably would.
Whether or not a small leak makes any real difference, I am thinking it could. Most of the time probably not--but during those border line times--yes?

I once modified a thermostat housing, back in the day before we had the 180 mazmart thermostat, to be able to use a barrel sleeve 180F thermostat. I had to permanently closed the by pass to use that thermostat. Now I dont know for sure which one affected the cooling more, but I actually had difficulty in getting the engine up to proper temps--period. remember now I do have a secondary radiator set up. It was a big enough difference that I have to remove it.
Dan--you are the only one I know that has and is running the ewp. Can I ask what makes it so "technical" ? A true ?, trying to learn.

dannobre 02-13-2011 11:48 AM

I'm not sure why the bypass needs to seal that well Denny.....if it leaks too much it will cause slightly slower warmup..but these engines aren't exactly slow in that deparment anyway.

As for the tecnical part..nothing too technical...the pump does add some complexity and a bit of an electrical draw....but in the grand scheme of things it isn't that much of a draw....I think the pump I have draws 5 amps or something when it is running...not a big deal really.
I have replaced the cooling fans with a larger unit that draws less current than the stock twin fans..so in my case it balances out anyway.

My logic for the pump is this....more circulation through the block will always equate to more even temperatures in the system....as long as the flow isn't too much that there isn't strange eddies from the flow. The engine will warm up the same if the bypass seals effectively enough to limit the flow through the rad when it is closed. With the double pass radiator I have..the extra flow will allow lots of time in the radiator to allow heat transfer

The biggest thing I am trying to correct with this is the inability to cool the system at slow speeds...and cool down time in the pits after a session.....it really makes a huge difference when the fans are running and the coolant is circulating with the motor off....I used to see the temperature in the pits climb way over what I was comfortable with..even with no load on the engine.

Old Rotor 02-13-2011 12:58 PM


Originally Posted by dannobre (Post 3879973)
I'm not sure why the bypass needs to seal that well Denny.....if it leaks too much it will cause slightly slower warmup..but these engines aren't exactly slow in that deparment anyway.

As for the tecnical part..nothing too technical...the pump does add some complexity and a bit of an electrical draw....but in the grand scheme of things it isn't that much of a draw....I think the pump I have draws 5 amps or something when it is running...not a big deal really.
I have replaced the cooling fans with a larger unit that draws less current than the stock twin fans..so in my case it balances out anyway.

My logic for the pump is this....more circulation through the block will always equate to more even temperatures in the system....as long as the flow isn't too much that there isn't strange eddies from the flow. The engine will warm up the same if the bypass seals effectively enough to limit the flow through the rad when it is closed. With the double pass radiator I have..the extra flow will allow lots of time in the radiator to allow heat transfer

The biggest thing I am trying to correct with this is the inability to cool the system at slow speeds...and cool down time in the pits after a session.....it really makes a huge difference when the fans are running and the coolant is circulating with the motor off....I used to see the temperature in the pits climb way over what I was comfortable with..even with no load on the engine.

What coolant do you use? Evans?

dannobre 02-13-2011 02:18 PM

I have used both standard EG and currently am using NPGR

I will see if it is worth the cost and hassle this year :)

olddragger 02-13-2011 04:34 PM

Thanks Dan---cooling in the pit is something the folks in this area do by using those big floor drying fans--but the engines are OFF.

TeamRX8 02-13-2011 10:06 PM

http://www.daviescraig.com.au/Contro...s-content.aspx

rjon17469 02-14-2011 01:06 AM


Originally Posted by dannobre (Post 3879281)
Believe it or not...all this discussion about regulation of EWP speed etc seems a bit overkill :)

What in hells name would you want to electrically regulate it for.....the thermostat does an amazing job of keeping the engine at a steady temperatre .....if it is closed you circulate the coolant in the block...if it is open it goes to the rad ;) The more circulation through the block the less chance of fluctations in temperature between the hot and cooler side

Having an electrical pump is complex enough.....

I don't think it is overkill, and here is why.

Let's say your coolant is at operating temperature and therefore the thermostat is partly open. The car is driving at highway speeds and therefore there is a constant flow of air over the radiator. Let's say that the system will balance if the ambient temperature is 70 degrees - that is, the amount of heat being released by the engine and the amount of heat be dispersed to the air by the radiator are equal. In this case, the engine maintains its operating temperature.

Now let's have everything be equal, except that now it's 20 degrees out. The thermostat has no concern of what the ambient temperature is, so it opens like usual. But since the air passing over the radiator is cooler now, more heat is dispersed to the air by the radiator than the engine is producing. Because of this, the engine temperature falls, potentially below the ideal operating temperature.

With the current setup, there is no way around this. A MWP/thermostat system is not able to control the engine temperature independent of the ambient temperature at high speeds. That is to say, if driving at highway speeds and the ambient temperature drops 20 degrees, that will be reflected by a drop (not necessarily the same amount, but a drop still) in the engine temperature.

This is an everyday example (assuming you live in a cooler climate) of why this idea is useful.

dannobre 02-14-2011 01:24 AM

Last time I checked the thermostat openned and closed with temperature changes .........so when the temp drops it closes till the temp raises and it opens again. I did live in a climate where -40 wasn't unusual...and there we had to block off the rad with cardboard to get thing to warm up.

DocBeech 02-14-2011 07:10 AM

but with electronic systems you wouldn't have to. you could just run it closed.

olddragger 02-14-2011 08:40 AM

that somewhat is one of my points also? Thanks for posting. I think the ewp (thanks for posting the link Team, people use that controller with different pumps too not just the davis one) can be made more sensitive to changing coolant temps?
Here is my thinking. The thermostat acts as a restrictor. That is the only way it can control the coolant's temperature. The MWP doesnt care. Its going to pump reguardless. Now what happens to coolant that is being squeezed through a restrictor? Yall get my thinking? Whether it is going through a by pass or not it doesnt matter. The coolant is not going to have a smooth flow. There is going to be a lot of turbulance. Now compound that with any possible air in the system, bubbles from steam etc? Not good IMHO.
Now evans helps some with that as it is a pressureless coolant BUT the turbulance will still be there?
Now I do realize that breaking up the coolants boundry layor can be a real good thing, but doesnt that depend on how that is done and where is is being done?

The ewp with sensor control and possibily evans just makes too much sense too me.

Again, I think it may make more sense for excellant temp control for street use rather than track?
Please also notice that the fans are under direct control from the emp controller, not from the pcm. So on an over run situation, when you shut it down, the fans can be made to continue to run too.
Add the S2 model fans and it would be one hell of a package?

Something else to think about? With the EWP and no thermostat--how about reverse cooling?
Am I crazy? Hope so, crazy folks seem to have a lot of fun:)
Reverse cooling has never been done in the rotory engine that I know off.
Why cool the exhaust ports before the combustion area?
Thinking is -- cool the hot spots in the engine 1st--right?
Now is the combustion side hotter than the exhaust side in our engine? I think it is the exhaust side?
Where does the renasis engine seem to have the most problem?
Apex seals?
Corner seals?
Side seals?
Well cooling the exhaust area 1st would benefit the corner and the side seals more? I think the apex seals can take a little more heat better than the side seals?

Cooling the exhaust side really doesnt saturate the coolant much at all. I have measured temps from the coolant before and after it passes through the exhaust area and it is only about a 20F difference. With reverse cooling I think that the cooler coolant would scrub more heat than it does now?
Does the rear rotor run hotter than the front one? Most people would say yes. Reverse cooling would take care of that. Well would that just make the front rotor hotter than the rear? I am not sure, but I do know that the front rotor has more airflow exposure which may help some?
Do yall see where I am trying to go with all of this?
PS --I did get out a little this w/e. I went to home depo!
OD

9krpmrx8 02-14-2011 09:50 AM


Originally Posted by TeamRX8 (Post 3880438)


That is pretty cool.

DocBeech 02-14-2011 10:40 AM

You don't want to heat the intake portion because that would heat the air/fuel mixture. You want the mixture as cold as you can get it, colder air means more oxygen which means more power. I would rather the intake receive the coldest coolant first, and keep more horsepower.


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