I still dont see what is to be gained from it though... I see what you are saying now. I think I misunderstood your theory a bit. Yes the pump still flows coolant thru the block. I was tinking to the rad. I dont see what is to be gained by slowing down the flow of coolant in the block. The idea here is to heat it up as quickly as possible. Swish it around to get it warm. Hold it still (or too still) and you can overheat a cyl wall or head and you may never see it depending on placement of the temp sensor. Granted we are talking about a very small cooling system here. I work on engines that hold 200 gallons +...

All this to extend the life of a $100 part seems a bit extreme to me. The controler and sensors required to monitor the temps and flow would probably cost more than the $100 pump and $8 t-stat, that already do the job just fine.

You wont gain 10 rwhp by slowing the pump or even shuting it off. IMO you are still over complicating a situation that does not need to be over complicated. Bolt the pump in and turn it on. Lets say it draws 5 amps. Slow it down and you now have 3 amps. (assuming your theory is correct and I am wrong about the pump speed)... what have you gained? Again NASA couldn't tell a difference at the wheels. Your $100 pump now will last you an extra 3 months of use on the 7 years it will be there... I dunno. Does not seem like its worth the effort. Test it out and see if you have anything. I bet no but maybe you will find something we are not thinking about.

 

Project, I think we're on the same page now...I never really thought of this from a horsepower standpoint, I didn't have any delusions that it would decrease the load on the electrical system to the point where it would free up some of the horsepower it theoretically takes to power electric devices via the alternator. I was thinking of it purely as a way to decrease the load on the electrical system, and increase the life of the EWP.

That's why I originally asked if anyone had any idea what the optimal flow rate to get the optimal cooling efficiency from the radiator was...and of course that would change if you switch to a Griffin, or put an intercooler in front of the stocker, etc. which are a couple reasons it might be nice to be able to change the flow rate of the EWP, because we don't really know what conditions Meziere had in mind when designing their EWP's. So, the guy with the huge FMIC and twins might need the HD EWP running 50GPM 100% of the time, but the guy with a drop in filter and a cat-back might not.

It's kind of like the way our fans work...if they ran all the time, we would never overheat, but the fans would be working harder than they needed to be, so we can configure the PCM to turn the fans on and off when we want to maintain a specific range of coolant temp that we desire based on t-stat opening temp and whatnot.

Now, it may very well be that someone who's tested the cooling efficiency of our radiators can definitively say that I would only be able to decrease the amount the EWP pumps, or the amount of time it has to pump by an average 10% under all conditions. And that would make the controller I describe a complete waste of time...however, it may be just as possible that the controller I'm describing could allow the pump to only work 50% of the time or 50% as hard theoretically doubling the life of the pump, which would seem somewhat more worthwhile.

I appreciate everyones help in making me think more critically about my own ideas and flesh them out more in my head, that's why I love this place.

 

[QUOTE=Projectz28;5042877]
99% of the people who have cooling problems or pump failures have install problems or a totally seperate cooling system problem they have not fixed. Sometimes changing things and combining parts not designed to work with each other just ends up with poorly operating cooling systems.

My example that fully agrees with this statement is my old project car.. a 461ci BBC in a 87 Trans Am. Had a problem with cooling only while moving. It would cool down when sitting still even in 100F temps. I tried everything to fix it, one being a $700 all aluminum custom radiator (only since the original radiator was getting completely hot). Even built metal air scoops mounted right behind the lower radiator support to force air up into the radiator... none of this did anything to help. I think it actually got worse.

I almost gave up then reinstalled the stock air damn under the nose of the car and WHOLA!! Problem fixed. I never reinstalled it from long ago, it goes right infront of the air opening to the radiator and must create low pressure right behind it and causes air to go up into the radiator. Instead I made some metal ducts that bolted right behind the opening to the radiator air inlet. This was actually the problem!

If the stock cooling system is operating properly it should be plenty enough to keep any motor cool unless your cruising at 80mph somehow using 200-300hp continuously (normal cruising probably uses ~40-50hp). Short 1000hp bursts arent sustained long enough to create any significant heat that cant be quickly removed.

 

Just to put the "power saver" in perspective......

7 amps at 12 volts = 84 watts. Assuming a 60% efficiency on the alternator, it will consume 140 watts of mechanical power to produce 84 watts of electrical power.

140 watts / 746 watts/HP = 0.19HP

Cycling an electrical device on and off may do more damage than leaving it running at constant speed. There is typically a high inrush current at startup.... generates heat, spikes the load on the alternator, etc. Running an electric motor on PWM would probably reduce its life span significantly.... just a guess though.

 

I think so too......I know any pump that cycles on and off kills the electric motor, Like a well pump or fuel pump in my experiences

 

Thanks, I didn't bother to work out the numbers... but I did figure it would be an insignificant amount of HP, hence my last statement.

Concerning longevity, I didn't suggest PWM or on/off operation. A closed-loop control system could change voltage gradually, in response to termperature changes.

 

I think you're trying to solve a problem that doesn't exist!

Honestly, how's your electric water pump working for you? Is your engine too cold now? Mine runs great, and if it keeps my two electric fans from coming on, then it's saving electricity right there!

 

What do you think would be the best way to vary the output of an EWP?

I understand your first point very well, just from watching the voltmeter in our cars when I flip my manual fan switch to engage both fans, the load spike to the alternator is plain to see...I gather that since the fans don't cycle on and off that much, it doesn't hurt them as much as it would to cycle an electric motor on and off once a second or some other higher frequency?

 

Why not ask Meziere or some other supplier how there pump motor would respond to variable voltage to control the flow? .....or a PWM circuit (intermittent voltage)? Without knowing the electrical characteristics of the DC motor, anything else would just be speculation.

The guys that built my engine wouldn't even consider running an electric WP, since it won't supply the flow required to insure maximum cooling with a 300-shot.

 

You know, every bit of efficiency helps. I am glad to hear that you are at least looking at ways to make it more efficient. The difference between a powerful and an incredibly powerful engine is usually found in about a dozen little tiny details.

Do it for fun, as I tend to agree that there's more efficient ways to performance and fuel mileage, such as the removal of 20 pounds of mass from the car.

Just a few "off the hip" ideas,

Since the motor is a DC motor, you should be able to use some simple robotics controls to modify the power delivery to the motor, based on thermocouple inputs that you place around the engine. Bring them into a microchip PIC, and use some of Microchip's motor control routines to increase or decrease the PWM duty cycle to the waterpump. To get extra fancy, you could even bring in engine load via the MAP sensor & RPM and program a hysteresis curve into the controller to compensate for latent heat caused by full-throttle runs.

 

Which is why you would put a variable control on a DC motor. Providing a soft start to the motor would prolong the life of it more than anything else.

 

I think you are giving the electric WAY too much credit flow wise, some guys who understand things and pay attention have noticed INCREASED coolant temps at cruise speeds. This is as opposed to those with blind faith who take the time to understand nothing more than marketting BS.

As Fred showed you the math on the electrics are VERY VERY low power and converting forms of energy is very inefficient. The mechanical takes as much as 11hp to move 66gpm restricted at 6000rpms, the electrics are free flow rated and being a simple impeller(so is the mechanical) not a positive displacement or the like restriction will choke flow signifigantly so the 42gpm is not a real use number.
The mechanical certainly has it's own issues, cavitation on high rpm motors possibly the worst of them, so I am not saying don't do the electric. Electrics absolutely do free up power and provide adequate cooling most of the time, they are not pushing some raging torrent through the block that needs to be tamed though.

 

Controlling the speed of a brushed DC motor with PWM control is very, very common, and if done properly it can extend the life of the motor by reducing the operating temp.

As stated by others in the thread, though, I'm not sure that the average LT1 electric water pump needs any throttling.

 

I'll chalk that one up to "lessons learned". Thanks