Electric Water Pumps

[81 Corvette]

Just searching Jegs looking for cool things while waiting for game 6


Does anyone have one installed?
Whats the best brand?
Pro's/Con's
How difficult is the wiring install?
Any other comments?

 

[BeaterShark]

I don't have one, so I cant comment on the best brand, but I do have some opinions on them.

Pros:
Gives some HP back to the engine. I've heard as much as 10HP from someone who dyno'ed their car with water pump belt off vs. water pump belt on.
Allows for water circulation which can be setup to remain on after engine is shut down. This would work really good with the use of an electric fan.

Cons:
They are pricey, but you probably already know that.
They might be less reliable than the mechanical type. I have not really researched this, but it is at least perceived that electric components are less reliable than mechanical.

Wiring could be as simple as adding in a relay.

As you can probable tell, I'm a fan of this. I just couldn't justify the $$$ or I'd have one. I do have a friend who has had one for a few years and he has had no problems with it. I don't remember which brand he has, though.

 

[Jack]

I don't have electric water pump ... never have. From what I can tell, seems not a good idea for chevy V8 that is regularly & routinely street-driven ... reliability may be compromised. However, electric fan does work well.
JACK:gap

 

[81 Corvette]

i have the flex-a-lite dual 11in set up and love it.

As for the price, i was checking out jegs last night and the electric's price wasn't that much different then an edelbrock price on a mechanical.

i did see one that i liked, but it didn't have a radiator hose inlet on it, although it did have a spot to go to the heater core. How do you get the coolant into the motor like that???

 

[Vettehead Mikey]

Pros:
Gives some HP back to the engine. I've heard as much as 10HP from someone who dyno'ed their car with water pump belt off vs. water pump belt on.QUOTE]

This is a myth, same as the electric fan-saves-horsepower myth. You need electrical power to drive the pump, (or fan) which comes from the alternator. It's much less efficient to mechanically drive an alternator, to produce electricity, to convert back to mechanical motion via an electric motor than it is to drive the pump mechanically in the first place.

Every one of the claims I read talks about power they gained by removing the drive belt, but conveniently forgets to mention how much extra load it puts on the electric system.

If you were to continue running the pump and fan after the engine shuts down,

1) what would you gain?
2) think how hard your alternator would have to work to recharge the battery next time you start the engine.

 

[photovette]

Okay, I've heard that the fan/clutch doesn't save you that much power over electraic fans/alt. That may be true in steady state, constant speed driving, but not when you accelerate rapidly from a stop on a hot day. When the fan clutch is fully engaged, it takes a lot of energy to accelerate the fan blades to 6000 rpm in a couple of seconds. I have never heard what the figure is for this in horsepower, but I know full well that performance from a standing stop on a hot day is considerably reduced by the fan load.

 

[81 Corvette]

i'm not concerned about the HP gain loss with my electric fan. I put it in because i'd heard good things about them, plus i really hated the look of the shourd, not to mention the pita removal of it for any front of engine work.

As for the HP, does the alternator have more resitance to turning when the load is increased. I never understood teh debate. The alt is already being turned whether there is a clutch fan or not.

 

[Tom73]

From what I have heard, the elect water pumps do not flow enough for street use. They are strictly a race item.

If you want improved water flow, check out something like the Stewart HighFlow pumps. They ARE very good on the street.

tom...

 

[drags1998]

I (WE) have drag raced for MANY years, EVERYONE that has a (real) racecar runs an electric pump!!! and fans. IF, I was going to run an electric pump on the street I would do ALL the research I could on the MOROSO STREET PUMP, I'm not sure I would ever TRUST ANY ELECTRIC WATER PUMP ON THE STREET!!!!!! If it quits!! your dead rite where you sit!!!!!!!!:cool

 

[JohnZ]

Electric water pumps were designed to cool engines down in the staging lanes and to speed up engine dyno setups, and the marketing guys have since figured out that if you anodize them nice and pretty you can peddle them as "race car parts for your street machine". A stock SB Chevy V-8 water pump moves 60 gallons per minute (82 for BB's), and virtually NONE of the whizbang anodized Meziere/Moroso/etc. pumps can come close to that volume on a continuous basis (but people buy them anyway because they see them on Pro Street cars featured in "Super Chevy") :eyerole

The alternator and relay makers love it - let's see - electric fans drawing 40 amps, electric water pump drawing 40 amps, MSD's drawing 20 amps, "killer" stereo drawing God-knows-how-many amps, A/C drawing 30 amps, and pretty soon you have a 200-amp Leece-Neville perforated-frame alternator with two drive belts - wonder how much power that draws?

Prediction: The "next big marketing thing" will be an anodized electrically-driven alternator - you read it here first

 

[Vettehead Mikey]

I have never heard what the figure is for this in horsepower, but I know full well that performance from a standing stop on a hot day is considerably reduced by the fan load.

Exactly the same load (or greater due to losses) as if the electric fans are on and your alternator is going full blast trying to supply juice to feed them.

C'mon guys, this is basic physics. You don't get energy for free!

 

[Vettehead Mikey]

As for the HP, does the alternator have more resitance to turning when the load is increased.

Sure, that's why you see an RPM drop when all the lights etc. are turned on- more load. If it took the same HP to drive a 100 amp alternator as a 20 amp, that'd be more 'free' energy.

Look at any gas powered generator- run it with no load, then flip the switch to add full load. Some of them just about die out before they recover.

 

[photovette]

It is not the same.

Assumptions:

1. It takes roughly 30 horsepower to maintain a car traveling at 60 mph. The engine has to overcome rolling resistance, air resistance, and parasitic loses from the motor, drivetrain, and accessories.

2. However, it takes roughly 300 horsepower to accelerate a car to 60 mph in 6 seconds. The engine has to raise the kinetic energy of the car from zero (when stopped) to what ever large number it is when the car is traveling at 60mph. Let's see, mass x velocity x time = energy.


Now, at a steady 60 mph, the mechanical fan uses about 2-5 horsepower when engaged and less when not engaged. An electric fan comes on only when needed. So, on a cool day, at highway speeds, electric fans may not come on at all thus using NO energy. However, since the mechanical fan is free wheeling at those temperatures too, than it is using a very small amout also. So, not much difference.

It's at FULL acceleration that the real advantage of electric fans show up.

At engine speeds of 1000 rpm to 6000 rpm, the electric fans use the SAME current. So, during full acceleration, the load on the engine is the same. Remember, the alternator will unload on over voltage conditions.

Not so with mechanical fans! It takes a considerable amount of energy to accelerate the heavy metal fan blades from 1000 rpm to 6000 rpm--it's a big drag to the engine while the fan blades are increasing rpm's. Hey, that's why they use aluminum fly wheels in race cars--less rotational torque to over come. Plus on a mechanical fan, you also have to over come wind resistance of the blades to raise its rpm's.

I would suspect that the amount of horsepower used to accelerate an 18" stock fan blade to be well over 20, maybe more.

An example of this is when you increase the speed of your lawn mower from 'turtle' to 'hare', the engine bogs down until the blade reaches it's new higher rpm. I submit that an 18" stock fan blade on a C3 weighs much more and pushes a heck of a lot more air than a lawn mower blade. I'll bet a 3.5hp Briggs & Straton engine couldn't turn a C3 fan blade faster than 1500rpm--so, think what it'd take to accelerate the fan blade up to 6000 rpm's in 2 seconds or so!

And, to me, that's where it really counts--acceleration--WOT from a standing stop!

 

[Vettehead Mikey]

Most of your assumptions are close enough to reality to accept them as-is. Your example also only applies when full throttle is required when the engine is hot enough to have the fan clutch engaged, or when the electric fans are 'on', throughout the acceleration run. This in itself is not a normal occurance and is the exception rather than the rule. I can't remember when I've been in a situation where I could (or would want to) apply full throttle with the engine that hot, but that's just me.

One data point is missing in your example - the amount of energy required to drive the electric fans at full tilt over the amount of time required to run the fans AND recharge the battery to it's former state. Long after the mechanical fan has accelerated to speed and finished cooling the engine (ie uncoupled), the electric fans are still labouring away to cool the engine and/or recharging the battery.

You assert that the alternator will unload on overvoltage condition. True, but if the fans are on, that won't happen, so you get full parasitic drag penalty.

Gotta compare apples with apples.

 

[BeaterShark]

This is a myth, same as the electric fan-saves-horsepower myth.

Nope, I'm talking about dyno results. I'm pretty sure it was more than 10 HP, but cannot find where I read it. I know you can't trust everything you read on the internet . . .

You need electrical power to drive the pump, (or fan) which comes from the alternator. It's much less efficient to mechanically drive an alternator, to produce electricity, to convert back to mechanical motion via an electric motor than it is to drive the pump mechanically in the first place.
Every one of the claims I read talks about power they gained by removing the drive belt, but conveniently forgets to mention how much extra load it puts on the electric system.

Right, but you are already mechanically driving an altenater. The question is, how much HP does an extra 6A draw from the altenator cost? 10 HP, I seriously doubt it?

If you were to continue running the pump and fan after the engine shuts down,

1) what would you gain?
2) think how hard your alternator would have to work to recharge the battery next time you start the engine.

1) Your engine temp wouldn't rise after engine shutdown.
2) 20 seconds or so would be all that would be needed and would not load your altenator very much at all upon next startup, especially since the fans are off. This is only benifecial for short stops.

I agree this is a really small "pro" and is no reason to switch, but IMHO, it is still an advantage of an elect pump.

 

[Vettehead Mikey]

Nope, I'm talking about dyno results. I'm pretty sure it was more than 10 HP, but cannot find where I read it. I know you can't trust everything you read on the internet . . .

You read correctly, it is actually 10HP or more- but that's with the fan clutch fully engaged, and the engine at red line.

Who actually does that in real life?

The event you read about was probably on one of the 'other' sites where some guy was doing repeated dyno pulls, so many in fact that his fan clutch kicked in due to imminent overheating. Obviously he had insufficient external fans blowing air through the radiator to cool the engine, as normally would happen with the car in motion. He noticed with the fan clutch engaged on the next pull that the engine made 10+hp less than with it not engaged. His erroneous conclusion was that all fan clutches always take 10+HP all the time to drive the fan, always no exceptions. Never occured to him that it therefore would only take 1-2 HP with the engine at normal speeds and virtually NO HP when the clutch is disengaged.

Again apples with apples.

 

[photovette]

You know, if it didn't make much difference, why do all newer cars use electric fans--and not just the front wheel drive cars.


My 'vette runs 3000rpm at 70mph and I drive long distances alot. With the electric fans, at that speed, they hardly come on at all. With the fan/clutch assembly, even when not engaged, there is drag. I think there is real savings for highway driving.

And some of us do push 6000rpm fairly often--there's a '77 Trans Am that lives near me; when we meet at a light every so often, I got to whop'em.

I had to take the electric fans off my 'vette. With the a/c on and my 355/350hp motor, they couldn't handle it on a 93F day. It would probably work well if I had an aluminum radiator. By the way, my engine cooling system has a new 4-core radiator, Edelbrock water pump, high flow thermostat, new hoses and seals, and the intake manifold is aluminum. All this was replaced in the last 6 months. I state this so you know that there's not another problem in the cooling system that is causing the electric fans to not cool correctly.

What I'm doing now is installing an auxilliary fan and shroud from an '81 'vette and re-installing the fan/clutch system. I will have the aux fan come on when the a/c compressor comes on and at 200F. When fall comes, I'll remove the fan/clutch and rely solely on the aux fan.

 

[MaineShark]

Alright, guys...

Here's some physics...

Fans, water pumps, etc. operate most efficiently in some particular (and narrow) rpm band. When driven too slowly, they don't produce the desired flow rate, so you have to have them producing enough flow, at or near idle. That means that they are being seriously over-revved, creating a low of unnecessary parasitic drag.

The advantage of electric fans and pumps is that they operate at a fixed speed, always operating most efficiently. Yes, it takes power to produce the extra amps, but it is similar to the power needed to run the mechanical fan and pump at idle. So, as soon as you go more than a little bit above idle, you see a net gain in horsepower with the electric units.

That's the cold, hard facts, as far as power savings go. It's not "free energy" - it's simply a reduction in parasitic drag.

The real issues revolve around reliability. Electric fans have advanced to the point of being superior to their mechanical counterparts. They haven't displaced mechanical fans in modern cars for no reason.

Electric water pumps are still a grey area. Some say that they are just as reliable as mechanical pumps. Others say that they are not. You'll have to make up your own minds on that one.

There is also an issue of flow rate. The electric pumps typically do not produce the same flow rate as mechanical pumps. Potentially, this could be a problem. It all depends on how much flow is actually necessary to properly cool the engine. Sure, the mechanical pump produces more, but how much of that is overkill, simply due to the pump being spun faster as the engine goes faster, even after it has already exceeded the amount needed to cool the engine? I don't have an answer to that one. I'd sure like to know what flow rate the stock mechanical pump produces at something like 3000 rpm. If an electric pump could match that flow rate, I'd put money on it being able to cool the engine properly.

So I guess the long and short of it is that the electric pump does free up horsepower, but it may or may not be reliable enough, and may or may not produce sufficient flow to cool the engine properly. If someone has some hard facts to address those last two issues, it would probably be quite helpful.

Joe

 

[Jack]

Dunno what stock pump flows ... but these tidbits may help put it's potential into perspective. Most of the circle track cars around here are sbc ... our is. Everyone that's running halfway decent or better is running speed reduction pulley setup on mechanical water pump ... anywhere from 25%-50% pump speed reduction from stock ... most of these motors tend to live at 5500-6500 rpm for 30-70 .4-.6 mile laps. Most have flow restrictor in water neck along with an OE-type iron pump ... I'm freshening one right now that I'll switch to an OE-type aluminum pump (painted cast iron gray). Most have a good autometer/sw mechanical temp gage ... avg temps around 220*. And where track rules permit (usually), we run electric fan.
JACK:gap

 

[Glensgages]

A few years ago, my buddy put an aluminum after-market radiator into his 468" '70 Chevelle, and asked me to help fabricate an aluminum block-off plate for the back-side, leaving ONLY 2 holes for his electric fans;
we fabricated shrouds for 'around' the fans from 3" aluminum strips.

He ALSO ran an electric water-pump on this car, and drove it to the strip & back regularly, 12+ miles each way, as-well-as to an occasional car-cruise...

While I thought for SURE it would over-heat in traffic, it never did, even with 11:1 CR & 12-second-flat ET-slips...

Just my $.02 worth...