Is anyone running a STEWART water pump?

[SwaveDave]

Fellas,

I agree 100 percent.

I have twin electric fans and they mooove the air ! With a stage 3 Stewart pump, im expecting the fans to come on less than they do now. Right now, if its 70 outside and im moving at least 35 mph...the fans wont come on at the setting of 190 ; i think that tells me i have a pretty efficient cooling system as it is.

'Twin' fans also have the advantage of a backup in case you loose one.

Dave

 

[sscam69]

I understand the concept of moving energy from one form to the other. Mechanical to electrical. You have to put energy from the engine to the pump and from the engine to the fan. Now if you go electrical to both you cut those losses. But it has to be driven by some other form of energy, electricity.

My question is you have to have a alternater that can handle the load of the electrical pump and electrical fan so does it take more energy to turn a 140 amp alternator compared to a 70 amp alt. If that difference is smaller than what it takes to turn the pump and fan mechanicaly you are actually gettng some change back!

I am not trying to be a smartalec I am just trying to ask a legit question because I was always curious about this.

Frank

 

[jsimpson]

There are significant losses in converting mechanical to electrical (the alternator) and from converting electrical back to mechanical (the fan motor). That's why the old dream of perpetual motion, a generator running a motor running the generator, cannot work. There is practically no loss in mechanical-to-mechanical (fan belt). But this is of little consequnce if what you're looking for is good flow at idle speed. Electric will do that and mechanical won't! And yes, the alternator must be of sufficient apacity to handle all lighting tasks, sound system, AC or heater blower, and fans and pumps simultaneously, with enough capacity left over to recharge the battery's loss from starting the vehicle.

 

[redmist]

From what I understand there is no hp gain. The alternator just drains the hp instead.

 

[jsimpson]

Redmist, you are correct. While the fan(s) are running , they use MORE horsepower than the mechanical fan. But they STILL provide better cooling at idle. And if idle speed cooling is what you need, electric fans are the only way to go. Interestingly enough, electric fans were initially used because of transverse engine mounting position in front wheel drive cars. Putting a mechanically driven fan on the side of an engine so it could pull from a front mounted radiator would have required a far more complex belt setup than even a Corvair had!

 

[redmist]

jsimpson, I should have been more explicit. I was refering to a electric water pump not electric fans. I run SPAL fans and enthusiastically endorse them.

 

[sscam69]

So I take it then that if you are using a 140 amp alternator but are running a mechanical pump & fan and lets say that you are only using 70 amps with all the electrical accesories. If you convert to electrical pump & fan and lets say you are using 110 amp, that alternator gets harder to turn because of the electrical load?

Frank

 

[jsimpson]

That is correct. The electrical energy ain't free; it costs horsepower. That's why the bigger the industrial generator, the bigger the engine that drives it. That's also why your little Honda generator purrs like a kitten when there's no load on it, and strains like it's constipated when you get a load near its rated capacity on it!
I run dual PermaCools on my Cummins. They cost me hp, but they keep my Ac cold at idle.

 

[sscam69]

Believe you me I would pay a few Hp to have a cold interior in my vette and it is not even full blow summer yet!

Frank

 

[wolf_walker]

It's been established for some time now that a correctly functioning clutch type mechanical fan is a better solution for most V8 aplications than either electric or a flex fan. They free wheel when not needed and tighten up and spin at idle. As long as they move a suffecient CFM to keep you cool at low speeds and idle, there golden. That being said I like the quiet and space saveings of electric fans, and if I get a good deal I dont mind haveing them at all.

Havent I seen some electric water pumps that were on temp sensors and didnt run full time?

 

[redmist]

I would like to see the support for that statement.
Electric fans don't run if they aren't needed either even at idle
No belts to break
When running cools better than the clutch fan I had
No ugly fan shroud
More compact for tight spaces
Allows use of shock tower frame support
Cleans up engine compartment
Can be manually operated if desired
Can be set to run for a period after the car is shut off.
Can be mounted in front or behind the radiator.
Can be precisely adjusted to operate at particular temperatures
Besides the cost what is one advantage that a clutch fan has over a dual SPAL fan setup??

 

[wolf_walker]

Well most of what you listed is asthetic or preference, yes there handy and definantly have a place in the world. But from a purly performance standpoint, there as good or better than anything else. It's very possible you switched to an electric setup and it worked better, either your clutch fan was in poor shape, the higher flow of the eletric fan is masking some deeper cooling problems, or you just plain old needed more air than the clutch fan could provide(I mentioned that in my post).

I'll address things in order..

I've never broken a belt, ever, I'm nosing under the hood too often to let that slip by.

See paragraph above for the better cooling in your case.

I like fan shrouds, especially on C3's. But it's an asthetic preference at any rate.

Yes it's more compact, I mentioned that too.

Shock tower frame suppose ~shrug~ I'm assuming that's a stress bar between the front A-arm mounting points? If I needed one that bad I believe I could make it work reguardless, but I also mentioned space saveings i my post.

Cleans up enging compartment, asthetic preference again.

Manually operated, clutch fan dosent need to be, and neither should your electric one.

Why would you want to run it for a time after the car shuts off, the coolent is not circulating unless you have an electric water pump and a way to hold the thermostat open so your just cooling down the radiator itself. I know many vehicles do this, dont know why.

Up fron or behind radiator mounting, this is true, falls under space saveing that I mentioned.

I've never had any trouble with a corectly functionig cooing system with a conventional water pump and fan not running as it should, +/- a few degrees is just fine with me. Hell I have a 78 Lincoln with the original clutch fan and over 200K on it that will peg an autometer temp guage like you wouldnt believe, it never moves.

As far as cost, it may actually be cheaper to go with electric's, say if you had to procure the shroud and fan and all, that stuff isnt cheap either. But if you already have it on a reasonably stock car, it should be plenty. Simplicity and originality while maintaining excellent functionality are plus's in my book. It's that old "if it aint broke" thing, modifying and increasing performance is one thing, but I dont see any problems with what came on the car in this case. And that's rare for a vette.

There's nothing wrong with wanting electric whatever, it's your car, go for it. But in most stock cases there is little benifit performance wise over a correctly functioning stock setup.

It's like flex fans, few years ago everyone ran out and got flex fans that would flatten out at higher RPM's and suposidly take less power to turn, wrong. Dyno test's consistantly show a good stock clutch fan taking less power than a flex fan with no clutch.

Looking at stewart componest, they say clutch fans are "inconsistant" and do not recoment there use at all. They have been exposed to cheap, made in tiawan clutches. No I wouldnt run one on a 7K RPM race motor, but a good one is alright for mild street in my experience.



To each his own though..

 

[Bullitt]

I think that Wolf might be right on the "mild/stock engine" argument. However most of us are "modding" our engines beyond that definition. What works against us is that the frontal cooling area of C3 Corvettes is relatively poor. That's why GM started making holes at the underside of the nose on the Corvettes. Also, the radiator sits at an angle and the stock air dam is marginal. Chris has mentioned installing a late-model F-body air dam to increase air flow through the radiator and I know he's right. When I damaged my old GTA's air dam, there was a noticeable increase in temperature, so that's an obvious vital part of the cooling system in any car. The stock Corvette one doesn't have enough area as compared to what is available now.

Living in Texas with a BBC during the summer will show the inefficency of the stock set-up quickly. Just sitting at a stoplight would make me nervous with the stock cooling fan. I had the 7-blade one, to boot. Knowing that there is a second fan for backup is a great piece of mind issue.

Tieing the shock towers together, goes a long way to having a more stable suspension. The benefits have been known for decades, but it's quite difficult to do, especially on a BB Corvette with a mechanical fan. You want the "connecting rod" to either be as straight as possible between the shock towers or in a triangular configuration, as witnessed on Shelby Mustangs. Shelbys use Export Braces and Monte Carlo Bars, which earned them the reputation for being such "great handlers" on the track. This would be akin to adding another framerail in the ladder frame between the right and left sides, but instead applies to suspension. There's other factors involved, but that's the jist of the argument for more clearance up front.

I'll be keeping my V-belt configuration, though. My reasoning has to do with my experience in dealing with sepertine belt loss. If the alternator siezes, the belt will usually break and all power to the other accessories is gone, namely the power steering pump. At least with it still running on a V-belt, I would be able to manuveure the car with more ease into an area out of traffic. While it may seem to be a small issue, it wasn't when an alternator blew off it's pulley on me in mid-day traffic, forcing me to steer a 4000lb. Cadillac onto a narrow entryway. Conversely, with a blown power steering pump, I could still get home with power. Albeit, with stiff forearms.

That's my experience though, so it won't suit everyone.

--Bullitt

 

[jsimpson]

Sorry, but it's been too long since engineering school for me to dig up the support for the known fact that there are significant losses when converting from one form of energy to another. Electric fans require two losses: mechanical to electrical, and electrical back to mechanical. Engine driven fans require none. Any current engineers on the forum, please feel free to inject the references. If you're happy with your Spals, that's what counts. I'm happy with my electric fans too, in spite of the inherent power losses.

 

[redmist]

I think there are more varibles to the equation necessary to evaluate the relative efficiency of the two alternatives. Why do ships use deisel engines to run generators which turn the propellers? There is your mechanical/electrical/mecanical scenerio. Did Naval engineers doze during class?
I think overall energy output in relation to cooling efficiency is the comparison that needs to be made.

From Chevy magazine:

"The use of electrical fans is becoming more prolific in hotrods, morphing from their popularity in modern day autos. These fans can be ever as bit reliable and actually can produce more airflow at idle and slow speeds than that of any mechanical unit, making them excellent performers for heavy traffic and warmer climates."

 

[wolf_walker]

I think there are more varibles to the equation necessary to evaluate the relative efficiency of the two alternatives. Why do ships use deisel engines to run generators which turn the propellers? There is your mechanical/electrical/mecanical scenerio. Did Naval engineers doze during class?
I think overall energy output in relation to cooling efficiency is the comparison that needs to be made.

From Chevy magazine:

"The use of electrical fans is becoming more prolific in hotrods, morphing from their popularity in modern day autos. These fans can be ever as bit reliable and actually can produce more airflow at idle and slow speeds than that of any mechanical unit, making them excellent performers for heavy traffic and warmer climates."

Ships are made that way mostly to avoid the overly complicated transmission it would take to keep the large motors in a good RPM range, same with diesel locamotives. It's much easier to vary current to electric motors than throttle a 3500+hp engine up and down. They usually have seperate generators for regular power onboard also. There are losses, but considering a locomotive would be three times the size to house the appropriate transmissoin it isnt such a bad trade-off.

 

[redmist]

Ok that makes sense, electrically driven mechanisms are easier to regulate, require less ancillary devices and save tremedous weight in those applications, I wonder if that generates any energy savings. mmmmm.

 

[wolf_walker]

I know a diesel train engine gets about 1mpg of fuel..

Or so I've read actually.. There darn sure impressive..

 

[jsimpson]

SwaveDave, what did that mechanical Stewart water pump run you, and where did you get it? I'm finally working on my 70....