GrandSportC3

I'm just broswing through the Summit Catalog and started thinking in replacing my regular water pump with a Moroso 19 gpm water pump..
They claim up to 20 HP gain from running a electrical water pump...
Does anybody here use one??

:cheers:

Olivier

Langadorf

I'm running an electric (Meziere) on my LT1 motor - I'm sure the classic SBC pumps are very similar. From what I've read, you can expect around 10HP/ft-lbs at the most from the switchover. I've seen independent back-to-back (mechanical vs electric) dyno runs that prove this.

Besides the HP gain, the electric pumps are thought to pump the coolant more efficiently, possibly helping out if you are experiencing overheating problems. One further benefit to an electric pump, you can wire it up w/ electric fans for cooling the engine with the motor off in between runs at the track.



[Modified by Langadorf, 5:20 PM 12/27/2002]

Ryan77

How hard is it to wire in these electric pumps? Does it only need a constant 12 volt lead? I was thinking about getting a electric conversion kit to use with an Edelbrock pump, but wasn't sure if it was worth it. Do they cool as well as the regular pumps?


[Modified by Ryan77, 8:07 PM 12/27/2002]

Mike Ward

C'mon guys let's use some common sense here!

If these electric pumps or fans can recoupe so many HP, where do they get their power from?

The battery, of course.

Where does the battery gets it's power from?

The alternator, of course.

Where does the alternator get it's power from?

The engine, of course.

All you're doing is transferring more load to the alternator and not 'recovering' anything.

An engine driving an alternator to charge a battery to run an electric pump (or fan) CANNOT be more efficent that driving the pump directly.

20 HP to drive the water pump? Come on. Go the any tool rental center and ask them how big a 20HP water pump is, and how much it can pump. My measley 1 HP swimming pool pump puts out more than 19 GPM and builds a 15 PSI differential while doing it! :D

75 BBC Stingray

I think that there is some truth to electic being more efficient in some instances than mechanical. While it seems to be anti-intuitive, changing the mechanical energy of the engine into electrical energy, then back into mechanical energy, some testing I think has proven otherwise. While I don't have any numbers to support this w/ me, I do remember reading an article last year stating that electrical devices were seen to be taking over many of the old mechanical applications because of increased efficiency. Examples: Electric power steering, Electric Fans, Electric pumps, Electric transmission shifting.
I think one of the main benefits was that the electrical devices did not put any load on the motor when they were off. The same could not be said of the mechanical units (mechanical fan and water pump are good examples)

Langadorf

This topic has been debated to death over in the C4 Tech Section. This is in regards to the Meziere electrice LT1 water pump but I don't see why an electric pump for the classic SBC would be any different. I think these quotes sum it up best:

"This is not really a math problem at all. Problem with a mechanical pump it is a simple centrifugal pump. In general, the volumetric flow rate delivered by these pumps varies with the speed (i.e. engine RPM). In general the flow rate will increase more than linearly with speed, but this variance depends on the specific pump design. Next, you must consider that the pump must be designed to deliver a minimum amount of flow rate at a very low speed (engine speed probably just off of idle). As the engine approches redline, the pump is delivering much more flow than is required, and in the process generates many more losses. For an analogy consider a turbocharger - it has the same sizing dilema, but here we are concerned more about the pressure than the volumetric flow. The mechanical water pump could have it's efficiency increased if there was a flow bypass (kind of like a wastegated water pump), but I think it would be easier just to go to an electrical pump!

An additional factor is that the alternator load does not vary directly with accesory load (i.e. electrical load). Not at least in the short run. As the accesory load increases, the battery voltage will drop, the alternator senses this, and then starts to charge the battery. For a brief (12 second) duration, the battery acts like a capacitor, and the work delivered by the alternator is less than the work developed by the water pump. It's as if the electric water pump exceeded 100% efficiency for the 12 second pass. This logic obviously would not hold true for an extended duration such as a road race."

AND:

"Picture an engine with a radiator fan on the front. Nothing fancy, no clutches, just driven straight off the water pump like they used to be. Drag increases with with engine RPM and let's just say for the sake of argument that it produces a CONSTANT drag of 10 hp, regardless of RPM. Eliminate the fan and you suddenly have 10 more hp.

What some people, who shall remain nameless, are trying to say is this:

If you removed the fan and replaced it with an electric fan that moved the same amount of air as the engine mounted fan operating at the redline you would not see any horsepower increase. The reasoning is that the increased power demand would be such that it would increase the rotating resistance of the alternator so much that it would drag down that 10 hp right off the motor.

We all know this is false, why you ask? An alternator can only produce a maximum of so much power, and with that max power it only creates so much drag on the engine. That drag may be variable, but it does have an upper limit. So what happens if you draw more current than the alternator can put out? Then current is pulled from the battery, remember it is a storage of energy that is just sitting there, not being otherwise used when the motor is running. The result is an absolute worse case scenario of draining your battery as if the alternator was not charging it.

An electric water pump works on the same principal, it is just another source of current draw used to eliminate parasitic drag on the engine. What do you risk my eliminating everything engine driven and going electric? You risk a dead battery. The solution to which would be to install an alternator that can keep up with the demand, something like a 140 or 200 amp unit. These would create more drag on the engine, but again it would peak. That peak would still not come close to the power gained by going with electric water pumps and fans.

On a pseudo related matter, think about a supercharger, it uses engine power, to make more engine power. The gains are tremendous. Sure there are tradeoffs in any situation, but if your electrical system is slightly over-sized (which it is) then you'll be just fine with an electric water pump. Only when you exceed your alternator's output do you run into problems, and even those don't drain horsepower. It's the solution to that problem (ie, bigger alternator) that drains horsepower."

AND:

"1) Electric waterpump - mine (meziere, LT1) takes 6.8A @ 12.4 volts (juse measured it). That's 84.32Watts. Assume the alternator is 25% effecient with mechanical -> electrical power conversion = 337W of mechanical power = 0.45 HP. So the electric waterpump takes ~ 0.45 HP to turn, everything taken into consideration.

Now all the values I have seen for what it takes to turn a mechanical water pump are much greater than this - but regardless, .45 is really a negligible amount.

One factor I don't know if anyone has mentioned is impeller effeciency. Since the electric turns at a fairly constant rotational velocity, the design of it's impeller can be more specialized, and thus hopefully more effecient - while the stock pump has to work over a large range of speeds.

Regradless of the theory though, there are three reasons why I would go with an electric waterpump

1) Testing has borne out a 8-10rwhp gain with the pump (this has been repeatedly dyno verified and proven)."

http://forums.corvetteforum.com/zerothread?id=174581 http://forums.corvetteforum.com/zerothread?id=93067


[Modified by Langadorf, 9:57 PM 12/27/2002]

epylant

19gpm is probably a little too small for the street. I ran both the CSI and Meziere (~35gpm), and they were perfect for continuous use... regardless what others will tell you, they are worth 8-10hp to the rear wheels across the ENTIRE power band.

427V8

Just remember the only time that extra 10hp matters is when you are at WOT.

If you are not at wot then it's not there ( unless you are going for gasmileage )