CALL911

About ready to put in the ATI D1SC, and need to know if running an electric water pump will sufficiantly cool the motor, even for long periods of time during wide open throttle. (maybe for 5 miles, high speed run) Should I change to the electric waterpump? Or stay with the stock one?

JZ28Max

i have not had a problem keeping mine cool with an electric pump even in summer. just need to make yourself watch the temp gauge often in case of pump failure or a kind of rare thing that happened to me last summer. i threw a belt a ripped the pump wires off. luckily i glanced at the gauge. temp goes up really quick in the summer with no pump flowing. just a little extra worry for not quite as much benefit i think. my .02

CALL911

So, how are the electric water pumps when compared to the stock ones when it comes to reliability? Do the hold up longer or not as long?

JZ28Max

from what i hear they are not expected to last as long as the stock mechanical pumps. could not tell you from personal expierience because mine is not a daily driver.

snorkelface

If you will be WOT for long periods of time (AKA, RR or open track racing), then the stock pump will be better at cooling your motor, and will be more reliable.

CALL911

Its not that it will be driven on WOT all the time, but here and there. I am one to play it more safe than sorry. The few extra ponies does not matter to me at all here. I am already going to be toning down the system to the power level I want as it is. The last thing I would want is for it to over heat or take a dump on me not too far down the road . It sounds like I will be sticking to the stock one for now, unless there is anyone else that can argue for the electric one. Thanks for the input! More opinions still welcomed.

Roadie

the only down side to the stock one is a heavier, more expensive timing chain setup. The stocker also takes up less engine bay room...

Fastbird93

Someone correct me if I'm wrong, but doesn't the Meziere or CSR pump flow greater than the stock unit?

JZ28Max

not sure about that. they may flow more at idle but i doubt they would at higher rpm's.

Fastbird93

Everything I've heard about them says that the reason cars with extended highway time run hotter than with a stock pump is due to how fast the electric pump actually cycles the coolant. Fast enough to actually reduce heat transfer while in the radiator.

markinkc69z

A problem that can occur with an electric pump is a lack of water pressure in the cylinder heads and block. Pressure collapses air pockets and bubbles which allows the water to absorb heat. A forced induction application needs excellect heat transfer to stave off hot spots which can induce detonation. I know most drag racers run electric pumps and blowers/turbos with much success, but these are limited run time situations and a more aggressive tunupo might be possible with a mechanical pump, but between round cooldown would not be as convenient.

Before its mentioned water pressure is different than coolant system pressure.
BMW or Mercedes just came out with a new engine that uses a pwm electric water pump, but it appears to be the size of a conventional starter and probably really draws some amps.

Fastbird93

How do you figure that the electric wp doesn't supply the pressure that the stocker does. Given that it's circulating the coolant through the same passages in the heads/block as the stock pump would be, and it flows more/faster than the stock pump, how is it feasible that the electric pump wouldn't put out MORE pressure??

97WS6Pilot

The stock pump flows 25 gallons per minute at 6000 rpm. The meziere electric pump flows 35 gpm all the time. Electric pumps don't last as long but they're alot easier to change

markinkc69z

Good question to ask!

Ask yourself why you want to replace the mechanical pump...to free up power right? Why does the factory pump take power? Because it moves a large volume of water at pressure. The electric pumps are rated in gpm free flow. If they were capable of that flow at high (relative) pressure we would be using them for fuel and oil pumps.

Ok, now how much power do you think you're going to gain? 5, 10, 15 hp? I've seen claims of over 10 hp, but let's just use 5 for this. 5 hp = 3728 watts. 3728 watts @ 14 volts is 266 amps! That's an old style gm starter motor at a pretty hard grunt. An electric pump is going to be hard pressed to ever draw more than 15 or 20 amps. 20 amps is 280 watts or 3/8hp, and that's being generous. You can't get something for nothing, we all know that. What we lose is volume at pressure and gain hp back from the parasitic loss. Your alternator will draw more power, but assuming you don't have to change your tune or detonate its a net gain, though I don't think a smart one for a supercharged driver.

Fastbird93

I thought the power gain seen from changing to an electric wp was due to the removal of the water pump drive shaft assembly and it's parasitic drag from the cam gear in the timing set. Correct me if I'm wrong but isn't that splined shaft a direct drive to the impeller in the stock pump (been a while since seeing the inside of one) with no step up gearing in it?? That alone is going to put a lot of pressure (and parasitic drag) on it.

You say that the electric is rated at 35GPM free flow (what's the stock pump GMP free flow rating btw??), but don't flow that rate as installed on the car when pushing the coolant mixture around. My question then is why is it that the cars run cooler at low rpm usage but a little warmer (when compared to a stock pump) at highway speeds??? The theory that the electric pump cycles the water at a faster rate than the stock unit seems to hold true there.

I'm not trying to be a turd or anything, just trying to clear this up as it's something that I'm just now seeing differentiating information on.