Marietta, you say "didn't gain much hp". Any idea how much that was? At that level of hp (489) I can understand, but we have only ~180 to start with, so 20 hp more or less is significant and would be much appreciated. Any idea? Thanks.

And hondasr4kids, I found the adapter, but no pump w/your link...did I just miss it. That site is pretty bare bones.

 

I highly doubt Mazda left 20 HP there ...

 

A well respected online performance magazine here in Australia tested a local big name electric water pump. Here is the result of the test.......

 

20 HP is a ridiculous claim.

Their electric water pump draws 0.1kW max which is about 0.14 HP: 7.5A *14V
http://www.hrpworld.com/client_image...pdf_3529_1.pdf

Why would a mechanical water pump require 140 times (!!!) more power?

 

Ahh.. that IS the point, isn't it? We DON'T know how much 'wasted' HP is used by the mechanical pump. The mechanical pump has no brain...it HAS to spin at the rate the engine does....from 800RPM to 9000RPM.

How much of that at any RPM is wasted spinning?

That IS the point...but I digress...

 

You guys should take a look at the tech info in the mazdaspeed website, above 6500 rpm cavitation starts. They also mentioned something about gutting the thermostat.

 

Even if there is cavitation. Why would a water pump require about 0.1 HP at 6000 rpm and 1HP, 2HP or even more at 8500 rpm?

Be realistic:
These guys go fishing with 15 HP:

and the RX-8 needs more power to flow some water through its radiator???

 

The point of an electric water pump is not power saving, it is control of the cooling flow.

http://www.siemensvdo.com/products_s...water-pump.htm

 

The new BMW 3 series uses an electric water pump. Their design point was that you actually need the most water flow when the car is at idle, since the radiator is a lot less efficent, and you don't want to pump the water at all when the engine is cold. It does increase the efficency of the engine at cruise, but it's not directly there for the peak HP number.

They claim a normal water pump uses "2KW" while their pump uses "200W" - 2KW is about 2.5HP. I'm assuming the 2KW is up near redline.

While everyone here assumes cavitation is bad for HP, I'm not sure that is true. Cavitation reduces efficency dramatically, so that the energy put into the shaft of the water pump doesn't pump as much water as pre-cavitation, but we don't care about that. We care if the shaft of the pump suddenly needs a lot more torque to keep it at the same RPM. I haven't found any evidence that torque/RPM suddenly goes way up when cavitation occurs- just that water flow/energy goes down. If this is true, then when the pump cavitates only matters for water flow, not HP draw.

 

Good info dsmdriver - if the 3 series [Power: 137 kW , 184 HP SAE @ 6,000 rpm] used 2.5Hp (assuming this is at 6000 RPM???) then extrapolating would perhaps give 3.75 at 9000rpm or perhaps more for us? Not sure if it works that way... but it may be close.

wo/FI, we are in a game of accuring small increases in HP, 1-5 HP for each mod. Still if it's say $500 for 4HP that's right in line if not better than intakes, exhausts, and the like.

 

is right under the adapter

 

Prehaps the cavitation is helping with the high coolant temps on the track? From what I understand most 8's are hitting coolant temps of 230F or more on the track. Course our dummy gauge will not give you any warning. Maybe that is one reason mazdaspeed really underdrives their water pumps?
One of my questions is how much flow rate do we need on the track?
Also people are hitting routinly 225F on the street.
Mustang review at 6k gave 3hp gain when swapped to electric water pump.
olddragger

 

addition mustang made 6 hp not 3 hp as mentioned before.
olddragger

 

Since we're on the subject of keeping our cars cool, specifically under high revs - track conditions - who here has overheated their 8 at the track? I don't recall yet reading that anyone has.

 

and the same pumps were used by the Prodrive farrari Maranello in lemans events in europe and usa.

 

Remember that caviation is actually the implosions of gas bubbles on the impeller vanes. This will basically destroy the impeller over time. Underdriving the water pump will definitely help give it more life.

 

The water pump..maybe. But for those who drive in traffic in hot areas will decrease the life of everything else under the hood. That would be my reason for considering electric. high flow at low rpm...reduced flow at high rpm. The bigger alternator that you may need may offset the high rpm gains.

 

The alternator may be big enough if you don't have a boombox mod

 

When I had my FD and I installed my underdrive pulley on it, I did notice better temperature at the track. It never made sence to me how but I know it did.

 

Just reporting what I read.

Davies Craig promote it's EWP's HP and fuel economy benefits, IMO these are the claims that AutoSpeed challenged. I'm sure the pump does a good job of controlling temperatures.

 

Do you remeber what issue of Autospeed that was talked about in? or is this the one they couldn't talk about for legal reason?

 

Yes to both questions. I'm a subscriber.

 

Likewise.

 

Issue 86, June 27 2000.

 

Interesting how some dumb companies want to sit in their own soup and stew in it - idiots thinking they are marketing geniuses.