So why not do a dyno test on the water pumps? Compare stock, Cobra, and electric. That would be an easy task, would it not? For $370, I want some proven HP, baby!

And it would satisfy the bench racers like me.

 

If been thinking over what the last thread about this that the "designer" was talking about.

Anyways, seems like a great idea. Tim has kept me away from the "Cobra" pump. I wonder if the belts are going at different speeds?

Sal,
Great stuff on real world experiences with them. Just 1 problem. I feel that you are misleading people when you say

NOTE: Must be used with an electric fan.

Seems to me that I could install that without having to use an electric fan.

 

thanks. that 100 bucks could go to better things. like those helix throttle body spacers! tornado air! woo!

 

Danny Swanson and I did some playing around on the dyno. Power with stock fan was 378.1 hp and 441.2 torque. We simply unscrewed the stock fan to represent an electric fan and made another pull. Power with fan removed was 384.4 hp and 453.9 torque. A gain of 6.3 hp and 12.7 torque. These runs were made back to back. Skip

 

Well, you COULD use it without an electric fan, however you're motor would overheat at idle without any fan at all .

Seriously, the stock fan threads onto a provision that's part of the stock water pump. When you go to a Cobra or electric pump, there is no way to attach the stock fan back on, hence the reason for that statement.

 

I agree with the Skeleton! Anyone want to step up to the plate and dyno the three water pumps with an electric fan and see once and for all which one is best. I would but I am working in Texas and my truck is in California. Of coarse some driving tests would probably need to be done to monitor water temp differences for real world figures as well...

 

Sal and everyone else,

I was the one that provided Tim with the information about the stock versus Cobra R water pumps. Being that I am a) obsessive-compulsive about dynoing my mods and documenting the results and b) a software designer with degrees in mechanical engineering and BioChemistry I tend not to take things too lightly and I want quantifiable, justifiable, accurate and repeatable results from my testing. The pumps were dynoed on the same day in the following manner:

Electric fan with stock water pump in place (stock fan obviously removed)

Electric fan with Cobra R water pump in place

The truck was driven between the installation of the Cobra R water pump to 'burp' the cooling system and ensure that coolant level/amount wasn't an issue (i'm **** to the point that I use the same tire gauge to insure that both rear tires have exactly 32 psi in them as that is what I had in them during my first round of testing). I also let my truck cool down approximately 30 minutes to an hour between runs with two large fans on the front. Each pump was tested for three pulls (again, with the requisite 30 minutes to an hour between each run) and on all three of the Cobra R pulls I showed a loss in hp (I can provided the .PEP files if anyone wants to see them).

Going from the stock fan to the electric fan with the stock water pump in place netted me a maximum gain of 11.0 hp and 10.4 ft.-lbs. of torque with an average gain of 4.6 hp and 5.1 trq respectively. The electric fan, for obvious reasons, showed larger gains as the rpms rose. Adding the Cobra R water pump (which did have the ring on the impeller - Motorcraft part number PW-402) resulted in a LOSS of on average 6.1 hp and 7.5 trq, which just about negates any horsepower gained from the fan.

I still have the Cobra R pump on because I'm planning on getting the Mezeire at some point in hopes of gaining my hp back from that Cobra R paperweight. I would also be more than happy to provide UNBIASED test results on the stock (which I still have in the Cobra R's box), Cobra R and Mezeire water pumps if one of the tuners wants to step up and provide one for testing with the caveats that they will get the pump back after testing (unless it performs as advertised, in which case I will pay for it and keep it on my truck) and all results will be posted here for all to see. I've got unlimited access to a dyno and can do pulls all day long and into the night if necessary.

Since the Cobra R water pump is touted to push more water it has to do one of two things...move it significantly more efficiently than the stock water pump or incur more parasitic losses to push more water through the cooling system... Check the classifieds as there will be one lightly used Cobra R water pump for sale in there soon.

 

Bringing this back up for several to review.

 

i run the meziere e-pump and have not had any problems...installed with my e-fan and total was about 600 including all fuses, wiring, even labor costs.

so i can attest to its reliability as a daily driver (mine is) however i dont have any #s or seat-of-the-pants feel since those goodies were installed with chip and pulley....

as for temps i think it DEFINITELY cools faster.....

and as for wiring mine is on ALL the time...

 

If the Cobra R Pump moves substantially more water, even if it does it a little more efficiently, chances are that it will consume more horsepower. Any pump engineer would confirm this.

However, on the assumption that it is, in fact a more efficient unit, then by slowing it down with an underdrive pulley so that it moves the SAME amount of water as the stock pump, it MUST consume less power.

So now we need to figure out how much to slow it down so that the water flow is the same as the stock pump. The shame of it is that the designer and the manufacturers have these numbers. Too bad they aren't available so that we don't have to do it by trial and error.

I think I want to find (or make) a pulley that will slow the pump down somewher between 25 and 30% but I don't want to change my Damper to do it.

I guess I'll do a little measuring today and see how large a pulley will fit.

 

I thought the purpose of the Cobra R pump was that the "ring" would keep the blades from breaking off and getting stuck in the water passage somewhere. And "if"a blade were to get stuck somewhere that would likely really mess up the cooling efficiency and generally wreak havoc inside the engine by preventing coolant from getting where it needs to etc. etc.

 

any update on this in 5 years

 

I learned some years ago, partially from personal experience, that the "Cobra R" pump will not keep a 5.4L cool, in traffic, on a hot day.

If you want to move sufficient water to stay cool under adverse conditions, it takes power. The best pump today is the 2005 Navigator Pump. It has an aluminum housing and the more efficient, closed impeller, it's what I have on my 4V and would recommend for any supercharged application.

 

I do not have experience with the Navigator pump, however I have had the cobra r pump and JDM electric fan kit on my Expedition for 5 years and 220K miles. I do alot driving (as you can see) in stop and go Houston traffic as well as alot of 300 to 500 mile trips stopping only for gas. I have not had any problem with overheating. As far as hp loss or gain I can not tell ya because I have not dyno'd the Expy. I do know it feels stronger than the stock setup.

 

There ia another thing about our trucks most guys don't know unless they have an aftermarket temperature gauge.

Again, from personal experience. The OE gauge will indicate "normal" range (center 1/3) at any temp from 160F up to about 250F and then it will start to rise up to the "hot" area. It is more like an analog warning light rather than a true temperature reading.

On this basis, you might not think your engine is hot but if you go WOT at 15psi with a 230F engine you could be in trouble with detonation.

However, I am not the real authority here by any means, that person would be "wydopenthrtl" on NLOC. He is a FoMoCo engineer in the cooling systems department. Rich has often said that the Cobra pump is inadequate for a high power engine and the later Navi pump is the way to go.