My ported D5 Pump P/Q results

[Martinm210]

Thanks guys!

To answer a few questions.

TEMP COMPARISONS
No I havn't tried temp comparisons, Cathar already pointed out in the tubing sticky and I truely believe this that water cooling is fairly resilient even at low flows. I saw 10% in the CPU + GPU loop I was running, but 10% flow rate improvement isn't much for temps if I'm talking 1.5 yo 1.65 GPM. I'm still pretty weak on the thermal part of this hobby, but from what I understand this flow rate change won't mean much in temperatures because of how flat the thermal properties are on most water blocks. For example look at the Apogee GTX here:

Even if you were to improve your flow rate from 1 GPM to 2 GPM, you only gain about .005c/w, for a 150watt CPU that's only going to amount to just under 1C. What's important to see is how the curve slope really steepens as you approach .5GPM and lower, so not to take the wind out of my own sails, but flow rate doesn't amount to a whole heck of alot unless you start getting way down there under .5GPM.

This is just all about modding, tweaking, and going doing that little extra to get to a very small improvement. For me, I'm just having fun learning more about how this all works and this is how I learn it. Have an idea, try it out, and measure how it worked. That part's more fun than the actual benefit, just one of those things...

IMPELLER MOD
The only thing I'm willing to do to the impeller is maybe some hand sharpening of the blades, that thing is just spinning way too fast to be anything but perfect and adding a blaed would have to be a machine shop type fabrication which I could get access to and I do have a few years of machinist experience, but I'll leave that to someone that really wants to make money with something like this. If it was feasible to make an impeller for low cost that made a big improvement in this pump and manufacture it for a low price, that could possibly be a marketable item. My guess is that it would be overly expensive to fabricate to make profitable. I'll see if cleaning up some of the mass production edges makes any difference for me. The most obvious to me is the rounded leading edge of the impeller on the inside, I think if these were sharper you might get some overall gain.


NON PORTED TEST
No I unfortunately was too impatient as soon as I saw the first pump gain I immediately modded the second one the when it arrived, the only thing I can see is the shape of my pump curve matches well to the Laing curves, particularly the larger barbed version. I believe the Laing curves are accureate, the D5-38/810 is what I think what you get when you buy any variable D5 or MCP655 pump. I'm not sure why Swiftechs curve is so different Looks to me they too some test data and apply a second order poly to the data that forced the curve in one smooth sweep, maybe that's just the way they produce curves as practice. I'm going to recreate the Laing curve and have it for my flow prediction spreadsheet I'm working on as the base placeholder.


D5 vs DDC
The D5 and DDC3.2 are fairly close in the real world loop restriction range of around 1.0 to 2.0 GPM range, with the DDC with top still having the advantage. The port mod seems to have improved things after 1.2GPM making them even closer. Overall I think the DDC is still the better pump for most watercooling applications, the D5 doesn't show it's strength until you have a low restriction loop like the MCW60 plus rad, in that case the modded D5 is better. The DDC2 on the other had is a really strong pressure pump, it's really too bad this impeller is being replaced by the 3.2. What was clearly a substantially better pump is now only a little better with the new 3.2 in favor of reliability, I guess laing was just having to much loss in failures which is a smart move really, they still own the market, so fewer returns means more profits. They are both good pumps and more than adequate for most systems, the DDC is a little better at higher restrictions, and the D5's strengths are in low restriction. The DDC with top is still better, but rember how close they are and remember how little effect flow rate above 1 GPM has on temperture.

IMPELLER STRUCTURAL INTEGRITY
I'm not sure, but I would guess anything that's simply making the pump work more efficiently wouldn't have a negative effect on the impeller, but I could be wrong.

CURVE SHAPE
Yeah I don't understand pump design either, and have too noticed you basically have the ability to shift the curve around, but generally you give up on one end to improve the other. There is always some areas of efficiency you can improve like the sharp outlet, this is a result of Laing choosing to use the same interior mold for both the 1/2" barb and 3/4" barb, just a cost savings is all. I am interested in trying some reduction nozzle combinations out to see if you can bulge the curve more on the pressure side. A completely new top with more refined channels and tighter tolerances would probably help in the pressure side, but it's a complicated top to machine, it would almost have to be cast to make affordable. Not really sure why the smaller openings help the low flow pressue side, I guess friction acts as sort of a valve to help the impeller ratchet more pressure.

NEXT ON MY LIST
One thing that is certain to me is my non-variable pump is not as powerful as the variable D5. I want to make the same curve using the same exact top to compare motors. Not sure exactly why this is, but it is at least at the right hand of the curve. Plotting it out to do a side by side will help me understand what's going on there...maybe I just have an oddity?

Then I might try a few nozzle combinations to see if I can get any more out of a real world loop.