In order to test the pump over the entire range of restriction conditions, I followed my normal pressure differential vs. flow rate routine using a King Instruments 7520 with valve and Dwyer 477-5 digital manometer. I also used three different multimeters to measure Voltage at the plug, Amperage at the plug, and Speed of the first pump. To maintain a precise 12.00V at the pump plug I utilized a Koolance CTR-SPD24 capable of 55W to adjust voltage to eliminate vdroop losses and power was supplied by my main computer via Corsair TX650. I initially tried using my variable test power supply, but was getting funny PWM control so I went back to the TX650 and incorporated the CTR-SPD24 to ensure/fix 12V supply. Speed was controlled using my MSI main board and Speedfan to manually adjust PWM settings.
This provided consistent power and tests the pump across the full spectrum of restriction conditions while also providing electrical and speed data.
These are the PWM test points I chose to test on:
This will give a good spread of several curves from 0% to 100% plus three in between.
Extremely minimal power setting, at most will produce around .5GPM at about a 5W power consumption.
Still very low setting, somewhere between 0.4-0.9GPM resulting flow rates at about 7W of power.
This is getting to be very similar to a single strong pumping power level where most systems would see over 1 GPM except the most restrictive types and only consuming around 12-14 watts. Noise is also subjectively very good at this level and would likely make most silent system users very happy. I think this is also better than running a single pump at full speed.
This is now getting to extreme levels exceeding 1.0GPM for even the most restrictive of systems and still relatively quiet compared to single pumps at full power. Power consumption is in the 22-26 watt range.
Nothing short of a power house!! Even the most restrictive systems will see a good 1.3GPM clear up to 2.8GPM (32-39W) Noise levels here are subjectively becoming audible, not what I would call loud, but a more pronounced whine is heard with lower fans speeds.
Here is how those settings stack up to each other, extreme low to extreme high:
An extremely WIDE range of pumping power levels, by far the widest range I have tested from extremely low power at 0% to massive fire hose power at 100%.
Alternate Inlet Comparison
Before digging into the comparison to other pumps I wanted to do a quick “Alternate Inlet” test and comparison. While it is intuitive that elbows in general add restriction, it is also accepted that a few throughout the loop is going to cause very minor impacts and ok. Pumps however are much more sensitive to elbow impacts particularly at the pump inlet because of how it influence the loading on the impeller depending on the elbow size and distance from the inlet. The alternate inlet on the 35X2 is larger in size so it should perform with less impact than the smaller factory Laing tops. So with that, a test was in order to see the loss:
And a comparison to the optimal at 100% to get a sense of scale:
You do loose a little efficiency using the alternate inlet, but frankly you have more than plenty to toss around and despite the small loss, a ton of power remains and still more powerful than any previous dual DDC pump top. I wouldn’t hesitate to use the alternate inlet if it provides for a cleaner build layout.
Optimal Inlet Comparison To Other Pumps
Here is how the optimal inlet curves compare to some common pumps to give you a better sense of scale and compare powers.
At the top power end, I compared it to my Koolance RP402x2 which is also running dual 18W DDC pumps. Here a combination of the 35X2 motor RPM advantage and superior volute efficiency is giving it a good 30+% pressure advantage over the 402×2. Moving on down the chart the single 35X2 with the same strong motor in single is producing a flatter curve but similar to the 35X2 at about 48% PWM or so. Continuing down in power the Koolance PMP450 (Same as MCP655) setting 5 is about equal to the 35X2 at approximately 43% PWM. Finally we have the Aquastream XT which is about equal to the 35X2 at 37% PWM.
Optimal Inlet Comparison Dual Laing Pumps 100% Power
Here is how it compares to other dual D5 and dual DDC tops I’ve tested (THE HEAVY WEIGHT ROUND):
Some folks have requested to see the same pump top tested with different motors, and or the same 35X motors tested on several different dual DDC tops. I will see about gathering some samples to do that, but this is what I have for now and I suspect the really strong curve is a combination of both the stronger 35X motor and the top combined.
The Swiftech MCP35X2 is KING of Power & Range producing the most power in a small DDC package tested to date!