Pump Performance Testing

The MCP655-PWM from Swiftech is a Laing D5 at heart and does, as such, already have a history of reliable and good performance behind it. But as with every product we receive, it underwent a full test suite, including that for the pump itself. To test a D5 pump, I use a reference D5 top from XSPC (XSPC D5 Bay Res) and the MCP655 provided with it. This is to help decouple the pump's performance from the pump top's performance, which will be separately tested below. Given this is a PWM pump, the first thing to test is its RPM response, and to do so, I used the MCP655 in a simple loop of reservoir-in to reservoir-out, with pump power from an EVGA SuperNova 1300G2 PSU and PWM control from an Aquacomputer Aquaero 6 XT, which also provided RPM monitoring.


As we saw with the dedicated review for the pump before, Swiftech worked with Laing directly to address the issue of Laing D5 PWM pumps not being as compatible with Intel PWM spec 1.3 controllers as desired. The pump that was part of this Maelstrom reservoir unit was within error margins of the discrete pump to where I felt comfortable using the results from before. This consistency is nice to see, as is the linear response of the pump's speed with the PWM signal, the increased range of control at the lower end as well as a full-speed operation when no PWM signal is provided.


Here, I have mapped out the RPM response curves for some high-performance PWM pumps, including three from Swiftech. The MCP655-PWM is the subject of attention here, while the MCP35X is Swiftech's take on the Laing DDC with a Swiftech-designed top on the Laing DDC PWM pump, and the MCP50X is an all-new Swiftech design and not a re-brand. I have also included the EK D5 PWM G2 (Gen 2), which is the aforementioned EK modification of the Laing D5 PWM pump. While the older Laing PWM pump would have had one of the least linear plots, the newer batch does much better and is basically on par with the EK-modified D5 PWM. The DDC pump remains the worst of the lot now. Overall, the MCP655-PWM is a much improved Laing D5 PWM provided you have one out of the newer batch.

In order to see how the pump performs, I used it in the same loop as before, but with a Dwyer 490-1 wet-wet manometer to measure pump head in PSI and a King rotameter to measure average flow rate in gallons per minute (GPM). This P-Q curve for a pump is extremely useful information as it dictates the average flow rate in a loop when any flow restriction is added from such components as blocks and radiators, under others. The P-Q curves below are thus for the pumps in a closed loop with minimal flow restriction to produce an ideal but realistic data set.


I have included here some other pumps that have been developed within the few last years, and have at the same time removed the DDC-style pumps from consideration to keep to a more D5/flow-optimized pump comparison. This keeps the plots as clean as possible and makes for direct comparisons. A lot of the more budget-oriented pumps introduced lately aim to match the Laing D5 Vario on Position #3, which corresponds to the MCP655 PWM at 70% PWM duty cycle. As such, I have included that setting as well, in addition to 100% PWM. The Alphacool VPP755 is a brand-new "D5-replacement" pump sold by Alphacool, with a different design but based in a similar housing as the Laing D5, and it ends up outperforming the MCP655 (w/XSPC top) ever so slightly. The rest of the lot are hovering around the lower end with only the XSPC X2O 420 in the XSPC Ion and the Topsflo TDC doing better.