To test pumps I use a flow meter and a differential manometer and vary restriction by adjusting a brass gate valve. I adjust the gate valve to give different flow points and measure the pressure “gain” across the pump using the differential manometer. To understand how to read these plots check out this guide.
Leaks
Before getting stuck into the data it’s worth mentioning the issues that I had with this particular top. The first test I ran with a D5 Vario and after tightening the screws “tight enough” for my liking I found that the pump was leaking slowly and bypassing the o-ring seal. I proceeded to tighten the screws further (really really tight) which did finally seal the block. However one of the bolt heads started to strip. When I fitted the D5 strong for testing the same thing happened but this time the bolt head stripped completely and I had to drill it out. I wondered why the leaking would occur when the design was so incredibly similar to the EK top (the internals and bolt/clamp pattern seem identical). As far as I can tell the difference is the o-ring. The EK had a thicker o-ring. The EK part was also made of acetal which might also help. For now I can’t recommend the Alphacool because of this leak.
Performance Data
The Alphacool top does at least perform well. Through the region of interest (0.75gpm-1.5gpm) there is a small gain in performance over the standard Laing top regardless of whether you use the optimal ports or the alternative ports. If the top is compared to other tops with a D5 at max we can see that it performs at the top of the pack:
Summary
A well priced high performing high flow top that sadly can’t be recommended as it is let down by a tendency to leak unless you over-torque the clamp bolts.
Where to buy: PPCs
[…] 8 screws give plenty of confidence and the setup did not leak (unlike the Alphacool D5 pump top we tested). Indeed the acetal fit around the D5 was so tight it was hard to remove the pump […]
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