Hey everyone! First post here...but you already know who I am
Anyway, that review was a nice start; however, I would have liked to see
performance curves <--link... because that would have provided a much more accurate indication of the performance characteristics that each top provides. As it stands, you're only seeing a few pieces of the puzzle which, really, doesn't tell you very much--each top is going to have its own "sweet spot" within the pump's operational range. That said, there are a few things worth pointing out here (keep in mind, this is supposed to be constructive criticism):
- According to your own results, the DDCT-01s performed better than the Alphacool top on the 18W DDC-3.2, despite having slightly lower head pressure--this is important with regard to what I said above (this is a performance curve thing... if one can manage to kick the curve outward within the pump's most useful pressure range, then the flowrate will be higher despite having lower static head. The rough curve that I did for the RD-30 at 18.1V is a perfect example of this [see above link]). For reference, my original testing, comparing my prototype to the Alphacool top, was done using an 18W DDC-2 (different pump, slightly different results, same story nonetheless).
- All of your static head numbers for the DDC-3.2 appear to be low (33kPa =~4.8psig...should have been closer to 5.6psig). However, because all of the tops were tested in the same manner, this really doesn't matter much (absolute standpoint, you're off... relative standpoint, you're fine). There are several things which could have let to this, that I can think of ATM: low voltage (which, since I'm assuming that you were monitoring it, shouldn't be an issue), a wonky pump (some performance variation has been known to exist with these pumps--not sure how much this applies to the DDC-3 series, though), your pressure gauge (and measuring point), etc. I don't have numbers for the DDC-3.1, so I really can't comment there (though the odd result is making me want to bust out the test setup again to see what's up...

).
- Since you already had a pressure gauge in the test setup, your "max. flowrate" data should have been represented as flow at a given pressure because, from your data, I'd estimate that your test setup was incurring a pressure drop of between 2.5psig and 3psig at 2.93 Gal/min (11.1 l/min)... same goes for your 'in loop' test (because it looks as if you were incurring about a 5psig drop in that test...and a lot of that was likely your flowmeter).
- You didn't include the stock top as a control (this would have also acted as an indication of absolute accuracy).
The DDCT-01s got its ass kicked on the 9W DDC-3.1... yeah, I kinda figured that would happen. Though, in my defense, I'm not designing for the 9W DDC (DDC-1 or DDC-3.1). Granted, I can't fully explain that large of a performance discrepancy right now...it's somewhat perplexing.
Overall, a decent review... but, as with all reviews, there's always room for improvement. The more you can teach someone with a review, the better.
name='WaterCoolingUK' said:
On a side note, adding to what Allsorts said regarding the new DDCT-01s from Petra's Tech.. The only real difference is the inside housing where the Impeller sits. Someone at Laing somewhere down the line decided to give the new European DDC a larger (Blue) impeller rather than the USA (Black) slimline impeller and on the PTS top there is a little 2mm lip on the underneath side which fouled on the new Impeller, hence the need to make a new top without this lip and slight improved performance while they did the revision.
Close, but.... The removal of the inlet ring had to be done because they shrunk the diameter of the impeller's inlet (which the ring was originally designed to fit within) and they did a heck of a lot more than just that. Take a look at my most recent testing thread in XS (
HERE <--link), you'll see the rather large performance difference between the 18W DDC-3.2 and the older 18W DDC-2 that's a result of the new motor.